High-Dairy Diet May Prevent Diabetes, Heart Disease: Study

A new study supports the notion that including dairy in your diet may offer protection against certain chronic diseases.

“Higher intake of dairy foods, such as milk, yogurt, and cheese, especially from whole-fat dairy rather than low-fat dairy, is associated with a lower prevalence of metabolic syndrome and with a lower risk of developing hypertension and diabetes,” says Andrew Mente, PhD, an epidemiologist at the Population Health Research Institute (PHRI) in Hamilton, Canada, who is one of the study’s authors. His research was published May 18 in BMJ Open Diabetes Research and Care.

“This is not a complete surprise, however," Dr. Mente says, "as there has been a growing body of evidence showing that whole-fat dairy might have beneficial properties and could be protective against high blood pressure and diabetes.” As for the other potential benefit, metabolic syndrome is a cluster of factors that heighten the risk of cardiovascular disease, type 2 diabetes, and stroke. It includes carrying extra weight and having elevated blood sugar or blood pressure, according to the Mayo Clinic.

Previous Research Suggests Dairy May Protect Against Diabetes and Heart Disease

“Dairy is known to lower blood pressure, which has been shown in the DASH trial and other well-conducted studies," Mente says.

For instance, a review and meta-analysis published in September 2017 in Nutrients concluded that dairy consumption may help protect people against developing type 2 diabetes. Similarly, a cohort study published in August 2016 in The American Journal of Clinical Nutrition analyzed 220,000 individuals’ health data and determined that dairy fat is not associated with a higher risk of developing cardiovascular disease, and people who replaced other animal fats with dairy fat saw a lower risk of cardiovascular disease.

Despite these findings showing dairy in a positive light, the reason why it may offer protection against these diseases is unknown.

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A Closer Look at the New Study on Eating Dairy and Disease Risk

The PHRI-led study used data from nearly 148,000 people age 35 to 70 in 21 countries, who were tracked over an average period of nine years.

Specifically, compared with no daily dairy intake, the following findings were assembled:

At least two servings a day of dairy was associated with an 11 to 12 percent lower risk of type 2 diabetes, rising to a 13 to 14 percent lower risk with three daily servings.
Likewise, at least two daily servings of dairy was associated with an 11 to 12 percent lower risk of hypertension, rising to a 13 to 14 percent lower risk with three servings per day.
With both diabetes and hypertension, the associations were stronger for consuming full-fat dairy than they were for low-fat dairy.
Also, at least two servings a day of total dairy were associated with a 24 percent lower risk of metabolic syndrome, rising to 28 percent when people consumed full-fat dairy alone.

Here are some examples of a serving of dairy, according to the U.S. Department of Agriculture (USDA):

1 cup milk
1 cup yogurt
1½ cups hard cheese, such as cheddar or Swiss
2 cups cottage cheese

Mente says there may be options for those who can’t tolerate lactose, pointing out that the findings on nonfermented dairy such as milk (which contains the milk sugar lactose) and fermented dairy such as yogurt and cheese (which contain less lactose) were similar. “The results appear to apply irrespective of lactose,” he says. “Therefore, lactose intolerant people can consume dairy from fermented sources or from lactose-free milk and probably see similar health benefits.”

What Is It About Dairy That May Offer These Health Benefits?

More research is needed to understand why dairy seems to help lower the prevalence of metabolic syndrome and the risk of developing hypertension and diabetes, particularly which types of dairy are most beneficial, Mente says.

“What is known is that dairy is nutrient dense and has many beneficial compounds. Dairy foods and dairy fat provide high-quality protein and a wide range of essential vitamins and minerals,” he adds.

For example, according to the USDA, a cup of milk offers the following key nutrients:

199 milligrams (mg) of calcium, which is 20 percent of the daily value (DV)
281 mg of potassium, or 8 percent of the DV
499 international units (IU) of vitamin A, or 10 percent of the DV
8 IU of vitamin D, or 10 percent of the DV

Type of Dairy Matters When It Comes to Preventing or Managing Disease

Before you start guzzling glasses of milk with abandon or slathering butter on your veggies, keep in mind that the study found that butter was neither beneficial nor harmful, says Mente. According to the USDA, though, it’s high in saturated fat, with 1 tablespoon of the salted variety containing 7.29 grams (g). For a healthy heart, the American Heart Association (AHA) recommends consuming no more than 13 g of saturated fat per day if you’re following a daily diet of 2,000 calories.

If you have or are at risk for diabetes, high blood pressure, or heart disease, or if you struggle with obesity, stick to the diet that you have discussed with your healthcare provider. And despite these study findings, know that you may want to choose low- or nonfat sources, as recommended by the AHA and American Diabetes Association.

In terms of the benefits of whole-fat dairy for preventing these disease, Rahil Bandukwala, a doctor of osteopathic medicine and endocrinologist at MemorialCare Saddleback Medical Center in Laguna Hills, California, says more studies are needed. Dr. Bandukwala was not involved in the PHRI-led study.

He speculates that mixing carbohydrates with healthy fat may offer more satiety, decreasing overall calorie intake and promoting a healthy weight, however, he adds, "That may be one pathway where it helps."

Study Limitations to Keep in Mind and What Future Research Could Explore

Bandukwala points out that the current study relies heavily on self-reported measures of blood pressure, blood glucose, and other factors. This data collection method leaves room for error, so he advises approaching the results with caution.

For his patients with diabetes, Bandukwala recommends a balanced diet with protein, nonstarchy carbohydrates, and healthy sources of fat. Their diet may include milk fat, too, but sources high in sugar, such as ice cream, shouldn’t be staples in a diabetes diet.

Mente echoes Bandukwala, saying that more research is needed to confirm his study’s findings. “A next step would be to study dairy, especially whole-fat dairy and possibly fermented dairy like yogurt and cheese, in a randomized, controlled trial to assess their impact on blood glucose and future risk of diabetes,” Mente says. “This would help to better assess whether the protective associations of dairy with health, as seen on observational studies, are causal.”