Vitamin D 101 – Foods, Deficiency, Benefits and Side Effects

Vitamin D Introduction: Our body is dependent on a variety of vitamins, minerals, fats, carbohydrates, proteins, and fiber to meet its daily nutritional requirements. These nutrients are required in a certain quantity to help the body stay healthy and develop normally.

A deficiency or excess of any nutrient can be very dangerous for your health. These days, with the introduction of technology into our daily lives and our changing lifestyles, vitamin deficiencies have become quite common, and vitamin D deficiency has gradually become a global health issue. This article will explain the causes, symptoms, sources, and uses of vitamin D in more significant details.

Vitamin D is one of the most important nutrients required by our body since it helps in the absorption of Calcium, which is essential for the development of our bones and keeping them strong as we Our body is un-able to produce calcium on its own so Vitamin D plays a very essential role in the absorption of calcium in our body. It is important to note that the uses of Vitamin D are not limited only to the growth and development of bones. It also plays a vital role in our nerve muscle and immune systems.

Also Read: Vitamin D helps in boosting Testosterone Levels 

Vitamin D is produced by the body after it comes in contact with direct sunlight, consumed as a part of your diet or through supplements. However, that process of absorption of vitamin D is not very simple. The body has to synthesize it several times before it can be used to manage the calcium in your body.

Deficiency of vitamin D can lead to a number of short and long term illnesses in children and adults alike which makes it essential to monitor and maintain optimum Vitamin D levels in your blood. Its role in your overall health is only emphasized by the extent of its functions in areas including our immune system, the cardiovascular system, the respiratory system, and brain development.

Since Vitamin D is an imperative requirement for our body for the creation of calcium and phosphorus, it has to be consumed or introduced in the body in line with the daily requirement for maintaining your overall health. The main source of vitamin-D is natural sunlight. Vitamin D can also be consumed as a part of our diet by the consumption of foods including fish like tuna and salmon which has a high-fat content, food items such as vitamin D fortified cereals, orange juice and soy milk, cheese, egg yolks, and mushrooms.

Irrespective of your food choices and preferences, Vitamin D can be found in foods suitable for all types of dietary choices. However, it is very difficult to meet your body’s Vitamin D requirements through diet alone so, in addition to all of this, Vitamin D can also be consumed by the intake of Vitamin D supplements which are very easily available in the market today. We shall discuss the sources of Vitamin D in greater detail in this article:

Vitamin D Sources



Exposing your body to direct and natural sunlight is the best way to meet your daily vitamin D requirement. The body is designed in a way that allows it to produce large amounts of vitamin D3 (cholecalciferol) by coming in contact with sunlight. A component of sun rays, known as Ultraviolet B is key to this.

Exposing bare skin to the sun for a short period of time can give you your daily vitamin D intake. The duration of exposure required varies from person to person. It depends on various factors including the time of the day, the color of your skin, the amount of skin you expose in the sun and your geographical location.

It is advisable to expose your skin to the sun around the middle of the day since the sun’s rays are at a better angle so your body can generate more Vitamin D around that time.

Additionally, your geographical location and more specifically, your proximity to the equator plays a vital role in determining the duration of skin exposure required to meet your daily Vitamin D needs. If you are closer to the equator, the sun’s rays will hit the atmosphere at a lesser angle. That will increase the amount of Ultraviolet B rays that your skin will be exposed to and vice versa. It is also easier to generate more vitamin D from the sun in the summer months, especially for people who live at a distance from the equator than it is during the winter months due to the angle of the earth’s rotation.

Another key factor contributing to the duration of sun exposure necessary to meet your Vitamin D requirements is the color of your skin. The skin has components known as melanin which determine the tone of your skin. The higher the melanin count, the darker your skin color will be. Melanin is also responsible for protecting your skin from excessive UV damage. Therefore, people with dark skin and high melanin content will have lesser Ultraviolet B entering the skin and producing Vitamin D so they will need more time in the sun as compared to lighter-skinned people

The duration of sunlight exposure needed varies from person to person so it is very difficult to determine the exact amount of time you would need in the sun. It is advisable to expose yourself to natural sunlight every day for some time at least since it the best and most effective source of vitamin D. However, when exposing your skin to sunlight, always keep in mind to not overexpose and burn your skin. Research shows that exposing your skin to the sun frequently for short periods of time is healthy but intense exposure can lead to an increased risk of skin cancer.

