Cardiovascular death rates were not related to overall dairy intake or low-fat dairy intake and all the dairy measures were not .... Posted online 5 January 2017.
Are whole-fat dairy foods better for health? The most recent research evidence supports the view that whole-fat dairy foods, such as milk cheese and yoghurt, are healthier than low-fat dairy foods In October 2016 I stayed at a hotel in Malaysia. I normally have wholefat yoghurt (with no added sugar) with muesli (granola) and fresh fruit. The breakfast selection had a range of yoghurt flavours, all with added sugar, and all ‘no-fat.’ Staff confirmed the kitchen only provided no-fat yoghurt. I put whole milk on my muesli instead. My experience at the hotel reflects the pattern of yoghurt and milk offered in supermarkets and in other places providing dairy foods. A 2013 US report noted that reduced fat milk consumption has been increasing as a proportion of fluid milk consumed since 1965. In 1988 reduced fat milk exceeded whole fat milk consumption. Whole-fat fat milk consumption declined steadily between 1975 and 2013. By 2013 reduced or no-fat milk comprised 74% of US fluid milk sales (Geuss, 2013). Among people consuming dairy foods, the trend in most Western countries is probably towards greater consumption of low-fat milk and yoghurt. The belief that low-fat or no-fat dairy foods are healthier that whole-fat has been driven for many years by public health messages. The influential Dietary Guidelines for Americans has consistently promoted low-fat dairy foods. In the 2015 update, these Guidelines stated that; ‘Most individuals in the United States would benefit by increasing dairy intake in fat-free or low-fat forms, whether from milk (including lactose free milk), yogurt, and cheese or from fortified soy beverages (soymilk). Some sweetened milk and yogurt products may be included in a healthy eating pattern as long as the total amount of added sugars consumed does not exceed the limit for added sugars, and the eating pattern does not exceed calorie limits.’ (U.S. Department of Health and Human Services & U.S. Department of Agriculture, 2015)(p.49) A 2015 report from the US Centers for Disease Control and Prevention (CDC) noted that US Department of Agriculture (USDA) regulations, updated in 2012, required all milk served in schools to be low-fat or fat-free (Yon & Johnson, 2015). Dietary advice for people trying to lose weight typically recommends consuming reduced-fat dairy products, such as flavoured milks (Nolan-Clark et al., 2013), even when such foods contain added sugar. Given the extensive promotion of low or no-fat dairy products as being healthier than whole-fat, it is not surprising that many people who wish to eat healthy food assume that low-fat or fat-free dairy foods (even with added sugar) are better than whole-fat dairy. However, much of the recent research on dairy foods does not support the view that reduced fat dairy is healthier and some research indicates that whole-fat dairy foods are healthier than low-fat.
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The purpose of the current review is to assess emerging research evidence on the relative health benefits of whole-fat versus low-fat dairy foods such as milk, cheese and yoghurt. Research on the health effects of dairy fats typically makes one or both of the following assumptions; (a) that all saturated fats are bad for health and that people should reduce or avoid eating foods containing ‘high’ levels of saturated fat, and (b) that saturated fats in dairy foods should be avoided for health reasons. Both these assumptions are now being challenged. In later reviews, I will cover other research evidence regarding the current controversy about the impacts of dietary saturated fats on health. This research is extensive and complex. Conclusions from different research groups are often in conflict. Many researchers are now challenging the view that fats in dairy foods are unhealthy. A well-known researcher on dietary fats and heart disease in the US, Dariush Mozaffarian noted that; ‘It is astounding, and unforgiveable, that nearly all our dietary recommendations about dairy foods (including the conventional emphasis on low-fat dairy) are derived from theories about isolated nutrient contents (e.g. calcium, vitamin D, and saturated fat) rather than direct empiric evidence on health effects. .... the current evidence provides little support to promote low-fat dairy, and suggests that whole-fat products, in particular yogurt and cheese, may be beneficial.’ (Mozaffarian, 2016) There are now a number of research studies, comparing the relative effects of whole-fat and low-fat dairy foods, on short and long-term health. Many of these studies support the view that whole-fat dairy foods, particularly cheese and yoghurt are healthy and that low-fat dairy is less healthy or unhealthy. The following are summaries of findings from a small selection of recent studies. •
A cohort study of 1529 Australians monitored deaths over 14 years. People who consumed the most full-fat milk, yoghurt and cheese (median intake of 339 g/day) died less often from cardiovascular disease compared to people who consumed the least full-fat dairy foods. Cardiovascular death rates were not related to overall dairy intake or low-fat dairy intake and all the dairy measures were not related to all-cause mortality. (Bonthuis, Hughes, Ibiebele, Green, & van der Pols, 2010). A limitation of this study was that the authors did not separately measure dairy foods with added sugar. For example, ice cream was included with full-fat dairy. The authors reported that no individual dairy product (milk, yoghurt, full-fat cheese or custard, cream or ice cream was associated with either cardiovascular or all-cause mortality.
