Vitamin D is often referred to as the “sunshine vitamin.” This steroidal hormone is synthesized in our body when the cholesterol in our skin is exposed to the ultraviolet rays of the sun; but it can be very variable how much an individual produced from person to person. Vitamin D is also found in a few foods, added to others, and taken in supplement form. 

The importance of Vitamin D is often quite underestimated. Nearly ½ of the US population is deficient in vitamin D, specifically in older adults, young women, infants, and those of color. This vitamin affects bone health, mental health,cardiovascular health, protection against many cancers, and most recently there have been reports of those battling COVID19 most determientally have been vitamin D deficient. 

• Vitamin D promotes bone health by promoting the absorption of calcium. Without Vitamin D, calcium obtained through food will simply go through you.
• It helps regulate mood. Studies have shown that low levels of vitamin D were linked to higher levels of depression and anxiety. 
• A study was done on individuals of high blood pressure. They were exposed to UV rays for three months, thus their vitamin levels increased. Most importantly their high blood pressure normalized. 
• “Active vitamin D is one of the most potent inhibitors of cancer cell growth,” says the head doctor of the Vitamin D, Skin, and Bone Research Laboratory at Boston University.

Data has suggested that vitamin D supplementation can lower the odds of developing respiratory infections, particularly in vitamin D-deficient groups. The COVID-19 pandemic has further escalated the discussion. It has long been clear that groups that traditionally exhibit vitamin D deficiency or insufficiency are the same groups that have also been disproportionately impacted by COVID-19.

Few foods naturally contain Vitamin D. Vitamin D2 is found in plant based products, while Vitamin D3 can be found in animal products and fatty fish. However, vitamin D3 has been found to be twice as effective at raising levels of the Vitamin D in the bloodstream, where it can then be used in its active form. 

If you don’t get out in the sun often, or don’t eat much fatty fish you may want to consider taking a  vitamin D supplement for optimal health. If you choose to take vitamin D supplements, children from the age of 1 and adults, 10 micrograms a day will be enough for most people. Do not take more than 100 micrograms (4,000 IU) of vitamin D a day as it could be harmful. 

It is important to note. Vitamin D is a fat soluble vitamin. Therefore it cannot pass through urine as a water soluble vitamin can. Overtime if supplementing too much a buildup of Calcium can occur in the body (hypercalcaemia). This can weaken the bones and damage the kidneys and heart. 

Vitamins are necessary for healthy metabolism in the body. Most vitamins need to come from food because the body either does not produce them or produces very little. However, how can we be sure we are absorbing our vitamins when ingested via food and supplement form. 

First it is important to understand how the absorption process of vitamins happens. There are two different types (therefore for routes) of vitamins. 

• Water-soluble vitamins are found into the watery portions of  foods. They are absorbed directly into the bloodstream as food is broken down during digestion or as a supplement dissolves. It is hard for these vitamins to reach toxicity because they can easily be released via excretion.
• Fat- soluble vitamins gain entry into the blood in the same way the macronutrient fat does. They are packed in micelle with fats, bile salts, and more, and then transported across the intestinal wall into the bloodstream. Therefore they are more likely to be absorbed when fat is present. 

Bioavailability is the percentage of the dose (of a nutrient or other substance) that is absorbed and able to be used by the cells for current use or stored for future use. This is why it is important to keep in mind that just because a supplement claims to contain a particular amount of a nutrient, it  doesn’t mean your body will absorb the entire amount. There are many different things that can interfere with a substance’s bioavailability, including alcohol, caffeine, competition with other foods, stress, and more. 

Some supplements contain special ingredients, or enhancers, which can improve the bioavailability of certain supplements, such as those at Klaire Labs.  Enhancers typically act in the gut to either improve solubility or reduce the amount of enzymatic breakdown.

Many substances and micronutrients can also interact with each other. For example Vitamin D, helps you absorb Calcium from food rather than taking it from bones, and Vitamin C increases iron absorption. But this is always a commensalistic relationship. This can be the quite opposite as well.  For example, oxalates found in some dark green leafy vegetables, interfere with the absorption of some minerals including Ca, Zn, ann Iron. Which is why we absorb significantly more iron from meants rather than leafy vegetables although they are both high in iron. Or even a minor overload of the mineral manganese can worsen iron deficiency.

Despite the complexity of nutrient interactions, don’t overwhelm yourself and keep it simple (: Eat a varied balanced diet,  skip fat diets (which often fail to supply necessary nutrients), and when possible try to receive your nutrients from foods before supplements.