When talking about vitamins that are important for our general health, vitamin C is usually at the top of the list. But all of the vitamins are crucial and important. Vitamin D, for example, is key to keeping our immune system strong and our bones, muscles, and teeth healthy.
The difference between other vitamins and vitamin D is that you can’t source the latter from many foods. Vitamin D is a vitamin our body produces when we’re out in the sun. But because there are cold, wintry months, vitamin D deficiency is common.
Every single cell in our body has a receptor for vitamin D, which is why vitamin D functions like a hormone, not like a vitamin. The vitamin can also be found in fatty fish, fortified products, and other sources. However, it’s hard to get it from vitamin D-rich foods only, and sometimes, you might need to take a supplement or two.
The daily recommended dosage of vitamin D is between 400 and 800 IU, but many experts say you need even more. According to studies, vitamin D deficiency is very common, and more than 40% of adults in the U.S. have it. Estimates are that 1 billion people worldwide have low vitamin D in their system.
Today, we’ll talk about the symptoms of vitamin D deficiency, how to get more of it, and the benefits of the sunny vitamin.
Causes of vitamin D deficiency
There are a number of reasons why you might not get enough vitamin D. First and foremost, if your exposure to sunlight is limited, you can’t expect standard levels of vitamin D. With that in mind, let’s check the causes of vitamin D deficiency.
Limited exposure to sunlight
Our body produces vitamin D when the skin is exposed to sunlight. That only applies during the spring, summer, and autumn months. Depending on where you live, during the winter months, the sun doesn’t get high enough in the sky for its ultraviolet B rays to get into the atmosphere and enable our skin to produce vitamin D. With that in mind, from March to October, you should spend at least an hour outside on the sun.
You don’t consume vitamin D-rich foods
Most of the sources of vitamin D are animal-based. So, if you are following a vegetarian or vegan diet, you should find another source of vitamin D. Supplements are always an option. We’ll discuss vitamin D-rich foods later on, but most of them are animal-based, like fish and fish oils.
You have dark skin
This is more of a risk factor than a cause of vitamin D deficiency. People with dark skin have high amounts of the pigment melanin, which reduces the skin’s ability to make vitamin D.
Your kidneys aren’t working properly
When you age, your kidneys lose their ability to work properly. More precisely, they can’t convert vitamin D to its active form. This increases the risk of vitamin D deficiency at a later age.
Your digestive system isn’t working properly
The kidneys aren’t the only organ in the body that influence the amount of vitamin D you have. The digestive tract is also responsible for absorbing vitamin D. Medical problems (such as celiac disease and Crohn’s disease) that affect the digestive tract might reduce the amount of vitamin D you absorb. All of these diseases affect the intestine’s ability to absorb vitamin D from the food you consume.
Same as with dark skin, this is more of a risk factor than a cause. However, obese people don’t absorb vitamin D properly. It all comes down to the way vitamin D is produced. Vitamin D is extracted from the blood by fat cells. And when you have a body mass index of 30 or higher, you have low blood levels of vitamin D.
Vitamin D deficiency symptoms
Getting sick more often than usual
The most important function of vitamin D is to keep your immune system functioning at a high level. And your immune system plays a crucial role in fighting off viruses and bacteria. Vitamin D directly interacts with the cells that are responsible for fighting off infections. When you have a vitamin D deficiency, one of the symptoms is becoming sick often. Colds, flu, and similar common diseases and illnesses are even more common with you.
There is a direct link between vitamin D deficiency and respiratory tract infections. Supplements of vitamin D can reduce the risk for diseases like bronchitis, flu, and common cold, but it’s up to you to get your vitamin D naturally.
General feeling of fatigue
Being tired and fatigued can be common and normal in some situations, and there are many factors that contribute to fatigue. One of those factors is vitamin D deficiency, although it’s often overlooked as a potential cause and risk factor.
In most cases, fatigue and tiredness are associated with iron deficiency. But vitamin D deficiency contributes to having low blood levels, and that directly affects your quality of life. Studies have shown that taking vitamin D supplements can greatly increase blood levels and make people feel happier.
