Vitamins are substances that your body needs to grow and develop normally. Vitamin D helps your body absorb calcium. Calcium is one of the main building blocks of bone. A lack of vitamin D can lead to bone diseases such as osteoporosis or rickets. Vitamin D also has a role in your nerve, muscle, and immune systems.
You can get vitamin D in three ways: through your skin, from your diet, and from supplements. Your body forms vitamin D naturally after exposure to sunlight. However, too much sun exposure can lead to skin aging and skin cancer. So many people try to get their vitamin D from other sources.
The amount of vitamin D your skin makes depends on many factors, including the time of day, season, latitude and your skin pigmentation. Depending on where you live and your lifestyle, vitamin D production might decrease or be completely absent during the winter months. Sunscreen, while important, also can decrease vitamin D production.
Vitamin D has multiple roles in the body, helping to:
Maintain the health of bones and teeth.
Support the health of the immune system, brain, and nervous system.
Regulate insulin levels and aid diabetes management.
Support lung function and cardiovascular health.
Influence the expression of genes involved in cancer development.
Reduces depression and other brain related disorders.
Health Benefits of Vitamin D
Cancer: Calcitriol (the hormonally active form of vitamin D) can reduce cancer progression by slowing the growth and development of new blood vessels in cancerous tissue, increasing cancer cell death, and reducing cell proliferation and metastases. Vitamin D influences more than 200 human genes, which could be impaired when we do not have enough vitamin D. Research suggests that vitamin D, especially when taken with calcium, might help prevent certain cancers.
Cognitive health: Early research suggests that vitamin D might play a role in cognitive health. In one small study of adults age 60 years and older being treated for dementia, researchers found that taking a vitamin D supplement helped improve cognitive function.
Inherited disorders: Vitamin D supplements can be used to help treat inherited disorders resulting from an inability to absorb or process vitamin D, such as familial hypophosphatemia.
Multiple sclerosis: Research suggests that long-term vitamin D supplementation reduces the risk of multiple sclerosis.
Osteomalacia: Vitamin D supplements are used to treat adults with severe vitamin D deficiency, resulting in loss of bone mineral content, bone pain, muscle weakness and soft bones (osteomalacia).
Osteoporosis: Studies suggest that people who get enough vitamin D and calcium in their diets can slow bone mineral loss, help prevent osteoporosis and reduce bone fractures.
Psoriasis: Applying vitamin D or a topical preparation that contains a vitamin D compound called calcipotriene to the skin can treat plaque-type psoriasis in some people.
Rickets: This rare condition develops in children with vitamin D deficiency. Supplementing with vitamin D can prevent and treat the problem.
Hypertension: Hypertension (HTN) or high blood pressure is one of the most chronic and deadliest disorders in the world. There are many risk factors responsible for HTN which include age, race, using tobacco, high salt intake, etc. One of the risk factors we would like to highlight is low vitamin D levels. Studies have shown an indirect relation between 25-hydroxyvitamin D serum level and blood pressure, and strong evidences from research has proven that Vitamin D helps regulate blood pressure and reduces the chance of hypertension.
Autism: Low vitamin D levels at birth were associated with an increased risk of autism spectrum disorders (ASDs) at the age of 3 years in a recent Journal of Bone and Mineral Research study. The present study revealed that Vitamin D deficiency was higher in autism children compared to healthy children and supplementing infants with Vitamin D might be a safe and more effective strategy for reducing the risk of autism. Autistic children who received a daily dose of vitamin D3 showed significant reduction of symptoms of the disorder .
