What’s the Deal with Dairy?

In the past few months, I have presented research that suggests that following either a plant based vegan or a traditional paleo diet may be better for your health than following diet recommendations of the American Heart Association or American Diabetes Association.

To review, a plant based vegan diet consists of mainly vegetables, fruits, whole grains, legumes, nuts, and seeds. A traditional paleo diet includes mainly vegetables, some fruit, lean meats, eggs, nuts, and seeds. The vegan diet excludes meat and eggs while the paleo diet excludes grains. Both diets exclude dairy, processed foods, added sugar, and most saturated fat (some versions of the paleo diet include high amounts of saturated fat that are not typical of the more traditional paleo diet usually used in research studies). Meanwhile, the recommended diets of most mainstream nutrition groups include all of the foods in the vegan and paleo diets plus low-fat dairy, but still exclude processed foods, added sugar, and saturated fat.

The key food that is excluded from the paleo and vegan diets, but included in other recommended diets is DAIRY. This has prompted me to research whether or not dairy has a place in a healthy diet.

The Claim: Dairy is bad for you. You should avoid dairy if you want to have a healthy diet.

Google search: When I searched, “Is dairy bad for you?” I found the following arguments against dairy:

• Milk is the perfect food, but only for calves
• Milk doesn’t reduce fractures and may increase your risk of fractures
• Countries that consume less dairy have the lowest rates of osteoporosis
• Calcium and/or dairy may increase your risk of prostate cancer
• 75% of the world’s population is lactose intolerant, especially people that are not of northern European descent
• If you give up dairy, you should notice improvement with your sinuses, post-nasal drip, headaches, irritable bowel syndrome, energy, and weight
• Dairy may cause acne

And the following arguments for dairy:

• Dairy is a good source of nutrition. It includes high amounts of calcium, vitamin D, riboflavin, vitamin B12, potassium and phosphorus. It also contains vitamins A, B1, B6, selenium, zinc and magnesium. Grass-fed, full fat dairy also contains high amounts of omega-3 fatty acids, conjugated linoleic acid and vitamin K2.
• Dairy improves bone density, reduces osteoporosis, and lowers the risk of fractures
• Full-fat dairy is associated with a lower risk of obesity, type 2 diabetes, and heart disease
• Dairy may be protective against colorectal cancer

Follow up questions

• Are some types of dairy better or worse than others?
• Is dairy good for some people and bad for others?

Peer-reviewed research

I searched “dairy consumption” on PubMed and included only reviews and meta-analyses. The 26 studies here are the most relevant reviews of how dairy consumption is associated with metabolic syndrome (heart disease, obesity, type 2 diabetes). Several of the studies included cancer and bone health outcomes. However, I did not include studies that only reviewed cancer or bone health outcomes without other components of metabolic syndrome. Of note, I did not come across any reviews that suggested dairy was associated with unfavorable cancer or bone health outcomes.

Complete abstracts are provided below with links to full studies. Many are free to access. Feel free to read them thoroughly, only read the sections in bold, or just skip to the “What We Know and Don’t Know Section”.

