Gastric Cancer and Vitamin A
In a recent study published in the American Journal of Clinical Nutrition, researchers found that higher levels of vitamin A intake were associated with lower rates of gastric cancer.
Specifically, researchers, in an observational cohort study, looked at vitamin A consumption through both food and supplements, and noted that:
[H]igh intakes of vitamin A and retinol from foods only (dietary intake) and from foods and supplements combined (total intake) and of dietary alpha-carotene and beta-carotene were associated with a lower risk of gastric cancer.
The reduction in gastric cancer risk ranged from 45 to 50 percent.
Vitamin A - Forms & Functions
There are three biologically active forms of vitamin A:
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retinal
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retinol
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retinoic acid
Retinal is primarily derived from beta-carotene, one of the plant pigments (carotenoids) found in foods such as carrots, spinach, yams, etc. It can be converted in the body into retinol in a reversible reaction and into retinoic acid in an irreversible reaction. Retinal plays an important role in vision.
Retinol is found only in animal products, such as liver, cod liver oil, and milk. It can also be created through conversion from retinal in a reversible reaction. Retinol plays important roles in reproduction and growth.
Retinoic acid is derived from retinal in an irreversible reaction and plays important roles in gene expression and growth.
Suspected Vitamin A Role in Gastric Cancer
Vitamin A (primarily retinoic acid and retinol) is key in controlling cell differentiation and proliferation, two activities that go awry in cancer. Vitamin A helps to:
- control protein synthesis and differentiation of epithelial cells that line the body’s surfaces, such as the skin and the linings of the mouth, stomach, and intestines.
- regulate differentiation of goblet cells that produce mucus that coats and protects the epithelial cells from both bacteria and potentially harmful substances, such as gastric juices.
Vitamin A also influences immune system function, and helps to ensure proper T-cell response and natural killer cell activity, both critical in helping to prevent cancer from developing.
Clearly, it’s important to ensure adequate intake of all vitamin A forms, from both food and potentially supplements, to help reduce gastric cancer risk.