Vitamin D Natural Sources

Apart from direct sunlight, Vitamin D levels in your body can also be maintained by the consumption of foods rich in vitamin D. Though very few food items have vitamin D and usually not in very high quantities, foods such as swordfish, sockeye salmon, rainbow trout, tuna, sardines, sturgeon, cod liver oil, whitefish, eggs, fortified milk and milk products; orange juice and cereals; cheddar cheese, mushrooms, and margarine have varying quantities of Vitamin D2 & Vitamin D3 in them.

Of all the above foods containing vitamin D, Cod liver oil has the highest vitamin D content containing 1,360 IUs (International Units) of Vitamin D per tablespoon and it also happens to be a good natural source of Vitamin A. Fishes with a fatty flesh have higher concentrations of vitamin D than the other foods and they are also rich in other vitamins such as Vitamin B12, Niacin, and Vitamin B6 and these foods should, therefore, be included in your everyday diet.

Vitamin D Vegetarian/Vegan Sources:

It might be difficult for vegetarians and vegans to get their daily dose of Vitamin D in their diet from food. Most items high in Vitamin D content are non-vegetarian so their options are quite limited so it is most advisable to get their daily dose of Vitamin D from direct sunlight. Vegetarians can also increase their intake of Portobello and Maitake mushrooms, Swiss cheese, Vitamin fortified milk, and yogurt as well as Fortified orange juice and cereals to meet their vitamin D requirements. Since vegans do not consume milk and milk products, they can substitute milk with fortified soy milk, almond milk, and soy yogurt.

Some of the foods listed above are very expensive or not easily available in India. Fatty fishes are some of the best naturally available sources of Vitamin D and fish like Salmon, Mackerels, Sole fish, canned tuna and swordfish are easily available in most parts of the country. Mushrooms, cheese, yogurt, egg and milk/soymilk are also found in all grocery stores and are a part of our daily diet. Some of the other easily available sources of vitamin D include salami, sausage fortified orange juice and cereal.

Vitamin D deficiency

Vitamin D deficiency is one of the biggest growing health concern all over the world today. Due to our fast-paced life, especially in urban and metropolitan areas, our exposure to direct sunlight has reduced drastically. Since very few naturally occurring foods have vitamin D in them, it is also very difficult to get the daily required amount of vitamin from food alone. Babies and the elderly tend to have low vitamin D levels since their exposure to direct sunlight is limited. The elderly face a bigger challenge because the skin gradually loses its ability to produce sunlight with age. Therefore, it is advisable to take daily supplements depending on your specific requirements after consulting with your physician.

Vitamin D deficiency can lead to soft and brittle bones, compromised immunity and overall poor health. It can cause rickets in small children and osteoporosis in adults, amongst other health concerns. The main symptoms of vitamin D are as below:

  1. Having low immunity and falling ill frequently
  2. Constant Fatigue
  3. Bone and Back pain
  4. Depression
  5. Slow wound healing
  6. Bone loss
  7. Hair loss
  8. Muscle Pain
  9. High blood pressure

Vitamin D is responsible primarily for the absorption of calcium and phosphorus in the body. Calcium is the main building block for bone health and a deficiency in vitamin D affects bone density as well as the immune system, the nervous system, and your muscles. It can also factor in to be an underlying cause for several diseases including:


According to a study which was published in the journal Neurology (August 2014), moderate to severe deficiency of vitamin D was associated with an increased risk for developing certain forms of dementia including Alzheimer’s disease. Though the study conducted on 1600 people was observational and couldn’t conclusively prove a direct relationship between vitamin D deficiency and dementia, they hypothesized that sufficient amounts of vitamin D could help to clear plaques in the brain related to dementia.

