Sydney University. Australia: It may be possible to live longer and increase fertility by
manipulating diet, according to world-first research in mice from the
University of Sydney's Charles Perkins Centre.
Researchers
showed for the first time in mammals that there is an ideal balance of
macronutrients (protein, carbohydrates and fat) for reproduction and
another, different ideal balance for increasing lifespan.
The
research, published in the Proceedings of the National Academy of
Sciences (PNAS), calls into question the long-standing theory that
animals are forced to trade-off between reproduction and longevity when
resources are limited. According to the researchers, it is possible to
manage diet at different life stages to both optimise fertility and
extend lifespan, rather than sacrificing either.
"This study takes
a very big step in explaining why trade-offs between reproduction and
longevity are not inevitable in mammals," said Dr Samantha Solon-Biet
from the Charles Perkins Centre, who co-led the research with Dr Kirsty
Walters from the Charles Perkins Centre and ANZAC Research Institute.
"Rather
than a trade-off, we now know that each evolutionary function has
different nutrient requirements. That means that as our nutrient
requirements change with our life stage, we can change our diet to suit
our current requirements, for example by increasing our protein to
carbohydrate ratio when in our reproductive prime and lifting our
carbohydrate to protein ratio in later life.
"Animals don't have
to choose between high fertility and a long life. By managing diet
throughout our life cycle, we can have both."
The findings open the door for the development of dietary treatments for infertility in humans.
"As
the findings based on insects are now shown to be true in mammals, we
are hopeful that they will be equally true in humans," said Dr
Solon-Biet.
"As women increasingly delay child-bearing, the demand
for assisted reproductive technologies increases. With further studies,
it's possible that instead of women with subfertility resorting
immediately to invasive IVF techniques, an alternative strategy may be
developed to change the ratio of dietary macronutrients to improve
female fertility. This would avoid the need for medical intervention,
except in the most severe cases."
The study is the most
comprehensive nutritional trial ever conducted in mammals exploring the
relationship between macronutrients, reproduction and lifespan.
Researchers
placed 858 mice on one of 25 ad-libitum diets with varying levels of
protein, carbohydrate, fat and energy content. At 15 months, they
measured the male and female mice for reproductive function. In both
male and female mice, they found that lifespan was enhanced on a high
carbohydrate, low protein diet, and reproduction was enhanced on a high
protein, low carbohydrate diet.