Smoking, Nutrition and Supplements

A single puff on a cigarette introduces more than 10¹⁵ (a thousand trillion or 1,000,000,000,000,000) free radicals and other oxidants into the smoker's lungs. This produces oxidative stress in the respiratory and circulatory systems and depletes the supply of antioxidants. Smoking one cigarette neutralizes the equivalent amount of vitamin C contained in a medium sized orange, about 25 mg. In addition, ascorbate concentrations in the blood of smokers are only 40-45% of that in non-smokers.

When free radicals interact with DNA, mutations can occur which affect the cell cycle and can cause a malignancy.

Cigarette smoke is the leading cause of emphysema. Several mechanisms have be proposed as the cause of emphysema. One theory is that the oxidants in cigarette smoke reduce the antioxidants in the lung and cause oxidative injury to lung tissue, which in turn produces emphysema. Another view is that benzo(a)pyrese, a chemical found in cigarette smoke, causes vitamin A depletion in the lung an liver. Since vitamin A protects and promotes synthesis of elastin, the reduction of vitamin A results in the breakdown of elastin, a key feature in developing emphysema.

People whose diets are rich in fruits and vegetables have a lower risk of getting cancers of the colon, mouth, pharynx, esophagus, stomach, and lung, and possibly prostate cancer. They are also less likely to get diabetes, heart disease, and hypertension. A diet high in fruits and vegetables helps to reduce calorie intake and may help to control weight.

Historically, most cancer researchers concentrated on exposure to potential carcinogens as cancer risk factors. Today, many believe dietary deficiencies could be a more important cancer risk. This connection between diet and cancer is heightened as more research is done to associate micronutrient deficiencies with DNA damage. Perhaps the most convencing evidence for this relationship is the association of increased cancer risk with low intake of fruits and vegetables.

To help prevent cancers and other chronic diseases, experts recommend 4 to 13 servings of fruits and vegetables daily, depending on energy needs. This includes 2 to 5 servings of fruits and 2 to 8 servings of vegetables, with special emphasis on dark-green and orange vegetables and legumes.

The quarter of the population who consume the lowest levels of fruits and vegetables have about twice the cancer rate as the quarter of the population consuming the most fruits and vegetables.

While the recommend intake is 4 to 13 services of fruits and vegetables, the Centers for Disease Control 2005 survey of 347,278 people from all 50 states indicated that only 32.6% of the U.S. adult population surveyed consumed fruit two or more times per day, and 27.2% ate vegetables three or more times per day. A number of studies indicate that smokers prefer foods containing saturated fat and found fruit and fruit juices unpalatable.

Antioxident nutrients such as vitamin A, vitamin C, vitamin E and polyphenol antioxidants (found in phytonutrient foods) play a role in defense against free radicals.

Avoiding tobacco smoke, increasing fruit and vegetable intake, and controlling infections are important factors in reducing rates of cancer. Additional positive actions to reduce cancers include limiting intense exposure to the sun, increasing physical activity, reducing alcohol use, and reducing consumption of red meat.

Vitamin C

Vitamin C (ascorbic acid) is a major free radical scavenger and a workhorse of antioxidant defense. Vitamin C is a water soluble antioxidant that scavenges free radicals in the cytoplasm, the watery fluid that "fills" most cells. Approximately 50% of the US population over age 20 get only 50% of the Recommended Daily Allowance (RDA) while 25% consume less than half the RDA.

Smoking causes a reduction in blood plasma ascorbate levels. Since damage to organs in smokers is generally thought to be caused by free radicals generated in tobacco smoke, defense against free radicals is compromised by smoking.

Research has found that adults exposed to environmental tobacco smoke (passive smoking) also suffered significant reductions in blood ascorbate levels. But, supplementation with 3,000 mg of vitamin C was sufficient to prevent the expected drop due to passive smoking.

Smokers eat significantly fewer fruits and vegetables than do non-smokers, and their intake of vitamin C is lower than that of non-smokers.

But, regardless of vitamin C intake, blood levels of vitamin C have been found to be 24% lower in smokers compared to never smokers. For 7.4% of smokers, blood levels of vitamin C were considered to be at high risk for clinical vitamin C deficiency (severe hypovitaminosis C), compared to 1.9% of non-smokers. In addition, another 19.7% of smokers were at marginal risk of hypovitaminosis C compared to 8.2% of non-smokers.