Prostate Cancer:

According to a May 2014 study published in the journal Clinical Cancer Research in which research was conducted on 667 European-American and African-American men between the ages of 40-79 undergoing prostate biopsies. Though this study was observational in nature, the results suggested that African-American men having low Vitamin D levels had higher chances of developing prostate cancer than men with normal vitamin D levels.

Rickets, Osteomalacia, and Osteoporosis:

People with low vitamin D in their body are susceptible to developing soft bones. This condition is known as Rickets in children and it leads to skeletal deformities. Since children need a lot of calcium to support their skeletal growth, low levels of vitamin D can be very harmful and if it is not diagnosed in time, this can have lifelong effects including the development of bow legs.

In adults, the softening of bones is known as Osteomalacia. It increases the probability to cause fractures. Low levels of vitamin D might result in the development of another condition known as Osteoporosis in which the bones become brittle and weak due to diminishing bone density and strength. This increases the chances of fractures, even when doing routine activities such as walking or standing.

The level of Vitamin D in the body can be assessed with the help of a blood test known as 25-hydroxyvitamin D test. This test measures the amount of serum 25(OH) D in the blood. A person having between 20 ng/ml to 50 ng/ml is considered as healthy and someone has less than 12.5 ng/ml is considered as deficient in vitamin D.  The test can be taken by going to a diagnostic center or a pathology laboratory or by ordering an in-home test kit. The good news is that vitamin D deficiency is treatable by the introduction of more vitamin D rich foods and supplements in the body along with regular exposure to sunlight for short durations.

Vitamin D Supplements

Some of the best brands manufacturing Vitamin D medicines in India are as below:

  1. Rocailtrol
  2. Calosto
  3. Alpha Calcirol
  4. Alfarich
  5. Alfado
  6. Alfa D3
  7. Rocaltrol
  8. Alphadol
  9. Vitanova SG
  10. Quente D3

If you feel that your Vitamin D levels might be low, you can also consider taking supplements as a precautionary measure to improve and essentially prevent developing a vitamin D deficiency. They are available in the form of tablets, soft gels, and oil drops. It is advisable to discuss the intake of supplements with your doctor so that he/she can advise a brand more suited to your individual needs.

Vitamin D Uses

For good hair

According to a study published in 2012 in Stem Cells Translational Medicine journal, vitamins are important for the creation of new follicles from which new hair growth. Vitamin D is one of the 13 essential vitamins needed for hair growth and strength. Meeting the daily quota of Vitamin D required by the body should help to increase hair density and make it look thicker. Studies also suggest that people suffering from alopecia areata also tend to have a low level of vitamin D.

A study was conducted by the Department of Dermatology, Cairo University in which 80 females test subjects between the ages of 18 – 45 years suffering from hair loss and 40 age-matched females who did not suffer from any hair loss condition participated. The study concluded that hair loss in women might be associated with low levels of vitamin D. However, more research needs to be conducted to determine the link between Vitamin D deficiency and hair loss conclusively.

For Skin

The best source of Vitamin D is natural sunlight which gets absorbed in the body through the skin. Some studies suggest that Vitamin D might have antimicrobial abilities and assist in the formation of a skin barrier. Vitamin D3 controls the expression of cathelicidin which is an antimicrobial protein associated with basic skin immunity which encourages healing and tissue repair. Some studies also suggest that vitamin D promotes angiogenesis (the development of new blood vessels).

However, more research needs to be conducted to determine the extent of Vitamin D’s role in promoting skin immunity and wound healing as well as the best method of introducing vitamin D for this purpose (through supplements or topical application).

For Kidney Stones

Kidney stones are stone-like collections in the kidney, usually made up of calcium or uric acid. Kidneys are responsible for cleaning your body of toxins, excessive unabsorbed minerals, and salts through urine. Sometimes, when the body isn’t hydrated sufficiently, the kidney is unable to remove these minerals from the body and they accumulate in the kidney to form painful kidney stones.

