While longevity supplements can cost up to $150, over in your local supermarket, foods linked to longevity cost almost nothing – red lentils at $4 per kilo or black beans at less than $2 per can. The price tags may be tiny but the benefits of eating them – like helping to lower cholesterol and blood pressure, and reducing diabetes risk – are huge.
But there’s another reason why more plant proteins might boost our lifespan. These foods deliver a healthier mix of essential amino acids, the building blocks that make up protein in foods from both animals and plants.
“Not all protein is the same and there’s now evidence that deriving more of our protein from plants can promote better health by reducing levels of some essential amino acids in the diet,” says Professor Luigi Fontana who heads the University of Sydney’s Fontana Healthy Longevity Group.
“For instance, the intake of one amino acid called methionine is about 40 per cent lower in a healthy plant-based diet, and animal studies have found that restricting methionine helps protect against chronic disease and extends lifespan.”
On the other hand, consuming high levels of methionine and branched-chain amino acids from animal foods can promote insulin resistance, type 2 diabetes, cancer and accelerated ageing, he adds.
So what is it about lower levels of these amino acids that might promote longevity?
“One explanation is that high levels of methionine and branched-chain amino acids activate biological pathways linked to cellular ageing,” says Fontana. “Diets that provide lower, yet still adequate, amounts appear to do the opposite, activating processes that help preserve cellular function and maintain metabolic health.”
Plant proteins and longevity
This may explain why a US study following 50- to 65-year-olds over 18 years found that those eating the most protein had a 75 per cent higher mortality rate and were four times more likely to die of cancer, says Fontana, who authored The Path to Longevity.
“These risks were reduced or eliminated when the protein came from plants. A more recent study in 2020, looking at over 700,000 people found that higher plant protein intake was associated with lower mortality from all causes, and a lower risk of heart disease and stroke,” he says.
Last year, University of Sydney research analysing data from 101 countries over a 60-year period found that countries consuming more plant-based proteins have longer adult lifespans.
Compared with many animal proteins, plant foods like legumes, whole grains, nuts and seeds provide less methionine and lower levels of branched-chain amino acids, Fontana explains. “But their benefits go beyond protein quality alone. These foods also deliver fibre, polyphenols, potassium and unsaturated fats.”
“By contrast, diets high in animal products tend to provide not only more methionine and branched-chain amino acids, but also excess saturated fat, which raises cholesterol levels, and excess iron, which can promote oxidative stress and increase the risk of colon cancer. ”
So why don’t we eat more beans and lentils?
Despite the many pros of eating more chickpeas, beans and lentils – including their affordability – Australia’s legume intake is dismal.
“ABS data from 2023 shows a downward trend since 2011 in overall vegetable consumption, and this includes legumes, down from 4 grams daily to 3.7 grams,” says Associate Professor Sara Grafenauer from the Nutrition, Dietetics and Food Innovation program at UNSW.
However, Grafenauer that there are some items people often forget belong in this food group, like peas, green beans and hummus.
“Our research points to people being unfamiliar with legumes, even with the word ‘legumes’ itself – we found people prefer ‘peas and beans’. I also think we plan meals around meat rather than plant foods, yet eating more legumes and less meat would be a massive cost-saver for families right now.”
Simple options include adding more peas to our meals and combining chickpeas, lentils or beans with smaller amounts of meat in stews, curries and bolognese sauces, she says.
“Add red lentils to a curry and they completely disappear, creating a natural thickening, and adding more protein and fibre. Small, black French-style lentils, also called Puy lentils are good in a bolognese sauce,” says Grafenauer.
Do we really need more protein?
With so many products labelled “high protein” now available, you’d think we were all protein-starved. But most of us already get enough, she says.
”Protein is useful for weight management, controlling appetite and maintaining muscle, but legumes can help with this and more – besides providing protein, they help control blood glucose and cholesterol, and their fibre feeds the microbiome, keeping the bowel functioning optimally.”
And let’s not forget our heating planet, she adds.
“Moving the proportion of protein we consume towards plant-based foods would be good for planetary health too.”
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