1. Dairy products consumption and metabolic syndrome in adults: systematic review and meta-analysis of observational studies. (2015) https://www.ncbi.nlm.nih.gov/pubmed/26416233
   • The association of dairy products consumption with risk of metabolic syndrome (MetS) has been inconsistently reported in observational studies. A systematic review and meta-analysis of published observational studies was conducted to quantitatively evaluate this association. Relevant studies were identified by searching PubMed and EMBASE databases and by carefully checking the bibliographies of retrieved full reports and related reviews. Eligible studies were observational studies that investigated the association between dairy products consumption and risk of MetS in adults, with risk estimates available. Random-effects model was assigned to calculate the summary risk estimates. The final analysis included 15 cross-sectional studies, one case-control study and seven prospective cohort studies. Higher dairy consumption significantly reduced MetS by 17% in the cross-sectional/case-control studies (odds ratio = 0.83, 95% confidence interval [CI], 0.73-0.94), and by 14% (relative risk [RR] = 0.86, 95% CI, 0.79-0.92) in cohort studies. The inverse dairy-MetS association was consistent in subgroup and sensitivity analyses. The dose-response analysis of the cohort studies conferred a significant 6% (RR = 0.94, 95% CI, 0.90-0.98) reduction in the risk of MetS for each increment in dairy consumption of one serving/d. No significant publication bias was observed. Our findings suggest an inverse dose-response relationship between dairy consumption and risk of MetS.
2. Yogurt and dairy product consumption to prevent cardiometabolic diseases: epidemiologic and experimental studies. (2014) https://www.ncbi.nlm.nih.gov/pubmed/24695891
   • Dairy products contribute important nutrients to our diet, including energy, calcium, protein, and other micro- and macronutrients. However, dairy products can be high in saturated fats, and dietary guidelines generally recommend reducing the intake of saturated fatty acids (SFAs) to reduce coronary artery disease (CAD). Recent studies question the role of SFAs in cardiovascular disease (CVD) and have found that substitution of SFAs in the diet with omega-6 (n-6) polyunsaturated fatty acids abundant in vegetable oils can, in fact, lead to an increased risk of death from CAD and CVD, unless they are balanced with n-3 polyunsaturated fat. Replacing SFAs with carbohydrates with a high glycemic index is also associated with a higher risk of CAD. Paradoxically, observational studies indicate that the consumption of milk or dairy products is inversely related to incidence of CVD. The consumption of dairy products has been suggested to ameliorate characteristics of the metabolic syndrome, which encompasses a cluster of risk factors including dyslipidemia, insulin resistance, increased blood pressure, and abdominal obesity, which together markedly increase the risk of diabetes and CVD. Dairy products, such as cheese, do not exert the negative effects on blood lipids as predicted solely by the content of saturated fat. Calcium and other bioactive components may modify the effects on LDL cholesterol and triglycerides. Apart from supplying valuable dairy nutrients, yogurt may also exert beneficial probiotic effects. The consumption of yogurt, and other dairy products, in observational studies is associated with a reduced risk of weight gain and obesity as well as of CVD, and these findings are, in part, supported by randomized trials.
3. The relationship between high-fat dairy consumption and obesity, cardiovascular, and metabolic disease. (2013) https://www.ncbi.nlm.nih.gov/pubmed/22810464
   • PURPOSE: To comprehensively review the data on the relationship between the consumption of dairy fat and high-fat dairy foods, obesity, and cardiometabolic disease.
   • METHODS: We have conducted a systematic literature review of observational studies on the relationship between dairy fat and high-fat dairy foods, obesity, and cardiometabolic disease. We have integrated these findings with data from controlled studies showing effects of several minor dairy fatty acids on adiposity and cardiometabolic risk factors, and data on how bovine feeding practices influence the composition of dairy fat.
   • RESULTS: In 11 of 16 studies, high-fat dairy intake was inversely associated with measures of adiposity. Studies examining the relationship between high-fat dairy consumption and metabolic health reported either an inverse or no association. Studies investigating the connection between high-fat dairy intake and diabetes or cardiovascular disease incidence were inconsistent. We discuss factors that may have contributed to the variability between studies, including differences in (1) the potential for residual confounding; (2) the types of high-fat dairy foods consumed; and (3) bovine feeding practices (pasture- vs. grain-based) known to influence the composition of dairy fat.
   • CONCLUSIONS: The observational evidence does not support the hypothesis that dairy fat or high-fat dairy foods contribute to obesity or cardiometabolic risk, and suggests that high-fat dairy consumption within typical dietary patterns is inversely associated with obesity risk. Although not conclusive, these findings may provide a rationale for future research into the bioactive properties of dairy fat and the impact of bovine feeding practices on the health effects of dairy fat.
4. Dairy products, yogurt consumption, and cardiometabolic risk in children and adolescents. (2015) https://www.ncbi.nlm.nih.gov/pubmed/26175484
   • The high prevalence of obesity in children is a global health issue. Obesity in children and adolescents can result in hypertension, dyslipidemia, chronic inflammation, and hyperinsulinemia, increasing the risk of death, as children grow into adulthood, and raising public health concerns. Type 2 diabetes in children and adolescents is a cardiovascular disease (CVD) risk factor. Dairy consumption may have a protective effect against the development of CVD, but there is scarce evidence of this in children and adolescents. Within the Healthy Lifestyle in Europe by Nutrition in Adolescence, the objective of this study was to investigate the relationship between dairy consumption and CVD risk factors in a sample of adolescents (aged 12.5-17.5 years) from 8 European cities. Overall, dairy products emerged as the food group that best identified adolescents at low CVD risk. Higher consumption of milk and yogurt and of milk- and yogurt-based beverages was associated with lower body fat, lower risk for CVD, and higher cardiorespiratory fitness.
5. Dairy consumption and pre-school, school-age and adolescent obesity in developed countries: a systematic review and meta-analysis. (2014) https://www.ncbi.nlm.nih.gov/pubmed/24655317
   • Childhood obesity, the primary health problem affecting children in developed countries, has been attributed in part to changes in dietary patterns. Secular trends suggest a decrease in childhood dairy consumption coinciding with the rise in obesity prevalence. The objective of the present systematic review and meta-analysis was to consider evidence of associations between dairy intake and adiposity in pre-schoolers, school-age children and adolescents in developed countries. Of 36 studies included in the systematic review, sufficient data for effect size estimation and inclusion in the meta-analysis were obtained from 22 studies. No significant association was found between dairy intake and adiposity in the aggregated data, although statistical heterogeneity was high (I(2) = 0.72). Among adolescents, however, dairy intake was inversely associated with adiposity (effect size -0.26, [-0.38, -0.14], P < 0.0001). Effect size was not predicted by exposure variable (milk vs. dairy), study design, statistical methods, outcome variables or sex. Interpretation of results was complicated by variability in study methods and insufficient adjustment for relevant confounders, particularly dietary reporting accuracy, sweetened beverage intake and pubertal development. Despite limitations, available data suggest a neutral effect of dairy intake on adiposity during early and middle childhood and a modestly protective effect in adolescence.
6. Dairy product consumption and the metabolic syndrome. (2015) https://www.ncbi.nlm.nih.gov/pubmed/25605674
