Majid Koozehchian, M.S.
Homocysteine (Hcy) is a non-proteinogenic amino acid (i.e., an amino acid not used in proteins) normally present in the blood. Hcy is a by-product of normal diet but high levels in the blood can endanger cardiovascular health. It is formed from methionine, a proteinogenic amino acid, and can biosynthesize back to methionine or into cysteine, another proteinogenic amino acid, as well as several other substances. Benefits of Hcy are unknown; however, its harmful effects are well-documented. Hyperhomocysteinemia (high Hcy levels in the blood) is a significant and independent risk factor for vascular disease and especially for stroke. Stroke occurs when blood is prevented from reaching certain areas of brain tissue resulting in neural damage to the brain. Stroke can cause loss of abilities such as speech, movement, and memory. Elevated Hcy levels are associated with a higher risk of stroke. Some physicians believe that Hcy levels should be as routinely monitored as checking cholesterol. An Hcy test (a simple blood test) is an outstanding way to determine a person’s vascular health. Hcy levels can be an important diagnostic method, as well as a lifesaving tool, especially for people with a high risk of stroke.
The effects of hyperhomocysteinemia can lead to 12-14 times higher risk of stroke compared to other cardiovascular risk factors, according to some research results. (1)(2)(3)
Treatment of Hyperhomocysteinemia
Fortunately, hyperhomocysteinemia can be (and should be) treated with vitamin supplementation. The most influential vitamin used to lower Hcy levels is folate (or vitamin B9). Recent research indicates a decline in Hcy levels with folate supplementation. The combination of folate and vitamin B12 results in more decline of Hcy levels than folate alone. Although vitamin supplementation can lower Hcy levels, currently there are insufficient data on the effectiveness of vitamin supplementation for reducing risk of venous/arterial thrombotic problems.
Homocysteine and exercise
The impact of physical activity on Hcy levels is unclear. In some studies, regular aerobic exercise was associated with lower hyperhomocysteinemia. For example, an inverse relationship has been shown between Hcy levels and exercise in stroke survivors. On the other hand, the results of other studies indicate that endurance exercise may cause a significant Hcy increase, which is most probably determined by the duration and intensity of exercise.
Dietary Sources and Recommended Daily Allowance (RDA) for Folate
The consumption of folate (vitamin B9) does not reduce the effects of cardiovascular disease, even though it lowers Hcy levels. Fruits and vegetables, whole grains, beans, breakfast cereals and grain products are excellent sources of folate. People should avoid foods that are heavily fortified with folic acid, if they take a multivitamin containing folic acid.
Results of some studies indicate that at least 0.35-0.4 milligrams/day of folate is required to maintain Hcy levels in the normal range. The RDA for folate is 2 milligrams/day, but physicians recommend 3.5 milligrams/day to prevent arteriosclerosis, among older adults.
In summary, Hcy can be related to the early development of cardiovascular disease. Hyperhomocysteinemia can cause a medical emergency called stroke, which results in loss of abilities such as speech, movement, and memory. There is an inverse relationship between Hcy levels and exercise in stroke survivors; however, the findings on the effects of exercise on Hcy are controversial. High Hcy levels are associated with low levels of vitamins B6, B12, and folate.
Further related information about homocysteine and exercise:
- Mishra PK, Awe O, Metreveli N, Qipshidze N, Joshua IG, Tyagi SC. Exercise mitigates homocysteine - beta2-adrenergic receptor interactions to ameliorate contractile dysfunction in diabetes. Int J Physiol Pathophysiol Pharmacol 2011;3(2):97-106. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3134004/pdf/ijppp0003-0097.pdf
- Boreham CA, Kennedy RA, Murphy MH, Tully M, Wallace WF, Young I. Training effects of short bouts of stair climbing on cardiorespiratory fitness, blood lipids, and homocysteine in sedentary young women. Br J Sports Med 2005 Sep;39(9):590-593. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1725304/pdf/v039p00590.pdf
- Vermeulen EG, Stehouwer CD, Twisk JW, van den Berg M, de Jong SC, Mackaay AJ, et al. Effect of homocysteine-lowering treatment with folic acid plus vitamin B6 on progression of subclinical atherosclerosis: a randomised, placebo-controlled trial. Lancet 2000 Feb 12;355(9203):517-522. http://ac.els-cdn.com/S0140673699073912/1-s2.0-S0140673699073912-main.pdf?_tid=db139b40-f730-11e3-987a-00000aacb35f&acdnat=1403127675_a375bacdeb41bd14a59ed2101f7d84f7