[Fine Chemicals] Nutrition 101 Part 6 — Vitamins (Part 2)

[Fine Chemicals] Nutrition 101 Part 6 — Vitamins (Part 2)

Vitamin B6 plays important physiological roles in the body. For example, it acts as a coenzyme in the metabolism of amino acids, glycogen, and fatty acids, making it indispensable for nutrient metabolism.

Vitamin B6 also helps maintain nervous system function and is involved in synthesizing the neurotransmitter serotonin, so it plays a fairly important role in mood regulation. It also promotes hemoglobin synthesis and helps convert tryptophan into niacin.

In addition, vitamin B6 lowers cardiovascular disease risk by reducing plasma homocysteine levels.

What is homocysteine? Homocysteine, also called HCY, is an intermediate product of methionine and cysteine metabolism. When blood levels of folate, vitamin B6, and vitamin B12 are low, plasma homocysteine tends to be high, which damages the vascular endothelium and raises blood pressure.

Hyperhomocysteinemia is an independent risk factor for hypertension and coronary heart disease and is extremely harmful to health. That's why more and more clinical tests now measure blood homocysteine as a cardiovascular risk marker, and supplementing vitamin B6, vitamin B12, and folate really does lower homocysteine levels.

Which foods are rich in vitamin B6? First, sunflower seeds, legumes, meat, liver, and fish are rich sources; next come eggs, fruits, and vegetables; dairy and fats/oils are low. Vitamin B6 from animal foods is more bioavailable than from plant foods. Overall intake among Chinese people is fairly stable, so no extra supplementation is needed.

4. Vitamin B12
   Also called cobalamin, it's the only vitamin that contains a metal element. Its food distribution is easy to remember and quite distinctive. Vitamin B12 comes almost exclusively from animal foods—mainly meat, organ meats, fish, poultry, shellfish, and eggs—and is virtually absent from plant foods, so vegans are very prone to deficiency. The biggest sign of B12 deficiency is neurological damage: people feel fatigued, depressed, and have worse memory.

However, microorganisms also produce some vitamin B12 during fermentation, so fermented foods like fermented grains, bean paste, enzymes, vinegar, and soy sauce are important sources for vegans to get B12.

Also, B12 absorption requires a component called "intrinsic factor" secreted by the pyloric part of the stomach, so elderly people with low stomach acid and gastrectomy patients are also prone to B12 deficiency.

5. Niacin
   Also called nicotinic acid or vitamin PP, it's a relatively stable vitamin. In the body, besides direct intake of niacin, the essential amino acid tryptophan can be converted into niacin, which is why Chinese people are basically not deficient in niacin.

In the body, niacin in its active forms NAD+ and NADP+ acts as an electron carrier or hydrogen donor in biological redox reactions. Niacin is also a component of the glucose tolerance factor and enhances insulin action. There's also evidence that niacin has some cardiovascular protective effect.

Although people eating a normal diet won't be deficient, populations relying mainly on corn can develop pellagra (niacin deficiency), mainly because corn's niacin is in a bound form and its niacin and tryptophan content is low.