Some recent studies have shown that the level of Vitamin D in your body is inversely proportional to your risk of developing kidney stones. According to a case-control study conducted in January 2016, in which 884 individuals with kidney stones and 967 controls participated, it was noted that vitamin D deficiency was prevalent in 56% of the patients with kidney stones compared to only 44% of the controls. Another case-control study was conducted on 366 subjects in April 2016 out of which 239 had a history of calcium stone forming. The deficiency of vitamin D was noted to be higher in stone-forming patients than non-stone forming patients.

Though high levels of Vitamin D is often associated with kidney stones, a lot of research also suggests otherwise. Therefore, it is important to maintain healthy levels of vitamin D because both Hypovitaminosis D, as well as Hypervitaminosis D, have a lot of health risks associated with them.

For Eczema

Eczema or Atopic Dermatitis is a skin condition which usually develops in infants and children. However, adults are also susceptible to developing this disorder as well. It is symptomized by red, dry and itchy skin as well as inflammation. Even though scientists haven’t been able to figure out the exact cause for Eczema, they believe that genetics and the environment contribute towards the development of this disease.

Studies suggest that most people suffering from eczema also have low levels of Vitamin D. According to two separate meta-analyses (a combination of multiple clinical trials) conducted in 2013 and 2016 by Kim G, Bae JH, and Samochocki Z at al respectively), Vitamin D might be capable of improving the symptoms associated with Eczema. According to these studies, Vitamin D can potentially assist in reducing the symptoms associated with Eczema and can be considered as a safe therapy. However, since sufficient research has not been conducted on the extent of the effectiveness of Vitamin D towards curing AD, it is better to get a consultation with your physician or dermatologist.

For Vertigo

Research and studies suggest that Vertigo (BPPV) is linked to the Vitamin D level in your body. Benign paroxysmal positional vertigo (BPPV) is a form of Vertigo characterized by a balance disorder which causes nausea, vomiting, and dizziness. It can be very severe and even prevent the patient from being able to perform simple daily tasks.

A clinical trial was conducted in Iran in 2016 to determine the effect of supplemental Vitamin D on the intensity of BPPV. The study concluded that the rectification of Vitamin D in patients suffering from BPPV did indeed provide some additional benefits to them with regards to the duration of their bouts of BVVP.

Another meta-analysis was conducted on November 2018 to better understand and establish the correlation between Vitamin D and BVVP. Even though the study failed to establish a direct connection between low levels of Vitamin D and BVVP, it did establish that patients with recurring BVVP episodes had significantly low vitamin D levels in their body.

So, more detailed trials and studies need to be conducted to truly understand the relationship between Vitamin D levels and BVVP (Vertigo). However, it is safe to say that low vitamin D levels is a recurring factor in most patients and should, therefore, be monitored.

For Pregnancy

The intake of sufficient Vitamin D is essential to a healthy pregnancy. Even though more research needs to be conducted in order to fully comprehend the effect of Vitamin D in pregnancy, some research associated the increased rate of cesarean delivery, bacterial vaginosis, and preeclampsia to the level of Vitamin D in the person’s body.

Since Vitamin D is important for bone health and overall immunity along with the absorption and metabolism of calcium and phosphorus, it helps the fetus to develop and has also been known to help minimize the chances of Preeclampsia. The mother is the main source of Vitamin D for the fetus as well as the infant once it’s born. So, it is crucial for the mother to maintain healthy vitamin D levels.

For Babies

Since babies get nutrition from their mother during pregnancy and primarily from breast milk after being born, the mother’s vitamin D blood level is directly correlated with the baby’s. Babies are usually born with low levels of Vitamin D so it becomes important to meet their daily nutritional requirements in order to protect them bring deficient in certain essential vitamins including Vitamin D.

Vitamin D deficiency is known to cause rickets in babies and children. Due to various factors including limited exposure to direct sunlight and limited consumption of Vitamin D rich foods, infants and toddlers are at a higher risk of developing Vitamin D deficiency and related diseases. It is very important to monitor and manage the intake of Vitamin D in babies and children since that is the only way to prevent rickets and other malnutrition-related illnesses.