   • AIMS: To briefly summarize findings from epidemiological studies on the relationship between dairy product consumption and the metabolic syndrome(MetS).MATERIALS AND METHODS: A search for relevant literature was undertaken on Web of Science, Google scholar, Pubmed (2000 to July 2013), to identify observational studies which examined the association between dairy intake and MetS (prevalence or incidence), and for any randomized controlled trials investigating the effect of dairy intake on MetS.
   • RESULTS: Here we review the physiological effects and possible mechanisms involved of three main dairy constituents (calcium (Ca), protein, fat) on important components of the MetS. Effects of Ca may be related to intestinal binding to fatty acids or bile acids, or to changes in intracellular Ca metabolism by suppressing calciotropic hormones. Dietary proteins may increase satiety in both the short and longer term, which may result in a reduced energy intake. Dairy proteins are precursors of angiotensin-I converting enzyme-inhibitory peptides, which may lower blood pressure. To reduce the intake of saturated fatty acids (SFA), the consumption of low-fat instead of high-fat dairy products is recommended.
   • CONCLUSION: More research is warranted to better understand the physiological effects and the mechanisms involved of dairy products in the prevention and treatment of the MetS.
7. Dairy products consumption and risk of type 2 diabetes: systematic review and dose-response meta-analysis. (2013) https://www.ncbi.nlm.nih.gov/pubmed/24086304
   • BACKGROUND: The consumption of dairy products may influence the risk of type 2 diabetes mellitus (T2DM), but inconsistent findings have been reported. Moreover, large variation in the types of dairy intake has not yet been fully explored.
   • METHODS AND RESULTS: We conducted a systematic review and meta-analysis to clarify the dose-response association of dairy products intake and T2DM risk. We searched PubMed, EMBASE and Scopus for studies of dairy products intake and T2DM risk published up to the end of October 2012. Random-effects models were used to estimate summary relative risk (RR) statistics. Dose-response relations were evaluated using data from different dairy products in each study. We included 14 articles of cohort studies that reported RR estimates and 95% confidence intervals (95% CIs) of T2DM with dairy products intake. We found an inverse linear association of consumption of total dairy products (13 studies), low-fat dairy products (8 studies), cheese (7 studies) and yogurt (7 studies) and risk of T2DM. The pooled RRs were 0.94 (95% CI 0.91-0.97) and 0.88 (0.84-0.93) for 200 g/day total and low-fat dairy consumption, respectively. The pooled RRs were 0.80 (0.69-0.93) and 0.91 (0.82-1.00) for 30 g/d cheese and 50 g/d yogurt consumption, respectively. We also found a nonlinear association of total and low-fat dairy intake and T2DM risk, and the inverse association appeared to be strongest within 200 g/d intake.
   • CONCLUSION: A modest increase in daily intake of dairy products such as low fat dairy, cheese and yogurt may contribute to the prevention of T2DM, which needs confirmation in randomized controlled trials.
8. Dairy consumption and CVD: a systematic review and meta-analysis. (2016) https://www.ncbi.nlm.nih.gov/pubmed/26786887
   • Inverse associations between dairy consumption and CVD have been reported in several epidemiological studies. Our objective was to conduct a meta-analysis of prospective cohort studies of dairy intake and CVD. A comprehensive literature search was conducted to identify studies that reported risk estimates for total dairy intake, individual dairy products, low/full-fat dairy intake, Ca from dairy sources and CVD, CHD and stroke. Random-effects meta-analyses were used to generate summary relative risk estimates (SRRE) for high v. low intake and stratified intake dose-response analyses. Additional dose-response analyses were performed. Heterogeneity was examined in sub-group and sensitivity analyses. In total, thirty-one unique cohort studies were identified and included in the meta-analysis. Several statistically significant SRRE below 1.0 were observed, namely for total dairy intake and stroke (SRRE=0·91; 95% CI 0·83, 0·99), cheese intake and CHD (SRRE=0·82; 95% CI 0·72, 0·93) and stroke (SRRE=0·87; 95% CI 0·77, 0·99), and Ca from dairy sources and stroke (SRRE=0·69; 95% CI 0·60, 0·81). However, there was little evidence for inverse dose-response relationships between the dairy variables and CHD and stroke after adjusting for within-study covariance. The results of this meta-analysis of prospective cohort studies have shown that dairy consumption may be associated with reduced risks of CVD, although additional data are needed to more comprehensively examine potential dose-response patterns.
9. Dairy consumption and risk of metabolic syndrome: a meta-analysis. (2016) https://www.ncbi.nlm.nih.gov/pubmed/26433009
   • AIMS: To conduct a systematic review and meta-analysis of epidemiological studies in order to assess quantitatively the effect of dairy consumption on risk of metabolic syndrome.
   • METHODS: We searched for eligible studies published up to March 2015 through the PubMed and Embase databases and reviewed the references of relevant articles. Random-effects models were used to calculate the pooled relative risks with 95% CIs after adjusting for several confounders.
   • RESULTS: We identified nine prospective cohort studies including a total of 35,379 subjects and 7322 incident cases of metabolic syndrome, and 12 cross-sectional studies including 37 706 subjects. In the meta-analysis of prospective cohort studies, the pooled relative risk of incidence of metabolic syndrome for the highest vs. the lowest category of dairy consumption was 0.85 (95% CI 0.73-0.98), and for a 1-serving/day increment of dairy consumption, the pooled relative risk was 0.88 (95% CI 0.82-0.95). In the meta-analysis of cross-sectional studies, the pooled relative risk of prevalence of metabolic syndrome for the highest vs. the lowest category of dairy consumption was 0.73 (95% CI 0.63-0.86). The association was not significantly different by geographical region, follow-up time and adjustment factors.
   • CONCLUSION: Our findings indicate that dairy consumption is inversely associated with the incidence and prevalence of metabolic syndrome. Further well-designed cohort studies and randomized controlled trials are warranted to provide definitive evidence.
10. Milk and dairy products: good or bad for human health? An assessment of the totality of scientific evidence. (2016) https://www.ncbi.nlm.nih.gov/pubmed/27882862
    • BACKGROUND: There is scepticism about health effects of dairy products in the public, which is reflected in an increasing intake of plant-based drinks, for example, from soy, rice, almond, or oat.
    • OBJECTIVE: This review aimed to assess the scientific evidence mainly from meta-analyses of observational studies and randomised controlled trials, on dairy intake and risk of obesity, type 2 diabetes, cardiovascular disease, osteoporosis, cancer, and all-cause mortality.
    • RESULTS: The most recent evidence suggested that intake of milk and dairy products was associated with reduced risk of childhood obesity. In adults, intake of dairy products was shown to improve body composition and facilitate weight loss during energy restriction. In addition, intake of milk and dairy products was associated with a neutral or reduced risk of type 2 diabetes and a reduced risk of cardiovascular disease, particularly stroke. Furthermore, the evidence suggested a beneficial effect of milk and dairy intake on bone mineral density but no association with risk of bone fracture. Among cancers, milk and dairy intake was inversely associated with colorectal cancer, bladder cancer, gastric cancer, and breast cancer, and not associated with risk of pancreatic cancer, ovarian cancer, or lung cancer, while the evidence for prostate cancer risk was inconsistent. Finally, consumption of milk and dairy products was not associated with all-cause mortality. Calcium-fortified plant-based drinks have been included as an alternative to dairy products in the nutrition recommendations in several countries. However, nutritionally, cow’s milk and plant-based drinks are completely different foods, and an evidence-based conclusion on the health value of the plant-based drinks requires more studies in humans.
    • CONCLUSION: The totality of available scientific evidence supports that intake of milk and dairy products contribute to meet nutrient recommendations, and may protect against the most prevalent chronic diseases, whereas very few adverse effects have been reported.

