Benefits of d3 vitamin

Vitamin D Has Some Important Benefits—Here’s How to Get Enough

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We’ve all heard about the connection between Vitamin D and sunshine: Those sunny rays keep us healthy—and certain foods (like fish, and milk) are important for boosting D, right? Well, a recent study published in the British Medical Journal found an impressive side affect of Vitamin D: It may help prevent cancer.

The study examined close to 34,000 patients across nine public health centers in Japan. Participants were broken down into four groups based on vitamin D levels and health history. Researchers observed that patients with higher levels of Vitamin D in their blood had a 20 percent lower risk of developing certain cancers. In addition, the risk of liver cancer, especially in men, dropped up to 50 percent.

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So what’s the deal with Vitamin D anyway? First know this: Vitamin D is not actually a vitamin, but a hormone.

The best way to supply yourself with all the D you need is to expose your skin to sunlight—moderately and responsibly, of course. Esteemed nutrition expert Marion Nestle lobbied the U.S. Food and Drug Administration (FDA) several years ago against including Vitamin D on its new Nutrition Facts panel, arguing that because it is a hormone, it doesn’t belong.

Related: What Vitamins Do I Really Need To Take?

Nestle went on to explain to the FDA, that D “is found naturally in very few foods, (e.g., fish); in them, it is present in small amounts. It is present in most foods as a result of fortification.”

She says because D supplements and foods fortified with Vitamin D are taken orally, they don’t produce the same benefits as sunlight on skin.

Other experts point to studies that suggest Vitamin D regulates calcium absorption, keeping teeth and bones healthy. It may also help guard against cancer and diabetes, some experts say. Fatty fish like salmon, mackerel, and sardines, and organ meats are among the best food sources for naturally occurring Vitamin D.

This Tuna, Egg, and Avocado Toast has a ton of naturally occurring Vitamin D, and the ultimate Immunity Soup incorporates Vitamin D enriched mushrooms for extra nutrients. Salmon also has a lot of Vitamin D, which you can enjoy in these 100 Ways to Cook with Salmon.

“Many scientific debates about hormone Vitamin D are as yet unresolved,” Nestle notes in her letter to the FDA. “The lack of compelling research has permitted Vitamin D to become ‘trendy.’ It is advertised on boxes of fortified cereals, has its own pro-supplement advocacy group, and generates millions in annual supplement sales … In the absence of stronger evidence for possible adverse consequences, the FDA should not contribute to further commercialization of this misnamed hormone by permitting it to be listed on food labels.”

The FDA ultimately chose to include Vitamin D on its nutrition labels, to be launched by July 2018.

  • By Timothy Q. Cebula
  • By Arielle Weg

Maren Caruso / Getty Images

Vitamin D is an important and elusive nutrient. It primarily helps our bodies absorb calcium, which promotes bone health and prevents osteoporosis and osteopenia. Unfortunately, getting enough of it isn’t exactly easy. Many of us know it as the “sunshine vitamin,” because it’s the vitamin we famously get from the sun. However, that’s only kind of true. What actually happens is that compounds in our skin react with the sun’s UV rays to create vitamin D. However, relying on the sun as your main source of vitamin D isn’t realistic for a couple of reasons.

Firstly, since most of us spend our days working indoors, sun can be hard to come by—this may have something to do with why a lot of U.S. adults are D-deficient. Even if you do manage to set aside some time outdoors, Kathleen Zelman, M.P.H., R.D., L.D., WebMD director of nutrition, says that the time of day and weather may negatively impact how much vitamin D you end up getting. Additionally, she says, there are the dangers involved with too much sun exposure (from sunburns to skin cancer). So it’s best to get your vitamin D from all possible sources.

That’s where these four foods come in. Zelman says they’re your best bet if you’re looking to up your vitamin D game. However, if you are D-deficient, she also strongly encourages using daily supplements to meet your goal, because these foods still won’t get you everything you need. Different sources have different takes on how much you should try to consume—The National Institutes of Health has a Recommended Daily Allowance (RDA) 600 international units (IUs) per day for anyone between the ages of one and 70, while The Vitamin D Council says adults should get 5,000 IUs. If that seems like a lot, Zelman suggests consuming between 800 to 1,000 IUs to satisfy your daily needs. However, you can safely consume more if you feel you need to. Use these four foods to get yourself closer to your goal.

Related: 15 Foods With A Shockingly High Amount Of Fiber

1. Fatty Fish

Fatty fish are inarguably the food with the highest content of vitamin D, says Zelman. According to the United States Department Of Agriculture, one filet of trout has about 502 IUs and one filet of salmon has 815 IUs. These fish are also a great source of lean protein and healthy fats.

Vitamin D is one of those nutrients that you hear a lot about. Experts say that you really need it for strong overall health, but it’s likely that you’re not getting enough of it. In fact, a 2009 report found that many Americans were deficient, even though it’s a fat-soluble vitamin that our bodies produce when skin is exposed to direct sunlight.

What gives? Despite being able to soak it in via Mother Nature (that’s why it’s often nicknamed the sunshine vitamin), there are a few reasons why adults are having difficulties meeting the National Institutes of Health’s recommended dietary allowance of 600IU (International Units). First, there’s your day-to-day lifestyle: Wearing sunscreen, spending the majority of your day indoors, covering up during the colder months — all of these things limit our skin’s opportunities to absorb the sun’s ultraviolet rays, says Eudene Harry, M.D., medical director for Oasis Wellness and Rejuvenation Center in Orlando. If you have darker skin tones, it’s even more difficult, as UV rays aren’t as easily converted, she adds. And as we get older, everyone’s ability to produce vitamin D slows down.

