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Vitamin D: Why You Need It and How to Get It

Vitamin D is a fat-soluble vitamin that has many important functions in the body. It helps your body absorb calcium, magnesium, and phosphate, which are essential for bone health. It also regulates your immune system, your mood, your brain function, and more. In this blog post, we will explain what vitamin D is, why you need it, how much you need, and where you can get it from.

What is vitamin D?

Vitamin D is not a single substance, but a group of compounds that have similar structures and effects. The two main forms of vitamin D are vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol). Vitamin D3 is the form that your body produces when your skin is exposed to sunlight. Vitamin D2 is the form that is found in some plants and fungi.

Both forms of vitamin D need to be converted into active forms by your liver and kidneys before they can be used by your body. The active forms of vitamin D are called calcitriol and calcidiol. Calcitriol is the most potent form of vitamin D and acts as a hormone that regulates various processes in the body. Calcidiol is the main form of vitamin D that circulates in your blood and reflects your vitamin D status.

Why do you need vitamin D?

Vitamin D has many benefits for your health and well-being. Here are some of them:

  • It supports bone health. Vitamin D helps your body absorb calcium, magnesium, and phosphate from your diet, which are the main minerals that make up your bones. Vitamin D also helps maintain the balance of these minerals in your blood and tissues. Without enough vitamin D, you can develop rickets in children or osteomalacia in adults, which are conditions that cause softening and weakening of the bones.
  • It boosts your immune system. Vitamin D helps modulate the activity of your immune cells, such as T cells, B cells, and macrophages. Vitamin D also helps produce antimicrobial peptides, which are substances that kill bacteria, viruses, and fungi. Studies have shown that vitamin D can protect you from infections such as colds, flu, tuberculosis, and COVID-19.
  • It improves your mood. Vitamin D can influence the levels of neurotransmitters such as serotonin and dopamine in your brain, which affect your mood and behavior. Studies have shown that vitamin D can reduce the symptoms of depression and anxiety in people with low levels of vitamin D.
  • It enhances your brain function. Vitamin D can support the development and maintenance of your brain cells and nerves. Vitamin D also helps regulate the expression of genes that are involved in learning, memory, cognition, and neuroprotection. Studies have shown that vitamin D can improve cognitive performance and prevent cognitive decline in older adults.
  • It prevents chronic diseases. Vitamin D can lower your risk of developing various chronic diseases such as diabetes, cardiovascular diseases, autoimmune diseases, and some cancers. Vitamin D can do this by improving your insulin sensitivity, lowering your blood pressure, preventing inflammation, inhibiting tumor growth, and modulating your immune responses.

How much vitamin D do you need?

The amount of vitamin D that you need depends on several factors such as your age, skin color, sun exposure, diet, health status, and genetic variation. However, a general guideline is to aim for a blood level of calcidiol between 20 and 50 ng/mL (50 and 125 nmol/L), which is considered adequate for most people.

To achieve this level, you may need to consume between 400 and 800 IU (10 and 20 mcg) of vitamin D per day from food or supplements. This amount may vary depending on your individual needs and preferences. Some people may need more or less vitamin D than others. For example, older adults, people with dark skin, people who live in northern latitudes, people who wear sunscreen or cover their skin, people who have obesity, kidney disease, liver disease, or malabsorption disorders may need more vitamin D than others.

To determine your optimal dose of vitamin D, you should consult your doctor or a registered dietitian. They can measure your blood level of calcidiol and recommend the best way to meet your vitamin D needs. They can also monitor your response to vitamin D supplementation and adjust your dose accordingly.

Where can you get vitamin D from?

There are three main ways to get vitamin D: from sunlight, from food, and from supplements.

  • Sunlight: Sunlight is the most natural and effective way to get vitamin D. When your skin is exposed to ultraviolet B (UVB) rays from the sun, it converts a substance called 7-dehydrocholesterol into vitamin D3. The amount of vitamin D3 that you produce depends on the time of the day, the season, the latitude, the altitude, the cloud cover, the air pollution, the sunscreen use, and the skin pigmentation. Generally, exposing your face, arms, and legs to direct sunlight for about 15 minutes a day during midday in summer can provide you with enough vitamin D. However, this may not be possible or advisable for everyone. Too much sun exposure can also cause skin damage and increase your risk of skin cancer. Therefore, you should balance your sun exposure with your skin protection and follow the recommendations of your doctor or a dermatologist.
  • Food: Food is another source of vitamin D, but not a very rich one. There are only a few foods that naturally contain significant amounts of vitamin D, such as fatty fish (salmon, mackerel, tuna, sardines, herring), cod liver oil, egg yolks, and mushrooms. Some foods are also fortified with vitamin D, such as milk, yogurt, cheese, orange juice, cereals, and margarine. The amount of vitamin D in these foods may vary depending on the type, brand, and country of origin. You should check the nutrition labels to see how much vitamin D they provide. Generally, eating two or three servings of vitamin D-rich foods per day can help you meet some of your vitamin D needs.
  • Supplements: Supplements are another way to get vitamin D, especially if you cannot get enough from sunlight or food. There are two types of vitamin D supplements: vitamin D3 and vitamin D2. Vitamin D3 is the same form that your body produces from sunlight and is more potent and bioavailable than vitamin D2. Vitamin D2 is derived from plants or fungi and is less effective and stable than vitamin D3. Therefore, you should choose vitamin D3 supplements over vitamin D2 supplements whenever possible. You can find vitamin D3 supplements in various forms such as capsules, tablets, drops, sprays, or gummies. You should follow the instructions on the label or the advice of your doctor or a pharmacist on how to take them. You should also store them in a cool and dry place away from light and heat.


Vitamin D is a vital nutrient that has many benefits for your health and well-being. It helps you absorb calcium and other minerals for your bones, it boosts your immune system and mood, it enhances your brain function and prevents chronic diseases. You can get vitamin D from sunlight exposure, food sources, or supplements. However, you should be aware of your vitamin D status and needs, as too little or too much vitamin D can cause problems. Therefore, you should consult your doctor or a registered dietitian to determine your optimal dose of vitamin D and the best way to get it.

I hope you found this blog post informative and helpful. If you have any questions or comments, please feel free to leave them below. Thank you for reading!

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