Vitamin D

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What is Vitamin D?

Calciferol, or Vitamin D, is naturally present in certain foods. The vital step in the production process of this nutrient is exposure to the sun – it is synthesized in the body when the ultraviolet rays strike the skin.

The human body can't produce Vitamin D without good food sources (or supplements) and ultraviolet rays (UV). Because of this reason, deficiency of this vitamin is common in winter, when the sun rays don't have enough ultraviolet components. Spending more time at home during this season adds to the challenge of maintaining recommended calciferol levels.

It is easy to neglect Vitamin D intake, not only during winter. Many healthy people risk developing deficiency symptoms simply by living their lives and having certain diet habits. Staying too much time at home and eating meals that lack essential nutrients lead to worse well-being caused by vitamin deficiency.

Calciferol deficiency may also have other, less common causes, such as living in an air-polluted environment, certain health conditions, and malfunctioning body organs. To learn more about what may prevent the human body from synthesizing Vitamin D, refer to ‘What causes Vitamin D deficiency?' Paragraph.

Roles of Vitamin D

Vitamin D plays some critical roles in the human body. Primarily, it is responsible for keeping bones, teeth, and muscles healthy. It protects bones from developing deformities in children and keeps adults safe from osteomalacia, a disease that weakens bones, and bone pain in adults.

Keeping the immune system in a good state is also an essential role of Vitamin D. It reduces the risk of autoimmune diseases and improves the response of human cells.

In addition to its primary roles, there are more benefits to Vitamin D intake. Some include anti-cancer properties, lower risk of developing certain diseases, faster weight loss, better memory, and heart health. Researchers are still investigating these additional functions of Vitamin D. Some ideas have yet to be supported by more substantial, high-quality evidence to reach a consensus among scientists.

The acknowledged, science-backed roles and some potential benefits of maintaining proper Vitamin D levels are as follows.

Supports Bone and Muscle Health

Regular Vitamin D intake guarantees healthy bonesTrusted Source and prevents osteoporosis. It is responsible for calcium absorption and maintaining proper levels of phosphorus and calcium in the blood, contributing to the healthy mineralization of bones.

Lack of Vitamin D in the body leads to bone and muscle issues such as bone fractures, poor bone density, muscle weakness, and rickets in children.

Vitamin D: Deficiency, Food Sources, and Dosage

Improves the Performance of the Immune System

Researchers believe that maintaining proper levels of Vitamin D supports the immune systemTrusted Source and reduces the risk of developing autoimmune diseases.

Such health conditions as asthma, diabetes, and rheumatoid arthritis are less likely to occur if a person does not maintain a Vitamin D deficiency for a prolonged time. However, more research is needed to confirm whether such a link exists.

May Help with Weight Loss

According to one small studyTrusted Source, people with obesity are more likely to have Vitamin D deficiency.

In the study, 44 trial participants were divided into two groups: one that followed a diet plan and underwent Vitamin D supplementation and the placebo group that only followed a diet. Surprisingly, the first group lost more weight and body fat than the second group. That led researchers to believe that Vitamin D may play a role in the process of losing weight and excess fat.

However, the available evidence does not suggest that the ‘sunshine vitamin' is directly responsible for weight loss but is somehow involved in the process.

May Help Reduce Depression Symptoms

Vitamin D may also be a significant factor in reducing the symptoms of depression and helps regulate mood.

Because it is involved in synthesizing neurotransmitters like serotonin, avoiding Vitamin D deficiency may prevent mood swings and bring more stability to mental health.

One study that involved 7,534 people suggests that Vitamin D supplementation may reduce negative emotions and improve symptoms of major depressive disorder.

The opposite resultsTrusted Source were found in a large-scale study that involved over 18 000 people suffering from major depressive disorder. Participants who took 2000 IU of Vitamin D daily for five years haven't experienced any notable changes compared with the placebo group that didn't take supplements.

There is no consensus among scientists on whether calciferol plays a significant role in reducing symptoms of depression or regulating mood. More high-quality evidence is needed to determine if this is the case.

Best Sources of Vitamin D

Vitamin D can be fully synthesized thanks to sun rays exposure. However, this requires outdoor activity, good weather, proper air conditions, and the time of the year.

Sun rays contain enough ultraviolet components from March/April to SeptemberTrusted Source. During this period, most people should be able to produce a good amount of Vitamin D from sunlight only. In other scenarios, foods abundant in calciferol or supplements are necessary to maintain proper levels.

Foods with Vitamin D include fatty fish, eggs, and certain mushrooms. Certain types of food can be enriched with extra vitamins and minerals and are referred to as ‘fortified.'

