Nutrition Diet: Which vitamins should smokers avoid?

October 21, 2025 •

5 min read

While antioxidants are often praised for their health benefits, research shows a concerning link between high-dose antioxidant supplements and increased cancer risk in those who smoke. This is why knowing which vitamins should smokers avoid is critically important for dietary safety and overall health.

Quick Summary

High-dose supplements of beta-carotene, vitamin A, and potentially vitamin E have been linked to increased lung cancer risk in smokers. This effect is not seen when getting these nutrients from whole foods and highlights a critical difference between synthetic and dietary sources.

Key Points

Avoid Beta-Carotene Supplements: High-dose synthetic beta-carotene dramatically increases lung cancer risk in current and former smokers, as evidenced by major clinical trials.
Steer Clear of High-Dose Vitamin A: When taken with beta-carotene, high-dose vitamin A (retinol) supplements have also been shown to increase lung cancer risk in smokers.
Use Caution with High-Dose Vitamin E: Studies show potential problems with high-dose vitamin E supplements for smokers, with some recent research even suggesting it could accelerate tumor growth.
Men Should Avoid High-Dose B6 and B12: Individual supplements of B6 and B12 have been linked to an increased risk of lung cancer in male smokers.
Emphasize Whole Foods over Supplements: The risks are associated with high-dose synthetic supplements, not the nutrients obtained naturally from a balanced diet rich in fruits and vegetables.

The Surprising Dangers of High-Dose Supplements for Smokers

For decades, public health messaging promoted the idea that antioxidant vitamins could counteract the damage caused by smoking. The logic was simple: smoking introduces vast numbers of free radicals, and antioxidants neutralize them. However, major clinical trials from the 1990s, such as the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) study and the Beta-Carotene and Retinol Efficacy Trial (CARET), revealed a startlingly different reality. Instead of providing protection, high-dose antioxidant supplements were found to increase the risk of lung cancer in smokers and those with a history of smoking. This discovery fundamentally shifted the medical community's advice regarding supplement use in this population.

Vitamins Smokers Should Absolutely Avoid

Beta-Carotene: The Most Documented Risk

Beta-carotene is a provitamin A carotenoid found in many fruits and vegetables, and is often included in antioxidant supplements and some multivitamins. However, the research on high-dose beta-carotene supplementation in smokers is unequivocally negative. The ATBC study observed an 18% increase in lung cancer among male smokers taking 20 mg of beta-carotene daily. The CARET study, involving smokers and asbestos-exposed workers, was stopped prematurely when participants taking a combination of 30 mg of beta-carotene and 25,000 IU of vitamin A daily showed a 28% higher incidence of lung cancer and a 17% higher death rate from the disease. This risk is specific to high-dose supplements, not the beta-carotene found naturally in foods like carrots and sweet potatoes. The mechanism is complex, but it is believed that components in cigarette smoke may interact with synthetic beta-carotene to produce harmful, pro-carcinogenic compounds in the lungs.

Vitamin A (Retinol): Harmful When Paired

As the CARET trial demonstrated, high-dose vitamin A (retinol) is particularly dangerous when combined with beta-carotene. The body converts beta-carotene into vitamin A, and this process appears to be disrupted by cigarette smoke, leading to potentially harmful outcomes. While some studies have been inconclusive, the risk identified in combination trials is significant enough that smokers should be cautious about high-dose vitamin A supplements, particularly those sold for eye health, which may contain high levels.

High-Dose Vitamin E

Caution is also advised for smokers considering high-dose vitamin E supplements. Some research indicates that problems may exist for smokers taking high-dose vitamin E, with one study showing increased oxidative stress markers in vitro at high doses. Although some studies have shown potential benefits, the contradictory findings and potential risks suggest a need for caution. Newer research also hints that antioxidants like vitamins C and E could potentially accelerate tumor growth once cancer has already developed, based on studies in mice.

B Vitamins (B6 and B12) for Men

More recent evidence has also flagged potential issues with high-dose B vitamin supplements for male smokers. A study showed that male smokers who took individual supplements of vitamin B6 and B12 had a significantly higher risk of lung cancer compared to non-users. The risk was higher in those with the highest 10-year average doses. The takeaway here is to stick to dietary sources of B vitamins and avoid large individual supplements.

