Often nicknamed the “sunshine vitamin,”vitamin D is synthesized from cholesterol when your skin is exposed to sunlight. Vitamin D is a fat-soluble vitamin that’s stored in the liver and fatty tissues. This means that increased body fat has the ability to absorb this vitamin and keep it from being used within the body. You can find vitamin D receptors in almost every cell and tissue in the human body, where it is responsible for regulating up to 200 genes.

There are two types of supplemental vitamin D:vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). The precursor to vitamin D is found in both plant and animal products, but animal-derived products of vitamin D3 are thought to be more absorbable and beneficial. Unfortunately, most vitamin D-fortified foods and dietary supplements mostly contain ergocalciferol, a type of D2, which is neither absorbable nor convertible by the body into what it needs.
D3 from animal products (specifically from the cholesterol within these products) is closest to what sunlight naturally produces in humans, when the skin works to convert UV light. Vitamin D3 is believed to convert up to 500 times faster than D2 and has been estimated to be four times more effective in humans.

The benefits of vitamin D are nearly endless, considering that it is involved in so many important biological functions.

1. Fights Cancer
Getting some daily sunshine could play a huge role in preventing and fighting cancer. Multiple studies show that vitamin D decreases cell proliferation and has potent anti-inflammatory effects – important factors in the development of cancers.
Several studies also show links between low vitamin D levels and the onset of cancer, with one revealing that participants with high vitamin D levels were half as likely to be diagnosed with colon cancer as those with low levels.

2. Contributes to Bone Health
Vitamin D plays a role in calcium absorption into the bones. Calcitriol (converted D vitamin) works with the parathyroid hormone to maintain calcium levels.Additionally, it has an effect on other important vitamins and minerals that contribute to both health, including vitamin K and phosphorus. Vitamin D is partially responsible for maintaining phosphorus levels in the blood, and since it affects calcium’s ability to bind to proteins, it’s believed that it’s also linked to vitamin K.
A deficiency in vitamin D can result in the softening of your bones, which is called osteomalacia, or a bone abnormality called rickets. Additionally, a deficiency increases your risk for developing osteoporosis and experiencing fractures or broken bones.

3. Lowers Cardiovascular Disease Risk
Getting enough vitamin D is essential not only for maintaining heart health, but a lack of it can create serious heart issues. Research shows that vitamin D deficiency is linked to an increased risk of developing cardiovascular diseases, including hypertension, heart failure, and ischemic heart disease. Luckily, spending some time in the sunshine can help the walls of your blood vessels expand and contract easily, reducing your risk of heart problems.

4. Improves Fertility
Before you look to expensive fertility treatments when trying to conceive, make sure your vitamin D levels are optimized. Studies show that vitamin D plays a large role in fertility, increasing levels of progesterone and estrogen in women while improving semen quality and sperm count in men. In addition, studies confirm that sperm has a vitamin D receptor, which shows the importance of the vitamin when it comes to healthy sperm.

5. Helps with Concentration, Learning and Memory
Several studies have shown that vitamin D also affects our ability to make decisions, concentrate and retain information. Researchers indicate that people with lower levels perform poorly on standardized exams, may have poor decision-making skills, and have difficulty with tasks that require focus and attention.

6. Improves Fertility
Before you look to expensive fertility treatments when trying to conceive, make sure your vitamin D levels are optimized. Studies show that vitamin D plays a large role in fertility, increasing levels of progesterone and estrogen in women while improving semen quality and sperm count in men. In addition, studies confirm that sperm has a vitamin D receptor, which shows the importance of the vitamin when it comes to healthy sperm.

Vitamin D deficiency symptoms

Two of the most common symptoms of vitamin D deficiency are chronic fatigue and widespread aches and pain throughout your muscles and joints. However, there are a few other symptoms, including:
• Frequent infections and catching colds often
• Back pain
• Depression
• Slow or impaired wound healing
• Bone loss
• Hair loss

Supplements and Foods for Vitamin D

Foods high in vitamin D include:

• Wild-caught fatty fish (salmon, sardines, mackerel)
• Cod liver oil
• Pasture-raised eggs
• Wild mushrooms

Combining daily sun exposure with these vitamin D-rich foods will ensure you’re getting all the benefits of this amazing vitamin. Again, if you’re experiencing any of the symptoms listed above, be sure to get your levels tested.
People can measure vitamin D intake in micrograms (mcg) or international units (IU). One microgram of vitamin D is equal to 40 IU.

Dosage

The recommended daily intakes of vitamin D are as follows:
Infants 0–12 months: 400 IU (10 mcg).
Children 1–18 years: 600 IU (15 mcg).
Adults up to 70 years: 600 IU (15 mcg).
Adults over 70 years: 800 IU (20 mcg).
Pregnant or lactating women: 600 IU (15 mcg).

Sensible sun exposure on bare skin for 5–10 minutes, 2–3 times per week, allows most people to produce sufficient vitamin D. However, vitamin D breaks down quite quickly, meaning that stores can run low, especially in winter.

Safety and side effects

Taken in appropriate doses, vitamin D is generally considered safe.
However, taking too much vitamin D can be harmful. Children age 9 years and older, adults, and pregnant and breast-feeding women who take more than 4,000 IU a day of vitamin D might experience:
• Nausea
• Vomiting
• Poor appetite
• Constipation
• Weakness
• Weight loss
• Confusion
• Disorientation
• Heart rhythm problems
• Kidney damage

Interactions

Possible interactions include:
Aluminum Taking vitamin D and aluminum-containing phosphate binders long term might cause harmful levels of aluminum in people with kidney failure.
Anticonvulsants The anticonvulsants phenobarbital and phenytoin (Dilantin, Phenytek) increase the breakdown of vitamin D and reduce calcium absorption.
Atorvastatin Taking vitamin D might affect the way your body processes this cholesterol drug.
CalcipotrieneDon’t take vitamin D with this psoriasis drug. The combination might increase the risk of too much calcium in the blood (hypercalcemia).
Digoxin .Avoid taking high doses of vitamin D with this heart medication. High doses of vitamin D can cause hypercalcemia, which increases the risk of fatal heart problems with digoxin.
Diltiazem, Verapamil Avoid taking high doses of vitamin D with this blood pressure drug. High doses of vitamin D can cause hypercalcemia, which might reduce the drug’s effectiveness.
Thiazide diuretics. These blood pressure drugs might decrease urinary calcium excretion. This could lead to hypercalcemia if you are taking vitamin D.
Steroids. Taking steroid mediations such as prednisone can reduce calcium absorption and impair your body’s processing of vitamin D.
Stimulant laxatives. Long-term use of high doses of stimulant laxatives can reduce vitamin D and calcium absorption.