Would you believe that the majority of the population — between 40 percent and 80 percent or more of adults in the U.S., depending on race — is believed to have a vitamin D deficiency?
It’s no wonder that this vitamin is now one of the most recommended supplements by physicians, taken in order to treat and/or prevent vitamin D deficiency symptoms.
People with dark skin, people who live in northern regions of the world where less year-round sun exposure is experienced and those who are overweight have an even greater chance of experiencing vitamin D deficiency symptoms.
Can vitamin D deficiency be cured? Yes, there are ways you can naturally increase your vitamin D levels and decrease your risk of developing related health conditions.
Spending time in the sun, without sunscreen, is your surest way to get enough. Eating vitamin D-rich foods also helps improve your blood levels.
Read on to understand just how much time you need in the sun and what foods help you avoid vitamin D deficiency.
What Is Vitamin D? (Why We Need It)
Vitamin D is a fat-soluble vitamin that’s stored in the liver and fatty tissues. It’s somewhat different than other vitamins because the body makes most of it on its own (with the help of sunlight), rather than solely relying on food sources to get enough.
Why Do We Need Vitamin D?
Here are some of the benefits associated with this vitamin:
- Contributes to bone health by aiding in calcium absorption into the bones, as well as other vitamins and minerals that contribute to skeletal health, including magnesium, vitamin K and phosphorus.
- Supports the immune system and may help prevent prolonged or excessive inflammatory responses. Adequate levels seem to help protect against some infections and viruses by regulating the role of white blood cells, decreasing viruses’ ability to reproduce and activating enzymes that prevent tissue damage.
- Can help support healthy cell replication and may play a role in protecting against the development of autoimmune conditions.
- Promotes cardiovascular health and helps regulates blood pressure, cholesterol levels and inflammation.
- Helps manage blood sugar levels and works with calcium to regulate insulin secretion.
- May help prevent depression and mood disorders. It helps keep your mood positive, energy levels up and can help treat seasonal affective disorder (a type of “winter depression”).
- Seems to play a role in preventing obesity. Studies show deficiency is tied to greater volumes of fat, serum, liver and muscle mass, although the relationship is still being researched.
How can you raise your vitamin D level quickly? For people who have low levels, vitamin D supplements are available, which come in two forms: D2 and D3.
D3 from animal products (specifically from the cholesterol within these products) is closest to the type humans produce. Vitamin D3 is therefore the more active form and believed to convert much faster than D2.
Vitamin D From the Sun:
Many people assume that the best way to maintain normal vitamin D status is through drinking milk, eating fish or even taking supplements like cod liver oil. While these do serve as food sources, direct exposure to the sun is actually the best way to absorb this important vitamin.
It’s believed that up to 90 percent to 95 percent of most people’s vitamin D comes from casual sunlight exposure.
When you sit in the sun exposed, without sunscreen, for roughly 10 minutes, you likely absorb about 10,000 units of natural vitamin D. However, keep in mind that this amount differs from person to person, depending on skin tone.
Melanin is a substance that affects how light or dark your skin color is, and the more melanin you have in your body, the darker your skin color will be. Melanin gets released when we are exposed to the ultraviolet rays.
The more UV rays we receive, the more melanin is released in our skin. The amount of melanin you have in your skin affects the amount of D vitamin you can produce, so the fairer your skin, the more easily you can make it.
Vitamin D Deficiency Symptoms
What happens when your vitamin D is low? According to scientific studies and reviews, the most common vitamin D deficiency symptoms include:
- heart disease and high blood pressure
- autoimmune diseases
- depression and mood disturbances
- poor skin health, including redness, inflammation and dryness
- arthritis and joint pain
- trouble concentrating
- hair loss
- multiple sclerosis
- chronic muscle or bone pain
Researchers suggest that anyone with these health conditions, or the following symptoms, should be tested for a deficiency:
- chronic fatigue
- trouble sleeping
- weak or broken bones
- weakened immune system
- inflammation and swelling
Is vitamin D deficiency serious? Public health experts tell us that it can be, and it’s now linked with a growing number of health conditions, such as heart disease, cancer, diabetes and mood-related problems.
Here are some of the potential health risks that may be associated with vitamin D deficiency:
- Weakened bones — 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. This is an especially big risk among older adults.
- Susceptibility to infections and viruses — Low levels have been linked with higher incidence of some serious infections, including those that affect the lungs and respiratory system.