A study on women with blood levels under 20ng/ml (or even 21-29 ng/ml) are more likely to feel tired and complain about fatigue than those with blood levels over 30 ng/ml.
You don’t need a study to know that when it’s sunny outside, you feel better. We all feel down when it’s rainy and dark. One link to all of that? Vitamin D!
There’s a reason why it’s called the sun vitamin. Our body produces vitamin D when we’re out in the sun. There are studies that show there’s a link between depression and vitamin D deficiency, and it’s more expressed in older adults.
There is also a link between low blood levels (which we already know is a symptom of vitamin D deficiency) and depression. To summarize, there are many ways vitamin D affects our mood and energy levels, and getting some vitamin D supplements can be an effective way to reduce the seasonal depression that occurs during the colder and winter months.
Bone and back pain
Vitamin D is crucial for our bone health. One of the primary functions of the vitamin is to help our body absorb calcium. And since calcium is the building block of bones and muscles, we feel the consequences.
There are many reasons why you might feel back and bone pain, and vitamin D is one of them. For your back pain, you’ll feel it in the lower part of the back.
There are studies that examined the connection between levels of vitamin D and back pain. One study examined the link in older women, and the results showed that women with vitamin D deficiency experience severe pain that can vastly limit their daily activities. Another study showed that people with vitamin D deficiency have a two times higher chance of feeling bone pain in their legs and joints than those with normal blood levels.
If not treated, that bone pain can get more and more severe, and you could end up with bone loss. Since vitamin D plays a crucial role in calcium absorption, it’s important that you keep normal levels of vitamin D for healthy bones.
Older women usually think that calcium is the reason they have bone pain and bone loss. But the reality might be totally different: you might need more vitamin D. Since there are fewer natural sources of vitamin D than there are of calcium, it might be a good idea to take vitamin D supplements to improve bone health.
Low bone mineral density is an indication that calcium has been lost from the bone, posing a risk for fractures. There is a direct link between low bone mineral density and vitamin D deficiency. Make sure to get enough vitamin D and maintain blood levels within the optimal range to avoid any bone loss, bone fractures, and bone pain.
Vitamin D deficiency might not be directly linked to muscle function, but there are indirect links. For example, we know that vitamin D helps our body absorb calcium. And calcium helps our body absorb magnesium.
The latter is the key mineral for muscle health. In many cases, the cause of muscle pain is hard to pinpoint and diagnose correctly. But there are studies that show vitamin D might play a role in muscle health. Some studies have shown that two-thirds of people with chronic muscle pain have low levels of vitamin D in their system.
The biological explanation is that the vitamin D receptor is present in nerve cells. These receptors are called nociceptors, and they can sense pain. When you have low vitamin D, the nociceptors in muscles are more stimulated, leading to pain and sensitivity.
Slower wound healing
Because vitamin D plays a key role in keeping our immune system healthy and ready to battle infections, it’s only logical that wounds heal slower. The symptom is even worse after surgery or injury.
Studies have shown that patients with dental surgery healed slower. Some aspects of the healing process were compromised due to a vitamin D deficiency. Vitamin D also plays a role in fighting infection and controlling inflammation, two key aspects for proper healing.
Slower and impaired healing is even present in internal bleeding as well. People with low levels of vitamin have higher levels of inflammatory markers that can disrupt healing.
The first association for hair loss is stress and iron deficiency, and that’s true in most cases. Usually, when we start losing hair, we think stress is the cause. And we all know that iron deficiency is manifested through hair loss.
However, sometimes, in severe cases of hair loss, the reason might be vitamin D deficiency, not iron deficiency. Although there is little research on this topic, there are studies linking “alopecia areata,” an autoimmune disease that is characterized by severe hair loss from the head and other body parts, with vitamin D deficiency.
How to correct a vitamin D deficiency
The best way to get vitamin D is from balanced sun exposure. But since there are months when there is little to no sun, we need to find different sources for the sunny vitamin. You might be deficient in vitamin D without even knowing it.
