The root of the word “tuberculosis” is, in fact, “root” — or “tuber,” the Latin term for the underground structure which stores and supplies the plant with nutrients it needs to survive.  One nutrient — vitamin A — supplied lavishly by the root tuber sweet potato, is receiving attention as a potentially powerful weapon in the fight against tuberculosis itself.

Every year, roughly two million people die from tuberculosis (or TB) — an infectious disease typically affecting the lungs.  Classic symptoms include chronic cough, fever, and weight loss (which is why sufferers were historically said to be afflicted with “consumption”).  While new cases of TB were thought to be in decline, recent high profile outbreaks in Los Angeles and London have once again raised concerns of a potential epidemiological “ticking time bomb” of a drug-resistant strain of the disease.  This prospect underlines the need — not just for new treatment options — but for preventive measures as well.

Diet, of course, is the best prevention particularly when it comes to strengthening the first line of immune defense.  In a recent issue of the Journal of Immunology, UCLA researchers exploring the role of nutrition in bolstering the body’s natural immunity found that all-trans retinoic acid, a metabolite of vitamin A, possesses unique potential in fighting TB.  How?  By attaching to the TB supply chain, in a sense.  These bacteria rely on cholesterol for nutrition and other needs.  “If we can reduce the amount of cholesterol in a cell infected with tuberculosis,” observed the study’s senior author, Philip Liu, PhD, “We may be able to aid the immune system in better responding to the infection.”

The research team looked at metabolites of both vitamin A (i.e., all-trans retinoic acid) and vitamin D (i.e., 1,25-dihydroxyvitamin D3), believing both metabolites might leverage the same metabolic mechanisms to aid the immune response, but only all-trans retinoic acid decreased cholesterol levels of infected human blood cells.  One important caveat: The effect relied upon expression of a particular gene (NPC2).  While more research will help clarify the interplay of genetic influences and nutrition, an overwhelming body of evidence points to the benefits of vitamin A, including healthy vision, embryonic development and reproductive health.

Where to get your vitamin A?  The aforementioned sweet potatoes supply 770% of vitamin A per one cup cooked; other sources include butternut squash (460%), carrots (430%), kale (350%), cantaloupe (110%) and mango (25%).  For a delicious way to get your vitamin A, try our featured recipe: Sweet Potato and Spinach Soup.

Published September 1, 2014