Which is why a lot of people then try to get their daily dose through food. The problem is that there aren’t that many that naturally contain vitamin D, says Toby Amidor, M.S., R.D., author of Smart Meal Prep For Beginners. “The best sources are fatty fish (such as salmon, tuna, and mackerel) and fortified foods, including milk, orange juice, yogurt, soy beverages, and cereals,” she explains. Egg yolks, cheese, and beef liver contain smaller amounts, and mushrooms that have been exposed to UV light will offer trace amounts of the nutrient.

So it makes sense, then, that some people turn to supplements. Both Amidor and Dr. Harry agree that taking a vitamin D supplement is probably necessary for the majority of adults, but they emphasize that your physician can confirm that for sure — and determine your dosage — as a 2017 study found that a number of adults may actually be consuming an excessive amount.

Whether you’re hitting your daily dosage from the sun, your plate, a supplement, or a combination of all three, here are six health benefits your body can score from getting enough vitamin D.

1. It can strengthen your bones.

First and foremost, this vitamin is necessary in order for the body to absorb calcium, a mineral that is essential in bone formation. “As we get older, we are more prone to fractures and osteoporosis, and vitamin D helps to ensure that calcium is deposited into the right place,” Dr. Harry says. What’s more: According to a review of 53 studies published in the journal The Cochrane Library, seniors who took a vitamin D supplement with calcium had a reduced risk of hip fractures.

2. It may improve muscle strength.

After looking at 116 healthy adults between the ages of 20 and 74, researchers realized that the active form of vitamin D, which your body makes when your skin is exposed to sunlight, was linked to lean mass in women; those with more muscle bulk were likely to have higher levels of the nutrient in their bloodstream. The same outcome was not seen in men, but now scientists are analyzing the role vitamin D plays in muscle building in larger clinical trials.

3. It can boost your immune system.

In an international study that looked at nearly 11,000 people over 25 clinical trials, researchers found that those with lower levels of vitamin D who then took a daily or weekly supplement were shown to cut their risk of an acute respiratory infection (such as pneumonia or the flu) and an upper respiratory infection (like a cold and sinus infection). A study published in Frontiers in Immunology also found that vitamin D could be therapeutic for those with an autoimmune disease, such as Lupus and multiple sclerosis, Dr. Harry adds.

4. It may lower your diabetes risk.

Study authors from the University of California San Diego School of Medicine and Seoul National University followed nearly 900 healthy adults over a 12-year period. Their vitamin D levels, as well as two measurements for diabetes — fasting plasma glucose and oral glucose tolerance — were recorded. Over that 12-year span, 47 people were diagnosed with type 2 diabetes and 337 were diagnosed with prediabetes. The connection? Those with higher blood serum levels of vitamin D had between one-third and one-fifth of the risk of developing diabetes compared to those with lower levels of the nutrient.

5. It may improve your chances of healthy pregnancy.

Researchers from the Eunice Kennedy Shriver National Institute of Child Health and Human Development uncovered two possible connections between vitamin D and motherhood. After analyzing several studies that involved women who were undergoing in vitro fertilization, they found that the females with higher levels of vitamin D also had higher rates of pregnancy. They also discovered that moms-to-be who had sufficient levels of vitamin D before conceiving were 10% more likely to become pregnant, and they had a 12% reduced risk of miscarriage once they were expecting.

6. It could reduce your risk of cancer.

Various studies over recent years suggest that vitamin D is associated with lowering your chances of developing different forms of cancer, including breast, colon, bladder, and liver. Plus, a September 2018 study published in Menopause, which looked at 600 women, found that post-menopausal females with obesity had an increased risk of vitamin D deficiency at the time they were diagnosed with breast cancer. Why does that matter? Those with higher levels of vitamin D during cancer treatment had a 50% lower mortality rate, so experts think there could be a connection between the nutrient and your chances of beating the disease — or even getting it at all.

Amy Capetta Amy Capetta has been writing health and lifestyle articles for over 15 years.

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By Alina Petre

Vitamin D is a fat-soluble vitamin that is essential for optimal health.

Only a handful of foods contain significant amounts of this vitamin. These include fatty fish, organ meats, certain mushrooms and fortified foods.

However, unlike other vitamins that you can only get through your diet, vitamin D can also be made by your body when your skin is exposed to the sun.

For this reason, vitamin D is technically considered a hormone.

The limited availability of vitamin D in the human diet, combined with most people’s insufficient sun exposure, may explain why up to 41.6 percent of the U.S. population has deficient blood levels (1).

Interestingly, having adequate blood levels of this vitamin can provide many important health benefits.

This article lists 15 science-based benefits linked to vitamin D.

1. Improves Bone Health

Vitamin D plays an important role in the health of your bones.

That’s because it increases the absorption of calcium and phosphorus from your diet—two nutrients important for bone health.

Studies show that individuals with low blood levels tend to suffer from more bone loss (2).

In addition, research shows that individuals taking vitamin D supplements may benefit from a 23–33 percent lower risk of bone fractures (3, 4).

