Too Much Vitamin A In The Diet

Vitamin A is a fat-soluble vitamin that is essential for eyesight, immune health, reproduction and cell differentiation. The Food and Nutrition Board recommends that adult men consume 900 mcg of vitamin A every day. Women should get 700 mcg. Consuming too much vitamin A can have adverse health consequences.

Vitamin A Forms

Although often referred to as a single vitamin, vitamin A is actually a family of several substances. These substances, collectively called retinoids, include retinol, retinal and retinoic acid. Retinoids are also called preformed vitamin A, because they are in a form that your body can use. Preformed vitamin A is found in foods from animal sources, such as milk, cheese and organ meats.
Provitamin A carotenoids are yellow-red pigments that are converted to vitamin A, specifically in the form retinol. Examples of foods that contain provitamin A carotenoids include carrots, spinach and sweet potatoes. According to "Nutrition and You" by Joan Salge Blake, provitamin A carotenoids account for 25 to 35 percent of the dietary vitamin A consumed by adults.

Vitamin A Toxicity

Because vitamin A is fat-soluble, your body is able to store excess amounts in the liver and fat cells. Consuming too much vitamin A can lead to nausea, vomiting, headaches and blurred vision. Excessive intake of vitamin A can also lead to thinning of the bones, which increases the risk of fracture.
To avoid toxicity from too much vitamin A, the Food and Nutrition Board has set an upper limit for vitamin A at 3,000 mg per day. This is the highest amount you can consume without experiencing adverse side effects.

Hypervitaminosis A

Chronic overconsumption of vitamin A can lead to a serious condition called hypervitaminosis A, which is characterized by toxic levels of vitamin A in the liver. Too much vitamin A can cause scarring of the liver and decreased liver function.
Blake notes that hypervitaminosis A is usually caused by excessive supplementation, and not too much vitamin A in the diet.

Carotenodermia

Carotenodermia is a condition caused by eating too many provitamin A carotenoids. Carotenodermia is characterized by orange-tinted skin, especially on the palms of the hands and the soles of the feet. While carotenodermia does not cause any serious complications, it can be unsightly.
Reducing the amount of carotenoid foods you consume, such as carrots, sweet potatoes, spinach, kale, collard greens and tomatoes, can allow your skin to return to its normal color. The Food and Nutrition Board has not set an upper level for carotenoids, because excess consumption is not considered toxic.