11. Long-term association between dairy consumption and risk of childhood obesity: a systematic review and meta-analysis of prospective cohort studies. (2016) https://www.ncbi.nlm.nih.gov/pubmed/26862005
    • BACKGROUND/OBJECTIVES: Data from small-scale, short-term, clinical trials suggest a beneficial effect of dairy consumption on the risk of childhood obesity; however, the long-term association is unclear. Therefore, we aim to examine the longitudinal association between dairy consumption and the risk of overweight/obesity in children and adolescents by conducting a systematic review and meta-analysis of prospective cohort studies.
    • SUBJECTS/METHODS: Eligible studies were identified by searching PubMed and EMBASE through March 2015. Additional studies were retrieved via Google Scholar or a hand review of the reference lists from relevant articles. Pooled associations of interest were estimated by using a random-effects model. The heterogeneity for each pooled analysis was evaluated by I(2) statistic as well as by Cochran’s Q test. Publication bias was assessed by using both Egger’s and Begg’s tests.
    • RESULTS: Ten studies comprising 46,011 children and adolescents with an average 3-year follow-up were included. As compared with those who were in the lowest group of dairy consumption, children in the highest intake group were 38% less likely to have childhood overweight/obesity (pooled odds ratio (OR)=0.62; 95% confidence interval (CI): 0.49, 0.80). With each 1 serving/day increment in dairy consumption, the percentage of body fat was reduced by 0.65% (β=0.65; 95% CI: -1.35, 0.06; P=0.07), and the risk of overweight/obesity was 13% lower (OR=0.87; 95% CI: 0.74, 0.98).
    • CONCLUSIONS: Accumulated evidence from prospective cohort studies suggests that dairy consumption is inversely and longitudinally associated with the risk of childhood overweight/obesity. Further studies are warranted to examine the types of dairy products in relation to the risk of childhood overweight/obesity.
12. Consumption of dairy foods and diabetes incidence: a dose-response meta-analysis of observational studies. (2016) https://www.ncbi.nlm.nih.gov/pubmed/26912494
    • BACKGROUND: A growing number of cohort studies suggest a potential role of dairy consumption in type 2 diabetes (T2D) prevention. The strength of this association and the amount of dairy needed is not clear.
    • OBJECTIVE: We performed a meta-analysis to quantify the associations of incident T2D with dairy foods at different levels of intake.
    • DESIGN: A systematic literature search of the PubMed, Scopus, and Embase databases (from inception to 14 April 2015) was supplemented by hand searches of reference lists and correspondence with authors of prior studies. Included were prospective cohort studies that examined the association between dairy and incident T2D in healthy adults. Data were extracted with the use of a predefined protocol, with double data-entry and study quality assessments. Random-effects meta-analyses with summarized dose-response data were performed for total, low-fat, and high-fat dairy, (types of) milk, (types of) fermented dairy, cream, ice cream, and sherbet. Nonlinear associations were investigated, with data modeled with the use of spline knots and visualized via spaghetti plots.
    • RESULTS: The analysis included 22 cohort studies comprised of 579,832 individuals and 43,118 T2D cases. Total dairy was inversely associated with T2D risk (RR: 0.97 per 200-g/d increment; 95% CI: 0.95, 1.00;P= 0.04;I(2)= 66%), with a suggestive but similar linear inverse association noted for low-fat dairy (RR: 0.96 per 200 g/d; 95% CI: 0.92, 1.00;P= 0.072;I(2)= 68%). Nonlinear inverse associations were found for yogurt intake (at 80 g/d, RR: 0.86 compared with 0 g/d; 95% CI: 0.83, 0.90;P< 0.001;I(2)= 73%) and ice cream intake (at ∼10 g/d, RR: 0.81; 95% CI: 0.78, 0.85;P< 0.001;I(2)= 86%), but no added incremental benefits were found at a higher intake. Other dairy types were not associated with T2D risk.
    • CONCLUSION: This dose-response meta-analysis of observational studies suggests a possible role for dairy foods, particularly yogurt, in the prevention of T2D. Results should be considered in the context of the observed heterogeneity.
13. Systematic Review of the Association between Dairy Product Consumption and Risk of Cardiovascular-Related Clinical Outcomes. (2016) https://www.ncbi.nlm.nih.gov/pubmed/28140321
    • The objective of this systematic review was to determine if dairy product consumption is detrimental, neutral, or beneficial to cardiovascular health and if the recommendation to consume reduced-fat as opposed to regular-fat dairy is evidence-based. A systematic review of meta-analyses of prospective population studies associating dairy consumption with cardiovascular disease (CVD), coronary artery disease (CAD), stroke, hypertension, metabolic syndrome (MetS), and type 2 diabetes (T2D) was conducted on the basis of the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. Quality of evidence was rated by using the Grading of Recommendations Assessment, Development, and Evaluation scale. High-quality evidence supports favorable associations between total dairy intake and hypertension risk and between low-fat dairy and yogurt intake and the risk of T2D. Moderate-quality evidence suggests favorable associations between intakes of total dairy, low-fat dairy, cheese, and fermented dairy and the risk of stroke; intakes of low-fat dairy and milk and the risk of hypertension; total dairy and milk consumption and the risk of MetS; and total dairy and cheese and the risk of T2D. High- to moderate-quality evidence supports neutral associations between the consumption of total dairy, cheese, and yogurt and CVD risk; the consumption of any form of dairy, except for fermented, and CAD risk; the consumption of regular- and high-fat dairy, milk, and yogurt and stroke risk; the consumption of regular- and high-fat dairy, cheese, yogurt, and fermented dairy and hypertension risk; and the consumption of regular- and high-fat dairy, milk, and fermented dairy and T2D risk. Data from this systematic review indicate that the consumption of various forms of dairy products shows either favorable or neutral associations with cardiovascular-related clinical outcomes. The review also emphasizes that further research is urgently needed to compare the impact of low-fat with regular- and high-fat dairy on cardiovascular-related clinical outcomes in light of current recommendations to consume low-fat dairy.
14. Dairy products consumption versus type 2 diabetes prevention and treatment; a review of recent findings from human studies. (2013) https://www.ncbi.nlm.nih.gov/pubmed/24160191
    • INTRODUCTION: It has been claimed that the appropriate consumption of dairy products can be beneficial for the prevention and treatment of type 2 diabetes mellitus (T2DM).
    • OBJECTIVE: The objective of this review is to critically analyze the main scientific evidence about this topic.
    • METHODS: MEDLINE, PubMEd, Science Direct, SCIELO and LILACS were searched for studies published over the past 12 years exploring the effects of the consumption of dairy products or its components (calcium, vitamin D and magnesium) on T2DM.
    • RESULTS AND DISCUSSION: Epidemiological studies indicate that consumption of at least three servings of low-fat dairy products per day as a part of a healthy diet is crucial to reduce the risk of developing T2DM. The majority of the analyzed intervention studies reported beneficial effects of increased calcium and vitamin D ingestion on insulin sensitivity improvement and T2DM prevention.
    • CONCLUSIONS: Although the impact of dairy consumption to treat T2DM needs further investigation, the consumption of low-fat dairy products may be an important strategy to prevent and control T2DM.

