That
chicken wing you’re eating could be as deadly as a cigarette. In a new
study that tracked a large sample of adults for nearly two decades,
researchers have found that eating a diet rich in animal proteins during
middle age makes you four times more likely to die of cancer than
someone with a low-protein diet — a mortality risk factor comparable to
smoking.
“There’s a misconception that because we
all eat, understanding nutrition is simple. But the question is not
whether a certain diet allows you to do well for three days, but can it
help you survive to be 100?” said corresponding author Valter Longo, the
Edna M. Jones Professor of Biogerontology at the USC Davis School of
Gerontology and director of the USC Longevity Institute.
Not only is excessive protein consumption
linked to a dramatic rise in cancer mortality, but middle-aged people
who eat lots of proteins from animal sources — including meat, milk and
cheese — are also more susceptible to early death in general, reveals
the study to be published March 4 in Cell Metabolism. Protein-lovers
were 74 percent more likely to die of any cause within the study period
than their more low-protein counterparts. They were also several times
more likely to die of diabetes.
But how much protein we should eat has
long been a controversial topic — muddled by the popularity of
protein-heavy diets such as Paleo and Atkins. Before this study,
researchers had never shown a definitive correlation between high
protein consumption and mortality risk.
Rather than look at adulthood as one
monolithic phase of life, as other researchers have done, the latest
study considers how biology changes as we age, and how decisions in
middle life may play out across the human lifespan.
In other words, what’s good for you at
one age may be damaging at another. Protein controls the growth hormone
IGF-I, which helps our bodies grow but has been linked to cancer
susceptibility. Levels of IGF-I drop off dramatically after age 65,
leading to potential frailty and muscle loss. The study shows that while
high protein intake during middle age is very harmful, it is protective
for older adults: those over 65 who ate a moderate- or high-protein
diet were less susceptible to disease.
The latest paper draws from Longo’s past
research on IGF-I, including on an Ecuadorian cohort that seemed to have
little cancer or diabetes susceptibility because of a genetic mutation
that lowered levels of IGF-I; the members of the cohort were all less
than five-feet tall.
“The research shows that a low-protein
diet in middle age is useful for preventing cancer and overall
mortality, through a process that involves regulating IGF-I and possibly
insulin levels,” said co-author Eileen Crimmins, the AARP Chair in
Gerontology at USC. “However, we also propose that at older ages, it may
be important to avoid a low-protein diet to allow the maintenance of
healthy weight and protection from frailty.”
Crucially, the researchers found that
plant-based proteins, such as those from beans, did not seem to have the
same mortality effects as animal proteins. Rates of cancer and death
also did not seem to be affected by controlling for carbohydrate or fat
consumption, suggesting that animal protein is the main culprit.
“The majority of Americans are eating
about twice as much proteins as they should, and it seems that the best
change would be to lower the daily intake of all proteins but especially
animal-derived proteins,” Longo said. “But don’t get extreme in cutting
out protein; you can go from protected to malnourished very quickly.”
•Source: sciencedaily.com
No comments:
Post a Comment