Healthy Aging A-Z: Vitamin A
by Gael Wheeler, DO
One of the first changes we may notice as we age is a decrease in visual acuity. Vitamin A is essential for the proper function of the retina of the eye. Inadequate vitamin A can lead to impaired vision, particularly in low light. Vitamin A is also essential for the proper functioning of the immune system and may help prevent development of autoimmunity. In addition, it is an important co-factor in the proper functioning of the thyroid gland. Thyroid dysfunction is common, particularly in older age.
Because vitamin A is a fat soluble vitamin, impaired pancreatic or biliary secretion, common in older adults, can result in deficiency. Cholesterol lowering medications such as cholestyramine, colestipol and orlistat interfere with absorption of fats and can impair absorption of fat soluble vitamins, including vitamin A. Dosing vitamin A must be done carefully, as toxicity can occur at lower doses in older adults. A maximum of 2500 IU vitamin A palmitate plus no more than 2500 additional IU beta carotene is recommended for older individuals. Levels of vitamin A palmitate of 5000 IU are linked to increased risk of hip fracture. Large doses of vitamin A may impair absorption of vitamin K2, a vitamin critical for transporting calcium to bone tissue.
Regular testing and monitoring of an individual’s nutritional status of vitamin A is advised in order to assure safety and to truly individualize dosing for each person’s unique needs.