A Sydney trial of 104 adults aged 65 to 75 found diet changes lowered "biological age" markers in 4 weeks. Promising, small and short.

Here's a study worth reading carefully, because "biological age" headlines tend to run ahead of the evidence. Researchers at the University of Sydney ran a trial with 104 people aged 65 to 75, BBC Science Focus reports, splitting them into four groups and providing each with a different type of meal for four weeks: semi-vegetarian high-fat, semi-vegetarian high-carbohydrate, omnivorous high-fat, and omnivorous high-carbohydrate. Biological age was measured before and after with the Klemera-Doubal Method, which combines markers including insulin, cholesterol and blood pressure. The omnivorous high-fat group, whose meals most resembled what participants were already eating, showed the fewest changes. The other three groups showed a reduction in biological age, the biggest in the group eating animal and plant foods with higher carbohydrates and lower fat. Those carbohydrates were minimally processed, the magazine stresses; white bread and chips wouldn't do the same. The findings, published in the journal Aging Cell, were "consistent with prior evidence that diets rich in complex carbohydrates can extend lifespan and improve metabolic health," the scientists wrote. "I think there's a lot to be said for shifting the focus away from restriction and more toward overall dietary quality and balance," said lead author Dr. Caitlin Andrews. Now the caveats. This was 104 people for four weeks, with meals provided by researchers, which is very different from real life. "Biological age" here is a composite score built from markers like cholesterol and blood pressure, not a measure of how long anyone will live, and the article doesn't say whether the changes last or who funded the work. The takeaway is modest. So before you overhaul your plate, bring your latest cholesterol, blood sugar and blood pressure numbers to your doctor and ask which one realistic change would help you most.