A study from the University of Milan shows the potential protective effect of vitamin B6 (pyridoxine) in the prevention of deep-vein thrombosis. Blood clots in the legs (deep-vein thrombosis) are a major cause of pulmonary embolism – a condition in which a blood clot lodges in the pulmonary artery. Pulmonary embolism is a very serious disorder that kills about 200,000 American every year. One of the main causes of vein thrombosis is immobilization, that is, lying or sitting still for extended periods of time. The condition is often found in hospitalized patients and, to an increasing degree, in long-distance air travel passengers particularly those crammed into economy class; hence the term "economy class syndrome". Several studies have shown that deep-vein thrombosis (DVT) is associated with a high blood level of homocysteine, a sulfur-containing amino acid also implicated in the development of atherosclerosis. Researchers at the University of Milano now confirm this connection with a new study that also clearly shows the potential protective effect of vitamin B6 (pyridoxine). The researchers compared blood levels of homocysteine, folic acid, vitamin B6, and vitamin B12 in 397 patients with previous DVT and 585 matched healthy controls. After adjusting for confounding variables they determined that the incidence of DVT was twice as high among the participants with high homocysteine levels as among those with lower levels. There was no association between DVT incidence and blood levels of folic acid and vitamin B12. The association between low levels of vitamin B6 and an increased risk of DVT was, however, quite strong. The participants with low vitamin B6 levels (less than 33.2 nanomol/L of pyridoxal-5'-phosphate[PLP]) had twice the risk of developing DVT than did people with PLP levels above 46.5 nanomol/L. The researchers point out that vitamin B6 supplementation has been found to inhibit platelet aggregation and prolong bleeding time as well as protecting against heart attacks and atherosclerosis. Further studies are underway to determine if vitamin B6 supplementation can help prevent DVT.
Cattaneo, M., et al. Low plasma levels of vitamin B6 are independently associated with a heightened risk of deep-vein thrombosis. Circulation, Vol. 104, November 13, 2001, pp. 2442-46