Schizophrenia: Vitamin D is now considered as a potent neurosteroid hormone, critical to brain development and normal brain function, and is known for its anti-inflammatory property affecting various aspects of human health. Vitamin D deficiency is common in patients with severe mental illness such as schizophrenia. Schizophrenia is a debilitating chronic mental illness characterized by positive symptoms, such as hallucinations and delusions, and negative symptoms including flat affect and lack of motivation. A recent study out of the journal Schizophrenia Research found that low vitamin D levels were associated with increased grandiosity, excitement, social anhedonia, and irregular speech among patients with schizophrenia. Most recently, laboratory tests of individuals with schizophrenia, psychosis, elective mutism, and bipolar disorders revealed consistent serum vitamin D levels below 20 ng/ml. As vitamin D levels normalized, symptoms improved.
Hyperlipidaemia: Familial Combined Hyperlipidemia (FCHL) is associated with decreased vitamin D concentrations, recent studies have suggested a possible link between deficiency of 25-hydroxyvitamin D and dyslipidemia.Hypercholesterolemia is the medical name for high cholesterol, inadequate absorption of Vitamin D increases the HDL-cholesterol, triglycerides, lipoprotein(a), hs C-reactive protein and Hemoglobin A1c, and lowers the LDL-cholesterol. Therefore, increasing the chances of obesity by multitudes.
Depression:Depression is the leading cause of disability worldwide, affecting more than 300 million people of all ages. Vitamin D affects the amount of chemicals called monoamines, such as serotonin, and how they work in the brain. People with low levels of vitamin D in their blood had more symptoms of depression. The lower the women’s levels of vitamin D, the more likely they were to have clinically significant symptoms of depression. Vitamin D is known to influence the immune system to promote a T helper (Th)-2 phenotype. Low vitamin D levels were associated with higher levels of the inflammatory cytokines IL-6 and IL-1β in the blood. Research shows that Suicide attempters are deficient in Vitamin D.
SADness: as many as 20 percent of Americans are affected by Seasonal Affective Disorder (SAD) each winter, suffering from the blues, fatigue, and in some cases, more serious depression as sunlight grows scarce. Scientists generally recommend full-spectrum light therapy over SSRIs like Prozac or Zoloft for this condition, your health and mood is intricately tied to exposure to sunlight. For example, your serotonin levels (the hormone typically associated with elevating your mood) rise when you’re exposed to bright light. Your melatonin level also rises and falls (inversely) with light and darkness. When it’s dark, your melatonin levels increase, which is why you may feel tired when the sun starts to set (and in the heart of winter, this may be at as early as 4:00 p.m.). Vitamin D is one of the cheapest and best treatment for being SAD.
Healthy Pregnancy: Pregnant women who are deficient in vitamin D seem to be at greater risk of developing preeclampsia and needing a cesarean section. Poor vitamin D status is associated with gestational diabetes mellitus and bacterial vaginosis in pregnant women.
Flu Prevention: A study by Harvard University confirms vitamin D protects against colds and flu. Acute respiratory infections (infections of the body’s airways, such as colds, flu, bronchitis and pneumonia) are responsible for millions of emergency department visits in the United States each year. Vitamin D deficiency is a major cause of influenza, people with the lowest vitamin D levels report having significantly more colds or cases of the flu. Among people vitamin D blood levels below 10 ng/mL, taking a supplement cut risk of respiratory infection by 50 percent.
Recommended intake of vitamin D
The amount of vitamin D you need depends on your age.
Vitamin D intake can be measured in two ways: in micrograms (mcg) and International Units (IU).
One microgram of vitamin D is equal to 40 IU of vitamin D.
The recommended intakes of vitamin D throughout life were updated by the U.S. Institutes of Medicine (IOM) in 2010 and are currently set at:
Infants 0-12 months – 400 IU (10 mcg).
Children 1-18 years – 600 IU (15 mcg).
Adults to age 70 – 600 IU (15 mcg).
Adults over 70 – 800 IU (20 mcg).
Pregnant or lactating women – 600 IU (15 mcg).
Causes of Vitamin D deficiency
Vitamin D deficiency can occur for a number of reasons:
You don’t consume the recommended levels of the vitamin over time: This is likely if you follow a strict vegan diet, because most of the natural sources are animal-based, including fish and fish oils, egg yolks, fortified milk, and beef liver.
