Life-prolonging
effect of a commonly used food supplement in worms and mice
Glucosamine has
been freely available in drugstores for many decades. It is widely used to
treat arthritis and to prevent joint degeneration. Moreover, glucosamine is
known to delay cancer growth. In addition, glucosamine reduces metabolism of
nutritive sugars, as was already shown some 50 years ago.
In 2007, Michael
Ristow showed that too much nutritive sugar shortens the lifespan of
roundworms, a widely studied model organism in ageing research. Conversely,
impairing carbohydrate metabolism in these worms was capable of extending
lifespan [reference 1]. Unfortunately, the method used in worms at that time
unexpectedly appeared to be ineffective in rodents [reference 2], and hence was
not studied further.
Extended
lifespan by almost 10%
In the recently
published study that was performed at ETH Zurich and four German research
institutions, Ristow and his colleagues applied glucosamine to roundworms and
found that they live around 5% longer than their untreated counterparts.
Next and most
importantly, the researchers fed glucosamine to ageing mice in addition to
their normal diet. The mice were 100 weeks of age, reflecting a comparative
human age of approximately 65 years. A control group of mice received no
glucosamine while otherwise receiving an identical diet. Feeding the supplement
to mice extended their lifespan by almost 10%, reflecting around 8 additional
years of human lifespan. Moreover, glucosamine improved glucose metabolism in
elderly mice indicating protection from diabetes, a life-threatening disease
most prevalent amongst the elderly.
Mimicking a
low-carb diet
Additional analyses
revealed that glucosamine feeding promotes the breakdown of amino acids in both
worms and mice. Amino acids are key components of proteins, and they become
preferentially metabolized in the absence of carbohydrates. As Ristow points
out, "this reflects the metabolic state of a low-carb diet due to
glucosamine supplementation alone – while these mice ingested the same amount
of carbohydrates as their unsupplemented counterparts." This implies that
glucosamine would mimic a low-carb diet in humans as well – without the
necessity of reducing the uptake of carbohydrates in our daily diet.
Should we now start taking
glucosamine supplements? Ristow replies: "This may be considered a valid
option, and yes, I have started taking glucosamine myself." However, he
points out that "diabetics should perform tight blood glucose control,
especially during the first weeks." Interestingly, two recent
epidemiological studies on more than 77,000 individuals suggest that intake of
glucosamine supplements is associated with reduced mortality in humans [references
3, 4]. "Unlike with our longer living mice, such an association is no
definite proof of the effectiveness of glucosamine in humans", says
Ristow. He continues, "But the chances are good, and since unlike with
most other potentially lifespan-extending drugs there are no known relevant
side effects of glucosamine supplementation, I would tend to recommend this
supplement."
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