15. Meeting and exceeding dairy recommendations: effects of dairy consumption on nutrient intakes and risk of chronic disease. (2013) https://www.ncbi.nlm.nih.gov/pubmed/23550782
    • The 2010 Dietary Guidelines for Americans indicate the US population is experiencing an epidemic of overweight and obesity while maintaining a nutrient-poor, energy-dense diet associated with an increased risk of osteoarthritis, cardiovascular disease, and type 2 diabetes. To build upon the review of published research in the Report of the Dietary Guidelines Advisory Committee on the Dietary Guidelines for Americans, 2010, this article aims to review the scientific literature pertaining to the consumption of dairy foods and the effects of dairy consumption on nutrient intakes and chronic disease risk published between June 2010, when the report was released, and September 2011. PubMed was searched for articles using the following key words: dairy, milk, nutrient intake, bone health, body composition, cardiovascular disease, type 2 diabetes, and blood pressure. Evidence indicates that increasing dairy consumption to the recommended amount, i.e., three servings daily for individuals ≥9 years of age, helps close gaps between current nutrient intakes and recommendations. Consuming more than three servings of dairy per day leads to better nutrient status and improved bone health and is associated with lower blood pressure and reduced risk of cardiovascular disease and type 2 diabetes.
16. Consumption of Dairy Products in Relation to Changes in Anthropometric Variables in Adult Populations: A Systematic Review and Meta-Analysis of Cohort Studies. (2016) https://www.ncbi.nlm.nih.gov/pubmed/27310919
    • BACKGROUND: The current state of knowledge regarding the association of dairy products and weight gain, overweight, and obesity is based on studies reporting contradicting and inconclusive results. The aim of the present study was thus to clarify the link between dairy consumption in relation to changes in anthropometric measures/adiposity by a meta-analytical approach.
    • METHODS: For the meta-analysis PubMed, EMBASE, Web of Sciences, and google scholar were searched by two independent authors up to May 2016 with no restriction to language or calendar date. Prospective cohort studies reporting about intake of dairy consumption (including milk, yogurt, cheese, butter) and changes in body weight or waist circumference, risk of overweight, obesity, or weight gain were eligible. Pooled effects were calculated using a random effects model, and also a fixed effect model for sensitivity analysis. Due to the heterogeneity of statistical analytical approaches of the studies the analysis were done separately for beta-coefficients of changes in body weight and/or waist circumference per serving of dairy, for differences in weight gain/gain in waist circumference when comparing extreme categories of dairy consumption, and for odds ratios in regard to weight gain, overweight/obesity, or abdominal obesity.
    • FINDINGS: 24 studies (27 reports) met the inclusion criteria for the systematic review, and 22 studies provided sufficient data for inclusion in the meta-analysis. The meta-analysis of the five studies on changes in body weight per serving of dairy no significant results could be found for whole fat dairy and low fat dairy. However, there was inverse association between changes in body weight for each serving’s increase of yogurt (beta: -40.99 gram/year, 95% CI, -48.09 to -33.88), whereas each serving’s increase of cheese was positively associated (beta: -10.97 gram/year, 95% CI, 2.86 to 19.07). Furthermore, the highest dairy intake category was associated with a reduced risk of abdominal obesity (OR: 0.85; 95% CI, 0.76 to 0.95), and risk of overweight (OR: 0.87; 95% CI, 0.76 to 1.00) compared to the lowest intake category. No significant association could be observed for risk of weight gain.
    • CONCLUSION: In summary the results of the meta-analysis still reflect that dairy consumption was not positively related to changes in body weight. Yogurt was the only dairy food that showed some evidence for a beneficial effect, where higher intakes were inversely associated a reduced risk of obesity, changes in body weight or waist circumference. Further research is needed, since the overall interpretation of the results is limited by heterogeneous risk estimates.
17. Effect of dairy consumption on weight and body composition in adults: a systematic review and meta-analysis of randomized controlled clinical trials. (2012) https://www.ncbi.nlm.nih.gov/pubmed/22249225
    • BACKGROUND: Although several observational and experimental studies have investigated the effect of dairy consumption on weight and body composition, results are inconsistent.
    • OBJECTIVE: This systematic review and meta-analysis was conducted to summarize the published evidence from randomized controlled clinical trials (RCTs) regarding the effect of dairy consumption on weight, body fat mass, lean mass and waist circumference (WC) in adults.
    • DESIGN: PubMed, ISI Web of Science, SCOPUS, Science Direct and EMBASE were searched from January 1960 to October 2011 for relevant English and non-English publications. Sixteen studies were selected for the systematic review and fourteen studies were included in meta-analysis.
    • RESULTS: Our search led to 14, 12, 6 and 8 eligible RCTs that had data on weight, body fat mass, lean mass and WC, respectively. Overall, mean difference for the effect of dairy on body weight was -0.61 kg (95% confidence interval (CI): -1.29, 0.07, P=0.08). Increased dairy intake resulted in 0.72 kg (95% CI: -1.29, -0.14, P=0.01) greater reduction in fat mass, 0.58 kg (95% CI: 0.18, 0.99, P<0.01) gain in lean mass and 2.19 cm (95% CI: -3.42, -0.96, P-value <0.001) further reduction in WC than that in controls. Subgroup analysis revealed that increasing dairy intake without energy restriction in both intervention and control groups does not significantly affect weight, body fat mass, lean mass and WC; consumption of high-dairy weight loss diets led to 1.29 kg (95% CI: -1.98, -0.6, P<0.001) greater weight loss, 1.11 kg (95% CI: -1.75, -0.47, P=0.001) greater reduction in body fat mass, 0.72 kg (95% CI: 0.12, 1.32, P=0.02) gain in body lean mass and 2.43 cm (95% CI: -3.42, -1.44, P<0.001) additional reduction in WC compared with controls.
    • CONCLUSION: Increased dairy consumption without energy restriction might not lead to a significant change in weight or body composition; whereas inclusion of dairy products in energy-restricted weight loss diets significantly affects weight, body fat mass, lean mass and WC compared with that in the usual weight loss diets.

