the gassy link between less meat and longer life

as a physiology researcher, i have long been interested in the strange role of h2s in the body. this is not a gas anyone wants around. it stinks, is a component of flatulence, and its toxicity has been  linked to at least one mass extinction .

this holds true for  yeasts, fruit flies, worms and monkeys . in mice, such diets  reduce cancer risk , strengthen the immune system and improve cognitive function.

studies since the 1990s have shown that reducing intake of certain sulphur-containing amino acids, the building blocks of proteins, can increase  longevity in rats  by around 30 per cent. more recently, a collaborative team involving me and led by scientists at harvard, performed a series of animal studies in which we restricted the intake of two sulphur amino acids — cysteine and methionine — to study what effects this had.

it caused the animals to  ramp up production  of h2s in their tissues, which triggered a cascade of beneficial effects. these included increased new  blood vessel generation , which promotes cardiovascular health, and better resistance to oxidative stress in the liver, which is linked to liver disease.

but it remained to be seen whether similar effects would occur in humans. earlier this year, a study using data from the 11,576 adults in nhanes iii, the u.s. national nutrition survey,  delivered evidence that they do . it found that reduced dietary intake of these sulphur amino acids is linked to lower cardiometabolic risk factors, including lower levels of cholesterol and glucose in the blood. cardiometabolic risk factors are those linked to heart disease, stroke and diabetes.

the upshot of this research is that there’s good evidence that limiting intake of foods containing high levels of sulphur amino acids can reduce the risk of chronic diseases like diabetes and heart disease, and promote healthy aging. in north america, most of us are a long way from achieving this. because these sulphur amino acids are abundant in meat, dairy and eggs, which feature prominently in our shopping carts, we eat on average  2.5 times our daily requirement  of them.

red meat is particularly high in sulphur amino acids, but fish and poultry white meat also contain a lot (the dark meat has less). switching to  plant-based proteins  would help reduce this intake.

it might seem odd that a toxic gas can help maintain health, but it may reflect the origins of life on early earth when the atmosphere was much richer in sulphur gas than it is today. indeed, we are starting to appreciate how fundamental h2s signalling may be. for example, it has also been shown to reduce inflammation, opening the door to potential  new treatments for arthritis or potential use as a painkiller .