Moreover, recent studies report that taking vitamin D supplements may help improve fracture healing, especially in people with low levels. However, more studies are needed to support these results (5).

Most experts recommend that individuals with blood values under 12 ng/ml (25 nmol/l) should consider taking a vitamin D supplement that provides at least 20–25 mcg (800–1,000 IU) each day (2).

However, some insist that this recommendation is too low and propose that people take higher dosages in order to maintain blood vitamin D levels above 30 ng/ml (75 nmol/l) (6, 7, 8, 9).

In any case, all experts agree that elderly individuals, who have an elevated risk of falls and fractures, should supplement at the higher end of the recommendation (2).

Bottom Line: Vitamin D helps increase the absorption of minerals that are important for bone health. Higher levels may also reduce the risk of fractures, limit bone loss and improve recovery from fractures.

2. Reduces Diabetes Risk

Diabetes is a disorder in which your body cannot process carbs normally. Several types of diabetes exist, but type 1 and type 2 diabetes are the most common.

Type 1 diabetes is an autoimmune disease generally diagnosed during childhood or adolescence, whereas type 2 diabetes usually occurs later in life and is related to lifestyle.

Interestingly, vitamin D may help reduce the risk of both types of diabetes.

Type 1 Diabetes in Children

Type 1 diabetes is a genetic autoimmune disease that destroys the insulin-producing beta cells in the pancreas.

For this reason, type 1 diabetics must inject insulin several times per day to ensure their blood sugar stays at a healthy level (10).

Although type 1 diabetes has a large genetic component, certain environmental factors—perhaps including low vitamin D intake—may act together to promote the disease.

For instance, studies show that infants and toddlers who take vitamin D supplements may have a 29–88 percent lower risk of developing type 1 diabetes than infants given no supplements (11, 12).

The recommended daily allowance is 10 mcg (400 IU) vitamin D for infants 0–12 months and 15 mcg (600 IU) for most children and adults (13).

However, many argue that these recommendations are too low, with one study observing that only daily doses of 50 mcg (2,000 IU) and above successfully reduced the risk of developing type 1 diabetes (14).

That said, few studies have so far investigated the link between vitamin D and type 1 diabetes. More research is needed before strong conclusions can be made.

Type 2 Diabetes in Children, Teenagers and Adults

Type 2 diabetes is a disease that develops over time. It can happen if your pancreas stops producing enough insulin or if your body develops a resistance to insulin—or both (15).

Interestingly, vitamin D levels may play a role in the development of type 2 diabetes (16, 17, 18, 19).

Experts believe that vitamin D may protect against type 2 diabetes by reducing insulin resistance, increasing insulin sensitivity and enhancing the function of the cells responsible for producing insulin (17, 20, 21).

In fact, two recent reviews report that people with low blood vitamin D levels may have up to a 55 percent higher risk of developing type 2 diabetes (22, 23).

What’s more, adults who consumed at least 12.5 mcg (500 IU) of vitamin D per day appeared to benefit from a 13 percent lower risk of developing type 2 diabetes than those who regularly consumed less than 5 mcg (200 IU) per day (23).

Similar results were also reported in vitamin-D-deficient children and teenagers with insulin resistance (24).

In another study, type 2 diabetics given 1,250 mcg (50,000 IU) vitamin D per week had a 5–21 percent decrease in fasting blood sugar levels and insulin resistance over the two-month study period, compared to controls (25).

It’s important to mention that not all reviews agree on the protective effects of taking vitamin D supplements (26, 27, 28).

Although it is possible that not all type 2 diabetics benefit from taking vitamin D supplements, it seems particularly beneficial to those with poor blood sugar control (26).

Bottom Line: Adequate vitamin D levels may help reduce the risk of developing both type 1 and type 2 diabetes. In certain cases, vitamin D supplements may also help improve blood sugar control in type 2 diabetics.

3. Could Improve Heart Health

Vitamin D may help improve the health of your heart and reduce the likelihood of heart attacks.

In one study, men with blood levels below 15 ng/ml (37 nmol/l) were twice as likely to get a heart attack as those with levels of 30 ng/ml (75 nmol/l) or higher (29).

In another study, the likelihood of developing heart disease was 153 percent higher for people with blood vitamin D levels below 15 ng/ml (37 nmol/l) (30).

The highest risk was seen in individuals with low vitamin D levels who also had high blood pressure (30).

That said, although low blood vitamin D levels are often linked to an increased risk of heart disease, many studies fail to find a decreased risk from taking vitamin D supplements (31, 32, 33, 34).

Experts speculate that other factors linked to a good vitamin D status may be at play, such as time spent outdoors or a preference for vitamin-D-fortified beverages instead of soft drinks (35).

Thus, although taking vitamin D supplements may be beneficial for other reasons, increasing your levels through lifestyle choices still seems to be the best strategy against heart disease.

Bottom Line: Individuals with a good vitamin D status have a lower risk of developing heart disease. However, taking supplements doesn’t seem to have an effect.

4. May Lower Your Risk of Certain Cancers

Maintaining adequate vitamin D levels may have some benefits for preventing cancer.

In fact, various studies suggest that individuals with higher levels have a lower risk of certain types of cancer (36, 37).

