Study Suggests B Vitamin Supplements May Not Prevent Alzheimer's
Do you know your plasma homocysteine levels? You probably don’t, but the levels of this sulfur-containing amino acid that is found naturally in blood plasma may affect your risk of developing dementia.
That’s because numerous studies have shown that people who have high levels of homocysteine have an increased risk of developing blocked arteries and atherosclerosis, which causes the arteries to harden, all of which can lead to dementia. Researchers also have done studies that suggest that high levels of homocysteine may be linked to poor mental function. (It also has been linked to osteoporosis.)
Experts believe that homocysteine irritates blood vessels’ lining, resulting in scars, narrowing and becoming harder. Thus, the heart has to work harder to pump blood through the body. The level of homocysteine in the blood can vary based on age, gender, diet, hereditary factors and overall health. It is estimated that approximately 5-10 percent of the U.S. population has high levels of homocysteine. However, there is no obvious sign or symptom of having too much of this substance.
Researchers also have found that the levels of this substance can be influenced by the presence of folic acid, vitamin B6 and vitamin B12. These nutrients cause the chemical changes that can break down the homocysteine, thus lowering blood levels.
So wouldn’t it just make sense to pop a large quantity of B vitamins to make sure you get enough? Actually, that might not be a good idea, according to a recent study that analyzed the effects of treatment of this condition using B vitamins. This meta-analysis looked at 11 large trials that involved 22,000 participants, most of whom were in their 60s and 70s. These participants were free of dementia when the studies started. Researchers asked participants in some of the studies to take B vitamins while others were given placebos for approximately five years.
The meta-analysis found that taking B vitamins decreased the levels of homocysteine by approximately 25 percent. However, the researchers also found that lowering homocysteine by taking B vitamins had no significant effect on an individual’s cognitive abilities, global cognitive function or cognitive aging.
So based on these findings, should you avoid these supplements? Maybe yes, maybe no. That's because after the age of 50, some people may experience difficulty getting B vitamins – particularly vitamin B12 -- from foods. Thus, many health care professionals recommend supplements at this point. However, some experts warn against automatically taking supplements or a multi-vitamin to correct deficiencies. However, too much may be a bad thing. “Knowing that an absence of something causes harm does not mean that an excess of it will prevent or undo that harm,” stated the Alzheimer’s Society of the United Kingdom website. “More importantly, it is not a good idea to take regular B vitamin supplements without advice from your doctor. There is a risk of re-activating cancerous cells with folic acid (also known as vitamin B9) and taking over 1mg of folic acid a day can mask signs of vitamin B12 deficiency.” Therefore, I’d encourage you to talk to your health care provider about what’s best your individual situation.
What you can do, though, is focus on eating a healthy diet that includes foods that are rich in B vitamins and is rich in other nutrients. Folate can be found in lentils, pinto beans, garbanzo beans, asparagus, spinach, black beans, navy beans, kidney beans, turnip greens and broccoli. While many grains, grain products and breakfast cereals are fortified, Harvard’s School of Public Health recommends avoiding foods that are heavily fortified with this nutrient. Vitamin B6 is the most common deficiency among the B vitamins in an American diet due to the consumption of processed foods. Vitamin B6 can be found in tuna, turkey, beef, chicken, salmon, sweet potatoes, potatoes, sunflower seeds, spinach and bananas. The best sources of vitamin B12 include sardines, salmon, tuna, cod, lamb, scallops, shrimp, beef, yogurt and cow’s milk.
Primary Sources for This Sharepost:
Alzheimer’s Society. (2011/2012). B is for…prevention? Living with Dementia Magazine.
Clarke, R., et al. (2014). Effects of homocysteine lowering with B vitamins on cognitive aging: meta-analysis of 11 trials with cognitive data on 22,000 individuals. The American Journal of Clinical Nutrition.
Fisher Center for Alzheimer’s Research Foundation. (2014). B vitamins fail to prevent Alzheimer’s.
Harvard School of Public Medicine. (ND). Three of the B vitamins: Folate, vitamin B6, and vitamin B12.
George Mateljan Foundation. (ND). Vitamin B6 - pyridoxine.
George Mateljan Foundation. (ND). Vitamin B12 - cobalamin.
George Mateljan Foundation. (ND). Folate.
The Free Dictionary. (ND). Homocysteine.