How Much Vitamin D Do You Need For Optimal Health?
Vitamin D is absolutely essential for good health.
Also known as the sunshine vitamin, it is made in your skin when exposed to sunlight.
Foods that do contain vitamin D include fatty fish like salmon, as well as fish liver oils. Photo credit: Shutterstock
In spite of that, vitamin D deficiency is one of the most common nutrient deficiencies in the world.
Vitamin D is particularly important for bone health and immune system function.
This article discusses how much vitamin D you need.
What is Vitamin D?
Vitamin D is a fat-soluble vitamin that functions like a steroid hormone in the body.
There are two forms of vitamin D in the diet:
- Vitamin D2 (ergocalciferol): found in some mushrooms.
- Vitamin D3 (cholecalciferol): found in oily fish, fish liver oil and egg yolks.
Large amounts of vitamin D can also be made in your skin when it is exposed to UV-rays from sunlight. Any excess vitamin D is stored in your body fat for later use.
Bottom line: Vitamin D functions like a steroid hormone in your body. There are two forms in the diet, D2 and D3. It can also be produced in your skin when exposed to sunlight.
How Common is Vitamin D Deficiency?
Vitamin D deficiency is a problem all over the world.
About 42 percent of the U.S. population is vitamin D deficient. However, this rate rises to 82 percent in African Americans and 70 percent in Hispanics (5).
If you have access to strong sun all year, then occasional sun exposure may be enough to fulfill your vitamin D requirements.
However, if you live far north or south of the equator then your vitamin D levels may fluctuate depending on the season. The levels may go down during the winter months, due to a lack of sufficient sunlight (14, 15, 16).
In that case, you need to rely on your diet (or supplements) for vitamin D, as well as on vitamin D that is stored in body fat during the summer (15).
- Cause muscle weakness.
- Intensify bone loss.
- Increase the risk of fractures.
In children, a severe vitamin D deficiency can cause delays in growth as well as rickets, a disease where the bones become soft.
Bottom line: Vitamin D deficiency is very common worldwide, but occurs at higher rates in specific populations. A deficiency in vitamin D is linked to various health problems.
How Much Vitamin D Should You Take?
How much vitamin D you need depends on many factors. These include age, race, latitude, season, sun exposure, clothing and more.
However, some studies have shown that the daily intake needs to be higher than that if you aren't being exposed to sun.
Depending on who you ask, blood levels above 20 ng/ml or 30 ng/ml are considered as “sufficient."
One study of healthy adults showed that a daily intake of 1120–1680 IU was needed to maintain sufficient blood levels (23).
In the same study, individuals who were vitamin D deficient needed 5000 IU to reach blood levels above 30 ng/ml.
All things considered, a daily vitamin D intake of 1000–4000 IU, or 25–100 micrograms, should be enough to ensure optimal blood levels in most people.
4000 IU is the safe upper limit according to the Institute of Medicine (IOM). Make sure not to take more than that without consulting with a health professional.
Bottom line: Vitamin D intake is recommended at 400–800 IU/day, or 10–20 micrograms. However, some studies suggest that a higher daily intake of 1000–4000 IU (25–100 micrograms) is needed to maintain optimal blood levels.
What are the Optimal Blood Levels of Vitamin D?
Blood levels of vitamin D are assessed by measuring 25(OH)D in the blood, which is the storage form of vitamin D in the body (28).
However, there has been some debate over the definition of optimal blood levels.
- Sufficient: 25(OH)D > 20 ng/ml (> 50 nmol/l).
- Insufficient: 25(OH)D <20 ng/ml (<50 nmol/l).
- Deficient: 25(OH)D < 12 ng/ml (< 25 nmol/l).
These organizations claim that blood levels of over 20 ng/ml meet the vitamin D requirements of more than 97.5 percent of the population.
A committee at the IOM did not find higher blood levels to be associated with any additional health benefits (21).
Bottom line: Vitamin D levels are generally considered sufficient when above 20 ng/ml (50 nmol/l). However, some experts claim that blood levels above 30 ng/ml (75 nmol/l) are optimal.
What are the Main Sources of Vitamin D?
You can get vitamin D from:
- Sun exposure.
- Foods that contain vitamin D.
Vitamin D intake is generally quite low, since very few foods contain significant amounts (32).
Foods that do contain vitamin D include fatty fish like salmon, as well as fish liver oils.
However, supplements are available almost everywhere and there is a good selection of vitamin D3 supplements on Amazon.
Bottom line: The main sources of vitamin D are sunshine, fatty fish, egg yolks, fish liver oils, fortified foods and supplements.
Can We Get Enough Vitamin D from the Sun Alone?
Summer sun exposure is the best way to get enough vitamin D.
However, the amount of sunlight needed varies.
Older individuals and dark-skinned people produce less vitamin D in the skin.
Geographic location and season are very important, because vitamin D can't be produced year round in countries that are far from the equator.
