Cutting down meat and dairy could help you live up to a decade longer

Want to know roughly how much longer you might live if you permanently adopted a healthier diet? The “Food for healthy life” website can give you an idea – and if you’re under 60 and eat a typical Western diet, the answer could be around a decade or more on average.

The website is based on data from hundreds of studies. “The estimated life extension is mainly due to a reduction in the risk of heart disease, diabetes and cancer,” says Lars Fadnes at the University of Bergen in Norway.

His team started with recent meta-analyses of the effect of eating various amounts of particular food types, such as fruits. These findings were combined with data on global mortality and what people currently eat to estimate the impact of a permanent change in diet.

The highest estimates of lifespan extension are based on a diet designed to maximise the health benefits. This optimised diet involves eating no red or processed meat, drinking no sugar-sweetened beverages, reducing dairy and egg consumption, and eating more legumes, whole grains and nuts.

The team also looked at a “feasibility” diet midway between the typical Western diet and the optimised diet.

A 20-year-old man who permanently switched from a typical Western to the optimised diet would reap the greatest benefits, living 13 years longer on average, and seven years longer if on the feasibility diet. For a woman, the equivalent figures are 11 and six years.

Eighty-year-olds of either sex would reap the smallest benefits, living about three years longer on the optimised diet and slightly more than half that on the feasibility diet.

The estimated extensions are based on averages and shouldn’t be taken as individualised forecasts, says Fadnes. There are many uncertainties including the effects of eggs, white meat and oils, not to mention other risk factors and lifestyle, he stresses. The estimates also don’t take into account future improvements in medical treatments.

The premise of the study is sound, and it is well thought out, says Tim Spector at King’s College London. “It does highlight the importance of diet on our general health,” he says.

However, it is based on many assumptions and may be too simplistic, says Spector. For instance, he thinks the way foods are processed is important, not just the general type. Spector’s work also suggests that there are big individual differences, with some people able, say, to eat far more fat without ill effects than others.

While this study looked only at health, eating less meat and dairy products also has big environmental benefits.

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