High doses of B vitamins slow rate of shrinking brain

Unfortunately, getting older comes with a common consequence affecting up to 16 percent of elderly people – gradual reduction in brain size, which is associated with problems in learning and memory. However, a new study reports that daily supplementation with high doses of B vitamins may help slow the rate of brain degeneration.

Oxford researchers gave 168 individuals over the age of 70 supplements containing high doses of folic acid (0.8 milligrams per day), B6 (20 milligrams per day) and B12 (0.5 milligrams per day), or a placebo as part of a randomized, double-blind controlled trial. Then, following two years of the supplementation program, the participants’ brains were assessed using serial volumetric magnetic resonance imaging scans.

The researchers reported their results in the September issue of PLoS One: the rate of brain shrinkage, or atrophy, in the group taking the supplements was 53 percent lower in comparison to the group taking the placebo. Their conclusion was that the high doses of B vitamins slowed the rate of brain shrinkage in elderly with mild cognitive impairment.

According to the authors, however, it is still unclear which vitamin provided the greatest benefit for the brain. They found that the reduced rate of brain atrophy was a result of an increase in either vitamin B12 status or folic acid status, but could not conclude which of the two “vitamins is the most important.”

They added that vitamin B6 may be less important for brain health since there was a, “lack of association of atrophy with the change in cystathione levels, a marker of vitamin B6 status.”

Folic acid and vitamin B12 play a role in protecting the brain, most likely because their presence helps to lower the concentration of the amino acid homocysteine in plasma. Higher levels of homocysteine are a risk factor associated with smaller brain size as well as problems with learning and memory — as well as related to poor heart and cardiovascular health.

The study adds to emerging evidence that supplementation with B vitamins may be a convenient way for elderly to help support memory and learning.

Source: Smith AD, Smith SM, de Jager CA et al. Homocysteine-lowering by B vitamins slows the rate of accelerated brain atrophy in mild cognitive impairment: a randomized controlled trial. PLoS One 2010;5:e12244.

Green tea EGCG in low doses boosts fat oxidation by amounts comparable to caffeine

Several studies have reported that green tea improves weight loss, which has largely been attributed to its content of caffeine. A pilot study, however, reports that green tea's main antioxidant catechin, epgallocatechin-3-gallate (EGCG), may also have thermogenic potential.

Thielecke et al of Germany report in the April issue of European Journal of Clinical Nutrition that consumption of EGCG at low doses taken after meals may contribute to increased fat oxidation similarly to caffeine (as much as 35 percent). The same effects of EGCG were not demonstrated while fasting.

The German researchers employed by DSM Nutritional Products performed a randomized, double-blind, placebo-controlled trial on 12 men that were screened for health problems, drugs and smoking. They also excluded men that had taken any dietary supplement within a week of the study.

Each male volunteer consumed an encapsulated supplement over three days (weeklong wash out in between) of either a low dose of EGCG (300mg), high dose of EGCG (600mg), caffeine (200mg), a combination of low-dose EGCG and caffeine (300mg EGCG/200mg caffeine), or a placebo.

The subjects were fed a standard meal of bread, butter, cheese, ham, tomato and cucumber according to the individual energy requiremens of each volunteer, calculated as 5 kcal/kg body weight with 50 percent enrgy from carbohydrates, 35 percent from fats, and 15 percent from proteins. They were prohibited from drinking caffeinated drinks during the study.

Fat and carbohydrate oxidation rates were calculated using a relatively new "respiratory quotient" that measures variance of oxygen consumption (VO2) and carbon dioxide production (VCO2). After three days of each treatment, the researchers took anthropometric measurements for body weight and BMI.

Here are their reported findings:

- 10 of the 12 successfully completed all five supplementation periods
- No adverse effects were reported
- There was no significant difference in fasting blood glucose and insulin from the different supplements
- Energy expenditure was not affected by EGCG
- Caffeine alone and in combination with green tea did have a pronounced effect on fat oxidation
- High dose EGCG boosted fat oxidation by a non-significant 20 percent
- Low dose EGCG surprisingly boosted fat oxidation by 33 percent after meals similarly to caffeine, but not before meals
- Low EGCG (300mg) and caffeine (200mg) maximized fat oxidation, increasing it by 49 percent, after meals

The researchers conclude: "This pilot study provides for the first time evidence that a single green tea catechin, EGCG, can increase fat oxidation in obese men, at least within 2 h after meal intake. Within this postprandial phase, EGCG is equipotent with caffeine with regard to fat oxidation."

My thoughts:

Why did the high dose EGCG not exhibit the same effects as the low EGCG? I understand that there may be a threshold point that is reached by caffeine and EGCG and its influence on fat oxidation, but I have a hard time buying that a low dose of EGCG may be more effective than a high dose. To that end, I'd like to see similar studies appear to clarify the relationship of EGCG on fat oxidation.

However, I am definitely glad to learn that we now know that EGCG does influence fat oxidation and that its effects of potentially improving weight loss have been pinned down to this mechanism instead of others such as reducing fat absorption. I am also glad to confirm that EGCG has no effect on body composition by means of influencing energy expenditure (meaning an influence on how many calories a person burns in a day).

I will continue recommending three or more cups of green tea a day, with or without the caffeine, for helping patients improve their weight loss. Despite the study, however, I think that across the board the most important reason why we continually see patients losing greatest amounts of weight while drinking green tea daily is because they are, at the same time, replacing their sugary beverages such as fountain drinks.

Reference

Thielecke F, Rahn G, Böhnke J, Adams F, Birkenfeld AL, Jordan J, Boschmann J. Epigallocatechin-3-gallate and postprandial fat oxidation in overweight/obese male volunteers: a pilot study. European Journal of Clinical Nutrition advance online publication 7 April 2010; doi:10.1038/ejcn.2010.47.