For Liver

Recent studies suggest that Vitamin D deficiency is common among people suffering from hepatic diseases. In fact, growing evidence suggests that one of the most common liver-related disease, known as Non-Alcoholic Fatty Liver Disease is linked to a low level of vitamin D in one’s body. NAFLD can lead to more serious conditions such as liver cirrhosis and liver cancer unless proper precautions are taken at the right time.

Since vitamin D is synthesized in the liver after being absorbed by the body and intestines, a weak and compromised liver greatly affects the conversion of inactive vitamin D into its active form (25-hydroxyvitamin D).  However, further research is required in order to fully comprehend the extent of the effects of Vitamin D deficiency on the liver.

For Headaches

A randomized, double-blind study was conducted on a group consisting of 48 migraine patients between the ages of 18 and 65 years. Out of the total patients enrolled, 36 were female and 12 were male. After a 4 week baseline period during which they were given 100 μg/day of Vitamin D3 supplements (24 patients) or placebo (24 patients), a 50% reduction rate was observed in patients who received the supplements from the baseline period to the next 24 weeks. The reductions were observed in terms of the frequency, severity and response rate of migraines. The study and its results were published on September 2018 in Current Medical Research and Opinion.

Another study was conducted in July 2018 to determine the effects of Vitamin D on the frequency of headaches in migraine patients. The study concluded that a large number of migraine headaches were related to vitamin D deficiency.

However, further research needs to be conducted in order to understand the extent of Vitamin D’s role in reducing migraines.

For sexual health in men

Erectile dysfunction refers to the inability of the penis to hold an erection and can be influenced by a lot of factors including age, stress levels, alcohol consumption, and smoking habit. The relationship between men’s sexual health and Vitamin D deficiency has not been clearly established yet. However, some studies do show that vitamin D deficiency can be a factor in erectile dysfunction and healthy sexual function.

A study was conducted on 114 men by assessing them on certain clinical, biochemical and sexual parameters. The study suggested that Vitamin D deficiency affected and aided erectile dysfunction. Subjects with a moderate level of Vitamin D after undergoing vitamin D replacement therapy saw an improvement in their sexual health.

Another study published in International Journal of Endocrinology also suggested that the subset of 41 men who participated in the study and underwent vitamin D therapy showed a marked improvement in their total testosterone and free testosterone levels as well as a reduction in erectile dysfunction.

Sexual health in women

Just like in men, a woman’s sexuality also depends on certain biological, social, psychological and emotional factors. Women also experience sexual dysfunction and some studies now suggest that Vitamin D deficiency can also impact sexual health in women by lowering their estrogen levels and thereby, their sex drive.

A study was conducted on 50 women suffering from Female Sexual Dysfunction (FSD) and 58 healthy women were also included as controls in the study. This study was conducted to understand that correlation, if any, between Vitamin D3 and FSD in premenopausal women. The results of the study concluded that women suffering from FSD had lower levels of Vitamin D in their body.

Another randomized, double-blind, placebo-controlled clinical trial conducted in 2019 also concluded that women deficient in Vitamin D undergoing FSD could possibly benefit from Vitamin D therapy. However, more research needs to be conducted before a definitive correlation can be established between the two.

For Ageing

The role of Vitamin D towards the development and sustenance of our musculoskeletal system has already been established. A clinical trial is currently underway to determine its role in the overall aging process of our body. For example, we all know that excessive sunlight (which is the best source of natural Vitamin D) can be damaging to the skin. It can cause premature aging, spots, increase the risk of developing cancer and cause an overall decline in skin health. However, recent studies also suggest that too little sunlight can be equally damaging and lead to cognitive diseases, depression, osteoporosis, and Type II diabetes.

Cognitive decline is one of the worst effects of aging. A study conducted in England on 1766 people, aged 65 or older suggested that people with low Vitamin D levels are at a higher risk of developing cognitive diseases. Another examination conducted on 3,325 people aged 65 years and older also linked low Vitamin D levels to cognitive impairment. However, more research needs to be conducted with lesser variable before the link between impaired cognitive function and Vitamin D deficiency can be confirmed.

