Your body can store fat-soluble vitamins anywhere from a few days to six months. These vitamins are metabolized in fat cells, absorbed by your small intestine, then stored in your fat cells, with any excess in your liver. Your body pulls them from these reserves when it needs them. Because they are excreted slowly from your body, they can become toxic if you take too much. The fat-soluble vitamins include A, D, E and K.
Recommended Daily Allowances
Fat-soluble vitamins are organic substances your body needs in small amounts for normal function, growth and maintenance of body tissue. Because your body can store them, you only need small amounts each day. You can get the needed fat-soluble vitamins from a well-balanced diet. Because taking supplements of fat-soluble vitamins can be toxic and cause health problems, sticking to the recommended daily allowances is wise.
You need some dietary fats to absorb fat-soluble vitamins. A very low-fat diet can lead to deficiencies of these vitamins. Choose sources of unsaturated fats, such as olive oil, flax oil, plant or seed sources. Eating a few raw nuts with each meal will ensure your body has the fats it needs to absorb fat-soluble vitamins. "Natural News" recommends macadamia, cashews, almonds, peanuts and pecans.
Physiology of Absorption
When fats enter your body, they are mixed with enzymes from the glands in your tongue called lingual lipases to begin the process of digestion. Once they are in your stomach, gastric enzymes are mixed in with the action of peristalsis; which are the wave-like movements in your stomach that send the mixture to your duodenum. Through processes called hydrolysis and micellization, fat-soluble vitamins are further broken down and absorbed into your small intestine.
Transportation and Deficiencies
According to Georgia Highlands College, 40 to 90 percent of fat-soluble vitamins are absorbed by the small intestines. Proteins called chylomicrones and lipoproteins carry fat-soluble vitamins into your bloodstream where they are used to keep your body functioning. The excess is stored in adipose tissue or fat cells and your liver. Certain diseases such as Crohn's disease, celiac disease and cystic fibrosis cause a malabsorption of these vitamins, resulting in deficiencies.
- MayoClinic.com; Vitamin D and Related Compounds (Oral Route, Parenteral Route); November 2010
- "American Journal of Physiology Endocrinology and Metabolism"; Intestinal Lipid Absorption; Jahangir Iqbal; January 2009
- Georgia Highlands College: Fat-Soluble Vitamins
- Colorado State University; Fat-Soluble Vitamins; J. Anderson, et al.; July 1996
- "Natural News"; Dietary Fat Is Necessary for Absorption of Vitamins, Nutrients and Phytochemicals from Fruits and Vegetables; Mike Adams; July 2004
- Bastyr University; Nutrient Combinations for the Best Absorption; Kristi Lyle, et al.