Vitamin D -- an essential nutrient found in dairy products, fatty fish and fortified cereals -- plays a role in your health. It helps maintain strong bones and teeth, supports nerve and muscle function and interacts with your parathyroid gland to help maintain your body's hormone balance. A number of factors affect the absorption of vitamin D in your digestive tract, helping your body access the vitamin D it needs to function.
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One factor that regulates the absorption of vitamin D is the presence of dietary fat in your digestive tract. Vitamin D is a fat-soluble vitamin and dissolves in the fat within your digestive tract. When your body absorbs this fat, it also absorbs the dissolved vitamin D. If you suffer from a digestive issue that hinders your ability to absorb fat, you also face increased risk of a vitamin D deficiency.
Your body also relies on proper liver functioning to properly absorb vitamin D, and requires the presence of liver enzymes for vitamin D absorption. Digestive enzymes produced and secreted by your liver help break down molecules of fat in the foods you eat, breaking the fat down into fatty acids that are easily absorbed by your digestive tract. This digestion process also helps release vitamin D from your food, so it can be absorbed along with the fatty acids. Individuals with decreased liver function sometimes require vitamin D injections, since they may not be able to absorb dietary vitamin D.
Absence of Absorption Inhibitors
Some compounds prevent your body from properly absorbing vitamin D, so the absence of these compounds promotes proper vitamin D absorption. For example, using mineral oil as a constipation treatment can prevent proper vitamin D absorption, since the vitamin absorbs in the oil, then gets flushed from your body. In addition, some weight loss drugs designed to slow dietary fat absorption also hinder vitamin D absorption, possibly leading to a vitamin D deficiency.
Effects of Inefficient Absorption
Decreased absorption of vitamin D -- whether due to inadequate dietary fat intake, an inability to absorb fat or treatment with therapies that affect vitamin D absorption -- can pose a health risk. Your body needs vitamin D to help control calcium metabolism, so a vitamin D deficiency can alter your body's calcium levels. Over time, the deficiency can cause your bones to lose calcium, weakening and softening your bone tissue, and potentially increasing your risk of osteoporosis. If you suffer from a condition that affects vitamin D absorption, talk to your doctor about the possible benefit of vitamin D injections to prevent a deficiency.