Updates on Brains, Vitamin D and Green Vegetables

Your brain on weights: You’ve probably heard that running, brisk walking and other aerobics increase blood flow to the brain and may be linked to the creation of new brain cells. Recent research shows that weight training may do the same. Rats with weights tied to their tails (!) who climbed ladders, or rats on loaded running wheels, packed on muscle mass and had higher levels of ‘brain derived neurotropic factor’, which is thought to spark the growth of new brain cells. Older women who lifted weights did better on tests of cognitive functioning than women in toning classes. Teresa Liu-Ambrose at the University of British Columbia speculates that resistance training, by strengthening the heart, improves blood flow to the brain, which is associated with better cognition.

Confusion on Vitamin D: A recent report from the Institute of Medicine (IOM) recommended that adults get 600 IUs of Vitamin D daily, and those over 71 get 800. They said that most people get this amount from foods (fatty fish and fortified milk) and sun exposure, and do not need supplements. These recommendations were contrary to the more widespread view in recent years that considered the importance of Vitamin D for bone health and other benefits, including protection against certain cancers and auto-immune diseases. Beth Dawson-Hughes, a vitamin D researcher at Tufts University, criticized the IOM recommendations as insufficient for the following groups:
*people with little sun exposure, including winter residents at higher latitudes, shut-ins, those who use sunscreen, those with dark skin (absorbs less D).
*osteoporosis patients
*obese people – it is thought that vitamin D is deposited in body fat and is less available from skin or dietary sources.
*people with gastrointestinal disorders that affect absorption.

Dawson-Hughes, as well as other vitamin D researchers, said that a laboratory level of 30 ng/mL (rather than the 20 ng suggested by the IOM) is good insurance, and is difficult to achieve by diet alone. Most adults need 1000 to 2000IU daily in supplement form, depending on their blood levels.

More benefits of Green Vegetables
Nitrate (NO-3) is found in vegetables such as red beets and spinach, and has been considered either without nutritional value or potentially toxic. Researchers at the Karolinska Institute in Sweden have found, however, that dietary nitrate is transformed by friendly bacteria in the mouth into nitric oxide (NO) – an important molecule in our bodies. NO helps blood vessels relax, lowering blood pressure and promoting more blood flow. It also makes the mitochondria that power our cells perform more efficiently. A high intake of vegetables and fruits has been found to protect against diabetes and heart disease. Boosting the nitrate to NO pathway may be one mechanism by which vegetables exert their protective effect. Readers may recall that dark chocolate also results in NO production in the body. But – try leafy greens first! And – think twice about using a strong mouthwash – we need oral bacteria for the system to work.
Sadja Greenwood, MD back issues on this blog. Leave a message or question.