One study found that after all subjects ingested very large daily doses (2,000 mg) of vitamin C the plasma concentrations of smokers equaled that of non-smokers. However, the amount of excess vitamin C excreted in the urine of smokers was significantly lower than that of non-smokers, indicating increased metabolism or destruction of vitamin C in smokers.

Some studies suggest that a smoker would need to take 200 mg of vitamin C per day to equal the protection afforded by 60 mg for a non-smoker. Other studies suggest that smokers require twice the recommended daily requirement of vitamin C. A recent study indicated that 50% of male and 30% of female smokers are not getting enough vitamin C.

Beta-Carotene

Beta-carotene is fat soluble and is carried by lipoproteins in the blood. It is a pro-vitamin A carotenoid that can be converted to retinol in the intestines. The poorer the level of vitamin A, the more beta-carotene is converted to retinol.

Beta-carotene scavenge free radicals and helps prevent oxidation of LDL which helps prevent cardiovascular disease. People with high intake and blood plasma concentrations of beta-carotene appear to have lower risks of cancer.

Beta-carotene is available in fruit and dark green and yell-orange vegetables.

Beta-carotene Plasma Concentrations Studies have shown that heavy smokers (20 or more cigarettes per day) or long time smokers (10 or more years) have significantly lower plasma concentrations of beta-carotene than non-smokers. Heavy or long time smokers showed beta-carotene concentrations from 49.3% to 83% of that of non-smokers. This lower concentration is believed to be due to metabolic or inflammatory effects of smoking rather than from poor diet.

Intake of beta-carotene in smokers is not as efficient as for non-smokers. Researchers found that per unit intake of beta-carotene, smokers plasma concentration increased only a quarter of that of non-smokers. This, they believe is due to one or more factors:

Poor absorption in smokers
Beta-carotene was being removed because of the increased concentration of free radicals introduced by tobacco smoke
Lower concentrations of vitamin A required more beta-carotene be converted to retinol
Inflammatory response to tobacco smoke's free radical damage required more beta-carotene to engage the free radicals

The lower concentration of serum beta-carotene typically found in smokers indicates that increased dietary supplies may be needed. While increased dietary intake appear to be safe, studies have found that high dose beta-carotene supplements may be associated with increased rates of lung cancer in smokers. This increased risk may be due to the instability of the beta-carotene molecule in a free radical rich environment and may bioactivate carcinogenic enzymes in smoker's lungs.

Smokers should probably not take beta-carotene supplements, but rather improve their diet to include fruits and dark green and yell-orange vegetables.

Vitamin E

Vitamin E works to scavenge free radicals in cell membranes. When lipid (such as triglycerides) concentrations in the blood increase, tocopherol (a form of vitamin E) leaves the cell membranes to go into circulation. About 1% of the total body tocopherol is found in the blood; the major reserve being in the cells. Vitamin E helps prevent lipid peroxidation and thus prevents oxidative deterioration of polyunsaturated fatty acids which would cause a disruption of cell function.

Studies of the blood plasma concentration of vitamin E have shown a potential difference between smokers and non-smokers related to age. Smokers and non-smokers less than 35 years of age seem to show little or no difference in plasma concentration. In subjects older than 35 years of age, smokers showed significantly lower vitamin E plasma concentrations. And, among older smokers, plasma concentrations declined as the number of pack years (cigarettes smoked per day x years smoked) increased. The longer you smoke, the more significant are the differences in plasma concentrations.

Cigarette smoking depletes vitamin E and other antioxidants. While cellular reserves of vitamin E are typically adequate, vitamin E supplementation in older smokers may be beneficial.

Vitamins B₁₂, B₆ and B₉ (Folic Acid)

Half the US population consumes less than the RDA for vitamin B₆ and 10% of the adult population consume less than half the RDA for B₆. Consumption of vitamin B₁₂ is better with only 25% of adult women and 10% of adult men consuming less than the RDA.

Homocysteine is a risk factor for coronary heart disease and cardiovascular disease in general. Folic acid and viatmins B₁₂ and B₆ help regulate homocysteine and thus, help prevent cardiovascular disease. Vitamin deficiencies of B₆ and B₁₂ may be risk factors of adult acute lymphocytic leukemia.

To make matters worse, ingredients in tobacco smoke (organic nitrites, nitrous oxide, cyanates, and isocyanates) interact with folate and vitamin B₁₂ to make them biologically inactive. This inhibits their effectiveness is regulating homocysteine.

