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Q: I hear the word ‘carotenoids’ a lot in conjunction with healthy eating. What are they exactly? What’s the best way to make sure I’m getting enough? —Stuart S., Austin, Texas
A: Carotenoids are the most abundant naturally occurring pigments in nature, found in many colorful foods. Plants have the incredible capacity to turn sunlight into sugar (biochemical energy), but this process generates a great deal of free radicals. Carotenoids are not only critical for the process of photosynthesis, but also for helping mitigate free-radical damage.
One carotenoid, carotene, turns into vitamin A, a pro-hormone, when split in two. Supplementing with carotenes (beta-carotene is the most important) has never been shown to cause harm, but too much vitamin A can be dangerous in pregnancy. Women who could become pregnant should avoid doses higher than 5,000 IUs daily. Otherwise, higher doses under a physicians supervision can help a wide range of health problems, including infertility, bumpy skin, irritable mucous membranes, and various vision and viral problems.
Carotenoids Food Sources
Pro-vitamin A carotenes abound in yellow-orange veggies (carrots, sweet potatoes, yams, and squash) and dark leafy greens (collards, spinach, and kale). The yellow color is covered up by chlorophyll in green leafy plants.
Vitamin A itself is found only in animal foods, especially liver and egg yolks, and this is the only type of vitamin A (called retinol) that your body can use directly. Carotenoids must be converted by the body to vitamin A, and this requires healthy digestive function, including good blood sugar regulation. Diabetics have difficulty forming vitamin A from carotenoids, as do alcoholics and people with pancreatic, gallbladder, or liver diseases. Healthy folks, on the other hand, should have no problem converting carotenoids from a plant-based diet to vitamin A.
It’s always better to supplement with natural food sources of carotenes and avoid synthetic vitamin A, which has been shown in some studies to reduce apoptosis (programmed cell death of old or diseased cells). Vitamin A is an important vitamin for healthy vision, immune system function, and cell growth. It works synergistically with a number of other vitamins and minerals, including vitamins D, K, and zinc, and magnesium, without which it cannot perform its functions.
Prolonged vitamin A deficiency can cause night blindness. Total blindness from vitamin A deficiency is rare in the U.S., but it’s the most common cause of blindness in Asia. Lack of vitamin A also causes dry eyes due to loss of moisture-producing cells (goblet cells) and a buildup of keratin, which is similar to vitamin A deficiency skin problems. Applying drops of vitamin A directly to the eyes at bedtime can reverse these cellular changes.
Vitamin A and carotenoids are well known for helping vision, but they’re also key for overall cell development (especially mucosal cells), and are critical for reproduction. Sometimes an infertile but otherwise healthy woman simply needs a high-carotenoid diet for three months to promote conception. Otherwise, vitamin A supplementation can be done under the supervision of your healthcare provider.
The female human egg has the highest concentration of beta carotene of any organ measured. Ovulation (an egg being released from one of the ovaries monthly) stimulates the production of progesterone, a necessary hormone for sustaining a pregnancy. An egg that doesn’t “drop” creates an ovarian cyst. Both ovarian and breast cysts can be effectively treated with vitamin A and a diet high in carotenoids.
Beta carotene and vitamin A are key for immune support, especially against viral illnesses, including hepatitis, measles, chicken pox, AIDS, Epstein Barr, and HSV (which causes cold sores and herpes outbreaks). Vitamin A deficiency may increase susceptibility to these illnesses (often acquired in childhood), but the illnesses also deplete vitamin A, creating a vicious cycle of illness that can be reversed.
A diet rich in natural orange and yellow pigments enhances thymus gland function and increases interferon’s stimulatory effect on the immune system. Interferon is a naturally produced substance that has been mimicked in the pharmaceutical world to make antiviral medicines. The thymus gland is responsible for maturing “B” cells (made in bone marrow) into more highly specialized white blood cells—the “T” cells that gobble up foreign or diseased material in our blood and tissues.
Mental Health & Longevity
Because antioxidant flavonoids, which are part of carotenoid chemistry, help improve blood flow in the brain, there is preliminary evidence that a high carotenoid diet may enhance cognitive function. The onset of certain chronic neurodegenerative diseases, including age-related dementia and Alzheimer’s disease, may be delayed when long-term intake of flavonoids has been strong. Tissue carotenoid content has been shown to be a significant factor in determining healthy longevity (MLSP, or maximal lifespan potential) in mammals. Human MLSP of approximately 90 years correlates with a serum carotene level of 50–300 mcg/dL, while other primates, such as the rhesus monkey, have a MLSP of about 34 years, correlating with a serum carotene level of 6–12 mcg/dL.
Prolonged vitamin A deficiency can cause hyperkeratosis (skin bumps, often on the backs of the upper arms). The most successful acne treatment involves various doses of a vitamin A analogue (retinoic acid) applied topically. Retinoic acid is a prescription item in the U.S., but taking vitamin A supplements (up to 10,000 IUs daily) will also enhance healthy skin turn over.
The bottom line? Eat colorful fruits and veggies every day, especially the yellow, orange, and dark green ones. You’ll boost your carotenoid intake, and live a longer, healthier life.