Even though the sun may be shining, it is not necessarily strong enough to produce vitamin D.
Here are a few facts about vitamin D production in the sun:
- In more than 70 countries that are positioned north of 35°N, no vitamin D is produced during the winter months (34, 35).
- Further north, in countries like Norway (69°N), no vitamin D is produced from October until March (36).
- Factors such as clothing, weather, pollution, sunscreen use, weight and genetics may also affect the body's ability to produce vitamin D.
In strong sun, exposing arms and legs for 5–30 minutes between 10 a.m. and 3 p.m. is usually enough to meet the daily requirements of most light-skinned people. People with darker skin may need a little more time (22).
One study showed that extended sun exposure during summer was enough to ensure excellent vitamin D levels during winter, regardless of vitamin D intake (37).
However, if you live far from the equator, you probably need to consume supplements or foods that contain vitamin D.
Bottom line: Vitamin D requirements can be met by sunshine alone during the summer. During the winter and for those living far from the equator, supplements may be needed.
How Much is Too Much?
Information about vitamin D overdose is outdated and toxicity is extremely rare.
It is associated with dangerously high amounts of calcium and phosphates in the blood, along with low levels of parathyroid hormone.
This is typically only seen in individuals who have accidentally or intentionally taken extremely high doses of vitamin D for long periods of time, such as 50,000–1 million IU/day for months (38, 39).
The upper level of harmless intake is set at 4000 IU, or 100 micrograms, per day.
However, up to 10,000 IU per day has not been shown to cause harm to healthy individuals (21).
That being said, very few people actually need more than 4000 IU a day (40).
A study of 17,000 people taking varying doses of vitamin D, up to 20,000 IU/day, did not demonstrate any signs of toxicity. Their blood levels were still lower than the upper range of normal, which is 100 ng/ml, or 250 nmol/l (26).
Also, it is not possible to overdose on vitamin D from sunlight.
Keep in mind that although large doses are unlikely to cause harm or toxicity, they may be completely unnecessary.
Bottom line: The recommended upper intake level of vitamin D is 4000 IU/day. However, even higher dosages have been shown to be safe in some studies.
Take Home Message
Vitamin D is essential for bone health and many other aspects of health.
A deficiency is incredibly common and may have severe health consequences for many people.
If you're thinking about adding more vitamin D to your diet, consider the following factors:
- If you live somewhere where there is sun year-round, then you may not need extra vitamin D as long as you make sure to get enough sun.
- If you do not have access to the sun, then vitamin D3 supplements of 1000–4000 IU (25–100 micrograms) should be enough for most people.
- The only way to know if you actually need to take a vitamin D supplement is to have your blood levels measured.
At the end of the day, vitamin D is highly important. Correcting a deficiency is simple, cheap and can have immense health benefits.
This article was reposted from our media associate Authority Nutrition.
YOU MIGHT ALSO LIKE
Disturbing footage of a snake in Goa, India vomiting an empty soft drink bottle highlights the world's mounting plastic pollution crisis.
By Melissa Hellmann
When her eldest son was in elementary school in the Oakland Unified School District, Ruth Woodruff became alarmed by the meals he was being served at school. A lot of it was frozen, processed foods, packed with preservatives. At home, she was feeding her children locally sourced, organic foods.
By James O'Hare
There are 20 million people in the world facing famine in South Sudan, Somalia, Nigeria and Yemen. In developed nations, too, people go hungry. Venezuela, for instance, is enduring food insecurity on a national level as a result of economic crisis and political corruption. In the U.S., the land of supposed excess, 12.7 percent of households were food insecure in 2015, meaning they didn't know where their next meal would come from.
Artists are taking the climate crisis into frame and the results are emotional, beautiful and stirring.
So you've seen the best climate change cartoons and shared them with your friends. You've showed your family the infographics on climate change and health, infographics on how the grid works and infographics about clean, renewable energy. You've even forwarded these official National Oceanic and Atmospheric Administration graphs that explain the 10 clear indicators of climate change to your colleagues at the office.
As the Trump administration moves full speed ahead on boosting the oil and fossil fuel industry, opposition to increased pipeline construction is cropping up in different communities around the country.
By Simon Evans
Last Saturday, two dead whales washed up on the coast of Suffolk, in eastern England, and a third was spotted floating at sea.
What happened next illustrates how news can spread and evolve into misinformation, when reported by journalists rushing to publish before confirming basic facts or sourcing their own quotes.
By Monica Amarelo and Paul Pestano
Sun safety is a crucial part of any outdoor activity for kids, and sunscreen can help protect children's skin from harmful ultraviolet rays. Kids often get sunburned when they're outside unprotected for longer than expected. Parents need to plan ahead and keep sun protection handy in their cars or bags.
By Joe McCarthy
A lot of people take part in community clean-up efforts—spending a Saturday morning picking up litter in a park, mowing an overgrown field or painting a fence.