Boost Immune Function with Vitamin D

Vitamin D is a fat-soluble vitamin our body generates from exposure to the sun. 

In recent times, Vitamin D has been associated with a strong immune system. 

What exactly is vitamin D, and how can it help protect us?

What is Vitamin D? How do we absorb it?

Vitamin D is a fat-soluble vitamin. Meaning, the body uses fat to absorb it. The other fat-soluble vitamins are A, E, and K. 

Vitamin D has two variations: D3 and D2.

D2 is made by plants and found within foods like mushrooms and those fortified with the vitamin like cereals. 

Other than sunlight, D3 is found in smaller amounts within animal foods, such as fish (and the supplement fish oil), butter, egg yolk, and liver. The sun does not directly inject Vitamin D3 through our skin. But, different enzymes are activated within the skin to enable a series of chemical reactions to take place. The end product is Vitamin D. 

During exposure to ultraviolet B light (UVB), 7-dehydrocholesterol in the skin is converted to pre-vitamin D. This is an intermediary step before being immediately converted to cholecalciferol.

Cholecalciferol then travels to the liver, where it is converted again to a pre-hormone called 25-Hydroxyvitamin D3, and then again at the kidneys into Calcitriol. 

Calcitriol is the active form of the nutrient. Our cells can then use it to facilitate a wide variety of bodily processes.

No other nutrient goes through this intricate of a conversion process. As such, some medical and nutritional professionals actually classify Vitamin D as a hormone. Hormones by definition are chemical messengers within the body.

When comparing the two variations, Vitamin D3 has been found to be the far more bioavailable, readily absorbed, and most efficient form. A scientific consensus is D3 is superior over D2.

Why do we need Vitamin D? The Immune System & Beyond...

As with most micronutrients, Vitamin D’s function within the body is multifactorial, impacting many bodily processes paramount to overall health. Your physical performance and cognitive function NEED Vitamin D to operate.

The body has a wide variety of immunological cells at its disposal, and virtually all have a relationship with vitamin D. Vitamin D is expressed in nearly every immune cell because it is a key modulator. Meaning, is has the ability to increase or decrease their function.

Immune cells typically have a Vitamin D receptor, and this mechanism increases the response of immune system proteins such as cathelicidin and defensin. These proteins are powerful antimicrobials and serve to fight viruses and bacteria.

Cathelicidin and defensin also have the ability to reduce the dangerous effects of pro-inflammatory cytokines. Cytokines are a type of messenger the immune system uses to communicate. Pro-inflammatory cytokines increase inflammation - a key mechanism in signaling your immune system to fight off a threat.

Too much inflammation, though, is not a good thing. Sometimes our immune system can be overactive, and these pro-inflammatory cytokines become a problem, such as the case with auto-immune disorders. Too high and active a production of cytokines can wreak havoc with the body, exasperating many respiratory and cardiovascular illnesses.

A ‘cytokine storm’ is a respiratory illness where pro-inflammatory cytokines overwhelm the body with their inflammation, which can result in Acute Respiratory Distress Syndrome (ARDS) and organ failure.

As such, Vitamin D’s powerful immunological role has been suggested in many studies to have a protective effect against infection and illness, particularly respiratory problems.

For a great Vitamin D supplement, check out MTS Nutrition Vega-D3.

Disease Risk Reduction

Many studies have also revealed Vitamin D to be paramount in disease reduction.

In regards to Cardiovascular Disease (CVD), Vitamin D has been found to promote a healthy cardiovascular system by promoting cardiac tissue regeneration. Similarly, Vitamin D deficiency is associated in many studies with a higher incidence of the disease.

Vitamin D deficiency has also been associated with an increased risk in many different types of cancers, including colon, breast, prostate, and ovarian.

The micronutrient has been found to inhibit tumor angiogenesis (new blood vessel formation), and also cell division of breast epithelial cells.

Then there is Osteoporosis and Vitamin D’s huge role in healthy bones.

Vitamin D is crucial for calcium absorption (the mineral responsible for bone strength), with a deficiency majorly promoting the risk of Osteoporosis and other bone disorders. It plays a large role in the movement of calcium in the intestines and between cells, facilitating proper calcium pathway functioning.

Vitamin D has even been found to be important for muscular health. Deficiencies are associated with an increased risk of disorders such as Sarcopenia (a muscle-wasting disorder) and Fibromyalgia (widespread muscle and bone pain).

Practical Recommendations

So, how much Vitamin D should we be having? 

The first thing to note is vitamins are measured in two ways - micrograms (mcg) or International Units (IU). The World Health Organisation currently recommends a range of values dependent on age.

For adults aged 19-50, it is 5 mg/200IU per day. Those aged 51-65 should have 10mg/400IU per day. For those older than 65, 15mg/600 IU per day. These are base values to prevent deficiency, however, it does not mean you cannot have more.

While sunlight is a great way to get vitamin D, it can depend on where you live. The best way to ensure you’re getting enough vitamin D is to take a daily supplement. 

Most supplements will exceed the above-recommended dose, but you do not need to worry about toxicity when supplementing; while vitamin D toxicity does exist, the doses required far exceed that of a supplement.

Of course, the aforementioned Vitamin D containing foods will also contribute to healthy levels, but a daily supplement is potent and cheap!

If you’re concerned you may be deficient, you can have your Vitamin D levels measured by a physician. Tests will measure the 25-Hydroxyvitamin D3 pre-hormone to see if your levels are optimal.

Vitamin D deficiency is fast becoming a major public health concern. In the U.S alone, 41.6% of the population are deficient in Vitamin D. The issue is even worse for darker-skinned populations, with 82.1% of African-Americans and 69.2% of Hispanics being deficient.

People with darker skin absorb more UVB light in the melanin of their skin and therefore are more likely to become deficient in Vitamin D.

Regardless of who you are, though, the prevalence of deficiency is worrisome to say the least. 

Use this knowledge to reap the benefits this amazing nutrient has to offer!

Linden Garcia Pepworth is a Sports Nutritionist (BSc Sports Nutrition) and YMCA Accredited Instructor. He is currently working on a review comparing the anabolic differences between plant and animal proteins.