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Vitamin A supplements are associated with potential health risks that must be considered along with possible benefits. Improper use of retinol in particular has been linked to certain health problems.

In contrast, beta-carotene supplements have not been linked to health problems affecting the bones or other parts of the body. Experts believe these supplements to be safe, according to the National Institutes of Health (NIH). However, the Institute of Medicine has concluded that beta-carotene supplements are not advisable for the general population. However, they may be appropriate as a provitamin A source for the prevention of vitamin A deficiency in specific populations.

Known health risks associated with vitamin A supplements include:

• Birth defects. Vitamin A is a known teratogen when consumed excessively by pregnant women, especially early in the pregnancy. Unless a deficiency is known, vitamin A is usually not part of recommended prenatal vitamin supplements during the first trimester.
  
  
• Osteoporosis and hip fractures. High doses of vitamin A supplements have been linked to an increased risk of hip fractures and osteoporosis in elderly populations. While it is necessary to remodel bone for growth, excess vitamin A in older patients causes bone cells to break down and weaken. Consuming too much vitamin A also may interfere with the work of vitamin D, which is essential to preserving bone.
  
   
• Delayed growth. In children and teens, growth delays have been associated with excess vitamin A.

Because of these potential risks, some experts urge people not to take vitamin A supplements unless a physician directs them to do so. In particular, men over age 30 and women over age 50 sometimes test for increased levels of retinol, according to the NIH.  

The ability to absorb and use vitamin A can be impacted by other medical conditions. Those that impact the body’s relationship with vitamin A include:

• Liver damage. Patients with damaged livers, as a result of disease or alcohol abuse, are more susceptible to toxicity from excess vitamin A.
  
  
• Inability to absorb fats. Because vitamin A is a fat soluble vitamin, a patient with decreased ability to absorb fats will also have limited absorption of vitamin A precursors. Reduced fat absorption may result from medications to help treat obesity, injury to the alimentary canal, genetic conditions, or certain medical conditions (e.g., pancreatic, liver or gallbladder diseases).
  
  
• Malnutrition. Any condition that causes a patient to consume insufficient nutrients may lead to vitamin A deficiency. Examples include gluten intolerance, Crohn’s disease, chronic diarrhea, pancreatic disorders and alcoholism.
  
  
• Iron deficiency or zinc deficiency. Iron and zinc are minerals involved in processes throughout the body, including the synthesis of vitamin A from foods. Without either of them, a vitamin A deficiency is likely to occur.