CORVALLIS, Ore. - Those who consume a vegetarian-type diet might shortchange themselves on vitamin B-6 because they could be eating foods that contain a less usable form of the vitamin.
Women are more likely than men to have a B-6 deficiency, which can weaken the immune system and make them more susceptible to heart disease.
Scientists from Oregon State University have found that some plant foods, like beans, contain as much as a third of their B-6 in the glycosylated form -a form not readily used by the body.
In the current issue of the Journal of Nutrition, OSU professors Jim Leklem and Lorraine Miller and graduate student Christine Hansen reported that the glycosylated form has a glucose molecule attached to it, so the vitamin in some plant foods is not absorbed and used efficiently.
The research was funded by OSU's Agricultural Experiment Station.
On the other hand, animal-type foods contain good forms of vitamin B. Good sources are beef, pork, turkey, chicken, tuna and salmon.
"Don't go to extremes and eat all-animal food sources. You'll miss out on other good things you need in your diet," said Leklem, a professor in the Department of Nutrition and Food Management.
Leklem, who subscribes to a variety-in-the-diet philosophy, said some good plant-food sources of usable vitamin B-6 include bananas ("the riper the better"), avocados, and nuts - especially filberts, cashews, peanuts, walnuts and pecans.
Potatoes are a moderately good source of B6, but part of it is glycosylated.
Legumes may have a lot of vitamin B-6, Leklem said, but as much as a third is in the glycosylated form. Some examples would be soybeans and pinto, garbanzo and navy beans.
Sunflower seeds are especially high in B-6; again about a third is glycosylated.
"That doesn't mean you should stop eating those foods," Leklem pointed out. "After all, they contain protein, fiber and other important B vitamins. But also make sure your diet contains other B-6 sources like meat or fruits."
Leklem, who has been studying B-6 for more than 30 years, said his recent studies focused on women because early studies dealt mostly with B-6 in men.
"We found that a woman's intake of B-6 is lower than that of men and they are often marginal in terms of B-6 status," Leklem said.
He said adequate B-6 levels, which can be determined by blood tests, are important for these reasons:
-To make efficient use of proteins (amino acids) in the body. "The more amino acids you take in, the more B-6 you need," Leklem said.
-To form blood cells.
-To maintain a good immune system.
Athletes and other active persons need B-6 to break down glycogen, the chief form of carbohydrate storage in the body.
Leklem said B-6 also works with folic acid to break down the amino acid homocysteine. That's important, he said, because too much homocysteine can lead to heart disease.