Brain benefits found in exercise, dietary restriction

by Richard Schulman

Our last summary of health research was a year and a half ago. Here we describe some interesting research that has been published since then. As before, caveat lector. It’s no secret that revisions and even reversals are common in the field. On net, however, we think the information below should be of interest and benefit to our readers.

More benefits of exercise documented

That exercise is beneficial to health has long been known, but new benefits are being identified:

• The brain: Exercise training increases the size of the hippocampus, improves memory, and is associated with higher levels of serum Brain-Derived Neurotrophic Factor (BDNF), a brain chemical that is key for the promotion of neurogenesis. (It used to be thought that only the fetus or infants could create new neurons.) Exercise out-of-door has the additional benefit that sunlight, especially in the spring and summer when there is more of it, also increases BDNF.
• The heart: Exercise, especially if it is begun before age 65 when the heart still retains plasticity, “can reverse damage to sedentary, aging hearts and help prevent risk of future heart failure,” according to Texas medical researchers. “[T]he exercise needs to be performed four to five times a week. Two to three times a week was not enough, the researchers found in an earlier study.”
• Muscles: “[E]xercise can stave off and even reverse muscle loss and weakness. Recent research has demonstrated that physical activity can promote mitochondrial health, increase protein turnover, and restore levels of signaling molecules involved in muscle function,” according to a summary of recent research in The Scientist.

Dietary restriction

Dietary restriction can help overweight people become normal weight and normal weight people become healthier and possibly longer-living. There are several different ways it can be practiced:

• Reduction of calories or protein consumed (while taking care to meet daily nutrient requirements),
• Daily time-limited feeding (just eating, say, within an eight-hour window and fasting for the other sixteen hours), or
• Practicing twenty-four-hour fasting one or two days each week or month (intermittent fasting).

Among dietary restriction’s beneficial effects on physiology, one of the most important is the reduction of the growth hormone / IGF-1 / insulin signaling pathway. This reduction is associated with life extension in most species. It is the antithesis of diabetes, in which insulin resistance causes the pathway to go into overdrive and accelerate the aging of the diabetic individual.

Dietary restriction also increases lifespan by slowing epigenetic drift. (The epigenome is a molecular structure attached to DNA which determines whether and how genes actually get expressed.)

Intermittent fasting (IF) also increases the production of BDNF. “Interestingly, cellular and molecular effects of IF and CR [calorie restriction] on the cardiovascular system and the brain are similar to those of regular physical exercise, suggesting shared mechanisms, prominent IF researcher Mark Mattson writes.”

Protein restriction, especially methionine restriction (methionine is one of the amino acids that make up protein), also shows promise in slowing the growth of cancer cells, according to a report published in July in Nature. So does fasting.

Dairy, fats, and eggs

Milk, although it is rich in nutrients, is a double-edged food for adults because of the intrinsic presence in it of growth hormones. They’re there because one of the key purposes of maternal milk is to foster growth in young offspring. But adults don’t need to enhance growth but just foster cell maintenance. Promoting unneeded growth in adults risks aging and cancer. That’s one reason why steroids are banned in sports. Milk consumption by adults stimulates unneeded IGF-1, a growth promoter. Interestingly, cheese and yogurt do not. Aged cheeses may have additional benefits, whereas whole milk has been identified as a risk factor for prostate cancer. There are other good calcium sources besides milk: cheese and yogurt, collard and turnip greens, bok choy, poppy and sesame seeds, and sardines (bone in).

Protein consumption beyond required daily levels also increases insulin signaling, growth in excess of that needed for cell maintenance, and accelerated aging. For related reasons, dog owners are supposed to switch to a lower protein chow once their puppy reaches full growth.

Food preservative propionate is said to be a metabolic disruptor

Propionate is widely used as a food preservative. A study by US and Israeli researchers reports that “Long-term exposure of mice to a daily low dose of propionate resulted in a gradual weight gain and insulin resistance. Studies in humans highlight the potential contribution of propionate in the diet to the development of insulin resistance and obesity.”

Does increased maternal fluoride intake lower a child’s IQ?

An estimated three-fourths of the US population consumes water that is fluoridated by municipal authorities to improve dental health. But according to a Canada-wide study just published in the respected medical journal JAMA Pediatrics, “[M]aternal exposure to higher levels of fluoride during pregnancy was associated with lower IQ scores in children aged 3 to 4 years. These findings indicate the possible need to reduce fluoride intake during pregnancy,” . The study’s validity is strongly disputed, however.

In Western Europe, according to an editorial in the same issue of JAMA Pediatrics, “Regions in which water fluoridation is rare, such as Europe, rely on more targeted strategies to deliver fluoride (e.g., supplements, dental treatments and products, fortification of milk and salt)…..[I]n most Western European countries, the prevalence of decayed, missing, or filled teeth is similar to or lower than the prevalence in the United States.”