Oxnard - Port Hueneme Optometry  Dr. Don Steensma 465 W. Channel Islands Blvd, Port Hueneme, CA 93041  805/486-3585

Smoking and the eye

Age Related Macular Degeneration (ARMD) is a leading cause of blindness. It is 6 times more common in smokers than non-smokers and we really are not sure why, but it may be related to an increase in free radicals,  Free radicals are organic atoms that have lost an electron.  They are very unstable, short-lived, and highly reactive.  As they steal an electron from another atom they start a chain reaction that alters molecules damaging tissues.  Antioxidants, are molecules that prevent free radicals from harming healthy tissue.  Vitamin E, beta-carotene (a pre-cursor to vitamin A), and vitamin C are the most common antioxidants.

Vitamin A is an essential vitamin which is necessary to maintain good health. Vitamin A is essential for good vision, but has a number of other important functions as well. Vitamin A is necessary for the growth of healthy bones and teeth, normal immune system function and reproductive function. It also helps maintain the health of the lining of the eyes, respiratory function and digestion. It is required for normal embryonic development.

Vitamin A precursors such as beta-carotene and other carotenoids are powerful antioxidants. Other antioxidants include zinc, selenium, manganese, and copper. They neutralize free radicals which can damage DNA and contribute to age-related eye disease (macular degeneration), heart disease (coronary artery disease) and cancer.  The antioxidant properties of beta-carotene and other carotenoids are highest when obtained from foods.  There seems to be a significant is less evidence for antioxidant benefit from high dose beta-carotene as a dietary supplement. This difference between foods and dietary supplements actually may be due to the presence of other compounds in fresh fruits and vegetables called phytochemicals.

One study showed that 20,000 IU supplemental beta-carotene and other antioxidants in a dose typical of a good diet decreased the incidence of cancer by 31% and reduced death rates from all causes by 37%.   Other studies suggest beta-carotene from food may be safer than synthetic beta-carotene found in dietary supplements.  Contrary to prior beliefs that high dose beta-carotene and vitamin A supplementation guard against some types of cancer and heart disease, recent studies suggess potential harmful effects. The Beta-carotene and Retinol Efficacy Trial (CARET) performed by the National Cancer Institute (NCI) showed that 30 mg (100,000 IU) of beta-carotene and 25,000 IU vitamin A failed to decrease the risk of cancer or heart disease.

The study was stopped 21 months early because the beta-carotene/vitamin A takers who were smokers, ex-smokers or asbestos workers had a 28% increase of lung cancer  and a 17% more likely chance of dying.

Another study in 1994 showed that smokers taking 20 mg beta-carotene per day had an 18% higher risk of lung cancer and an 8% higher risk of dying from lung cancer or heart disease.   A 12-year Physicians’ Health Study taking 50 mg (166,667 IU) of beta-carotene every other day in 22,000 non-smoking men showed no benefit or risk.

Almost all multi-vitamins (Centrum, Centrum Silver, etc.) contain Vitamin A. I would suggest that all smokers, ex-smokers and second-hand-smokers should reconsider their use of these products.

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