Two recent reviews report that those with adequate levels may have up to a 25 percent lower risk of developing bladder cancer. Higher vitamin D levels may also reduce the risk of dying from the disease (38, 39).

Similarly, several other studies show that maintaining higher blood vitamin D levels may reduce the risk of developing colorectal cancer (40, 41, 42, 43).

In addition, some studies report that vitamin D may play a role in slowing down the progression of cancer. That said, it remains unclear whether taking vitamin D supplements provides any anti-cancer benefits (44).

In fact, several studies failed to find protective effects against cancer after participants took vitamin D supplements, despite having increased blood levels (45, 46, 47, 48, 49).

In sum, more studies are needed to determine cause and effect, as well as the true value of taking vitamin D supplements as an anti-cancer strategy.

Until then, it may be wise to focus on maintaining adequate vitamin D levels through lifestyle choices that are known to reduce the risk of cancer. For instance, through a healthy diet and regular physical activity—preferably outdoors.

Bottom Line: Vitamin D may play a role in cancer prevention. However, more studies are needed to determine its exact role.

Vitamin D is a fat-soluble vitamin that the skin makes upon exposure to direct sunlight. Read on to learn about the potential benefits of vitamin D supported by science and find out why maintaining normal blood levels is so important for good health.

What is Vitamin D?

Vitamin D is a fat-soluble vitamin the body needs to build and maintain strong bones. It helps absorb calcium in the gut, keeping calcium and phosphorus in balance to mineralize bones. Vitamin D also helps support immune balance .

Without enough vitamin D, bones can become thin, weak, brittle, or misshapen. Getting enough vitamin D prevents rickets in children and osteomalacia in adults. Along with calcium, vitamin D also helps protect older adults from osteoporosis .

Some scientists view vitamin D as a prohormone because it is involved in many metabolic processes in the body .

The body naturally makes vitamin D when exposed to sunlight. Getting regular, moderate sun exposure is a safe way to maintain normal vitamin D levels during the summer months.

Vitamin D is also found in certain foods, such as fatty fish like salmon and sardines. Additionally, many vitamin D supplements are available on the market.

Many older adults don’t get enough vitamin D from sunlight. The elderly also tend to have poor vitamin D absorption and less elastic skin, which puts them at a higher risk of deficiency. Taking a supplement with vitamin D may be beneficial for bone health in such cases .

Taken at the recommended doses, vitamin D supplements are considered safe. However, taking too much can be harmful. Vitamin D supplements may also interact with prescription medications. Remember to talk to your doctor before supplementing!

Strong evidence points to the importance of vitamin D for maintaining strong bones. Supplementation may be beneficial in people who can’t get enough of this vitamin from sunlight and food.

Health Benefits of Vitamin D

Research Limitations

It’s important to note that many of the studies regarding vitamin D are association studies, which means that deficiency is correlated with a certain issue but doesn’t necessarily cause that issue.

In many of these cases, the reason why people’s health is worse is because they aren’t getting enough sun, rather than being deficient in vitamin D.

Research suggests that the sun has a lot of health benefits that are independent of vitamin D. Thus, low vitamin D is often more of a signal that someone isn’t getting enough sun, which is the real cause of the health problem.

For these purported benefits, vitamin D supplements are clearly marked as lacking effectiveness data.

1) Familial hypophosphatemia

Vitamin D is effective for treating bone disorders from familial hypophosphatemia, an inherited condition .

2) Fanconi syndrome

Vitamin D2 is effective for treating hypophosphatemia associated with Fanconi syndrome, a rare disorder .

3) Hypoparathyroidism

Vitamin D effectively increases calcium blood levels in people with hypoparathyroidism .

4) Osteomalacia & Bone Health

Vitamin D3 supplements are effective for treating osteomalacia.

Vitamin D maintains calcium and phosphorus balance in the body. Specifically, it promotes calcium and phosphorus absorption from the gut, calcium reabsorption in the kidney, and calcium mobilization in bone .

Osteomalacia and rickets attributable to vitamin deficiency are preventable with an adequate nutritional intake of this vitamin. Varying doses and treatment regimes have been described with the aim is to achieve a blood level between 20 and 50 ng/mL .

Additionall, low blood levels of vitamin D are associated with lower bone mineral density, mineralization defects, and an increased risk of bone loss or fracture in both men and women .

Evidence supports the use of vitamin D and calcium supplements at the recommended doses for bone health in older people who are at risk of deficiency. Studies suggest this combination may reduce bone fractures .

5) Vitamin D Deficiency and Rickets

Supplementation effectively prevents vitamin D deficiency in a range of doses.

Vitamin D deficiency causes rickets in infants, young children, and adolescents and osteomalacia in adults. Supplementation prevents and treats rickets .

6) Low Calcium Levels in People with Kidney Disease

Vitamin D2 by mouth effectively manages low calcium levels (hypocalcemia) and prevents complications (renal osteodystrophy) in people with chronic renal failure undergoing dialysis .

Likely Effective for:

Along with calcium, vitamin D supplements likelt help protect older adults from osteoporosis .

Additionally, various forms of vitamin D3 by mouth prevent osteoporosis from corticosteroid drugs, which are prescribed to reduce severe inflammation. Evidence suggests that vitamin D3 metabolites (including calcitriol and alfacalcidol) are more effective in this population .

