In early 1977, the US Senate Select Committee on Nutrition and Human Needs had recommended Dietary Goals for the Americans that everyone except young children should opt for low-fat or nonfat dairy products over high-fat dairy products as part of an overall goal of reducing saturated fat intake and calories.
However, recent studies have suggested that high-fat milk, cheese, and yogurt are at least as healthful as their low-fat or nonfat counterparts. A review article over this issue was published in JAMA Network.
According to Dariush Mozaffarian, MD, dean of the Friedman School of Nutrition Science and Policy at Tufts University, just as the evidence suggests that not all food sources of saturated fats such as animals, plants, and dairy are the same, neither are all sources of dairy fats.
”Because cheese is fermented and some yogurts contain probiotics, “they are probably better for you than milk but scientists and dietary guidelines tend to lump all dairy products together,” he added.
Medical Dialogues has earlier reported that a study published in the American Journal of Clinical Nutrition researchers have found no significant link between Saturated fats in dairy products and, heart disease, stroke and associated mortality.
One of the largest observational studies to look at the association between dairy intake and cardiovascular disease (CVD) and mortality was the Prospective Urban Rural Epidemiology (PURE) study, which involved 136 384 individuals aged 35 to 70 years in 21 countries on 5 continents.
Participants were asked to record their intake of high-fat and low-fat milk, yogurt, and cheese on a food frequency questionnaire at the beginning of the study. During the 9.1-year follow-up, there were 6796 deaths and 5855 major cardiovascular events (death due to cardiovascular causes, nonfatal heart attack, stroke, or heart failure) among study participants.
The investigators found that a higher intake of total dairy, defined as more than 2 servings a day, was associated with a lower risk of death or a major cardiovascular event than no intake. However, the authors found no significant association between dairy intake and heart attack, and only consumption of milk and yogurt, not cheese or butter, was significantly associated with the studied outcomes.
“Whole-fat dairy products appeared to be more protective than nonfat or low-fat products, which aren’t available in some PURE countries, including India and South Africa, noted coauthor Mahshid Dehghan, Ph.D., an investigator with the Population Health Research Institute at McMaster University. “In some countries,” Dehghan added, “daily [dairy] consumption is not part of the diet. In Malaysia, people do not drink milk or consume yogurt.”
As dairy consumption varies in different countries, Dehghan and her coauthors, who included Mozaffarian, conducted a subgroup analysis to determine whether the associations between dairy intake and outcomes were similar in each region. To minimize the possibility of reverse causality, they excluded people with known CVD, who might be more likely to choose low fat or nonfat dairy.
So instead of depending on study participants to accurately report their dairy intake, the authors looked at the relationship between circulating biomarkers of fatty acids found in dairy products and total mortality, cause-specific mortality, and CVD risk among 2907 US adults aged 65 and older who did not have CVD when the study began. The researchers measured participants’ fatty acid concentrations at baseline and then 6 years and 13 years later.
During 22 years of follow-up, none of the fatty acids was significantly associated with total mortality. But high levels of one type of fatty acid, heptadecanoic acid, were inversely associated with CVD and stroke mortality. However, the authors note that other components of dairy products, such as protein, lactose, and minerals, could have confounded these findings.
One reason people opt for low-fat or nonfat dairy products is that they think consuming whole-fat milk, yogurt, and cheese will make them gain weight and will elevate their blood lipids.
In fact, Kratz said, “the data never overwhelmingly showed that full-fat dairy made you gain weight, contributed to heart disease, contributed to metabolic disease.” Actually, he added, “people who eat the most full-fat dairy products in observational studies are usually among the ones who gain the least amount of weight.”
Further research is being carried out to find out the role of confounding variables in observational studies that rely on biomarkers or food frequency questionnaires and to see how different amounts and types of dairy products affect blood glucose regulation and cardiometabolic health.
There is no clear picture as to which is more beneficial or harmful or scores equally in terms of cardiovascular health— low-fat dairy products or high-fat dairy products.
For full information log on to https://jamanetwork.com/journals/jama/fullarticle/2718080