Deficiency of the B vitamin folic acid (folate) is believed to be one of the most widespread deficiency conditions in the Western world. Only a few people eat enough green vegetables (2-300 gram) to achieve the recommended intake of 0.3 mg folic acid daily. In the USA 0.4 mg per day is recommended and grain products are fortified with folic acid by government mandate.
Most women know that they should take folic acid (o.4 mg per day) when planning a pregnancy to avoid giving birth to a child with a neural tube defect. Fewer know that there is a lot of evidence which indicates that folic acid also prevents atherosclerosis and some forms of cancer.
Many studies have indicated that folic acid also prevents Alzheimer’s dementia. Lately, the first issue of a newsletter from the American scientific Alzheimer’s association was came forth with an especially solid result: elderly people who have received at least the recommended 0.4 mg folic acid daily, have less then half the Alzheimer’s rates as those who do not!
If this is not just a statistical coincidence, the importance is enormous. One out of every five people get Alzheimer’s sooner or later, and not many receive the possibly protective 0.4 mg folic acid daily. Almost all (87%) of them who reached the end of the American study took vitamins as supplements.
This find is supported by others, but it must be emphasized that it only shows a connection, not an underlying reason. On the other hand it is easy to picture a cause and effect relationship. Alzheimer’s is caused by deposits in the brain of a substance called beta-amyloid which is so poisonous to the brain cells that they can die. With folic acid deficiency, the body’s content of the just as harmful substance homocystein increases. This can be thought to strengthen the poisonous effects of beta-amyloid. This is actually supported by animal studies.
Another explanation has to do with folic acids significance in the so called carbon-one metabolism. Folic acid is, together with vitamin B12, responsible for the delivery of very small biochemical building blocks, the so called methyl groups which contain a carbon atom. These small building blocks are used in the construction of the many proteins as well as DNA. Lack of folic acid could therefore hinder the mechanisms which are normally responsible for stopping the build up of beta-amyloid. This is also supported by scientific studies.
The production of beta-amyloid with the resulting destruction of brain cells is a complicated process where enzymes, DNA, proteins which reduce cholesterol, free radicals, etc. play a role.
This is mirrored in the American Alzheimer’s Association’s very general advice to those who want to avoid Alzheimer’s: Stay mentally and physically active, eat low fat foods, hold cholesterol levels down, and eat a lot of dark fruits and vegetables.
It is in these vegetables and fruits where folic acid can be found. The new insight, given with some restraint, is that folic acid plays a much more direct role as a preventative factor.
References:
- Corrada MM. et al. Alzheimer’s & Dementia. 2005;1:11-18.
- Fuso A. et al. S-adenosylmethionine/homocysteine cycle alterations modify DNA methylation status with consequent deregulation of PS1 and BACE and beta-amyloid production. Mol Cell Neurosci. 2005 Jan;28(1):195-204.
- Quadri P. et al. Homocysteine, folate and vitamin B12 in mild cognitive impairment, Alzheimer disease aqmd vascular dementia. Am J Clin Nutr 2004,80:114-22.
