Fat-soluble vitamins are absorbed in the body and transported by dietary lipids. These types of vitamins can be stored in adipose tissue until they are needed or can be excreted with feces. Fat-soluble vitamins play important roles in the body, such as maintaining skin integrity and blood coagulation and fighting free radicals.
Vitamin A
Vitamin A plays an important role in vision and immunity. It can be found in cow's milk and beef liver. Also, breakfast and dairy products are fortified with retinol, a form of vitamin A. A deficiency of this vitamin may lead to blindness and susceptibility to infections. Excessive intake may result in liver disease, according to the U.S. Food and Drug Administration. Hair loss, fatigue and gingivitis may be signs of toxicity.
Vitamin D
Vitamin D is produced in the body. Exposure to ultraviolet light helps the body to produce it. Vitamin D is important in calcium and phosphorus balance. It may be found in fish liver oils. A deficiency of this vitamin may lead to rickets in children, according to Medline Plus, and osteomalacia in adults. An excessive intake may elevate calcium and phosphorus levels in the body. Nausea, vomiting and constipation may be signs of toxicity.
Vitamin E
Nuts, seeds and green vegetables are good sources of vitamin E. This vitamin acts as an antioxidant, fighting free radicals in the body. Certain gastrointestinal diseases, such as Crohn's disease, may affect vitamin E absorption; this results in problems of the neuromuscular and reproductive system. Excessive vitamin E intake may interfere with the blood coagulation process.
Vitamin K
Green leafy vegetables, such as spinach, are excellent sources of vitamin K. This vitamin is also produced by intestinal microflora. Vitamin K is essential for blood coagulation. A deficiency may cause hemorrhage and anemia. No toxicity has been established, but high amounts of the synthetic compound menadione, a precursor of vitamin K, may cause jaundice.
Malabsorption
Fat-soluble vitamin absorption may be affected by poor dietary fat intake or malabsorption. Diseases such as pancreatitis, cystic fibrosis and Crohn's disease may affect fat absorption. In these cases vitamin supplementation may be needed.
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