Consumption of at least two servings of dairy appears to be associated with a lower incidence of metabolic syndrome (MetS), and incident hypertension and diabetes, according to a new prospective multinational cohort epidemiology study. This association was strongest with the consumption of full-fat dairy products.
“Possible pathways for metabolic benefits of dairy include angiotensin converting enzyme, peroxisome proliferator activated receptors, hepatic de novo lipogenesis, hepatic and adipose fatty acid oxidation, and inflammation,” Andrew Mente, PhD, from the Population Health Research Institute, Hamilton Health Sciences and McMaster University, Hamilton, Ontario, and and colleagues report in BMJ Open Diabetes Research & Care. “Further, bioactive peptides or amino acids produced through yogurt or cheese fermentation improves insulin sensitivity, while branched chain amino acids in whey has been shown to improve postprandial insulin response.”
The study authors noted that their study, which set out to perform a cross sectional analysis of potential association between dairy intake and metabolic syndrome (MetS) and to prospectively study incident hypertension and diabetes, is among the first studies to do so.
“The Prospective Urban Rural Epidemiology (PURE) study is a prospective epidemiological study of individuals aged 35 and 70 years from 21 countries on five continents, with a median follow-up of 9.1 years,” Mente and colleagues wrote.
Using food frequency questionnaires, the researchers collected data on total dairy intake — milk, yogurt, yogurt drinks, cheese, and dishes prepared with dairy — over a period of 12 months. The responses were grouped into whole fat dairy and low-fat dairy. They did not include butter and cream in the total dairy and whole fat groups, as these foods are not common in some countries, so assessment of the intake of these foods was separate and related only to those countries in which they are consumed.
Individual medical history, medications taken, education, and smoking level were also ascertained by questionnaire. They also recorded data on weight, height, waist and hip measurements, and resting blood pressure. Fasting blood samples were also collected and analyzed for total cholesterol. LDL-C, HDL-C, triglycerides, apolipoprotein A1, and apolipoprotein B.
Out of 153,220 participants, 147,812 were considered to have a plausible energy intake of 500-5,000 kcal/day. Of these, 112,922 participants who had information on the five MetS components — elevated blood pressure, increased waist circumference, reduced HDL-c, elevated triglycerides, and elevated fasting blood glucose — were entered into the cross-sectional analysis, and 55,547 individuals without hypertension and 131,481 individuals without diabetes were entered into the prospective analysis after 9.1 years of follow-up.
In the cross-sectional analysis, Mente and colleagues found that there was a lower prevalence of MetS with a higher intake of total dairy — at least two servings per day versus no servings (OR 0.76, 95% CI 0.71-0.80, P-trend<0.0001).
This association was also seen with “higher intakes of whole fat dairy consumed alone (OR 0.72, 95% CI 0.66-0.78, P-trend< 0.0001), or consumed jointly with low fat dairy (OR 0.89, 95% CI 0.80-0.98, P–trend= 0.0005), were associated with a lower MetS prevalence,” the researchers wrote.
They noted in a media statement that this translates to a 24% lower risk of MetS increasing to 28% with a full-fat dairy diet.
This association with a lower prevalence of MetS was not seen when the participants consumed only low-fat dairy (OR 1.03, 95% CI 0.77-1.38, P–trend=0.13).
In the prospective analysis, following 9 years of follow-up, 13,640 individuals reported incident hypertension and 5,341 reported incident diabetes.
“Higher intake of total dairy (at least two servings/day versus zero serving/day) was associated with a lower incidence of hypertension (HR 0.89, 95% CI 0.82-0.97, P-trend= 0.02) and diabetes (HR 0.88, 95% CI 0.76-1.02, P-trend= 0.01),” Mente and colleagues wrote. “Directionally similar associations were found for whole fat dairy versus each outcome.” This translates to 11-12% lower risk for both conditions, and if three daily servings are consumed, the risk reduction is increased to 13%-14%. Again, full fat dairy was seen to have a stronger association than low fat dairy.
Interestingly, the researchers found that the highest intakes of total dairy were found in Europe/North America, Middle East, and South America. South Asia, China, Africa, and Southeast Asia had the lowest intakes. Not surprisingly, North America and Europe consumed the most low-fat dairy, while other regions consumed more whole fat dairy. The regions with the highest BMIs were the Middle East and South America, while South America, North America, and Europe were ahead of the pack when it came to physical activity. College educated individuals were most common in North America and Europe.
Mente and colleagues noted that “at baseline 78,533 (56%) individuals had elevated blood pressure, 67,897 (48%) had elevated waist circumference, 63,415 (53%) had low HDL-C, 35 595 (30.2%) had elevated triglycerides, and 33,082 (27.8%) had elevated blood glucose. A total of 46,667 (41.3%) were classified as having MetS.”
The study authors suggested that large randomized trials looking at the effects of whole fat dairy on MetS, hypertension, and diabetes should be undertaken.
Limitations of the study include that diet was self-reported and that dairy may have been misclassified. Mente and colleagues also noted that it was not possible to assess incident MetS as several components could not be assessed or were only assessed in a random sampling at follow-up. They also noted that the higher impact of increased dairy intake might be influenced by overall diet.
Consumption of at least two servings of dairy appears to be associated with a lower incidence of metabolic syndrome, and incident hypertension and diabetes, according to a new prospective multinational cohort epidemiology study. This association was strongest with whole fat dairy.
Be aware that these findings only show association and not causation, which can only be confirmed in a randomized, clinical trial.
Candace Hoffmann, Managing Editor, BreakingMED™
The study was mainly funded by the Population Health Research Institute (PHRI). The PURE study is an investigator-initiated study that is funded by the Population Health Research Institute, Hamilton Health Sciences Research Institute (HHSRI), the Canadian Institutes of Health Research, Heart and Stroke Foundation of Ontario, Support from Canadian Institutes of Health Research’s Strategy for Patient Oriented Research, through the Ontario SPOR Support Unit, as well as the Ontario Ministry of Health and Long-Term Care and through unrestricted grants from several pharmaceutical companies (with major contributions from AstraZeneca (Canada), Sanofi-Aventis (France and Canada), Boehringer Ingelheim (Germany and Canada), Servier, and GlaxoSmithKline), and additional contributions from Novartis and King Pharma and from various national or local organizations in participating countries.
Cat ID: 12
Topic ID: 76,12,730,305,446,6,12,307,192,669,916,918,925