8) Psoriasis

Topical creams with specific forms of vitamin D (such as calcitriol and other analogues such as calcipotriene, maxacalcitol, and paricalcitolare) likely beneficial in people with psoriasis when prescribed by a doctor

Possibly Effective for:

Both vitamin D3 and D2 may reduce the risk of cavities, but vitamin D3 is likely more effective. Both were compared to placebo in babies children, and adolescents in one analysis of clinical trials .

10) Heart Failure

Limited research suggests that vitamin D may prevent the risk of heart disease in some women. Early research also points to lower vitamin D levels in heart disease patients, but more research is needed .

11) Bone Loss from Overactive Hypothyroid

Vitamin D3 by mouth may help reduce hyperparathyroidism and bone turnover in women. In one study, supplementation increased vitamin D blood levels, reduced levels of parathyroid hormone, and improved markers of bone turnover .

12) Airway Infections

Scientists discovered that people deficient in vitamin D are more likely to get tuberculosis. Limited research suggests supplementation may prevent tuberculosis or shorten the disease duration by strengthening the immune response, but more quality research is needed .

A couple of studies also revealed that vitamin D supplementation, especially over the winter months, may protect children against the flu and respiratory infections. Stronger evidence for supplementation in adults is needed .

Additionally, people with HIV are often deficient in vitamin D, which can further weaken their immune response. Some evidence suggests supplementation can safely improve their immunity and vitamin D status .

13) Reducing Tooth Loss in the Elderly

Vitamin D3 with a calcium supplement by mouth seemed to reduce the risk of tooth loss in the elderly in one study .

Possibly Ineffective for:


No evidence supports the use of vitamin D for cancer prevention or treatment.

Some studies found that sufficient vitamin D levels protect against some types of cancer and the risk of dying. Vitamin D may help prevent cancer by strengthening the immune response, but its cancer-preventive effects are still being researched. .

For example, some studies suggest that women who get more sun and eat foods high in vitamin D are less likely to get breast cancer, while other studies found no link. Large-scale studies should clarify these findings .

According to limited research, maintaining higher vitamin D blood levels may also aid in colon cancer prevention. On the other hand, deficiency might increase prostate cancer risk. More research is needed before any conclusions can be drawn .

Studies about vitamin D and prostate and ovarian cancer have had mixed results. Therefore, It’s still uncertain whether vitamin D can help prevent pancreatic or ovarian cancer, though early studies hint at its potential .

Normal vitamin D levels appear to be important for cancer prevention, but large-scale studies are needed to further explore this link.

Heart Disease and High Blood Pressure

Vitamin D deficiency has been associated with increased risk of cardiovascular disease (including high blood pressure, heart attacks, peripheral arterial disease, and stroke) in several studies .

Though studies linked vitamin D deficiency with heart disease, supplementation might not have a protective effect. Additional studies are needed.

On the other hand, several studies have linked sun exposure, which increases vitamin D levels, to lower blood pressure. Limited evidence suggests that UVB therapy might also reduce blood pressure, though larger studies are needed .


Despite some positive findings, vitamin D alone probably does not prevent fractures in older adults. There’s conflicting evidence about its effectiveness for preventing fractures in older adults, when used in combination with higher calcium doses. More research is needed .

Insufficient Evidence for:

The following purported benefits are only supported by limited, low-quality clinical studies.

There is insufficient evidence to support the use of vitamin D for any of the below-listed uses.

Remember to speak with a doctor before supplementing. Vitamin D should never be used as a replacement for approved medical therapies.


Scientists discovered that people deficient in vitamin D are more likely to get tuberculosis. Limited research suggests supplementation may prevent tuberculosis or shorten the disease duration by strengthening the immune response, but more quality research is needed .

Sleep, Brain Health & Development

Normal vitamin D levels support emotional balance, cognitive function, and quality sleep .

Additionally, vitamin D is important for brain developement, which is why pregnant women are advised to get at least 600 IU of vitamin D per day. Babies and children up to 12 months require 400 IU/day.

What’s more, vitamin D deficiency has been associated with a wide range of psychiatric and neurological diseases .

According to some researchers, low levels of blood vitamin D are associated with low mood, memory problems, and dementia .

Limited research suggests that normal vitamin D levels may be protective against Parkinson’s disease, though solid evidence is still lacking .

Though vitamin D seems to contribute to mental health and normal sleep patterns, more research is needed to determine the benefits of supplementation.

Vitamin D supports healthy brain development and cognition. Low levels have been linked with memory problems and low mood. The benefits of supplementation in these cases are still an active area of research.

Inflammation & Autoimmunity

Vitamin D helps reduce inflammation in the body. Studies have shown that it may act as an immune balancer. It has the potential to influence a wide range of immune problems, infectious and autoimmune diseases .

So far, limited studies hint at the promising effects of vitamin D for the following inflammatory and/or autoimmune conditions:

All in all, studies have confirmed that vitamin D deficiency is more common in people with these autoimmune, inflammatory, and allergic problems or tendencies. Nontheless, evidence is lacking to support vitamin D supplementation in the majority of the cases.

Vitamin D deficiency has been linked with autoimmune and inflammatory problems. The benefits of supplementing are still uncertain.


Clinical evidence suggests that vitamin D plays a role in muscle metabolism and function .

Vitamin D may help strengthen muscles, improve fitness, and reduce the risk of falls in the elderly. Deficiency might make athletes more prone to injuries, according to some studies .