With age, our immune system also becomes weak and is eventually rendered incapable of protecting us from diseases. This process is known as immunosenescence. Some studies suggest that Vitamin D also helps to control immune responses and strengthen the body against infectious organisms such as the tuberculosis bacillus and can, therefore, be beneficial for people with compromised immune systems.

Therefore, maintaining optimum levels of Vitamin D can be beneficial for aging people. Its benefits also extend to regulating the cardiovascular system, Type II diabetes, and hypertension which are usually associated with aging.

For bones and bone-related diseases

One of the primary functions of Vitamin D is to regulate the absorption of calcium and phosphorus in the body. Bones are comprised of almost 99.5% of the total calcium in the body. Healthy levels of vitamin in your body will help you to maintain strong and healthy bones as well as aid in bone development and overall bone health.

Low levels of vitamin D can catalyze the onslaught of bone-related health issues such as the development of rickets (bow legs) in children by inhibiting the growth and development of bones. In adults, it can cause osteoporosis wherein the bones become weak and fragile due to loss of tissue. It can also cause osteomalacia wherein the bones become soft and deformed rendering the patient incapable of performing daily tasks.

For Cancer

Certain epidemiology studies have linked optimum vitamin D levels with a reduced risk of developing certain types of cancers. The studies suggest that people living in areas with greater exposure to Ultraviolet B rays have noted lower cancer-related mortality rates.

A randomized clinical trial conducted by the Women’s Health Initiative (WHI) concluded that Vitamin D supplementation could prove to be beneficial for women suffering from colorectal cancer. A serum 25 (OH)D level of 20 ng/ml or greater was linked to a 30% to 50% reduced risk of developing colorectal and prostate cancer. In fact, Calcitriol (active Vitamin D) is also associated with reducing the metastatic potential of many malignant cells as well.

However, it is advisable to check with your physician before starting Vitamin D supplementation therapy for any benefits.

Vitamin D is essential for our overall health and with the introduction of technology in our lives, both professional and personal, our exposure to natural sunlight has reduced drastically. Add to this our changing eating habits and you can see how crucial it has become to monitor the level of vitamin D in our body routinely. However, the focus should be on having the optimum amount of vitamin D since excessive quantities of this nutrient is also damaging to your health.

Excessive vitamin D build-up in the body can lead to Vitamin D toxicity, also known as hypervitaminosis D. This is usually caused due to excessive and unmonitored intake of vitamin D supplements. Fatigue, nausea, forgetfulness, vomiting and slurred speech are some of the common symptoms of Vitamin D toxicity. The Vitamin D Council recommends that anything above 100 ng/ml can be considered as excessive and therefore, be harmful. It can also lead to an increase in the blood calcium levels and cause hypercalcemia. (46)

Some other side effects of excessive Vitamin D intake include stomach pain, constipation or diarrhea, poor appetite, bone loss, and kidney failure. Too much of anything is bad and in this case, it can lead to hospitalization.

Ideally, an average intake of 400-800 IUs (International Units) of Vitamin D per day is enough to meet your body’s nutritional requirements. However, if you do not get regular exposure to the sun, you might need to up your vitamin D intake from your diet and supplements. According to some studies, a daily intake of 1000-4000 IUs is required to maintain optimum blood levels.

Though vitamin D deficiency is an epidemic and it is estimated that about 1 billion people worldwide have a vitamin D deficiency, there is no need to worry.  You can check with your general physician and take a 25-hydroxyvitamin D test to better asses your body’s vitamin D requirements. Based on the results of your test, your physician can then guide you on how to increase, decrease or maintain your vitamin D intake through diet, sun exposure and the intake of supplements. The intake of any supplements, however, should also be as per the advised dosage on the product.

Note: Please go through the dosage column before using the product.

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About Dhruv Athi, Nutritionist, Dietician

Dhruv Athi is a Licensed Nutritionist based in India. Dhruv is a Health Care Professional & Diet Consultant with a successful track record of helping people cure their ailments with natural and alternative means of healing medicine. In a nutshell, Dhruv offers every assistance for your Health-related concerns and Goals.

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