Six Everyday Foods Linked to Longer Life in Global McMaster-Led Study

Researchers at McMaster University in Hamilton have built a simple scoring system out of six everyday food groups, and they report that people who scored highest on it were 30 per cent less likely to die of any cause over nine years than people who scored lowest.

The work draws on the Prospective Urban Rural Epidemiology study, known as PURE, a long-running multinational project that enrolled 166,762 people aged 35 to 70 in 21 low-, middle- and high-income countries across five continents. The researchers took dietary data already collected from those participants and used it to create a new "PURE healthy diet score." Hundreds of earlier studies, most of them done in Western countries, had tied higher intakes of fruit, vegetables, nuts, beans, lentils and fish to a lower risk of coronary heart disease, stroke and Type 2 diabetes. This work tests that idea on a global scale.

The score rests on six categories: fruit, vegetables, legumes, nuts, fish and dairy, the dairy being mostly whole fat. Each category has been linked to longevity in past research. The definitions are specific. Fruit counted fresh, dried and canned, but not juice. Vegetables excluded potatoes, canned vegetables and pickles. Legumes covered kidney, black, pinto and navy beans, lentils, chickpeas, peas and black-eyed peas. Dairy covered milk, yogurt, yogurt drinks, cheese and mixed dishes made with dairy, while butter and whipped cream were left out. Each component earned a value from 0 (unhealthy) to 1 (healthy) based on intake, so total scores ran from 0 to 6.

The top group scored at least five. Each day, these participants ate five servings of fruit and vegetables, about a quarter cup (28 grams) of nuts, and two servings of dairy, mainly whole fat milk, yogurt or cheese. A dairy serving was one cup of milk, one cup of yogurt or half an ounce of cheese. Each week they also ate three to four half-cup servings of legumes and 6.5 ounces of fish.

Compared with participants who scored one point or less, those top scorers had the 30 per cent lower risk of death from any cause over the nine-year study period. They also had a significantly lower risk of heart attack, stroke and death from cardiovascular disease. The researchers adjusted for age, waist circumference, physical activity, smoking status, history of diabetes and socioeconomic status. Similar protective effects appeared in five independent international studies with a combined 97,000 participants, bringing the total to 244,957 people from 80 countries at different economic levels. Size and diversity are the work's notable strength.

The inclusion of whole fat dairy is the part most likely to surprise readers. It is not the first study to suggest benefits: recent observational research indicates that higher dairy intake, whole fat included, may protect against heart disease, stroke and cardiovascular death. Earlier PURE data, published in 2020, found that two to three dairy servings a day, versus none, was associated with a lower risk of hypertension and Type 2 diabetes, with whole fat dairy especially beneficial. Whole fat dairy contains high-quality protein, distinctive fatty acids and many vitamins and minerals. Bioactive peptides in fermented products such as yogurt and cheese are thought to improve how the body uses insulin.

Writing in The Globe and Mail, Toronto dietitian Leslie Beck cautions against reading this as permission to fill up on ice cream and cheese. Her takeaway is that two daily servings of whole fat dairy can fit into a healthy diet, provided it also holds decent amounts of fruit, vegetables, nuts, legumes and fish. She notes that the PURE pattern is not high in saturated fat and sits within Health Canada's advice to keep saturated fat under 10 per cent of daily calories. The findings are observational, so they show association rather than proof, and the weight rests on the whole pattern rather than any one food.