Vitamin D supports heart health and physical fitness. Sun exposure may help lower blood pressure, but vitamin D supplements probably don’t have a protective effect.

Obesity & Metabolic Problems

Vitamin D helps the pancreas produce insulin, which controls sugar levels. Deficiency may impair this process and is common in people with type 2 diabetes .

Limited studies suggest vitamin D supplementation might lower the risk of type 2 diabetes, but the available evidence is sparse .

Additionally, several studies found a link between low vitamin D levels and obesity. Higher blood levels might prevent people from obesity and metabolic syndrome, limited studies suggest .

Vitamin D supports healthy insulin production and sugar control. Deficiency has been linked with type 2 diabetes and obesity, though more research is needed.

Reproductive Health

Vitamin D deficiency during pregnancy can harm both the mother and the baby. It may lead to bone loss and osteomalacia in the mother. In newborns, it may cause impaired growth, bone, and enamel formation .

The recommended daily intake of vitamin D for children above 1 year old and adults up to 70 years old is 600 IU. The recommended intake stays the same for pregnant and breastfeeding women. Newborns and babies require at last 400 IU/day until 12 months .

Most experts consider vitamin D doses up to 4000 ID/day safe during pregnancy. Evidence is lacking to suggest supplementation can prevent pregnancy complications such as preterm birth and preeclampsia, though .

Experts concluded that ongoing randomized clinical trials need to be completed to determine if vitamin D supplements (beyond that contained in prenatal vitamins) should be routinely recommended to pregnant women .

Vitamin D might also support men’s reproductive health and fertility. Limited studies suggest vitamin D may improve sperm motility, but the evidence is far is inconclusive .

Data on the effects of vitamin D on fertility in women is sparse. Limited evidence suggests it may help women with PCOS, which impacts ovulation and fertility. Large-scale, clinical studies are needed (123, 124, 125, 126, 127).

At the recommended doses, vitamin D supports fertility and contributes to a healthy pregnancy. It also provides breastfed babies with vitamin D for bone development.

Hair & Skin Health

Vitamin D helps reduce inflammation in the body. Maintaining healthy levels might support skin and hair health.

Some scientists believe that people with skin problems like eczema, psoriasis, and hair loss need to be monitored to ensure they’re not deficient in vitamin D. More evidence is needed to support this practice .

According to limited studies, vitamin D shows promise for:

  • Eczema
  • Acne
  • Wound healing
  • Autoimmune hair loss

Nonetheless, hard evidence is lacking to support vitamin D supplementation in the majority of the cases.

Vitamin D Deficiency, Dosage & Supplementation

How to Maintain Normal Levels

Vitamin D levels can be increased and maintained by:

  • Regularly getting natural sunlight
  • Eating foods high in vitamin D
  • Supplementing

Most of the vitamin D3 in humans is derived from synthesis in the skin.

Deficiency Prevalence

Vitamin D deficiency is fairly common in the United States, according to some estimates. It is defined as 25(OH)D blood levels of 20 ng/mL or below. Many factors can contribute to vitamin D deficiency. Some of them include inadequate sun exposure, gut disorders, liver disease, kidney disease, strict vegan diets, obesity, and certain medication .

Vitamin D deficiency may cause fatigue, back and bone pain, mood problems, and muscle weakness. Not all people with deficiency experience symptoms .

People who don’t get enough vitamin D through sunlight or dietary sources might need vitamin D supplements.

Supplement Types

Two forms of vitamin D exist: vitamin D2 and vitamin D3. Vitamin D2 (ergocalciferol) is mostly human-made and commonly added to foods.Vitamin D3 (cholecalciferol) is synthesized in the skin and found in animal-based foods .

Vitamin D3 is approximately 87% more effective in raising and maintaining the vitamin D levels in the body than vitamin D2. This form should be used for supplementation and fortification .

Since vitamin D fat-soluble and better absorbed when taken with fats. Bile salts help absorb vitamin D in the gut. Gut disorders, blocked bile flow, and bile-binding medications reduce vitamin D absorption .


The recommended vitamin D doses are :

  • For children up to 12 months old: 400 IU
  • For children and adults ages 1-70 years: 600 IU (including breastfeeding and pregnant women)
  • For people over 70 years old: 800 IU

Aim to get regular vitamin D from sun exposure and food to avoid deficiency. Adults up to 70 years old should get 600 IU/day.


Vitamin D is an essential fat-soluble vitamin produced by the skin during direct sunlight exposure. Some foods also contain small amounts of vitamin D. Most adults should aim to get 600 IU/day.

Vitamin D plays important roles in the body. It helps build strong bones, balance the immune system, reduce inflammation, prevent infections, and maintain overall good health.

Plus, it’s being researched for contributing to restful sleep and emotional balance, and it’s also a key prenatal vitamin.

Studies have linked various health problems with vitamin D deficiency. However, strong evidence is lacking to support supplementation in most of the cases.

Some experts say this might be because vitamin D deficiency is a result of inadequate sun exposure, which has many other negative health consequences aside from low vitamin D blood levels.

Nonetheless, people who are deficient or at risk of deficiency may need to supplement to support bone health–particularly the elderly who have higher daily requirements, poor absorption, and reduced vitamin D production in the skin.

