Lowering homocysteine doesn't improve cognitive ability in healthy elderly

A number of studies suggest that elevated levels of the amino acid homocysteine are a risk factor for developing Alzheimer's disease. Given the large group of baby boomers moving into later life, this topic is an important one. So, it is interesting that a new study in the New England Journal of Medicine found that giving the B vitamins that can lower homocysteine levels in the blood did not change cognitive abilities in initially healthy elderly over a two-year period.

The link is: 

http://content.nejm.org/cgi/content/short/354/26/2764

This is useful information to know, but it raises one of the most common problems with simplistic interpretations of complementary medicine research. From just the headline, people might register only the conclusion that taking B vitamins isn't much use. The trouble is, the study only answered the question as to whether taking B vitamins such as folate, B12, and B6 to protect healthy cognitive function is useful. It doesn't tell us anything about whether it might help people at higher risk for Alzheimer's or multiinfarct dementia or any other health problem that has already been linked to elevated homocysteine.

High homocysteine has various adverse effects all over the body, including various forms of blood vessel disease (heart disease, stroke, peripheral vascular disease, etc). Extreme forms of high homocysteine can foster osteoporosis (thinning bone) and related fractures in older people. Homocysteine is even a contributor to seizures in children with leukemia who receive certain chemotherapy drugs.

Over 20 years ago, there was a classic study on nutrition and cognition in "healthy" community-living elderly. They found that there was not a linear dose-response relationship between B vitamin levels or intake and memory, but there was a connection. The people living in the community who fell into the very bottom 5-10% of the population for levels or intake of the various B vitamins and other nutrients had the poorest memory and other cognitive test performance.

So, the more useful question would have been - in healthy elderly who are very low in B vitamins to start, will supplementation help prevent them from losing memory function. In other areas of nutritional research, the answer has often been yes - that giving the nutrient is preventative if the person really needed it in the first place. But for people whose nutritional status was OK to start, taking more vitamins didn't change things.

The new study also did not answer the question as to whether lowering homocysteine levels had other health benefits over the long haul. Conventional research stays focused, which can be good, but it can also cause the scientists to lose sight of the big picture, i.e., the rest of the body. Nutrients always have roles in multiple pathways - and so have multiple effects. Nutrients are not drugs, they are nutrients.

So, go beyond the headlines before you decide what to do about any given intervention.

To your health,

Iris Bell, MD PhD
Alternative medicine information from a doctor who is also a patient.
Blog   http://www.dririsbell.com
Multimedia program http://www.arthritiscaremap.com
Ebook  http://www.gettingwhole.com
Newsletter http://www.holisticmedicinetips.com
Email      ibell@gettingwhole.com

Comments

[steven davies]

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