Less on Your Plate, More on Your Mind?
We all know how much satisfaction we get from devouring the foods we like most. Eat, drink and be merry, or so goes the clichÃÂ©. Is it good advice? Or, over time, will this approach actually produce disease, unhappiness, and premature death? Not to mention impair our shorter-term ability to remember the â¬Åmerry times we've had?
When it comes to eating and drinking, a recent study, at the University of Munster, Germany, seems to recommend not just moderation, but deprivation. This research indicates that caloric restriction (CR) may not only enhance our long-term health but also, in a much shorter period of time (a few months), improve our memory.
Fewer Calories Count
For some time, scientists have noted that, as we age, restricting the number of calories we consume each day has a significant positive effect on multiple key health indicators. These include increased insulin sensitivity, decreased levels of blood glucose and insulin, and decreased serum fat and markers of inflammation, among others. (See Juvenon Health Journal Volume 3, No. 5, May 2004, â¬ÅCaloric Restriction: Life Extender for Mice and Men?)
The German investigators theorized that caloric restriction could also improve the age-associated decline in human memory. Their theory evolved from earlier animal studies that established a correlation between a calorie restricted diet and the condition of some brain structures. Specifically, microscopic examination of an area involved in memory function, the hippocampus, revealed significantly less age-associated damage for the animals on a CR diet, as compared to an age-matched control group on a non-restricted diet. The caloric restriction group also showed superior memory and learning abilities.
Moving on to Man
To test whether caloric restriction would improve brain health and memory in people, the investigators recruited 50 subjects - 29 females and 21 males - with a mean age of 60.5 years and a body mass index of 28 (on the plump side). To evaluate not only the effects of caloric restriction on memory function, but also findings from earlier studies indicating that unsaturated fatty acids (UFA) could contribute to improvement, the subjects were divided into three groups.
One group, the calorie restricted group, was assigned a diet containing 30% fewer calories per day than they would normally consume. A second group, the UFA group, continued with their usual, non-restricted diet, but increased their daily intake of unsaturated fatty acids by 20%. A third group, the controls, continued with the diet they were accustomed to.
All of the subjects were tested before the start of the study for 1) verbal memory, 2) serum insulin, 3) serum CRP (a marker of inflammation), 4) brain growth factors, and 5) serum triglycerides. These tests were repeated at the three-month study's conclusion.
In those three short months, the calorie restricted group showed noteworthy improvement in memory scores. Also significant were the inverse associations between this increase in memory and lower levels of serum insulin and serum CRP.
For the UFA group, on the other hand, neither memory scores nor insulin and CRP levels were measurably different from the controls. The serum triglycerides and brain growth factors did not change in any of the three subject groups.
The calorie restricted group results are consistent with findings from earlier work on caloric restriction. They also support previous studies that demonstrated how critical the pathway involved in insulin-regulated glucose metabolism is to our health in general. Furthermore, a dysfunction in insulin regulation has been associated with inflammation, which has been linked to an increase in the common marker of inflammation, CRP.
As we age, our serum insulin levels increase along with our CRP levels; in other words, we become less sensitive to insulin and more inflamed. The Munster study sends a clear message: lower the levels of these two serum proteins for improved memory and overall health.
Trying this at Home
The Munster results are encouraging. It seems that leaving the dinner table before reaching the food-saturation point may do more than help us look better and feel more comfortable. We may actually be able to influence at least one aspect of getting older, reversing, or at least avoiding, the age-associated decline in memory.
A 30% decrease in the amount of calories, as well as an increase in the quality of the food on our plates (vegetables, fruits, whole grains, legumes), seems to be one method of attaining this goal. But 30% is a challenging, somewhat arduous goal.
What if we could achieve the same result as caloric restriction by simply taking a supplement? The nutrient resveratrol, specifically the active trans-resveratrol form, seems to have that potential. Animal studies have produced encouraging results. Whether these results will translate to humans remains to be determined.