This is because the symptoms of vitamin D deficiency are often non-specific and subtle. As we saw previously, they are often symptoms linked with other deficiencies and health conditions. With that in mind, here are some vitamin D-rich foods you can get.
Wild caught fish
There is a reason why cultures in which fish is the staple product in cuisine are healthier and live longer. Fish has some of the key nutrients we need, including vitamins, minerals, and most importantly, omega-3 fatty acids. In terms of vitamin D, salmon and mackerel are the best options, as you get 425 IU of omega-3 fatty acids from one serving of salmon along with 537 IU of vitamin D.
Beef or calf liver
The liver is an organ that people aren’t fond of eating. We’re more prone to lean meats. But the liver is packed with healthy nutrients, including vitamin D. If you can stomach it, get yourself some beef liver.
You’ve probably heard that egg yolks aren’t healthy. Well, that’s only partly true. It all depends on how often and how many egg yolks you eat. The reason egg yolks are considered to be an unhealthy food is cholesterol and fat. Having more than one egg yolk per day can increase your cholesterol levels. But one egg per day is more than enough to get some decent amounts of vitamin D, as egg yolks pack 41 UI of the sunny vitamin.
The two canned fishes you can consume guilt-free are canned tuna and canned sardines. If you didn’t know, canned sardines contain almost the same amount of vitamin D as wild-caught fish. Sardines also pack an extremely high amount of fatty acids. We recommend avoiding canned salmon, canned crab, and canned shrimp, however.
There are different types of mushrooms—some are richer in protein, some in iron, and some in vitamin D. When it comes to vitamin D-rich foods, shiitake mushrooms are the ones you need. One cup of these mushrooms delivers 40 IU of vitamin D.
Whole and non-fat milk
Milk products are usually fortified with vitamins and minerals. Usually, whole and non-fat milk contain 100 IU per 8oz container. But you can find less or more—just check the label.
Commercial yogurt products are also fortified with vitamins and minerals. A 6oz container of yogurt contains 80 IU of vitamin D.
Speaking of different types of milk, almond milk is another product you should go for. And it’s healthier than cow’s milk—you get the same amount of vitamin D plus some extra nutrients and vitamins.
Orange juice is also usually fortified with vitamin D and other minerals, and this especially applies to orange juice for children. You can find many orange juice products with calcium, magnesium, and vitamin D.
You might have noticed that a lot of the vitamin D-rich foods are great for breakfast. Well, cereals also fall into this category. You can get between 50 and 100 IU of vitamin D in one cup of breakfast cereal (it all depends on the formula of the cereal, of course).
Since vegetarians need vitamin D as well, they can enjoy fortified tofu, which includes 80 IU of vitamin D in a 3oz serving.
Some people prefer cereal for breakfast, others prefer oatmeal. It doesn’t matter which you choose—both products are fortified with vitamin D (oatmeal can sometimes contain more vitamin D).
If you ever needed a reason to drink more eggnog during the holiday season, this is it. You get 120-130 IU of vitamin D in 8oz of eggnog.
How to get vitamin D from the sun
We talked about vitamin D-rich foods. But the best way to get your daily dose of vitamin D and avoid deficiency is from sun exposure. Vitamin D is essential to help our body absorb calcium and phosphate from our diet. Combined with these minerals, vitamin D is the key to improving and maintaining the health of our bones, muscles, and teeth.
How we create vitamin D
Our body is able to create vitamin D from direct exposure to sunlight. That applies only when we’re outdoors. The problem is there are months when the sun is hiding behind clouds. From March to September, most people should be able to get their daily dose of vitamin D directly from the sun.
How much exposure is too much exposure?
While sun exposure is beneficial, there are also situations where too much sun can cause skin cancer. The UV rays from the sun aren’t always beneficial for our health.
The question is: how long should we spend in the sun? You can get vitamin D from short periods of sun exposure. All you need is to have your lower legs, hands, and forearms uncovered. No need for sunscreen, though (so that your skin can absorb the vitamin D).