- Mood disorders — Because it acts like a hormone within our bodies and affects brain function, vitamin D deficiency has been linked to an increased risk for mood disorders, including depression, seasonal affective disorder, and severe mood problems experienced during PMS, insomnia and anxiety.
- Hormone imbalances — Low levels can interfere with proper testosterone and estrogen production, leading to imbalances that can result in many unwanted symptoms. Can lack of vitamin D cause weight gain? It’s possible. Some studies show that lower levels may be linked to weight gain in older adults, but the weight gain is usually relatively small. There’s more to learn about this connection, but it’s speculated that this vitamin may affect where fat cells shrink or get bigger.
- Cognitive/mental health problems — Researchers indicate that deficient adults may perform poorer on standardized exams, may have poorer decision-making skills, and may have difficulty with tasks that require focus and attention. Some research has demonstrated a correlation between low levels of vitamin D and an increased risk for developing schizophrenia and multiple sclerosis.
- Susceptibility to some cancers — Vitamin D deficiency symptoms have been correlated with increased risks for cancer development, especially breast, colon and prostate cancers. According to research published in Frontiers in Endocrinology, D vitamin plays a role in factors that influence tumor growth, cell differentiation and apoptosis. Research shows that it can affect the risk of breast, colon and ovarian cancers, possibly due to its role in the cell life cycle or its ability to block excess estrogen.
Why do some people develop a deficiency in this vitamin? It’s believed that one of the biggest reasons that vitamin D deficiency is now a public health problem is because of our modern, primarily indoors lifestyle.
Below is more about the common causes of vitamin D deficiency:
1. Lack of Sun
Most children today spend unprecedented hours inside — watching television, playing video games and surfing the internet. Similarly, most adults work indoors, exercise inside gyms and spend their free time inside their homes where they are sheltered from the sun.
With all this time indoors, it’s no wonder we don’t get enough of the “sunshine vitamin” and that vitamin D deficiency affects over a billion people worldwide.
2. Frequent Use of Sunscreens
As the risk for developing skin cancer has also risen in recent years, doctors strongly encourage the use of sunscreen for children and adults, even through the winter months and when sun exposure is generally limited.
Alarmingly, some research shows that when you wear sunblock SPF 8, you reduce your body’s ability to make vitamin D by 90 percent.
If you choose a sunblock with a higher SPF of 30 (which is the number normally recommended by doctors), you reduce your body’s ability by up to 99 percent. This results in further deficiencies because even though we spend time outdoors, the sunscreen doesn’t allow our bodies to convert vitamin D from the sun.
Other vitamin D deficiency causes and risk factors include:
- Underlying health conditions — Research shows that certain health conditions, such as abdominal obesity, type 2 diabetes, insulin resistance and hypertension, also increases a person’s risk of vitamin D deficiency.
- Having darker skin — According to the National Health and Nutrition Examination Survey, the newest statistics demonstrate that more than 90 percent of people with darker skin pigments (including African-Americans, Hispanics and Asians) living in the United States now suffer from vitamin D insufficiency, while 75 perfect of the white population is deficient.
- Certain occupations — A 2017 study recently revealed that occupation can also play a big role in levels of this vitamin. Researchers found that shift workers, health care workers and indoor workers are at a high risk of developing a deficiency due to reduced outdoor time.
- Being overweight — As the population of overweight and obese adults and children has risen steadily over the past several decades, so has the incidence of vitamin D deficiency symptoms. Sadly, research shows that vitamin D deficiency is correlated with increased risks of developing common cancers, autoimmune diseases, hypertension and various infectious diseases, too.
How can you increase your vitamin D level? While some foods provide vitamin D, exposure to sunlight is still the best way to get the amount you need in order to prevent vitamin D deficiency symptoms.
Importance of Sunlight Exposure:
Most experts recommend getting about 10 to 15 minutes of direct sunlight daily, without wearing sunscreen, if you are fair- to medium-toned. If you have dark skin, you likely need more time outdoors to make enough vitamin D because you naturally have more protection against effects of UV rays.
Some experts recommend that darker-toned people spend about 40 minutes to one hour in the sun daily if possible. If you live farther from the equator (in the U.S. this would be the middle states or farther north), then you need more time (closer to one hour a day).
If it’s the winter, you need to double the recommended time to allow enough vitamin D production to occur.
