“For
the last 25 years, scientists have been trying to find factors
that not only let us live longer, but also increase health
span, the time we remain healthy in our old age,” says
the study’s leader, Vijay Yadav, PhD, assistant professor
of genetics & development at Columbia University Vagelos
College of Physicians and Surgeons.
“This
study suggests that taurine could be an elixir of life within
us that helps us live longer and healthier lives.”
Over
the past two decades, efforts to identify interventions that
improve health in old age have intensified as people are living
longer and scientists have learned that the aging process
can be manipulated.
Many
studies have found that various molecules carried through
the bloodstream are associated with aging. Less certain is
whether these molecules actively direct the aging process
or are just passengers going along for the ride. If a molecule
is a driver of aging, then restoring its youthful levels would
delay aging and increase health-span, the years we spend in
good health.
Taurine
first came into Yadav’s view during his previous research
into osteoporosis that uncovered taurine’s role in building
bone. Around the same time, other researchers were finding
that taurine levels correlated with immune function, obesity
and nervous system functions.
“We
realized that if taurine is regulating all these processes
that decline with age, maybe taurine levels in the bloodstream
affect overall health and lifespan,” Yadav says.
First,
Yadav’s team looked at levels of taurine in the bloodstream
of mice, monkeys and people and found that the taurine abundance
decreases substantially with age. In people, taurine levels
in 60-year-old individuals were only about one-third of those
found in 5-year-olds.
“That’s
when we started to ask if taurine deficiency is a driver of
the aging process, and we set up a large experiment with mice,”
Yadav says.
The
researchers started with close to 250 14-month-old female
and male mice (about 45 years old in people terms). Every
day, the researcher fed half of them a bolus of taurine or
a control solution. At the end of the experiment, Yadav and
his team found that taurine increased average lifespan by
12% in female mice and 10% in males. For the mice, that meant
three to four extra months, equivalent to about seven or eight
human years.
To learn how taurine impacted health, Yadav brought in other
aging researchers who investigated the effect of taurine supplementation
on the health and lifespan in several species.
These
experts measured various health parameters in mice and found
that at age 2 (60 in human years), animals supplemented with
taurine for one year were healthier in almost every way than
their untreated counterparts.
The
researchers found that taurine suppressed age-associated weight
gain in female mice (even in “menopausal” mice),
increased energy expenditure, increased bone mass, improved
muscle endurance and strength, reduced depression-like and
anxious behaviors, reduced insulin resistance, and promoted
a younger-looking immune system, among other benefits.
“Not
only did we find that the animals lived longer, we also found
that they’re living healthier lives,” Yadav says.
At
a cellular level, taurine improved many functions that usually
decline with age: The supplement decreased the number of ‘zombie
cells’ (old cells that should die but instead linger
and release harmful substances), increased survival after
telomerase deficiency, increased the number of stem cells
present in some tissues (which can help tissues heal after
injury), improved the performance of mitochondria, reduced
DNA damage, and improved the cells‘ ability to sense
nutrients.
Similar
health effects of taurine supplements were seen in middle-aged
rhesus monkeys, which were given daily taurine supplements
for six months. Taurine prevented weight gain, reduced fasting
blood glucose and markers of liver damage, increased bone
density in the spine and legs, and improved the health of
their immune systems.
The
researchers do not know yet if taurine supplements will improve
health or increase longevity in humans, but two experiments
they conducted suggest taurine has potential.
In
the first, Yadav and his team looked at the relationship between
taurine levels and approximately 50 health parameters in 12,000
European adults aged 60 and over. Overall, people with higher
taurine levels were healthier, with fewer cases of type 2
diabetes, lower obesity levels, reduced hypertension, and
lower levels of inflammation. “These are associations,
which do not establish causation,” Yadav says, “but
the results are consistent with the possibility that taurine
deficiency contributes to human aging.”
The
second study tested if taurine levels would respond to an
intervention known to improve health: exercise. The researchers
measured taurine levels before and after a variety of male
athletes and sedentary individuals finished a strenuous cycling
workout and found a significant increase in taurine among
all groups of athletes (sprinters, endurance runners and natural
bodybuilders) and sedentary individuals.
“No
matter the individual, all had increased taurine levels after
exercise, which suggests that some of the health benefits
of exercise may come from an increase in taurine,” Yadav
says.
Only
a randomized clinical trial in people will determine if taurine
truly has health benefits, Yadav adds. Taurine trials are
currently underway for obesity, but none are designed to measure
a wide range of health parameters.
Other
potential anti-aging drugs—including metformin, rapamycin,
and NAD analogs—are being considered for testing in
clinical trials.
“I
think taurine should also be considered,” Yadav says.
“And it has some advantages: Taurine is naturally produced
in our bodies, it can be obtained naturally in the diet, it
has no known toxic effects (although it’s rarely used
in concentrations used in this study), and it can be boosted
by exercise.
“Taurine
abundance goes down with age, so restoring taurine to a youthful
level in old age may be a promising anti-aging strategy.”