Further Reading

  • Can Vitamin D3 Help Prevent Infections?
  • Vitamin D for Fitness, Cardiovascular & Metabolic Health
  • Can Vitamin D Help Protect Against Inflammation & Autoimmunity?
  • Can Vitamin D Reduce the Likelihood of Cancer?
  • Vitamin D Benefits for Brain Health & Sleep
  • How Vitamin D Improves Bone & Kidney Health
  • Is Vitamin D Safe for Fertility, Pregnancy & Breastfeeding?
  • Does Vitamin D Improve Hair & Skin Health?
  • Vitamin D: Dosage, Sources, Deficiency, Toxicity

Why Is Vitamin D So Important for Your Health?

Vitamin D is one of the most important vitamins for our overall health, but many people in the United States, as well as worldwide, are not getting enough of this vitamin. And the only way to know if you’re getting enough of this vitamin is by doing an expensive test. And everyday it seems, new studies show new reasons why this vitamin is so important to our health.

Although vitamin D can be stored in your body fat until it is needed, the problem is that it’s not so easy to get enough vitamin D into your body.

The main job of vitamin D is to keep the right amount of calcium and phosphorus in your blood?these are the 2 nutrients that work together to make your bones strong. If you don’t have vitamin D in your body, only a small amount of the calcium from your diet can be absorbed by your body, and only a little more than half of phosphorus is absorbed. Without enough calcium and phosphorus being absorbed in your body, your bones would become brittle and break easily.

Until recently, experts believed that the main role of vitamin D was to keep our bones healthy and prevent them from breaking up. But new research has shown many other reasons why this vitamin is so important for our health.

The Reasons Why Vitamin D Is So Important

It helps to:

  • Prevent bone fractures
  • Prevent falls in older people and osteoporosis
  • Reduce the risk of cancer, especially colon cancer, prostate cancer, and breast cancer
  • Reduce the risk of diabetes, especially in young people and in those living in high altitude
  • Protect against heart disease, including high blood pressure and heart failure
  • Reduce your risk for multiple sclerosis
  • Improve you mood
  • Improve your lung function.

If You Don’t Get Enough Vitamin D

  • Your bones can become weak and can break
  • Children can get “rickets,” a disease that prevents their bones from growing properly, delays their growth, and causes problems with their immune system
  • Adults can develop “osteomalacia,” a disease that weakens the bones and makes them hurt, and also causes fractures
  • Older adults can get osteoporosis, which doesn’t cause pain, but makes the bones thin and easy to fracture

The best way to know if you are getting enough vitamin D is to have a specific blood test. Otherwise, you may not know that you’re not getting enough vitamin D until you start having symptoms associated with vitamin D deficiency. The vitamin D test is very expensive, so it’s not routinely done.

How Much Vitamin D Do You Need?

The amounts of vitamin D the US government now recommends for the different age-groups are too small. Most experts say that people should take much more of this vitamin every day than is now recommended. They believe that if you don’t get enough exposure to sunlight, all children and adults need about 800 to 1000 units (marked as “800 IU”) of vitamin D every day.

People who are older than 65 probably need even more than 1000 IU, because they usually don’t spend much time in the sun and their bodies don’t absorb vitamins the way it used to. And people who are at risk for vitamin D deficiency, and those who are already vitamin D deficient, need even higher levels of the vitamin.

People have been taking as much as 2000 IU units of the vitamin without any problems. But just like you can get too much of any good thing, you can also get too much vitamin D if you take much greater amounts, although this rarely happens. Vitamin D overdose will cause you to become sick with nausea and vomiting. It can also make you feel weak and confused, and make your heartbeat irregular.

What Are the Best Sources?

The best source for vitamin D is sunlight. Only few foods supply vitamin D in significant amounts. The best source for this vitamin for humans is the sun, not supplements. The problem is that too much exposure to the sun can cause skin cancer, but too little sun exposure is the reason that many people today don’t get enough vitamin D.

Because it’s difficult to get all the vitamin D you need from food, and since you don’t want to be exposed to too much sunlight, most people need short-time sun exposures and daily vitamin D supplements. Spending a short time in the sun each day, without sun block, may not be a bad idea, unless you have a special sensitivity to sun exposure. Check with your doctor if you’re not sure.

You can get vitamin D supplements over the counter at the supermarket, a drugstore, or any health food store. Some vitamin D supplements are available only by prescription and are given to people who are vitamin D deficient.

If your skin is exposed to summer sunlight for about 10 to 15 minutes at least twice a day, you’re probably getting enough vitamin D. But when you use sunscreen, it prevents the skin from soaking up enough vitamin D.

And in the winter, the sun isn’t strong enough to give us sufficient amounts of vitamin D. People who live in northern regions might not get enough vitamin D from sunshine, even in the summer. People who live in big cities might not get enough vitamin D, because pollution can block the sun’s rays.

Foods that Provide Vitamin D

Only a few foods naturally contain vitamin D, but some foods are fortified with this vitamin. These are some of the best sources:




Cod liver oil

1 Tablespoon

Salmon, cooked

3 1/2 ounces

Mackerel, cooked

3 1/2 ounces

Sardines, canned in oil and drained

1 3/4 ounces

Tuna fish, canned in oil

3 ounces

Milk (skim, low fat, whole), vitamin D fortified

1 cup

Margarine, fortified

1 Tablespoon

Pudding (from mix, with vitamin D-fortified milk)

1/2 cup

Cereal, vitamin D fortified

3/4 to 1 cup


1 whole

Liver or beef, cooked

3 1/2 ounces

Cheese, Swiss

1 ounce

Who Is at Risk for Vitamin Deficiency?

