Review Finds Calorie Restriction Has Beneficial Effects In Rhesus Monkeys

An important collaboration between 2 research teams has revealed that calorie restriction has a mixed, but positive effect on rhesus monkeys

Calorie restriction (CR) has shown remarkable effects on many lab animals, and to date is one of the most reliable ways of extending healthspan and lifespan in most species. However, in a few species it doesn’t work very well and a big questions remains – what about humans? Primates, being our closest cousins, are usually an excellent indication of effects in humans, so 2 important studies previously sought to test calorie restriction on rhesus monkeys in an attempt to unravel whether such a diet could improve human health too.

Reviewing a complex picture

Both studies, one from the University of Wisconsin-Madison and another from the National Institute on Aging, have already revealed contrasting data. The UW study suggested that CR extended survival in monkeys and reduced rates of cardiovascular disease, cancer and insulin resistance. The NIA study found some health improvements but little in the way of overall survival extension. A new collaboration between both teams has therefore sought to unravel why the studies found different results.

“These conflicting outcomes had cast a shadow of doubt on the translatability of the caloric-restriction paradigm as a means to understand aging and what creates age-related disease vulnerability”

A 27-year-old monkey on the left subject to CR, contrasted with a 29-year-old monkey on the right allowed unrestricted food intake. Credit: Jeff Miller/University of Wisconsin-Madison

After comparison of data involving over 200 monkey subjects, the first finding is intriguingly that CR may actually harm younger monkeys if began early on. It only appeared to have benefits when applied in adulthood, in contrast to some other rodent studies in which earlier intervention produced stronger results.

Diet and sex matters

The second conclusion was that control groups in the studies eat different amounts. The NIA study control group was fed less than the UW group, which suggests that even a small difference may have some beneficial effects. Furthermore, the diet of the UW group involved far greater sugar intake and as a result has higher adiposity (a higher body fat percentage). The NIA monkeys ate an arguably ‘better’ diet, and as a result that was less difference between the control group and CR group.

The last inference was that sex appeared to effect insulin sensitivity and adiposity. Females did not respond as negatively to higher body fat content, and retained higher insulin sensitivity. Males on the other hand, seemed more acutely vulnerable.

In conclusion?

Of course, CR in the best case scenario is still relatively weak; we desperately need to develop more potent technologies to improve human health. However, this sorely needed review reinstates that CR likely does have beneficial effects in primates. This means humans may have similar responses too. The picture is obviously complex though, and for those already eating a balanced, reasonable diet, extra restriction may yield very small rewards. Additional factors such as age and gender may also play a big factor in response.

Read more at MedicalXpress

Brain Shrinkage May Be Reduced By A Mediterranean Diet

Adherence to a Mediterranean style diet appears to reduce age-related brain shrinkage, according to recent analysis

The mediterranean diet has great press over the last few years, and countries in the region generally have excellent life expectancy. But what do we mean by such a diet? Typically an abundance of vegetables, olive oil, legumes, whole grains, fruits, and moderate intake of fish, dairy and wine. Meat intake is fairly low, and generally not processed.

Studying a cohort of 401 people in their 70s and examining brain scan data, researchers discovered brain shrinkage was significantly reduced in those keeping to a ‘mediterranean’ style dietary pattern. Interestingly, simply reducing meat intake but eating more fish did not have the same effect.

“As we age, the brain shrinks and we lose brain cells, which can affect learning and memory. This study adds to the body of evidence that suggests the Mediterranean diet has a positive impact on brain health. While the study points to diet having a small effect on changes in brain size, it didn’t look at the effect on risk of dementia. We would need to see follow-up studies in order to investigate any potential protective effects against problems with memory and thinking”

Of course, simply delaying shrinkage isn’t good enough, but until we develop more effective cures simple dietary changes may help health outcomes.

Read more at The New Scientist