For instance, fortified milk is a type of milk that consists of nutrients that are not naturally found there. Some dairy products are fortified with Vitamin D and are an excellent choice for those who want something fancier than vitamin supplements like pills or powders.

The tabel below contain the best food sources that have Vitamin D:

Fatty fish:Trusted Source

14.2mcg per 3 ounces
14mcg per 190 grams
16.7mcg per 100 grams
Cheddar cheese0.4mcg per 1.5 ounces
Beef liver1.2 µg per 100 grams
Egg2.2mcg per 100 grams
Orange juice 1mcg per 100 grams
Soy milk 1.2mcg per 100 grams
Cod liver oil34.0mcg per tablespoon
Fortified milk 1.3mcg per 100 grams
Fortified tofu2.5mcg per 100 grams
Fortified yogurt 1.3mcg per 100 grams
Shiitake Mushrooms0.8 µg per 100 grams
Oyster Mushrooms1.4 µg per 100 grams
Pork chops 1mcg per 100 grams
Fortified cereal8.3mcg per 100 grams
Vitamin D: Deficiency, Food Sources, and Dosage

Recommended Daily Intake

So how much Vitamin D do you really need? According to the USDA's official recommendationTrusted Source, infants should take no more than 10 mcg until 1 year old, while people aged 1 to 70 should increase this amount to 15 mcg. As for adults older than 70 years, they should take 20 mcg per day.

Some people who suffer from certain medical conditions may not handle these amounts well and need to discuss the correct amount with a doctor.

What Causes Vitamin D Deficiency?

Various possible factors may contribute to Vitamin D deficiency. These may include medical conditions, body state after surgery, and taking certain medications.

All causes come down to either an inability to absorb enough Vitamin D or not getting enough nutrients from food and sunlight.

Some health problems may contribute to lower calciferol production and put you at risk of experiencing deficiency symptoms. The most frequent culprits behind low Vitamin D levels include:

Certain drugs may also cause Vitamin D deficiency and are as follows:

Environmental factors, lifestyle, age, and work conditions may also put some people at more risk of having insufficient levels of the ‘sunlight vitamin.' The most obvious environmental causes include the following:

If you have reasons to believe that you are at risk of having low Vitamin D levels, take a blood test at your local clinic to find out if you should increase the amounts of foods containing this nutrient. You may also consider taking pills or powder supplements, a quick and easy way to boost low Vitamin D levels.

Symptoms of Vitamin D Deficiency

The most common symptoms of Vitamin D deficiency are as follows:

If calciferol levels stay low for a prolonged time, it may result in serious health complicationsTrusted Source and lead to dangerous conditions. Here are the symptoms typically experienced by people who don't get enough of this nutrient for a long time:

Infectionssepsis, tuberculosis, COVID-19
Autoimmune diseasesrheumatoid arthritis (RA), inflammatory bowel disease (IBD), type 1 diabetes (T1DM), vitiligo, psoriasis, multiple sclerosis (MS)
Neurological diseasesschizophrenia, major depressive disorder, neurodegenerative disorders
Cancerscolon cancer, breast cancer, prostate cancer
Cardiovascular problemshypertension, heart failure
Allergic diseasesatopic dermatitis, asthma, wheezing disorders, urticaria

Signs of Vitamin D Toxicity

Taking too much Vitamin D may harm health as well. It is rare to overdose on this vitamin, which is usually linked to the uncareful dose of supplements for a very long time. For instance, taking more than 10,000 IU of Vitamin D in the form of pills or powder for months can have adverse effects on the body, causing calcium buildup (hypercalcemia).

Vitamin D toxicity may cause the following symptoms:

In the most extreme cases, Vitamin D toxicity may lead to calcification of tissues in the body, renal failure, and cardiac arrhythmias.

If you take Vitamin D supplements, stick to the recommended amounts listed on the product packaging. As mentioned previously, this amount should be at most 4000 UI daily.

Closing Comments

It is important to keep Vitamin D levels in check. The consequences of deficiency can be severe and lead to serious complications such as autoimmune diseases, cancer, and infections.

Low Vitamin D levels decrease the performance of the immune system, cause fatigue, and worsen the mood, which as a result, may collapse your health like a house of cards.

To stay healthy, make sure to consume fatty fish like tuna or mackerel, eggs, fortified dairy products, and drink orange juice.

If you are not a fan of the food and drinks listed in this article, you can also consider Vitamin D supplementation. Make sure to choose FDA-approved brands and take no more than 4000 IUTrusted Source per day. If you suffer from a chronic condition, you may need to take less amount than is recommended. In this case, discuss how much IU you need with a health professional you trust.


June 12, 2023
8 minutes read

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