Your exposure to sunlight is limited: Because the body makes vitamin D when your skin is exposed to sunlight, you may be at risk of deficiency if you are homebound, live in northern latitudes, wear long robes or head coverings for religious reasons, or have an occupation that prevents sun exposure.
You have dark skin: The pigment melanin reduces the skin’s ability to make vitamin D in response to sunlight exposure. Some studies show that older adults with darker skin are at high risk of vitamin D deficiency.
Your kidneys cannot convert vitamin D to its active form: As people age, their kidneys are less able to convert vitamin D to its active form, thus increasing their risk of vitamin D deficiency.
Your digestive tract cannot adequately absorb vitamin D: Certain medical problems, including Crohn’s disease, cystic fibrosis, and celiac disease, can affect your intestine’s ability to absorb vitamin D from the food you eat.
You are obese: Vitamin D is extracted from the blood by fat cells, altering its release into the circulation. People with a body mass index of 30 or greater often have low blood levels of vitamin D.
Symptoms of vitamin D deficiency
Symptoms of vitamin D deficiency may include:
Getting sick or infected more often.
Painful bones and back.
Impaired wound healing.
If Vitamin D deficiency continues for long periods of time it can result in:
chronic fatigue syndrome
neurodegenerative diseases, such as Alzheimer’s disease
Vitamin D deficiency may also contribute to the development of certain cancers, especially breast, prostate, and colon cancers.
Vitamin D food sources
Sunlight is the most common and efficient source of vitamin D. The richest food sources of vitamin D are fish oil and fatty fish. Here is a list of foods with good levels of vitamin D:
cod liver oil, 1 tablespoon: 1,360 IU
herring, fresh, raw, 4 ounces: 1,056 IU
swordfish, cooked, 4 ounces: 941 IU
raw maitake mushrooms, 1 cup: 786 IU
salmon, sockeye, cooked, 4 ounces: 596 IU
sardines, canned, 4 ounces: 336 IU
fortified skim milk, 1 cup: 120 IU
tuna, canned in water, drained, 3 ounces: 68 IU
egg, chicken, whole large: 44 IU
Risks with Overdosage
Guidelines from the Institute of Medicine increased the recommended dietary allowance (RDA) of vitamin D to 600 international units (IU) for everyone ages 1-70, and raised it to 800 IU for adults older than age 70 to optimize bone health. Taken in appropriate doses, vitamin D is generally considered safe. Excessive consumption of vitamin D (hypervitaminosis D) can lead to over calcification of bones and hardening of blood vessels, kidney, lungs, and heart.
However, taking too much vitamin D can be harmful. The Upper Level limit recommended for vitamin D is 4,000 IU per day. However, the National Institutes of Health (NIH) has suggested that vitamin D toxicity is unlikely at daily intakes below 10,000 IU per day. 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:
Heart rhythm problems
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 (Lipitor). Taking vitamin D might affect the way your body processes this cholesterol drug.
Calcipotriene (Dovonex). Don’t take vitamin D with this psoriasis drug. The combination might increase the risk of too much calcium in the blood (hypercalcemia).
Cholestyramine (Prevalite). Taking this weight-loss drug can reduce your absorption of vitamin D.
Cytochrome P450 3A4 (CYP3A4) substrates. Use vitamin D cautiously if you’re taking drugs processed by these enzymes.
Digoxin (Lanoxin). 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 (Cardizem, Tiazac). 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.
Orlistat (Xenical, Alli). Taking this weight-loss drug can reduce your absorption of vitamin D.
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.
Verapamil (Verelan, Calan). 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.
Tests for Vitamin D Deficiency
The most accurate way to measure how much vitamin D is in your body is the 25-hydroxy vitamin D blood test. A level of 20 nanograms/milliliter to 50 ng/mL is considered adequate for healthy people. A level less than 12 ng/mL indicates vitamin D deficiency.