Vitamin D is a vitamin and hormone that your body can make from regular sun exposure. Nature appears to expect us to get most vitamin D from sun exposure because very few foods contain significant amounts of it. However, people are spending less time outdoors and putting on more sunscreen, so our production of vitamin D is often inadequate. According to HealthDay, 37% of the U.S. population take supplements vitamin D supplements (2005-2006 National Health and Nutrition Examination Survey, NHANES), and one in four Americans is at risk for vitamin D deficiency.

How can you get vitamin D?

Vitamin D is one of the few nutrients the body needs, that does not come from a wide variety of foods. Although salmon, mackerel, sardines, and tuna can deliver about 200 I.U./serving, they are not an adequate source of D3. After fortification, milk delivers only vitamin D2 – not D3, the real thing. Vitamin D2 is also added to fortified dairy products but does not function in the same way as D3. Vitamin D3 can be more than 3 times as effective as D2 in maintaining and raising vitamin D blood levels.

Most of the vitamin D from plant foods is artificially added or fortified. Whole grain breakfast cereals is the most common plant food fortified with vitamin D. Shiitake mushrooms naturally contain vitamin D-2. UV-B enhanced mushrooms boost the vitamin D content and have been used commercially to produce white, brown, and portabella mushrooms that can meet 100 percent of your daily need in a 3oz. serving, according to the USDA.

The body was designed to manufacture a sufficient amount of vitamin D simply by skin exposure to sunlight, which converts 7-dehydrocholesterol to cholecalciferol. Cholecalciferol in turn is hydroxylated at the liver forming 25(OH) D. At the kidneys, 25(OH)D is metabolized to the most active form of vitamin D 1,25(OH)2D3. Sadly, we as a nation do not spend much time in sunlight and when we do, our skin is mostly covered with clothing or sunscreen. As a consequence, most people have low levels of vitamin D3 which has initiated a groundswell of scientific research calling for increased daily vitamin D3 intake for all Americans.

In 1941, the RDA (recommended dietary allowance which is a minimum recommendation) of vitamin D was 400 I.U./day to prevent D deficiency and rickets. Today, scientists are calling for an increase in this daily intake, recommending 1,000 to 2,000 I.U./day. They believe these levels can best provide the support for the body’s critical vitamin D needs now identified to include immunological, vascular, cognitive, mucosal, and reproductive health, and more.

Experts now consider vitamin D3 blood levels less than 20ng/ml to be gross D3 deficiency, while 20-39ng/ml is still too low; 40-50ng/ml is considered to be reasonable but not ideal. At all of these levels, supplementation with D3 is recommended at 5,000 to 7,000 I.U./day for 6-8 weeks. Ideally, the individual would be re-tested every 3 months until their blood levels are in the ideal range (i.e. D3 levels greater than 50ng/ml but less than 60ng/ml).
Some experts believe the upper limit of vitamin D intake should be 2,000 to 10,000 I.U./day.* However, when vitamin D blood levels are greater than 200ng/ml, a toxic reaction could potentially lead to hypercalcemia/ hyperphosphatemia. Hypercalcemia is rare but could be triggered by a D3 intake of over 50,000 I.U./day.

In published cases of vitamin D toxicity, intake was greater than 400,000 I.U./day. Common signs of hypercalcemia are anorexia, nausea, and vomiting. Prolonged excessive intake could lead to calcification of the kidneys, heart, and lungs.

Key Benefits of Live-Source Vitamin D3


Population groups with greater direct sunlight exposure or more vitamin D3 exposure were found to have stronger immune function than those with restricted sunlight exposure.* Vitamin D3 receptors are known to exist on most immune cells and play a role in maintaining healthy immune cell maturity, differentiation, and integration.*

Breast and Mucosal Organs

Research indicates optimal serum levels of vitamin D3 may be important in maintaining the best health of the cells of the breasts, lungs, colon, esophagus, stomach, pancreas, bladder, prostate, uterus, ovaries, and kidneys.*

Bone Metabolism

In a 3-year randomized controlled study, vitamin D3 and calcium supplementation promoted bone strength and reduced risk of falling in women aged 65 or older.* Vitamin D3 supplements were shown to support hip and non-vertebral bone health in a meta-analysis of twelve double-blind randomized controlled trials of 20,000 people.* Vitamin D is essential for healthy calcium metabolism; it promotes intestinal calcium and phosphorus uptake and can reduce urinary calcium excretion.*

Nerve Function

Research indicates vitamin D may promote neural health by supporting healthy nerve conduction potential, antioxidant defense and neuronal calcium regulation.* High circulating blood levels of end-chain vitamin D3, 25- hydroxyvitamin D, were associated with nerve and myelin health in a study of 7 million U.S. military personnel, published in JANA, 2006.*


Higher levels of vitamin D were correlated with healthy mood and mental function in two studies of more than 300 elderly people.* Additionally, we now know that vitamin D receptors and vitamin D hydroxylation pathways exist in areas of the brain responsible for memory and cognition.*

Heart Health

Healthy blood vessel relaxation and blood flow are associated with ideal levels of vitamin D3. Healthy inflammatory response, antioxidant defense, and cytokine production are associated with optimal blood levels of vitamin D as well.*

*Disclaimer:  The FDA has not evaluated any of these statements.  Practice at your own risk and gain.  Please seek immediate medical care for any urgent trauma. This article is not intended to diagnose, treat, cure or prevent any disease.