Here is a good rule of thumb to know that your body is making vitamin D:
- You want to look at your shadow and see that it’s shorter than you are. This tells you that the UV index is high enough.
- Between the hours of 10 a.m. to 3 p.m. is usually when the UV index is highest.
If you are worried about not wearing sunscreen and worried about skin cancer, try applying sunscreen to your face and hands but not on your limbs right away (assuming your limbs are exposed). This leaves enough unexposed skin to properly create the vitamin D you need.
Overall, increase your levels naturally through the following practices and foods:
- Sunlight exposure: Aim to spend 10–20 minutes in the sun daily (to get between 1,000 and 10,000 international units). The range is so wide as it depends on the time of year, how far from the equator you live and how much skin is exposed. If you have lighter skin, less time is needed. If you have darker skin or live farther north (in the Northern Hemisphere, like Boston), you need about an hour of sun in the summer to get about 1,000 IUs of vitamin D.
- Cod liver oil (take about one tablespoon daily)
- Carp fish
- Wild-caught salmon
- Rainbow trout
- Pastured eggs
- Beef liver
- Raw milk
- Fortified milk and dairy products
- Fortified milk alternatives, such as nut-based milks
- Maitake and portobello mushrooms (when exposed to UV light)
Vitamin D in Mushrooms:
Mushrooms are a very interesting and rare food when it comes to vitamin D. In some mushrooms that are now available in certain health food stores, the vitamin D content is boosted by exposing these mushrooms to ultraviolet light.
Mushrooms nutrition contains plant sterols that are able to convert UV light to vitamin D. Exposing mushrooms to as little as five minutes of UV light is believed to produce a substantial amount of vitamin D.
While mushrooms are typically grown indoors, many growers are beginning to grow them outdoors to take advantage of this — or they place the growing mushrooms under special lamps.
Rare and sometimes difficult-to-find maitake mushrooms, for example, contain a huge amount of vitamin D. Portobello mushrooms and other mushroom varieties also make good sources, but they are not nearly as high.
You can ask the workers at your health food store or the farmers at your local market if their mushrooms were grown indoors or outdoors in order to know if the mushrooms you are purchasing contain higher amounts of vitamin D.
Vitamin D in Dairy Products:
Interestingly, and despite what many people think, regular, pasteurized milk and dairy products do not naturally contain much vitamin D at all. Synthetic vitamin D is added to pasteurized cow’s milk, soy milk and rice milk.
Almost all of the U.S. milk supply is fortified with 400 IU of vitamin D per quart, according to the U.S. Department of Agriculture, but foods made from milk, like cheese and ice cream, are usually not fortified. Synthetic vitamin D added to foods is believed to be much less effective than naturally occurring vitamin D and can also potentially block natural vitamin D’s effects.
Raw milk, on the other hand, is believed to contain a small amount of vitamin D naturally, which is found in its fat and not destroyed during pasteurization. Some sources show that raw milk has about 38 IUs of vitamin D per quart (four cups).
However, it’s hard to know for sure how much is in raw milk because it differs greatly depending on the specific milk tested and correlates with the health of the animal that it came from.
On top of this, the USDA does not list the official vitamin D content of raw milk, and many sources claim different amounts to be present within raw milk. Keep this in mind if you consume raw milk to increase your vitamin D levels.
Vitamin D Supplementation and Dosage:
Vitamin D deficiency treatment usually involves supplementing with this vitamin.
You may wonder: How much vitamin D should I take? Because vitamin D deficiency symptoms are a growing concern worldwide, especially in Western developed nations, authorities recently increased the recommended daily intake of vitamin D to double the previous amount for newborns, children and adolescents.
Certain supplements provide the preferred type of vitamin D3. To get the best vitamin D3 supplement, look for a fermented, food-based source of D3 (preferably fermented with a healthy bacteria such as L. bulgaricus) paired with fermented botanicals and supplementary probiotics for maximum absorption and effectiveness.
How Much You Need
The recommended daily allowance for vitamin D, according to the USDA, is 600 IU per day for adults. However, getting significantly more, around 5,000 IU per day, may be more effective — especially since there is little risk in over-supplementing in most cases.
Keep in mind that this is a general recommendation, and there is no way to know the exact amount that’s best for you without a blood test. You may need a higher or lower amount and should speak to your doctor.
