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Ultimate guide to Vitamin D

Advice from Public health England is that adults and children over the age of one should use a vitamin d supplement with a dose of 10mcg, particularly during colder months and low levels of sunshine.

Those classed as having a high risk of vitamin D deficiency should consider taking a supplement all year round.

But what is vitamin D and why is it so important? 

Vitamin D is a type of secosteroid that is known for its fat soluble properties. It is an important vitamin that serves many functions in the human body. It supports the intestinal absorption of nutrients such as zinc, magnesium, iron, calcium and phosphate.

Even though vitamin D is considered to be a type of vitamin, it is actually not. Vitamin D functions more like a hormone. To be more specific, it is a type of steroid hormone. Vitamin D is produced from cholesterol when the skin undergoes sun exposure. This is why vitamin D is also known as the “sunshine” vitamin.

Speaking of sun exposure or the sunshine, the lack of it is why most of us need to obtain our supply of vitamin D from supplements and food sources.

Maintaining an optimum supply of vitamin D is necessary to keep the body healthy. However, not too many food sources are rich in vitamin D and the deficiency associated with this vitamin is more common than you’d expect.

Statistics published in the year 2005-06 estimated that around 41.6% of people in the US have vitamin D deficiency.

The Types of Vitamin D

Vitamin D actually exists in 2 forms. They are:

Vitamin D2 (Ergocalciferol): Can be obtained from particular mushroom varieties.

Vitamin D3 (Cholecalciferol): Can be obtained from egg yolk, fatty fish, and other animal products.

Among the 2 varieties, D3 has a more significant role to play as it is much more effective than D2 in boosting vitamin D blood levels.

The Role of Vitamin D in the Body

Vitamin D in itself does not offer much. However, when it undergoes two conversion processes, it becomes active and starts to carry out the intended purpose.

The first process is the conversion of vitamin D into calcidiol (25(OH)D) in the liver. Calcidiol is the form in which vitamin D is stored in the body.

The second conversion process involves turning vitamin D into calcitriol (1.25(OH)2D) in the kidneys. Calcitriol is the active steroid hormone version of vitamin D. It makes its way throughout the human body penetrating cell nuclei. Once it penetrates cell nuclei, it interacts with the cell’s vitamin D receptors. These receptors exist in almost every cell in the human body.  Once calcitriol binds to the receptors, it causes changes to occur in the cells by switching the genes off or on. This is actually similar to the functioning of a majority of steroid hormones.

Vitamin D also has an effect on bone health by the way it affects certain cells. For example, it is responsible for instructing gut cells to absorb phosphorous and calcium. However, newer studies indicate that vitamin D does much more than that. In fact, it may have a role to play in increasing immunity and even combating cancer.

Sunshine – Your Best Chance at Getting Vitamin D

As mentioned earlier, vitamin D is produced from cholesterol when our skin is exposed to the sun. The energy requirement for the reaction is actually obtained from the sun’s UV-B (Ultra-Violet B) rays. So, we can say that people who live in a location with plenty of sunlight can receive their supply of vitamin D by just spending some time in the outdoors at least once or twice a week.

However, how much vitamin D is produced in your body has a lot to do with how much of your body is actually exposed to the sun. Just exposing the head or the neck will result in low vitamin D production.

Another interesting thing to note here is that applying sunscreen for skin cancer protection will lead to vitamin D deficiency. This will further lead to other complications of its own.

Therefore, the key to maintaining vitamin D production and preventing skin cancer lies in controlling how much time we spend under the sun. Generally, the idea is to make sure your skin doesn’t start burning. If it does, then it means you have been overexposed to the sun’s rays.

Burnt skin can result in early ageing and also increase the possibility of developing skin cancer. Ideally, the first 10 to 30 minutes is enough for sun exposure. After that point, it is advisable to use sunscreen or avoid sunlight completely.

Also, vitamin D is stored in the body for considerable periods of time. So, sun exposure isn’t required on a daily basis. It can be practised occasionally to keep the vitamin D blood levels steady.

However, for those who do not have enough sunlight in their locations, the only way to substitute is to consistently eat foods that are rich in vitamin D or take supplements. This is especially important for those who live in colder climates or people with darker skin. 

Other Sources of Vitamin D

Vitamin D is actually quite hard to come by in your diet. There are fatty fish that contain vitamin D. This would include varieties like trout, swordfish, tuna, mackerel, sardines, and salmon. However, they do not possess the optimum vitamin D content required by humans. You would need to eat them every day to meet your actual requirement, which isn't always possible. 

However, cod fish liver oil and other fish liver oils are an excellent source of vitamin D. A tablespoon of fish liver oil contains twice the daily vitamin D requirement.

Here is a breakdown of vitamin D content in the various types of fatty fish:

1. Cod Liver Oil (1 Tablespoon) – 225% of daily requirement.

2. Cooked Salmon (3 Ounces) – 75% of daily requirement.

3. Canned Tuna in Water (3 Ounces) – 26% of daily requirement.

4. 1 Sardine (Canned in Oil and Drained) – 4% of daily requirement.

Some cereals and dairy products are fortified with vitamin D.

There are also specific varieties of mushrooms that provide vitamin D. Other than that, you can get vitamin D in egg yolk. But again, the problem is that these sources do not provide enough of the vitamin daily requirement.

Vitamin D Deficiency

Not having enough vitamins D can lead to a deficiency. This can, in turn, lead to other severe medical conditions. In fact, it is one of the most prevalent vitamin deficiencies.

In the US, 41.6% of the population has vitamin D deficiency.

Out of the 41.6%, 69.2% are Hispanics and 82.1% are African-American.

Aged individuals have a very high risk of being vitamin D deficient.

In developing nations, many children are affected by a condition called rickets, which is a direct consequence of vitamin D deficiency. In Western Nations, Rickets was combated by fortifying many food products with the vitamin.

Some studies have even shown that people affected by a particular disease are also capable of developing vitamin D deficiency.

One particular study found that 96% of heart attack patients were vitamin D deficient.

Vitamin D deficiency has also been linked to medical conditions such as osteoporosis, fractures, low mineral density, dementia, cancer, and autoimmune diseases etc.

However, it is not known as to whether vitamin D deficiency contributes to the development of these conditions or whether people with vitamin D deficiencies are more likely to be affected by these conditions.

Vitamin D is a vital nutrient that is required to maintain good health and wellbeing. However, since it isn't present in food sources abundantly, we must put in special effort to make sure that we get our daily requirement either through exposure to sunlight, supplements, or food.

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