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A cohort study of 26,930 adults, over a period 14 years, in Malmo, Sweden looked at the association between dietary fat intake and development of type 2 diabetes. Among the participants, 2860 developed diabetes. Greater intake of high-fat dairy products was associated with decreased incidence of diabetes. Specifically they noted that high intakes of cream and high-fat fermented milk products (yoghurt, sour milk and cheese) were associated with significantly decreased risk of diabetes. (Ericson et al., 2015)
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A study of 2745 Toronto children aged between 1 and 6 years reported that whole milk consumption (compared to consumption of low-fat or skim milk ) was associated with higher levels of vitamin D (measured from blood samples) and lower levels of obesity (measured by body mass index - BMI). This was a cross-sectional (descriptive) study. (Vanderhout et al., 2016) Findings from this study support the view that it is healthier to provide whole-fat milk for children, not low-fat milk.
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An RCT (randomised control trial with a crossover design) of 36 adults in Berkeley, California compared the effects of three different diets on the blood lipids (cholesterol) levels and blood pressure. All participants experienced each of the 3 diets for three weeks. The DASH diet (DASH= Dietary approaches to stop hypertension) included ‘an abundance of fruit and vegetables; increased whole grains and low-fat dairy products; limited servings of meat, poultry, and fish; and inclusion of nuts, seeds, and legumes several times weekly.’ The HFDASH (high-fat DASH) was a higher-fat and lower carbohydrate version of the DASH diet, with full-fat dairy products, mostly in the form of whole milk, cheese, and yogurt, and reduced sugars. The HF-DASH with full fat dairy (and lower carbohydrate) diet reduced both hypertension, triglycerides and LDL - low density lipids (sometimes referred to as ‘bad cholesterol’) compared to the control diet and had similar effects to the low-fat, higher carbohydrate DASH diet. (Chiu et al., 2016) The authors noted that, ‘modification of the DASH diet to allow for more liberal total and saturated fat intake in conjunction with moderate limitation of carbohydrate intake, primarily from fruit juices and sugars, results in lower concentrations of triglycerides and VLDL particles, with no increases in total or LDL cholesterol and no attenuation of the favorable [blood pressure] response to the standard DASH diet.’ They noted that the high-fat DASH diet presents an effective alternative to the widely recommended DASH diet, with less stringent dietary fat constraints.
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A group of 4545 elderly Spanish people (55-80 years) with high cardiovascular risk were followed for up to 5 years. The food intake measures included whole-fat and low-fat yogurt consumption. Higher intake of whole fat yogurt was associated with significantly reduced abdominal obesity. There was no association between either total yoghurt or low-fat yoghurt and obesity. People may compensate for the lower calorie content of reduced-fat yoghurt by eating more of other foods. The authors noted their findings were consistent with previous studies reporting that high-fat dairy consumption within typical dietary patterns is associated with lower risk of obesity. (Santiago et al., 2016).
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Intake of high-fat yogurt, but not low-fat yogurt or prebiotic foods was related to lower risk of depression in women in a Spanish cohort of 14,539 university graduates who were followed for 10 years. There were no significant associations between yoghurt consumption and depression among men. (Perez-Cornago et al., 2016) The authors noted that depression is related to low-grade inflammation, as well as with low folate consumption. Whole-fat yogurt contains a higher amount of fat (including conjugated linoleic acid) and folate. This could explain why there were the beneficial effects for whole-fat yogurt consumption but not for low-fat yogurt. A limitation of this study is that the authors did not report separate measures of sugar-sweetened yoghurts and unsweetened yoghurts.