18. How sound is the science behind the dietary recommendations for dairy? (2014) https://www.ncbi.nlm.nih.gov/pubmed/24646824
    • This review examined the evidence behind dietary guidelines for dairy. Most countries recommend consumption of dairy products; and when amounts are specified, recommendations are typically for 2 or 3 servings per day. Specific recommendations for dairy products are based partly on culture and availability but primarily on meeting nutrient requirements. Dairy products are a rich source of many minerals and vitamins as well as high-quality protein. Thus, dairy consumption is a marker for diet quality. A recent report found that yogurt specifically is a good marker of diet quality. The food patterns recommended by the 2010 Dietary Guidelines for Americans Advisory Committee (DGAC) include 3 cups of low-fat milk and milk products. Few people achieve their recommended intakes of several shortfall nutrients without meeting their recommendations for dairy. The evidence for a benefit of dairy consumption is moderate for bone health in children but limited in adults and moderate for cardiovascular disease, blood pressure, and diabetes and limited for metabolic syndrome. Newer data since the recommendations of the 2010 DGAC are presented. However, the strength of the evidence for dairy consumption and health is limited by the lack of appropriately powered randomized controlled trials.
19. Association of dairy products consumption with risk of obesity in children and adults: a meta-analysis of mainly cross-sectional studies. (2016) https://www.ncbi.nlm.nih.gov/pubmed/27756684
    • PURPOSE: The association of dairy products consumption with risk of obesity remains controversial. Therefore, we reviewed and quantitatively synthesized the evidence from observational studies with a meta-analysis.
    • METHODS: A literature search was performed in relevant databases. Random-effects model was used to pool odds ratios with 95% confidence intervals. Dose-response relationship was assessed by restricted cubic spline model.
    • RESULTS: Seventeen studies for total dairy products and 16 studies for milk with risk of obesity were eligible. The pooled odds ratios (95% confidence intervals) of obesity for the highest versus lowest category of total dairy products consumption were 0.54 (0.38-0.77) in children, 0.75 (0.69-0.81) in adults, and 0.74 (0.68-0.80) for both. Evidence of a nonlinear relationship was found (Pfor nonlinearity = .009). Milk consumption was also associated with risk of obesity [0.81 (0.75-0.88)] both in children [0.87 (0.80-0.95)] and in adults [0.77 (0.68-0.87)], and a linear relationship (Pfor nonlinearity = .598) suggested that risk of obesity decreased by 16% [0.84 (0.77-0.92)] for every 200 g/d increment of milk consumption.
    • CONCLUSIONS: This meta-analysis indicates that dairy products consumption may be associated with a decreased risk of obesity. This association may be of public health significance.
20. Fermented dairy food and CVD risk. (2015) https://www.ncbi.nlm.nih.gov/pubmed/26148916
    • Fermented dairy foods such as yoghurt and cheese are commonly found in the Mediterranean diet. Recent landmark research has confirmed the effect of the Mediterranean diet on reducing the CVD risk, but the relative contributions of fermented dairy foods have not been fully articulated. The present study provides a review of the relationship between fermented dairy foods consumption and CVD risk in the context of the whole diet. Studies show that people who eat healthier diets may be more likely to consume yoghurt, so there is a challenge in attributing separate effects to yoghurt. Analyses from large population studies list yoghurt as the food most negatively associated with the risk of weight gain (a problem that may lead to CVD). There is some suggestion that fermented dairy foods consumption (yoghurt or cheese) may be associated with reduced inflammatory biomarkers associated with the development of CVD. Dietary trials suggest that cheese may not have the same effect on raising LDL-cholesterol levels as butter with the same saturated fat content. The same might be stated for yoghurt. The use of different probiotic cultures and other aspects of study design remain a problem for research. Nevertheless, population studies from a range of countries have shown that a reduced risk of CVD occurs with the consumption of fermented dairy foods. A combination of evidence is necessary, and more research is always valuable, but indications remain that fermented dairy foods such as cheese and yoghurt are integral to diets that are protective against CVD.
21. Effects of dairy intake on body weight and fat: a meta-analysis of randomized controlled trials. (2012) https://www.ncbi.nlm.nih.gov/pubmed/22932282
    • BACKGROUND: Some intervention studies have suggested that dairy products may influence body weight, but the results remain controversial.
    • OBJECTIVE: We identified and quantified the effects of dairy consumption on body weight and fat mass from randomized controlled trials (RCTs).
    • DESIGN: We conducted a comprehensive search of PubMed and EMBASE databases (to April 2012) of English reports of RCTs regarding dairy consumption on body weight, body fat, or body weight and body fat in adults. The results across studies were pooled by using a random-effects meta-analysis.
    • RESULTS: Twenty-nine RCTs were included with a total of 2101 participants. Overall, consumption of dairy products did not result in a significant reduction in weight (-0.14 kg; 95% CI: -0.66, 0.38 kg; I² = 86.3%). In subgroup analysis, consumption of dairy products reduced body weight in the context of energy restriction or short-term intervention (<1 y) trials but had the opposite effect in ad libitum dietary interventions or long-term trials (≥1 y). Twenty-two RCTs that reported results on body fat showed a modest reduction in the dairy group (-0.45 kg; 95% CI: -0.79, -0.11 kg; I² = 70.9%), and further stratified analysis indicated significant beneficial effects of dairy intervention on body fat in energy-restricted or short-term trials but not in long-term or ad libitum studies.
    • CONCLUSIONS: This meta-analysis does not support the beneficial effect of increasing dairy consumption on body weight and fat loss in long-term studies or studies without energy restriction. However, dairy products may have modest benefits in facilitating weight loss in short-term or energy-restricted RCTs.
22. Effects of dairy protein and fat on the metabolic syndrome and type 2 diabetes. (2014) https://www.ncbi.nlm.nih.gov/pubmed/25396403
    • The incidence of the metabolic syndrome (MetS) and type 2 diabetes (T2D) is increasing worldwide. Evidence supports a negative relationship between the consumption of dairy products and risk of MetS and T2D. Dairy proteins are known to have a directly beneficial effect on hypertension, dyslipidemia, and hyperglycemia, but a detailed understanding of the underlying mechanisms is missing. It has been confirmed by observations that the insulinotropic effect of dairy proteins is associated with the amino acid composition; in particular branched-chain amino acids (BCAA) seem to be of vital importance. Dairy protein-derived peptides may also contribute to the insulinotropic effect via dipeptidyl peptidase-4 (DPP-4) inhibitory activity, and may lower the blood pressure (BP). The lipid metabolism may be improved by whey protein (WP), which acts to reduce the postprandial triglyceride (TG) response. The effect of dairy fat is much more controversial because of the potentially harmful effect exerted by saturated fatty acid (SFA) on metabolic health. Recent observations suggest less adverse effects of SFA on metabolic health than previous assumed. However, little is known about dairy lipid fractions belonging to the groups of monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), and phospholipids (PL). Dairy fat seems to act differently depending on the dairy product and the composition of macronutrients in the meal. Therefore, for a better understanding of the mechanisms behind the dairy protein and fat effect on MetS, we suggest that more human studies should be carried out to clarify the interactions of dairy protein and fat with macronutrients in the meal and other dairy components, such as micronutrients and microorganisms from fermented products.
