Vitamin void: heart disease may lurk in [B.sub.12] deficiency. (Science news: this week).Meatless eating typically improves cardiovascular health, but new research suggests that a dietary shortage of a crucial vitamin leads to an overabundance o·ver·a·bun·dance
A going or being beyond what is needed, desired, or appropriate; an excess: teenagers with an overabundance of energy. of the amino acid amino acid (əmē`nō), any one of a class of simple organic compounds containing carbon, hydrogen, oxygen, nitrogen, and in certain cases sulfur. These compounds are the building blocks of proteins. homocysteine Homocysteine Definition
Homocysteine is a naturally occurring amino acid found in blood plasma. High levels of homocysteine in the blood are believed to increase the chance of heart disease, stroke, Alzheimer's disease, and osteoporosis. in some vegetarians, which could pose a risk to their hearts.
A high homocysteine concentration in blood is associated with an elevated risk of heart disease. In past studies, people who have a homocysteine concentration of 15 micromoles per liter ([micro]mol/l) in their blood while fasting have a 60 to 80 percent greater risk of cardiovascular disease than do study volunteers with 10 [micro]mol/l, a more typical concentration.
Metabolic processes continually derive homocysteine by converting another amino acid, methionine methionine (mĕthī`ənēn), organic compound, one of the 20 amino acids commonly found in animal proteins. Only the L-stereoisomer appears in mammalian protein. , and also reconvert re·con·vert
intr. & tr.v. re·con·vert·ed, re·con·vert·ing, re·con·verts
To undergo or cause to undergo conversion to a previous state or condition. homocysteine into methionine. The latter reaction requires several essential nutrients, including vitamins [B.sub.6] and [B.sub.12]. Deficiencies of these vitamins, therefore, can result in a buildup of homocysteine.
Since these B vitamins are abundant in many animal products but not in fruits or vegetables, vegetarians may not get enough of them unless they eat vitamin-fortified foods or take dietary supplements.
To test whether some vegetarians come up short on B vitamins, a team of eight researchers from three Taiwanese universities measured concentrations of several vitamins and amino acids in the blood plasma of 90 women--half of them vegetarians--from Hualien, Taiwan.
The vegetarians had an average plasma-homocysteine concentration of 11.2 [micro]mol/l when fasting, compared with a value of 8.64 [micro]mol/l among the women who regularly ate animal products. The vegetarians also had only about half as much vitamin [B.sub.12] in their blood as the others did.
Vitamin [B.sub.12] deficiency was highly predictive of elevated plasma homocysteine among the vegetarians. The researchers, led by Hsu-Fang Chou of Tzu-Chi University in Hualien, report their findings in the February Journal of Nutrition.
A proper vegetarian diet could remedy any potential deficiencies, suggests Ella Haddad of Loma Linda University Founded in 1905, Loma Linda University (LLU) is a private, Christian, coeducational, health sciences university located in Southern California 60 miles east of Los Angeles close to San Bernardino and near beaches, mountains, and the desert. in California. She and her colleagues previously reported that American vegetarians have lower, not higher, plasma homocysteine than their omnivorous omnivorous
eating both plant and animal foods. counterparts. Haddad attributes this, in part, to the fact that U.S. vegetarians and vegans, who avoid all animal products, "consume more vitamin [B.sub.12] [from fortified fortified (fôrt´fīd),
adj containing additives more potent than the principal ingredient. foods] and generally show higher blood levels of the vitamin" than the Taiwanese study participants do.
Nevertheless, says Haddad, the new finding emphasizes that "vegetarians should make sure they eat a regular and reliable source of vitamin [B.sub.12], either from fortified food, supplements, or both."