Got milk? Drink up, say a group of French-Canadian researchers. Dairy products such as milk, yogurt, cream, cheese, and butter may play a role in helping to combat metabolic disorders such as obesity and type-2 diabetes, according to research published September 16 in the journal Applied Physiology, Nutrition, and Metabolism.
Worldwide, most dietary guidelines recommend that adults and children consume 2 to 4 servings of low- or non-fat milk-based products each day. Those recommendations are based largely on the recognition that dairy products are important sources of calcium, a mineral important to healthy bones, potassium, which helps to lower blood pressure, and other nutrients. In addition, most dairy products are fortified with Vitamin D, which also helps build strong bones, among other functions. Low levels of vitamin D have been linked to other health problems ranging from heart disease to dementia.
Some recent research suggests that dairy products may also play an important role in helping all cells in the body function properly, called metabolic health. These studies have suggested that people who consume more dairy may be at reduced risk of metabolic diseases such as obesity, metabolic syndrome, and type-2 diabetes. Yet other studies have shown no association between dairy consumption and metabolic health.
Some of the conflicting results may result from the way data have been collected for previous studies. Most studies have relied on study participants’ self-reports of dairy consumption, a method that is prone to error.
What the Researchers Did
This cross-sectional study was conducted by a research team led by Dr. Iwona Rudkowska, a research scientist in the Endocrinology and Nephrology Department at the CHU de Québec Research Center and assistant professor at Laval University in Quebec City.
The team set out to do two things: first, look for associations between dairy consumption and metabolic health, and second, identify substances in the body that could be used as to track how much dairy people were consuming, called biomarkers.
To answer these questions, Rudkowska’s team recruited 254 people from the greater Quebec City metropolitan area to participate in the study. Of those 233 participants (105 men and 128 women) had healthy metabolic profiles and thus met eligibility criteria for the study.
Because they were conducting a cross-sectional study, investigators didn’t ask participants to do anything differently. They just asked them to track how much dairy they consumed and took blood samples so they could measure indicators of metabolic health status. Then they compared dairy intake to a set of specific metabolic risk factors, including anthropometric status (i.e. body measurements), blood sugar and blood lipids (fats), inflammatory markers, and blood pressure.
What they Found
Study results showed that people who consumed more dairy – including high-fat dairy – had better metabolic health profiles. Higher dairy consumption was associated most strongly with lower blood glucose and lower blood pressure. However, there was no correlation between dairy intake and insulin levels, body mass index (BMI), body weight, or two inflammatory markers. However, higher levels of one inflammatory marker – CRP – were associated with increased dairy consumption.
The research team also found a big variation in the amount of dairy that people consumed. On average, study participants consumed 2.5 ± 1.4 servings of dairy products per day. Nearly half of study participants were not getting the recommended 2 servings of dairy products per day.
Researchers also identified a potential biomarker for dairy consumption, a fatty acid that occurs naturally in dairy products such as milk, cheese, yogurt, and butter (as well as meat fats), called trans-palmitoleic acid. Trans-palmitoleic acid cannot be synthetized by the body, but is thought to come only from the diet. Other studies have shown beneficial effects of trans-palmitoleic acid, including better metabolic health. Higher trans-palmitoleic acid levels were related to lower body weight in men as well as lower blood pressure in both men and women.
Why It’s Important
This study adds to a growing body of literature that suggests that eating and drinking dairy products may help reduce obesity, metabolic syndrome, and type-2 diabetes. Researchers suggested that new guidelines calling for 3 to 4 servings of dairy products per day might be appropriate (U.S. dietary guidelines released in 2010 already call for 3 servings of low-fat or skim dairy products per day, although that guideline has been hotly debated).
In addition, the identification of a potential biomarker for dairy consumption may help to clarify conflicting results about the health effects of dairy consumption from earlier studies.
Researchers cautioned that because of the cross-sectional study design, they could not draw any conclusions about cause and effect. Their study showed only an association between dairy product consumption and lower blood glucose and blood pressure in a specific population of healthy French Canadians. In addition, the study size was relatively small, with only 233 participants.
These results may not extend to other populations, nor did researchers control for other factors that might have affected participants’ metabolic health. For instance, those who consumed more dairy products could also have consumed more fruits and vegetables, drank fewer sugary drinks, exercised more, or smoked less – all of which could affect blood glucose and blood pressure levels.
Recognizing these limitations, Rudkowska said in a press release that “additional well-designed intervention studies are needed to ascertain the effects of increased dairy consumption on metabolic health in healthy and in metabolically deteriorated populations.”
What It Means for You
Consuming two to three servings of dairy products per day may help reduce blood glucose and blood pressure and improve overall metabolic health. So if you like milk, cheese, yogurt, butter, and other dairy foods, enjoy them.
Remember, though, that dairy foods – especially full-fat versions such as whole milk – contain significant calories and cholesterol. Make them part of a healthy diet, not the basis for one.
Article Primary Source
Da Silva, M.S., Julien, P. Couture, P, Lemieux, S., Vohl, M.C., and Rudkowska, I. Associations between dairy intake and metabolic risk parameters in a healthy French-Canadian population. Applied Physiology, Nutrition, and Metabolism, Published on the web 16 September 2014, 10.1139/apnm-2014-0154. http://www.nrcresearchpress.com/doi/abs/10.1139/apnm-2014-0154#.VBpiThawQXs
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