What Are Fat-soluble Vitamins?

Vitamins are classified as either water-soluble or fat-soluble, depending on how your body absorbs them. Fat-soluble vitamins, which are absorbed in the beginning of your small intestine, require the presence of dietary fat. Once the fat-soluble vitamins travel through the small intestine, they combine with fats and other lipids and enter your lymphatic system, where they circulate until they reach the bloodstream. Fat-soluble vitamins include vitamins K, A, D and E.

Vitamin K

Vitamin K plays a major role in blood clotting. Vitamin K ensures that your blood is able to clot correctly, so that a small cut does not lead to severe bleeding. Vitamin K also helps regulate enzymes that contribute to the health of your bones. Adult women should consume 90 mcg of vitamin K every day, whereas adult men should consume 120 mcg of vitamin K daily. The best sources of vitamin K are broccoli, asparagus, Brussels sprouts, spinach, salad greens and cabbage. Vegetable oils and margarine are also good sources.

Vitamin A

The light-sensitive proteins in your eyes require the presence of vitamin A in order to function properly. Vitamin A also plays an important role in cell differentiation, which is the physiological process that determines what a cell becomes in your body. Vitamin A is also involved in reproduction, immune health and skin health. Adult men should consume 900 mcg per day, whereas adult women should consume 700 mcg daily. Because vitamin A is a fat-soluble vitamin, the presence of fat in your intestinal tract increases the absorption of the vitamin. The book "Nutrition and You" by Joan Salge Blake recommends consuming vitamin A-rich foods (such as milk, cereal, eggs, cheese, carrots, spinach, sweet potatoes and organ meats) with a tablespoon of oil.

Vitamin D

Vitamin D contributes to the health of your bones by increasing the absorption rate of calcium and phosphorus in your intestinal tract. Adults require 5 to 15 mcg of vitamin D per day. Food sources of vitamin D are limited -- the best sources include fortified milk, enriched cereals, yogurt, salmon and sardines.

Vitamin E

Vitamin E acts as an antioxidant, which helps protect your cells from becoming damaged by substances called free radicals. Vitamin E is also an anticoagulant that helps prevent your blood from clotting abnormally. Adults should consume 15 mg of vitamin E daily. The best dietary sources include vegetable oils, nuts, seeds, leafy green vegetables and enriched cereals.

Considerations

Your body can store excess amounts of fat-soluble vitamins for use when your dietary intake falls short. Therefore, it's not as vital to consume fat-soluble vitamins every day as it is to consume water-soluble vitamins every day. Fat-soluble vitamins also have a higher potential to accumulate to toxic levels in your body. Vitamin toxicity usually occurs as a result of excess supplementation, rather than high dietary intake.