It’s true you can have too much of a good thing, especially when it comes to beta-carotene. Beta-carotene is a form of vitamin A, an essential nutrient. Orange skin from excessive carrot consumption is well known. But a new study has found that too much beta-carotene cancels out the benefits of vitamin A, which may lead to serious health complications.
Too much vitamin A
When the biography of Steve Jobs was released after his death, the world learned that at one time he took on a “sunset-like orange hue” from living solely on carrots. His carrot obsession may have lead to a number of other health problems.
The antioxidant beta-carotene is a plant pigment that gives color to vegetables such as carrots, sweet potatoes and certain greens. Foods and supplements are the only sources for this essential nutrient that the body converts to vitamin A. Scientists at Ohio State University have found that when beta-carotene is metabolized, other molecules are produced that can actually block vitamin A from doing its thing, like supporting vision, bone and skin health, metabolism and immune function.
Previous research found that when beta-carotene is metabolized, it is broken in half by an enzyme, which produces two vitamin A molecules. The new study found that the “anti-vitamin A” molecules are produced when beta-carotene is broken in the wrong places. Consequently, too much vitamin A results in a sufficient amount of anti-vitamin A, which interferes with the actions of this essential nutrient.
The new findings may help explain the puzzling outcome of a study conducted many years ago to test the theory that vitamin A would benefit people at high risk for lung cancer. For the study, smokers and asbestos workers were separated into groups receiving either massive doses of vitamin A or no vitamin A. The study was discontinued because the supplemented patients developed cancer at a much higher rate than the controls.
The research also has implications for efforts to bio-engineer crops in developing countries for excess beta-carotene to ensure these populations get healthy levels of vitamin A. Crops engineered for unusually high levels of vitamin A could also deliver a harmful dose of anti vitamin A.
Vitamin A toxicity
Vitamin A toxicity develops when a person takes about 25,000IU or more per day for an extended period. Symptoms include blurred vision, bone pain, headaches, diarrhea, loss of appetite, skin scaling & peeling and muscular weakness. Vitamin A toxicity often occurs when someone takes vitamin A supplements such as retinyl palmitate or retinyl acetate. This preformed vitamin A is absorbed quickly and eliminated slowly. To utilize vitamin A, the body pairs up its molecules with binding proteins. When the binding proteins are at capacity, harmful free retinol is released into the body.
Go easy on the carrots
The most well known, and perhaps least harmful, side affect of vitamin A toxicity is orange skin. People who eat too many carrots get orange skin because the extra beta carotene is stored in fat under the skin. Laying off the carrots for a couple of weeks will solve the problem.