There is no specific answer as to how much sun exposure is enough for our daily requirement of vitamin D. Many factors contribute to the answer, and they all influence how vitamin D is made. For example, factors like skin color. Some skin colors are more sensitive to sun exposure, others can stay in the sun longer. People with dark skin usually have to spend more time in the sun to produce the daily dose of vitamin D. People with lighter skin need less time.
The UK Cancer Research has a useful tool to calculate how much sun exposure you need to produce enough vitamin D . Bear in mind, staying by a sunny window doesn’t help with vitamin D production; the sunny vitamin can’t get through the glass.
What to do in the winter
While there may be some sunny days in the winter, winter sunlight does not contain UVB radiation (the radiation our skin needs so that it can produce vitamin D). Therefore, in the winter, your source for the sunny vitamin should be vitamin D-rich foods. You can also get it from supplements.
What about babies?
It’s important to note that all babies under six months old should be kept away from direct sunlight. Of course, you can take them out, but you need to properly protect your young ones.
Cover babies under six months old with suitable clothing. That includes a hat and wrap-around sunglasses. From 11am to 3pm, when the sun is at its peak, try to spend more time in the shade than in sunlight. For babies and children, apply SPF 15 sunscreen.
Children aged five years and younger should be given vitamin D supplements, even if they do go out in the sun.
Benefits of vitamin D
As mentioned time and time again, vitamin D is one of the more overlooked and underconsumed vitamins. And that needs to change, as vitamin D plays a major role in our overall health and daily performance.
Out of the many roles vitamin D plays in our body, some of the major ones include maintaining the health of the bones and teeth, supporting the immune system, supporting the brain system and the nervous system, regulating insulin, diabetes management, supporting lung function, and supporting cardiovascular health. And those are all benefits we can’t reap when we have a vitamin D deficiency.
With that in mind, let’s take a look at the overlooked and surprising benefits of vitamin D.
As mentioned previously, vitamin D regulates insulin and helps with diabetes management. The sunshine vitamin is closely connected to obesity and losing weight. Without vitamin D, you’ll have trouble losing weight.
It’s still unclear whether vitamin D deficiency causes obesity, or if it’s the other way around. In any case, if you want to control your weight, you need vitamin D.
We mentioned in the section about the symptoms of vitamin D deficiency that bone pain and bone fractures are common signs. Well, when you get enough vitamin D, you’ll have stronger bones because the vitamin helps with the absorption of calcium. In fact, vitamin D is a strong stimulator of calcium deposition in bones, making them healthy and strong.
Improved muscle function
Vitamin D deficiency is relatively common in athletes, and is associated with muscle weakness and atrophy. Skipping on vitamin D is as bad as skipping out on a leg day. Simply put, you need vitamin D to keep your body strong and healthy.
Reduced risk of diabetes
We mentioned that one of the key roles of vitamin D is to help manage diabetes and insulin in your body. When there is nothing there to regulate these functions, you are at risk of developing type 2 diabetes. And we all know the devastating problems that come with diabetes type 2, including nerve damage, heart disease, vision loss, eye damage, and so on.
Reduced risk of flu
We said that one of the main functions of vitamin D is to keep your immune system strong. And we also mentioned that common illnesses are a symptom of vitamin D deficiency. So, stay out in the sun for the right amount of time to get your vitamin D and reduce the risk of flu, cold, and similar illnesses.
Vitamin D deficiency is associated with bacterial vaginosis and gestational diabetes mellitus in pregnant women. In simple terms, low amounts of vitamin D might increase the risk of developing preeclampsia and the need for a Cesarean section.
Keeps cholesterol in check after menopause
One of the biggest challenges for women is staying healthy after menopause. Hormones go nuts, and the result is often stress, increased cholesterol levels, and increased risk of cardiovascular disease. Cholesterol is also the thing that contributes to obesity in women after menopause. Vitamin D can help with all of that.