23. Dairy product intake in children and adolescents in developed countries: trends, nutritional contribution, and a review of association with health outcomes. (2014) https://www.ncbi.nlm.nih.gov/pubmed/24330063
    • Despite its contribution to nutrient intake and status, consumption of milk and dairy products by children and adolescents in many countries has waned in recent decades, with a substantial proportion of youth failing to meet intake recommendations. Dairy products remain an important dietary source of multiple micronutrients, including calcium, phosphorus, magnesium, zinc, iodine, potassium, vitamin A, vitamin D, vitamin B12 , and riboflavin (vitamin B2 ). In addition, dairy products provide children with energy, high-quality protein, and essential and nonessential fatty acids. A review of evidence was conducted to evaluate associations between milk or dairy product intake and health outcomes in children and adolescents. Results suggest a neutral or inverse association between consumption of milk and dairy products in children and adolescents and indicators of adiposity, incidence of dental caries, and hypertension. Available data indicate that dairy products are important for linear growth and bone health during childhood. Additional research–in particular, controlled intervention trials and long-term prospective cohort studies–is warranted to better understand how dairy intake affects health outcomes in children and adolescents.
24. Dairy products on metabolic health: current research and clinical implications. (2014) https://www.ncbi.nlm.nih.gov/pubmed/24445013
    • Dairy products have been thought to have a beneficial role in the metabolic syndrome (MetS). MetS constitutes a cluster of risk factors for an increased mortality, including obesity, impaired glucose homeostasis, hypertension and atherogenic dyslipidemia. Individuals with MetS are also often in a chronic, low-grade inflammatory state. The objective of this review is to examine recent meta-analyses and clinical studies on the association between dairy products consumption and these MetS risk factors. Findings from studies demonstrate that weight loss related to dairy product intake is due to the combination of an energy-restricted diet with consumption of dairy products. Further, a limited number of studies have shown beneficial effects of dairy consumption on plasma lipids, blood pressure, glucose homeostasis or inflammatory and oxidative stress profiles. Overall, this review article suggests that adults should consume at least 2-3 servings of dairy products per day within a well-balanced diet and a healthy lifestyle for metabolic health. Yet, higher dairy product consumption may have additional beneficial effects, but more well-designed intervention studies are needed to ascertain these effects.
25. Comprehensive Review of the Impact of Dairy Foods and Dairy Fat on Cardiometabolic Risk. (2016) https://www.ncbi.nlm.nih.gov/pubmed/28140322
    • Because regular-fat dairy products are a major source of cholesterol-raising saturated fatty acids (SFAs), current US and Canadian dietary guidelines for cardiovascular health recommend the consumption of low-fat dairy products. Yet, numerous randomized controlled trials (RCTs) have reported rather mixed effects of reduced- and regular-fat dairy consumption on blood lipid concentrations and on many other cardiometabolic disease risk factors, such as blood pressure and inflammation markers. Thus, the focus on low-fat dairy in current dietary guidelines is being challenged, creating confusion within health professional circles and the public. This narrative review provides perspective on the research pertaining to the impact of dairy consumption and dairy fat on traditional and emerging cardiometabolic disease risk factors. This comprehensive assessment of evidence from RCTs suggests that there is no apparent risk of potential harmful effects of dairy consumption, irrespective of the content of dairy fat, on a large array of cardiometabolic variables, including lipid-related risk factors, blood pressure, inflammation, insulin resistance, and vascular function. This suggests that the purported detrimental effects of SFAs on cardiometabolic health may in fact be nullified when they are consumed as part of complex food matrices such as those in cheese and other dairy foods. Thus, the focus on low-fat dairy products in current guidelines apparently is not entirely supported by the existing literature and may need to be revisited on the basis of this evidence. Future studies addressing key research gaps in this area will be extremely informative to better appreciate the impact of dairy food matrices, as well as dairy fat specifically, on cardiometabolic health.
26. Impact of dairy products on biomarkers of inflammation: a systematic review of randomized controlled nutritional intervention studies in overweight and obese adults. (2013) https://www.ncbi.nlm.nih.gov/pubmed/23446894
    • BACKGROUND: Recent data from cross-sectional studies suggest that consumption of dairy products is inversely associated with low-grade systemic inflammation, but a cause-and-effect relation can be confirmed only with results from randomized controlled trials.
    • OBJECTIVE: We reviewed the results of randomized controlled nutritional intervention studies that have assessed the impact of dairy product consumption (ie, milk, yogurt, and/or cheese) on biomarkers of inflammation in adults (aged ≥18 y).
    • DESIGN: We performed a systematic literature search in PubMed in April 2012, which was limited to randomized controlled trials in humans published in English. Studies that included pregnant or lactating women or that did not include a low-dairy control intervention were excluded.
    • RESULTS: Eight trials that were conducted in overweight or obese adults were included in the review. The only study that had identified change in the inflammatory profile as its primary outcome measure showed that dairy food consumption improved pro- and antiinflammatory biomarker concentrations compared with the low-dairy control diet. Three of the 7 studies in which inflammation was a secondary or undefined outcome showed improvement in key inflammatory biomarkers, ie, C-reactive protein, IL-6, or TNF-α after dairy product consumption, whereas the other 4 studies showed no effect.
    • CONCLUSIONS: Dairy product consumption does not exert adverse effects on biomarkers of inflammation in overweight or obese adults. Several methodologic factors and limitations among existing studies do not allow differentiation between a beneficial or neutral impact of dairy products on inflammation. Further studies specifically designed to assess inflammation-related outcomes are warranted.

