Vitamin D Absorption

Vitamin D plays an important role in maintaining calcium and phosphorus levels in the body. Vitamin D, a fat soluble vitamin, mainly helps in the absorption of calcium from digested food in the stomach into the blood stream and thus keeps the bones strong. Two major forms of this vitamin are ergocalciferol or Vitamin D2 and cholecalciferol or Vitamin D3. D2 comes from plants and D3 comes from exposure to morning sunlight and certain foods. Kidney and liver play an important role in absorption of this vitamin.

Importance of Vitamin D

• It controls the supply of calcium to bones from blood and vice versa.
• It is responsible for bone growth and bone remodeling by osteoblasts and osteoclasts.
• It prevents rickets in children.
• It prevents osteomalacia in adults.
• It helps fight depression, prostate cancer, breast cancer, osteoporosis, high blood pressure, some cardiovascular diseases, phagocytosis activity.
• It boosts anti-tumor activity.
• It controls secretion of the parathyroid hormone from the parathyroid gland.
• It helps to have a healthy immune system.

Absorption of Vitamin D in the Body
Vitamin D is found in food but your body can also make it when exposed to ultra violate rays from the sun. In fact, this vitamin exists in various forms but some forms are relatively inactive in your body. The liver and kidney can convert vitamin D to its active hormone form. D3 or cholecalciferol is found in animal foods. Most milk contain vitamin D. Fatty fish (herrings, kippers, salmon and tuna), liver, egg yolks, cod liver oil and halibut liver oil, etc. are good sources of this vitamin. Problem in the absorption of this vitamin may arise if

• Dietary intake of vitamin D is insufficient
• Absorption of Vitamin D present in the rays of the sun is insufficient (due to limited exposure to sunlight)
• The kidneys cannot convert vitamin D to its active form
• The gastrointestinal tract cannot absorb the vitamin adequately.
• Steroids are taken as anti-inflammatory medications. Steroids lower calcium absorption and impair vitamin D metabolism.

Recommended Daily Intake of Vitamin D
A dose of 200-400 international units (IU) of vitamin D is sufficient to prevent rickets in children but it is not at all sufficient to maintain your overall health. According to The Food and Nutrition Board of the Institute of Medicine, an intake of 25 mcg (1,000 IU) for infants up to one year of age and 50 mcg (2,000 IU) for children, adults, pregnant and lactating women is the tolerable upper intake level (UL). Scientists say, "the minimal daily requirement of vitamin D should be in the range of 4,000 IU from all sources, rather than the 200-400 currently suggested, or ten times the Recommended Daily Allowance (RDA)."

Vitamin D Absorption Rate
Vitamin D deficiency symptoms are commonly noticed in persons with Alzheimer's disease, post-menopausal women and seniors. Many of these individuals often stay home and get little sunlight. Moreover, aging can lower skin's capacity to convert vitamin D to its active form. Doctors may suggest them a good liquid multivitamin that can provide them ample vitamin D for their body. To increase the absorption rate, liquid supplements are prescribed, since they have much better absorption rate as compared to pill form.

Vitamin D deficiency implies that the person will be able to absorb 10 to 15 percent of the calcium in his diet. An individual with adequate vitamin D is able to absorb 30 per cent. In healthy individuals, 30% absorption rate is observed. During pregnancy, lactation and growth spurts (for example, in teenagers), the body responds automatically and increases the absorption rate to up to 80 per cent.

What Helps Vitamin D Absorption

• Intake of liquid vitamin supplements or pills.
• Balanced diet with vitamin D
• Maintaining correct weight. Studies have shown that obese are prone to vitamin D deficiency. As vitamin D sets deep in the fat tissues, body is unable to use it effectively.
• Adequate minerals supply. For instance, without adequate supply of calcium and magnesium along with other minerals, vitamin-D supplementation will withdraw calcium from the bone and will allow the uptake of toxic minerals.
• Healthy liver and kidney. People who have severe liver problems will not be able to absorb sufficient vitamin D (because vitamin D is a fat soluble vitamin and liver helps in fat digestion). Similarly, people who have intestine problems, will not be able to absorb vitamin D sufficiently. Excessive use of alcohol, caffeine, sugar, tobacco should be avoided.
• Because of increased levels of polyunsaturated and monounsaturated fatty acids in your diet, you will decrease the binding of vitamin D to D-binding proteins. Saturated fats such as those found in butter, tallow and coconut oil and the omega-3 fats do not have this effect. Vitamin D absorption and utilization is thus influenced by the kinds of fats you consume. This means you need to consume all types of fats in proper proportions.

As seen above, your body can produce vitamin D. But people from different descents can produce different amounts of vitamin D due to the different pigmentation. For instance, a Caucasian may require 20minutes of sunlight, 2-3 times per week to obtain sufficient vitamin D while an African-American with deep skin pigmentation may need double or triple the frequency and duration to get the similar effect. The frequency and duration will also vary according to the time of day, season, weather condition (cloudy or sunny) and location (stronger sun intensity on and near equator). Moreover, the intensity of the sun is at its strongest between 10am to 4pm. It is recommended that overexposure to the sun during this time should be avoided. Remember, chronic excessive exposure to sunlight increases the risk of skin cancer. It is a fact that vitamin D prevents many cancers, but moderate sun exposure is recommended.

How much of vitamin D your body will be able to absorb depends upon your age and overall health. Those who exercise regularly, have healthy digestive system. It is noticed that modern lifestyle is responsible for poor digestive health. City life, working in offices and factories, screening out ultraviolet light with glass windows, wearing more clothing when farming, using sun screens and dark glasses all contribute to the deficient Vitamin D levels detected today. Human body receives ultraviolet light through the eyes and skin. Studies show that ultraviolet deprivation may be responsible for the dramatic increase in cancer seen in certain parts of Africa. According to the studies, Africans could not absorb vitamin D through eyes, because of sunglasses and it made them vulnerable to ultraviolet light deficiency since black skinned persons do not absorb much ultraviolet through their skin. Thus, several factors are involved in the process of absorption of vitamin D. Simple lifestyle and dietary changes can help improve the rate of absorption.