A meal of salmon accompanied by lightly steamed broccoli or asparagus and a tossed salad that includes romaine lettuce, sweet red peppers, and parsley will do a lot more than delight your palate—it will provide three B vitamins that are associated with the prevention of Alzheimer's and cardiovascular disease.
The B vitamins folate, B6, and B12 are necessary cofactors in an essential cellular process called the methylation cycle. In this cycle, all three B vitamins are used to convert a potentially damaging molecule called homocysteine into the useful amino acid cysteine. When levels of these B vitamins are low, blood levels of homocysteine rise—a situation that has been shown in numerous studies to significantly increase the risk for heart disease, and as the studies reported here suggest, may also be related to Alzheimer's.
Four studies published within the last two months suggest that homocysteine can cause the type of brain and blood vessel deterioration that leads to dementia as well as cardiovascular disease. Fortunately, homocysteine levels can be kept in check by consuming the World's Healthiest Foods rich in the B vitamins folate, B12 and B6.
Homocysteine promotes atherosclerosis by directly damaging blood vessel walls and by interfering with the formation of collagen (the main protein in connective tissue). Elevations in homocysteine are found in approximately 20-40% of patients with heart disease, and it is estimated that daily consumption of 400 mcg of folate alone would reduce the number of heart attacks suffered by Americans each year by 10%.
Since homocysteine can cause damage to the blood vessels delivering oxygen and nutrients to the brain, it's not surprising that homocysteine also appears to be a contributing factor to Alzheimer's disease and other forms of dementia.
Two of the four recent studies on this subject appeared in the May 28 issue of Neurology along with an accompanying editorial.
In the first study, Joshua W. Miller, PhD, and his colleagues at the University of California, Davis, School of Medicine, found that elevated levels of homocysteine were linked to blood vessel damage, and that having low levels of vitamin B6 in the blood was common among Alzheimer's patients, suggesting a relationship between B6, homocysteine, and Alzheimer's—although they were uncertain whether having high levels of homocysteine or low levels of vitamin B6 directly influences Alzheimer's disease onset or progression.
In the second study, Perminder Sachdev, MD, PhD, and his colleagues at Prince of Wales Hospital in Randwick, Australia, looked at the brains and homocysteine levels of 36 healthy seniors. Those with high homocysteine levels were found to be twice as likely as those with normal levels to show loss of brain cells.
These researchers were also uncertain as to the exact nature of homocysteine's role, and ended their report saying that whether the excess homocysteine actually causes the brain deterioration remains to be seen.
A third study published this June in another journal, Dementia and Geriatric Cognitive Disorders suggests that the elevated blood levels of homocysteine may be a reflection of concurrent vascular(blood vessel) disease in Alzheimer's patients.
And lastly, a fourth study, published in the May 2002 issue of Biochemical and Biophysical Research Communications may provide at least one explanation for the link between high levels of homocysteine and Alzheimer's disease.
This study shows that in Alzheimer's patients, levels of another compound, hydrogen sulfide, are severely decreased compared with the brains of healthy individuals of comparable age.
Hydrogen sulfide is involved in communication between brain cells and is also a smooth muscle relaxant—an important fact here since the interior of blood vessels is composed of smooth muscle cells, so a lack of hydrogen sulfide would result in a lessened ability of the blood vessels in the brain to dilate, and thus in a lessening of blood flow and nourishment to brain cells.
So, how does this link up to homocysteine? In the brain, hydrogen sulfide is produced from cysteine, the amino acid that homocysteine is converted into via the activity of an enzyme called cystathionine beta-synthase. This same enzyme, cystathionine beta-synthase also catalyzes another metabolic pathway in which homocysteine is used to produce cystathionine.
In some individuals, due to their genetic inheritance, this enzyme, cystathionine beta-synthase, is not produced in normal amounts and/or is not as active as it should be, so neither of its jobs—converting homocysteine into cysteine, so hydrogen sulfide can be made or producing more cystathionine, so more cystathionine beta-synthase can be produced—get done.
When this happens, not only do brain cells not get as much nourishment since blood vessels cannot dilate as well, but levels of homocysteine, which itself has been shown to directly damage blood vessel walls, build up.
Fortunately, homocysteine can also be converted into cysteine by the B vitamins, folate, B12 and B6. When an individual consumes large amounts of foods rich in these B vitamins, not only will homocysteine levels go down, but hydrogen sulfide levels can go up since the body uses cysteine to make hydrogen sulfide. This is definitely a win-win situation, particularly for those individuals whose have a genetically inherited problem with the production and activity of the enzyme cystathionine beta-synthase.
While the connections among these four studies are complex, the bottomline is not: Daily consumption of foods rich in folate, vitamin B12 and vitamin B6 may be protective not only of your heart, but your mind as well.
You can easily increase your intake of these very important nutrients by frequently enjoying the World's Healthiest Foods ranked as excellent sources of these B vitamins.
Excellent sources of folate include spinach, parsley, broccoli, beets, turnip and mustard greens, asparagus, romaine lettuce, calf's liver, and lentils.
Excellent sources of vitamin B6 include bell peppers, turnip greens, and spinach.
Excellent sources of B12 include calf's liver and snapper.
For many more ideas, click on the food(s) that appeal to you above and take a look at the "How to Enjoy" section.
For quick, easy, and truly delectable recipes featuring these B-vitamin-rich members of the World's Healthiest Foods, click on the Recipe Assistant, select any of these foods on the healthy foods list, and click on the Submit button. A list containing links to all the World's Healthiest Foods' recipes containing the food chosen will appear immediately below.
References: J. W. Miller, PhD, R. Green, MD, D. M. Mungas, PhD, B. R. Reed, PhD and W. J. Jagust, MD. Homocysteine, vitamin B6, and vascular disease in AD patients. Neurology 2002;58:1539-1541. Sachdev PS, Valenzuela M, Wang XL, Looi JC, Brodaty H.Relationship between plasma homocysteine levels and brain atrophy in healthy elderly individuals. Neurology 2002 May 28;58(10):1539-41. Nilsson K, Gustafson L, Hultberg B. Relation between Plasma Homocysteine and Alzheimer's Disease. Dementia and Geriatric Cognitive Disorders. 2002 Jun;14(1):7-12. Eto K, Asada T, Arima K, Makifuchi T, Kimura H. Brain hydrogen sulfide is severely decreased in Alzheimer's disease. Biochem Biophys Res Commun 2002 May 24;293(5):1485-8.