If you belong to any of the following groups, you may be at risk of vitamin D deficiency, in which case you should ask your doctor to for the vitamin D test:

  • Infants who are only breast-fed or who get less than 2 cups each day of vitamin D?fortified formula or milk
  • People with dark skin (which doesn’t absorb the sunlight as well as light skin)
  • People who don’t get a lot of exposure to sunlight
  • People who use sunscreen often
  • Older people are at very high risk, in part because aging skin doesn’t absorb sunlight as well as younger skin
  • People who are obese
  • People who have medical conditions that interfere with their body’s ability to absorb fat, such as cystic fibrosis, celiac disease, or pancreatitis
  • People who have liver or kidney problems
  • People who live in the northern hemisphere in the winter months
  • People who take certain medicines, like anti-seizure drugs or steroids.

Manuel Breva Colmeiro / Getty Images / WIRED

For many, the winter months mean leaving for work in the dark, coming home in the dark and spending all day in an office lit by fluorescent lights. Without the blue skies of summer, your skin isn’t soaking up much sunlight for your body to create vitamin D.

Between the months of January and March, more than a quarter of adults (29 per cent) in the UK are vitamin D deficient. To tackle this, Public Health England has suggested that from October to March everyone should consider taking vitamin D supplements. It seems like an easy fix: not enough sunlight? Just take a pill instead.

Earlier this year, research firm Mintel reported that vitamin D overtook vitamin C as the UK’s most used supplement. But for those who aren’t lacking the vitamin, supplements could prove to be completely unnecessary. So is it really worth everyone taking on extra vitamin D?

First, the physiology. Vitamin D helps the body to absorb calcium – a key ingredient in keeping bones strong. Severe deficiency can lead to rickets in children and osteomalacia in adults where the bones are softened.

“Adults, especially in wintertime, often experience aches and pains in their bones and muscles,” says Michael Holick, a professor of medicine at Boston University. “It turns out to be vitamin D deficiency osteomalacia that causes aches and pains, and taking vitamin D can help prevent that from happening.”

In the world of medicine, vitamin D has taken on almost mythic properties. Recently it was found that every cell in the body has a vitamin D receptor, and so the benefits of maintaining a healthy level could be more than we currently realise. This is why studies into the impact of vitamin D are experiencing a boom at the moment, with some claiming that deficiency can increase the risk of multiple sclerosis, diabetes or even cancer.

The UK government has been advised by the Scientific Advisory Committee on Nutrition (SACN) that everyone should try to get 10 micrograms per day of vitamin D. SACN found that there was an increased risk of poor musculoskeletal health when the concentration of vitamin D in the blood dipped below 25 nmol/L. It concluded that the best way to prevent it from falling below this level was to suggest a supplement.

It’s a better-to-be-safe-than-sorry approach as in the UK we don’t get our milk fortified with vitamin D, unlike other countries such as the US. You can get vitamin D from dietary sources like fatty fish and leafy greens, but not enough to provide what you need in the winter. Supplements seem like the ideal solution, though many people end up taking it without knowing what it’s actually doing for them.

There is the risk of taking too much. Vitamin D isn’t a nutrient that will simply flush away if your body gets too much of it. As it helps with the absorption of calcium, too much vitamin D may mean that calcium ends up in other parts of the body.

“If you are also taking in a huge amount of calcium and you already have a high level of vitamin D, you might get high calcium,” says Edward Zawada, a researcher and medical doctor from the University of South Dakota. “That is not good for your body. It starts depositing not only in bone like it’s supposed to, but it starts depositing in other tissues too.”

The Vitamin D Council suggest that this problem, called hypercalcemia, can be caused by taking over 250mcg per day over a period of months. This means that while supplements shouldn’t be taken in large quantities or when you don’t need them, like in summer, taking a 10mcg tablet every day won’t cause too much harm. “As long as you’re not simultaneously downing a lot of calcium in the way of supplements are our dairy products then it’s probably pretty safe,” Zawada says.

If you’re one of the 71 per cent of people who aren’t deficient in vitamin D, taking supplements over winter may not harm your body, but it may harm your wallet. The cost involved means that not everyone will be able to afford supplements. Though the government currently has its Healthy Start scheme to give vitamins to parents and pregnant women from low income backgrounds, this doesn’t cover everyone.

Mark Bolland, associate professor of medicine at the University of Auckland worries that the government strategy of suggesting supplements for everyone will mean people in lower socio-economic groups will get left behind.

“For the last few years, the UK population has been spending more than £100 million every year on vitamin D supplements,” Bolland claims. “However, there is little evidence that rates of rickets or osteomalacia are declining,” he says, adding that people on lower incomes “would probably benefit most from supplements” and that such policies risked “entrenching health inequality”.

So should you consider taking a vitamin D supplement? If you’re sensible and only consuming 10mcg per day with not too much calcium, you should be okay. While we still don’t know all of the health benefits, between October and March you have little chance of being able to get the vitamin D from your diet or the sun alone, so it’s worth thinking about it. Although, it’s always worth considering consulting your doctor to find the best plan for you.

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