Folate helps in the production and maintenance of new cells and is especially important during pregnancy. Lack of folate is a significant predictor of low birth weight.

Lack of folic acid can lead to chromosome breaks. Lymphoid cells may have higher folate requirements, and there be more susceptible to folate deficiency and DNA damage than cells originating in the bone marrow (myeloid). This may be a risk factor in adult acute lymphocytic leukemia.

Folate deficiency is common in people who eat few fruits and vegetables. This deficiency can cause chromosome breaks in human genes.

Folic acid is required for DNA synthesis. Lack of sufficient folic acid can lead to breaks in DNA through incorporation of excess uracil. The federal government in 1996 required that grain-based foods in the United States be fortified with folic acid as the most effective method to increase folate intake in middle-aged and older people as well as for women of child bearing age. This supplementation has resulted in a 20% decrease in neural tube defects in live births in the United States.

Exposure to tobacco smoke is associated with both lower dietary folate intake and suppressed blood serum folate concentrations (even after taking lower consumption into account). A study of pregnant inner city African American women found that 57% had lower levels of serum folate than recommended and both maternal smoking and exposure to the father's second hand smoke were associated with lower serum folate levels.

The major dietary source of vitamin B₆ and folate is liver. Folate is also found in green vegetables. In a recent study of women in Spain, intake of folate was found to be significantly lower among smokers than for non-smokers. But, both groups had intake below the US recommended daily level.

In general, smokers should ensure that their dietary intake of these B vitamins provides adequate protection from adverse health consequences of tobacco smoke's effects.

Other Nutrients

In one study of rats exposed to cigarette smoke (20 cigarettes per day, 5 days per week for 6 weeks) found significantly reduced levels of vitamin A (retinol) in their blood, lungs and liver. In addition, clear signs of emphysema were seen in their lungs.

Selenium helps prevent cancer and cardiovascular disease. Studies generally find lower blood plasma concentrations of selenium in smokers. In a study of 100 Bangladeshi men admitted to a hospital for heart disease, those who smoked more than 10 cigarettes a day had a quarter of the selenium concentration of non-smokers.

The Nutritional Prevention of Cancer Trial found that a daily supplement of 200 μg of selenium was associated with significantly lower rates of all cancer and specifically, prostrate cancer in former smokers. Although the risks of cancer were also found to be lower for current smokers, they were not significantly lower.

References

Bruce N Ames; Cancer prevention and diet: Help from single nucleotide polymorphisms; Proceedings of the National Academy of Scienes; 96(22); 12216-12218.
Christine F Skibola, Martyn T Smith, Elenor Kane, Eve Raoman, Sara Rollinson, Ramondy A Cartwright & Gareth Morgan; Polymorphisms in the methylenetetrahydrofolate reductase gene are associated with susceptibility to acute leukemia in adults; Proceedings of the National Academy of Scienes; 96(22); 12210-12215.
Ting Li, Agusto Molteni, Predrag Latkovich, William Castellani & Richard C Baybutt; Vitamin A Depletion Induced by Cigarette Smoke is Associated with the Development of Emphysema in Rats; Journal of Nutrition, 133(8), 2629-2634.
Alan M Preston, Cindy Rodriguez, Cynthia E Rivera & Hardeo Sahai; Influence of environmental tobacco smoke on vitamin C status in children; American Journal of Clinical Nutrition, v 77, 167-172.
Gordon Schectman, James C Byrd & Harvey W Gruchow; The Influence of Smoking on Vitamin C Status in Adults; American Journal of Public Health, 79(2), 158-162.
Christine A Northrop-Clewes & Davit I Thurnham; Monitoring micronutrients in cigarette smokers; Chinica Chimica Acta, 377, 14-38.
Ken D Stark, Robert J Pawlosky, Skadi Beblo, Mahadev Murthy, Vincent P FFlanagan, James Janisse, Michelle Buda-Abela, Helaine Rockett, Jamice E Whitty, Robert J Sokol, JJohn H Hannigan & Norman Salem Jr.; Status of plasma folate after folic acid fortification of the food supply in pregnant African American women and the influences of diet, smoking, and alcohol comsumption; American Journal of Clinical Nutrition; v 81; 669-677.
Bruce N Ames & Patricia Wakimoto; Are Vitamin and Mineral Deficiencies a Major Cancer Risk?; Nature Reviews; v 2, September 2002; 694-704.

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