The only way to know if you are deficient is to have your doctor perform a test, called a 25-hydroxy vitamin D test. This will tell you if, and how severely, you are deficient.
When your doctor performs a blood test and gives you the results for your vitamin D levels, keep these numbers in mind:
- 50+ equals a good level. A 25(OH)D level of >50 nmol/L is now considered the “primary goal.”
- 30–50 means you want to supplement with vitamin D, work on spending more time in the sun and/or add vitamin D foods into your diet.
- Less than 30 means you are very deficient and definitely want to take immediate action to bring those levels up.
How long does it take to recover from vitamin D deficiency? It depends on how deficient you are.
Some studies have shown that in patients with documented vitamin D deficiency, a very high level of vitamin D supplementation may be best. Your provider might recommend a cumulative dose of at least 600,000 IU administered over several weeks, which appears to be necessary to replenish stores within the body.
This goes to show that having a blood test to detect your exact vitamin D levels can be beneficial in telling you exactly how to replenish your body levels properly. Ideally, you want to supplement with a high-quality, whole food-based multivitamin or vitamin D supplement until your blood level of vitamin D is between 50–60 nanograms per milliliter.
Here are more recommendations:
Dosage Recommendation for Children:
- 1–3 years: 600 IU (15 mcg/day)
- 4–8 years: 600 IU (15 mcg/day)
For Older Children and Adults:
- 9–70 years: at least 600 IU (15 mcg/day)
- Older adults over 70 years: 800 IU (20 mcg/day)
- Pregnant and breastfeeding: 600 IU (15 mcg/day)
How Much Vitamin D Is Too Much?
Luckily for most people their skin is able to regulate vitamin D conversion according to heat and other factors. It can store previtamin D for future use and destroy amounts above and beyond what is safe.
Therefore deficiency is usually a much bigger concern than consuming too much vitamin D.
Vitamin D toxicity is believed to be very rare. It usually consists of a buildup of calcium in the blood, called hypercalcemia.
That said, a 2019 study found that higher doses of vitamin D supplements did not improve bone health but actually lowered bone mineral density among healthy adults.
In this three-year study involving over 300 participants, vitamin D supplement doses of 400 IU, 4,000 IU and 10,000 IU were taken per day. Results showed that compared to the 400 IU group, high doses vitamin D supplementation resulted in statistically significant lower radial bone mineral density but did not change bone strength.
Further research is needed to determine whether or not higher doses of vitamin D daily impact bone health negatively.
Also, keep in mind that because vitamin D is a fat-soluble vitamin, it ideally needs to be consumed with fat in order to have optimal absorption. If you are going to eat a food source of vitamin D, it’s best to combine it with some more of essential fat source too, like ghee, coconut oil, nuts, seeds or fish.
Vitamin A and vitamin D have an important relationship as well. Some studies have suggested that there is a possibility for vitamin D deficiencies to become worse when a person takes a high supplemental intake of vitamin A.
These studies reveal that when blood levels of vitamin D fall below 50 on a vitamin D blood test (which means the person is nearing deficiency), higher supplemental intake of vitamin A can worsen the problem. The good news is that when vitamin A and D levels are both sufficient, research has shown that they work together to help your body metabolize the vitamins and use them to their best ability.
Supplementing with very high doses of vitamin A is not recommended, so if you have a known vitamin D deficiency or experience vitamin D deficiency symptoms, it can lead to certain problems.
- Between 75 percent and 90 percent of adults in the U.S. may suffer from vitamin D deficiency symptoms, which can lead to major health issues, such as cardiovascular disease, diabetes, autoimmune disease and cancer.
- Two major causes of vitamin D deficiency symptoms are a lack of sun exposure and the use of sunscreen.
- Sunlight exposure, without sunscreen, for roughly 10 minutes per day helps your body make about 10,000 units of natural vitamin D.
- There are also food sources, including fish, mushrooms exposed to UV rays, eggs and dairy products.
- What are the symptoms of vitamin d deficiency in adults? The most common include weakness, chronic fatigue, depression, anxiety, trouble sleeping, weak bones and weak immune system.
- Meanwhile, vitamin D fights against bone loss, cancer, heart disease, poor immunity, trouble focusing and more.
- Vitamin D deficiency treatment usually involves vitamin D supplementation, ideally D3 (the more active form). Most adults should take between 600 and 5,000 IU daily.