Systematic reviews generally provide stronger evidence regarding possible associations between food intakes and health outcomes. However, all of the systematic reviews found so far, related to whole-fat versus low-fat dairy foods, have methodological problems. These limitations will be covered in later reviews. The main reason why some people assume whole-fat dairy products are less healthy is the level of saturated fats they contain. Many dietary studies use a research design that focuses primarily or solely on three predefined nutrient groups; fats, carbohydrates and proteins. Designs using these three categories are becoming increasingly discredited as it is clear that patterns of food intake are more predictive of health outcomes than single large nutrient groups. Studies that measure only fats, carbohydrates and proteins usually ignore the growing evidence that refined carbohydrates, 3
processed meats and added sugars are bad for health and that vegetables, fruits whole grains and whole-fat dairy are health-protective. Research on dairy foods is a contested topic Multiple research studies and systematic reviews on dairy foods have come to conflicting conclusions regarding whether whole fat dairy foods are good or bad for health. Who are we to believe? What is needed is a critical analysis of the systematic reviews and published research reports to assess whether there are any sources of bias in the studies reported, especially those included in systematic reviews. The purpose of these series of review articles is to provide critical analyses of recently published research on diet and health. Critical analyses need to take the following potential sources of bias into account. • Many cohort studies and systematic reviews have not adequately adjusted for the effect of food patterns where whole-fat dairy foods are often consumed by people who have otherwise unhealthy dietary patterns which include foods with added sugars, refined carbohydrates and processed meats. • Researchers’ beliefs about the nature of food groups has biased studies on dairy foods and resulted in confounded measures in studies examining the impacts dairy foods on health outcomes. • Many of the research reports on dairy foods have used combined measures of dairy foods that represent poor research practice and which confound different types of dairy foods. These points will be covered in later reviews. David Thomas Posted online 5 January 2017 URL: https://healthresearchnz.wordpress.com/ This review may be reproduced or cited with suitable acknowledgement of the source document. Note: The term 'yoghurt is used here; both 'yogurt' and 'yoghurt' are used in the various versions of English. References Bonthuis, M., Hughes, M. C. B., Ibiebele, T. I., Green, A. C., & van der Pols, J. C. (2010). Dairy consumption and patterns of mortality of Australian adults. European Journal of Clinical Nutrition, 64(6), 569-577. doi:http://dx.doi.org/10.1038/ejcn.2010.45 Chiu, S., Bergeron, N., Williams, P. T., Bray, G. A., Sutherland, B., & Krauss, R. M. (2016). Comparison of the DASH (Dietary Approaches to Stop Hypertension) diet and a higher-fat DASH diet on blood pressure and lipids and lipoproteins: a randomized controlled trial. American Journal of Clinical Nutrition, 103(2), 341-347. doi:10.3945/ajcn.115.123281 Ericson, U., Hellstrand, S., Brunkwall, L., Schulz, C.-A., Sonestedt, E., Wallström, P., . . . OrhoMelander, M. (2015). Food sources of fat may clarify the inconsistent role of dietary fat intake for incidence of type 2 diabetes. American Journal of Clinical Nutrition, 101(5), 10651080. doi:10.3945/ajcn.114.103010 Geuss, J. (2013). Why does the US continue to drink less milk? Retrieved on 18 August 2016 from www.dairyreporter.com/Commodities/Why-does-the-US-continue-to-drink-less-milk Mozaffarian, D. (2016). Natural trans fat, dairy fat, partially hydrogenated oils, and cardiometabolic health: the Ludwigshafen Risk and Cardiovascular Health Study. European Heart Journal, 37(13), 1079-1081. doi:10.1093/eurheartj/ehv595
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Nolan-Clark, D., Mathers, E., Probst, Y., Charlton, K., Batterham, M., & Tapsell, L. C. (2013). Dietary Consequences of Recommending Reduced-Fat Dairy Products in the Weight-Loss Context: A Secondary Analysis with Practical Implications for Registered Dietitians. J Acad Nutr Diet, 113(3), 452-458. doi:http://dx.doi.org/10.1016/j.jand.2012.10.017 Perez-Cornago, A., Sanchez-Villegas, A., Bes-Rastrollo, M., Gea, A., Molero, P., Lahortiga-Ramos, F., & Martínez-González, M. A. (2016). Intake of High-Fat Yogurt, but Not of Low-Fat Yogurt or Prebiotics, Is Related to Lower Risk of Depression in Women of the SUN Cohort Study. Journal of Nutrition, 146(9), 1731-1739. doi:10.3945/jn.116.233858 Santiago, S., Sayón-Orea, C., Babio, N., Ruiz-Canela, M., Martí, A., Corella, D., . . . Martínez, J. A. (2016). Yogurt consumption and abdominal obesity reversion in the PREDIMED study. Nutrition, Metabolism and Cardiovascular Diseases, 26(6), 468-475. doi:10.1016/j.numecd.2015.11.012 U.S. Department of Health and Human Services, & U.S. Department of Agriculture. (2015). 2015 2020 Dietary Guidelines for Americans. Retrieved on 2 January 2017 from http://health.gov/dietaryguidelines/2015/ Vanderhout, S. M., Birken, C. S., Parkin, P. C., Lebovic, G., Chen, Y., O’Connor, D. L., . . . Collaboration, t. T. K. (2016). Relation between milk-fat percentage, vitamin D, and BMI z score in early childhood. American Journal of Clinical Nutrition, Online 16 November. doi:10.3945/ajcn.116.139675 Yon, B. A., & Johnson, R. K. (2015). New School Meal Regulations and Consumption of Flavored Milk in Ten US Elementary Schools, 2010 and 2013. Preventing Chronic Disease, 12(E166), 1-5. doi:10.5888/pcd12.150163
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