Global diet study challenges advice to limit high-fat dairy foods

New Delhi: Up to two servings a day of dairy, mainly whole-fat, can be included in a healthy diet as it may protect against high blood pressure and metabolic disorders, according to a study using data from 80 countries.

The research, published on Friday in the European Heart Journal, found that diets emphasising fruit, vegetables, dairy (mainly whole-fat), nuts, legumes and fish were linked with a lower risk of cardiovascular disease (CVD) and premature death in all world regions.

The addition of unprocessed red meat or whole grains had little impact on outcomes, the researchers said.

Low-fat foods have taken centre stage with the public, food industry and policymakers, with nutrition labels focused on reducing fat and saturated fat, they said.

"Our findings suggest that the priority should be increasing protective foods such as nuts (often avoided as too energy dense), fish and dairy, rather than restricting dairy (especially whole-fat) to very low amounts," said study author Andrew Mente from McMaster University, Canada.

"Our results show that up to two servings a day of dairy, mainly whole-fat, can be included in a healthy diet. This is in keeping with modern nutrition science showing that dairy, particularly whole-fat, may protect against high blood pressure and metabolic syndrome," Mente said.

The study examined the relationships between a new diet score and health outcomes in a global population. A healthy diet score was created based on six foods that have each been linked with longevity.

Associations of the score with mortality, myocardial infarction, stroke and total CVD (including fatal CVD and non-fatal myocardial infarction, stroke and heart failure) were tested in the study which included 147,642 people from the general population in 21 countries.

During a median follow-up of 9.3 years, there were 15,707 deaths and 40,764 cardiovascular events, the researchers said.

Compared with the least healthy diet (score of 1 or less), the healthiest diet (score of 5 or more) was linked with a 30 per cent lower risk of death, 18 per cent lower likelihood of CVD, 14 per cent lower risk of myocardial infarction and 19 per cent lower risk of stroke, they said.

Associations between the healthy diet score and outcomes were confirmed in five independent studies including a total of 96,955 patients with CVD in 70 countries.

"This was by far the most diverse study of nutrition and health outcomes in the world and the only one with sufficient representation from high-, middle- and low-income countries," Mente said.

"The associations were strongest in areas with the poorest quality diet, including South Asia, China and Africa, where calorie intake was low and dominated by refined carbohydrates," he said.

"The study suggests that a large proportion of deaths and CVD in adults around the world may be due to undernutrition, that is, low intakes of energy and protective foods, rather than overnutrition," said Professor Salim Yusuf, senior author and principal investigator of the study.

Dariush Mozaffarian from Tufts University, US noted that the new results, in combination with prior reports, call for a re-evaluation of unrelenting guidelines to avoid whole-fat dairy products.