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Dietary choices and behaviors can also impact vitamin A intake and the body’s reaction to the nutrient. Some examples include:

• Vegetarian and vegan diet. Vitamin A precursors from animal sources (retinyl esters) are more efficiently converted to forms the body can use than the carotenoids from plants. Additional servings of fruits and vegetables or beta carotene supplements are necessary for patients who consume only plant materials.
  
  
• Smoking. Vitamin A supplements containing beta carotene are not recommended for smokers. Studies have shown their use is associated with a higher mortality rate than smokers in general. Researchers are investigating the potential reasons.
  
  
• Alcohol abuse. Alcohol impacts the body’s relationship to vitamin A in multiple ways. It depletes vitamin stores, increasing the possibility of a deficiency and damages the liver, causing the body to become more susceptible to a possible overdose.