What We Know and Don’t Know

• This topic has been studied extensively. I was able to find more than 20 literature reviews or meta-analyses on how dairy impacts metabolic syndrome. Each of these reviews detailed many other studies of moderate or high quality. In all, tens of thousands of participants of all ages have been studied.

24 of the 26 reviews reported an inverse relationship between dairy consumption and markers of metabolic syndrome. Each study varied in terms of which types of dairy and which markers of metabolic syndrome were studied as well as which findings were the most significant. The two remaining reviews found that increasing dairy in calorie restricted diets helped reduce weight in the short term, but did not help reduce weight in long term non-restricted diets. None of the studies found dairy to be harmful to health in any way. All analyses showed dairy to be either neutral or beneficial to health with a majority claiming benefits for at least one symptom of metabolic syndrome.

Of the studies that separated low-fat from regular-fat dairy, the regular-fat dairy fared either equal to or better than the low-fat. Saturated fat in dairy (including cheese) did not adversely affect participants’ health or blood lipids as expected and several of the reviews called for reconsideration of the recommendation to consume low-fat dairy. A few of the studies continued to recommend low-fat dairy, but this seemed to be due to staying consistent with previous recommendations rather than presenting results showing adverse effects of regular fat dairy.

Of the studies that separated different dairy products, yogurt consistently had the most favorable outcomes. Yogurt seemed especially protective against cardiovascular disease, obesity, and type 2 diabetes. One study found that people who consumed more cheese were more likely to be obese, but this finding was not consistent across the research.

A few of the studies focused on children and adolescents. They found that the children who consumed the most dairy had the fewest problems with obesity.

Most of the studies found an inverse relationship between dairy consumption and markers of metabolic syndrome. That suggests that the more dairy a person consumes, the healthier they are. Some studies recommended 2-3 servings per day while other recommended more than 3.

The research I found did not address the topic of lactose intolerance. The majority of the research I found was done on participants from “developed” countries that recommended dairy in their health guidelines. These included the U.S., Canada, and Europe. Therefore, it’s hard to say whether the outcomes would apply to Africa and Asia. Common sense would suggest that people who are lactose intolerant should avoid dairy or use medication to assist digestion.

Conclusions and Applications

If you’re not lactose intolerant, you can and should include dairy in your healthy diet. Regular-fat is just as good, or, maybe even better for you than low-fat. Consuming about 3 servings of dairy per day, especially yogurt and milk, is likely to be beneficial to your health. The benefits include helping you maintain a healthy weight, decreasing your likelihood of developing heart disease and type 2 diabetes, and providing tons of necessary nutrients. Although I did not specifically research the association between dairy and cancer or bone health, the evidence I came across all suggests dairy is beneficial in these areas as well.

Dairy is not as it seems, likely to be the reason people who follow a paleo or vegan diet tend to be healthier. Perhaps simply cutting large groups of food out of your diet tends to make you eat less overall. Or maybe it makes you more likely to cook healthy foods at home rather than go out and risk being unsure of which ingredients are being used.

Based on a TON of research, we can confidently keep dairy in the “healthy” category. Evidence supports all the traditional paleo foods, all the plant-based vegan foods, and all the dairy as good for health. The general consensus across all nutrition camps still discourages consumption of highly processed foods, refined grains, and added sugar. The jury is still out on saturated fat, so that will be my next topic to tackle!

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