The Crucial Difference: Supplements vs. Whole Foods

One of the most important takeaways from this research is that the risk is associated with isolated, high-dose supplements, not with eating a diet rich in fruits and vegetables. The vitamins in whole foods are part of a complex matrix of other compounds that the body is designed to process. This balance is likely what makes natural food sources beneficial, while synthetic, mega-doses can become harmful when interacting with cigarette smoke. A diet high in fruits and vegetables remains the most recommended approach for obtaining nutrients, as observational studies continue to show that such a diet is protective against cancer.

A Quick Comparison: Risky vs. Recommended Intake


Nutrient	Risky Supplementation for Smokers	Recommended Dietary Approach for Smokers
Beta-Carotene	High-dose synthetic supplements (e.g., 20+ mg daily), often found in eye health formulas.	Plentiful intake of colorful fruits and vegetables (carrots, sweet potatoes, spinach).
Vitamin A (Retinol)	High-dose retinol supplements, especially those combined with beta-carotene.	Dietary intake from food sources like milk, eggs, and liver.
Vitamin E	High-dose supplements, especially long-term use (e.g., >400 IU daily).	Consumption of nuts, seeds, and leafy greens.
B6 and B12	High-dose individual supplements, particularly for men.	Dietary sources like meat, fortified grains, and dairy products.
General Antioxidants	Supplementation with high-dose antioxidant blends.	Focusing on an overall balanced diet rich in antioxidant-rich foods.

How to Prioritize a Healthy Diet as a Smoker

Since the priority is always smoking cessation, the best nutritional strategy is to support overall health with a balanced, whole-food diet. Instead of seeking a magic bullet in a bottle, focus on foods that provide a wide array of protective nutrients naturally. The following lists offer better alternatives to risky supplements.

Fruits and Vegetables: Load up on brightly colored produce. Sources rich in beneficial carotenoids include beets, grapes, berries, squash, and mangoes. Leafy greens like spinach are also packed with nutrients.
Healthy Fats: Get vitamin E from natural sources like nuts, seeds, and healthy oils instead of supplements.
Lean Protein: Lean meats, poultry, and fish provide necessary B vitamins without the potential for dangerous megadosing from synthetic pills.
Hydration: Stay well-hydrated to help your body's natural detoxification processes. Green tea is a good option as it is rich in antioxidants.

The most important action a smoker can take for their health is to quit. A proper diet can be a supportive measure, but it is not a cure-all. For those looking to quit, many resources are available. For more information, the CDC offers resources on quitting smoking.

Conclusion: Prioritize Diet Over Supplements

The evidence is clear: high-dose supplements of beta-carotene, vitamin A, and potentially vitamins E and certain B vitamins can be harmful to smokers and former smokers. The promise of these synthetic antioxidants protecting against smoking's ill effects has proven to be a dangerous oversimplification. The safest and most effective nutritional strategy is to obtain vitamins and minerals from a balanced, whole-food diet rich in fruits, vegetables, and lean proteins. Combined with the crucial step of smoking cessation, this approach offers the best path forward for improving long-term health outcomes.

Frequently Asked Questions

The risk is tied to high-dose, isolated synthetic vitamins found in supplements. The complex mixture of compounds in whole foods allows the body to process nutrients differently, in a way that doesn't cause the harmful pro-oxidant interactions seen with synthetic supplements in smokers.

Yes, former smokers should also be cautious. The CARET study, which linked beta-carotene and vitamin A supplements to increased lung cancer risk, included former smokers in its cohort, highlighting the lingering risk even after quitting.

Many multivitamins contain beta-carotene. You should check the label and avoid brands with high doses. Some specific multivitamins formulated for eye health, for example, may contain higher levels. It's best to consult a healthcare provider for personalized advice.

While Vitamin C supplements have also been investigated, the evidence is less conclusive than for beta-carotene and vitamin A. Some studies have found no link to lung cancer risk, though newer research suggests caution, especially once cancer has developed. A diet rich in Vitamin C from food is safe and beneficial.

While diet cannot undo all the damage from years of smoking, a diet rich in fruits, vegetables, and antioxidants can help support the body's natural repair processes, reduce inflammation, and provide essential nutrients to support overall health. The best step is always to quit smoking.

There is currently limited research specifically on vaping and vitamin supplementation. However, vaping still introduces chemicals and oxidative stress to the lungs. Given the known risks with cigarette smoke, a precautionary approach would be to avoid high-dose supplements if you vape, and focus on a whole-food diet.

The most important action is to quit smoking entirely. For nutrition, prioritize eating a variety of whole, antioxidant-rich foods like fruits and vegetables, rather than relying on high-dose synthetic supplements.