Recent research in nutrition suggests that, when examining the potential health risks and benefits of food, researchers look beyond the major food groups such as those described in the FDA’s food pyramid and look more closely at specific foods or types of foods within a food group. Recently a group of British researchers examined the relationship of specific types of dairy to the risk of developing type 2 diabetes. None of the dairy foods evaluated were associated with raising the risk of diabetes, but low-fat fermented dairy products reduced the risk of developing diabetes by a surprising 24 percent. Low-fat fermented dairy products include yogurt, fromage frais, and low-fat cottage cheese. Most of the low-fat fermented dairy consumed by the participants in the study was yogurt (87 percent), which reduced the risk of diabetes by 28 percent.
All types of yogurt, including yogurt made from whole milk, were classified as low fat in this analysis. (The dividing line between what was considered high and low fat in this study was 3.5 percent fat, which is the fat content of whole milk and whole-milk yogurt.) In this study, high-fat dairy included hard and soft cheeses, crème fraiche, and sour cream. Based on this categorization, 65 percent of dairy intake in this study was from low-fat sources. The most consumed dairy product by far was milk (82 percent). Cheese (9 percent) and yogurt (8 percent) were the next most-consumed dairy products. The average total dairy intake was 269 grams a day, equivalent to a little over a cup of milk a day; however, there was considerable variation across all participants.
Interestingly, the individuals with higher average overall dairy consumption were more likely to be men, to have lower body mass index, drink less alcohol, smoke less, be more physically active, and have higher calorie intake. On average, higher dairy consumers were also more likely to consume higher amounts of calcium, magnesium, vitamin D, fiber, fruit, and vegetables, and to consume lower amounts of monounsaturated and polyunsaturated fat. Those individuals with higher yogurt consumption were more likely to be women and to have lower consumption of saturated fat.
Although a preliminary analysis showed that intake of all low-fat dairy foods was associated with a 19 percent lower risk of type 2 diabetes, that association disappeared when the analysis was adjusted to account for other demographic or behavioral factors. On the other hand, when the highest third of low-fat fermented dairy consumers was compared to the lowest third, the 24 percent decrease in type 2 diabetes risk remained even after adjusting for age, sex, body mass index, family history of diabetes, smoking, alcohol consumption, physical activity, social class, and education. This analysis also adjusted for a range of dietary factors such as total calorie intake and consumption of fiber, fruit, vegetables, red meat, processed meat, and coffee. Potential differences in high blood pressure, high cholesterol, sugar-sweetened beverage consumption, and trans-fat consumption were also examined. When accounting for the potential impact of all of the above, low-fat fermented dairy products and yogurt consumption were still associated with a decreased risk of type 2 diabetes.
The researchers also statistically examined the impact of substituting a serving of yogurt for an alternative snack and found that substituting yogurt for snacks was associated with a 47 percent lower hazard of type 2 diabetes. On the basis of this analysis, the authors suggest that some of benefit associated with yogurt and other low-fat fermented dairy could be attributed to not consuming unhealthy alternatives.
As for the levels of low-fat fermented dairy products and yogurt that were associated with this decreased risk of diabetes, the highest third of these consumers were eating an average of 4.5 standard-sized portions (125 grams or ½ cup) of these dairy products per week.
The reasons for these benefits associated with low-fat fermented dairy are not yet entirely clear, but the authors suggest that the probiotic bacteria found in these dairy products are one possible explanation. Priobiotic bacteria have been associated with better levels of cholesterol, antioxidant levels, and lipid levels. Another possibility suggested is that yogurt and other low-fat fermented dairy products are low in fat and high in water. This makes them less dense in calories, and such low-calorie dense foods have also been associated with lower levels of insulin and lower incidence of metabolic syndrome and type 2 diabetes. Further research will be required to determine why this lowered risk is occurring.
O’Connor LM, Lentjes MAH, Luben RN, et al. Dietary dairy product intake and incident type 2 diabetes: a prospective study using dietary data from a 7-day food diary. DOI: 10.1007/s00125-014-3176-1