The Five Supplements Anyone Should Consider Taking - Part 2 - Vitamin D
Disclaimer: This article is for informational purposes and does not serve as medical advice. Please consult your medical practitioner before committing to a supplement regime.
When you zoom out and take a look from afar it seems quite odd that people need to supplement their diet with pills in order to become or stay healthy. Nature has designed and made available for us everything we need to live and thrive. Unfortunately, we have not only cut ourselves from eating food directly from nature, but we have also depleted the environment of many nutrients.
Vitamin D is a nutrient that is essential to our health and is extremely rare in food and hard to come by. The best sources are the flesh of fatty fish and fish liver oils (especially cod liver oil). Smaller amounts are found in egg yolks, cheese, and beef liver.
Luckily, there is another pathway to accessing vitamin D - through sun exposure. Yet, once again, with the modern lifestyle, we have removed that from our lifestyle as well. Even in the sunshine country of Australia, as many as one in four people are vitamin D deficient while around 70 per cent of the US population lacks this essential vitamin.
The basics
Vitamin D is a fat-soluble vitamin that exists in various forms. Nearly every tissue and cell in our body has a vitamin D receptor which suggests its incredibly important role that is still to be fully understood by science.
For example, without enough activated vitamin D in the body, dietary calcium and phosphorus cannot be absorbed. They are both critical for the development of bone and teeth, and calcium is also essential for signalling between brain cells.
Vitamin D3 (cholecalciferol) comes from animals, while the plant form is vitamin D2 (ergocalciferol). They are not biologically active which means they must be modified in the body to have any effect.
Once it is activated mainly in the kidneys (for nutrition geeks: it is known as 1,25-dihydroxy vitamin D3 [1,25(OH)2D3] or calcitriol) it acts as a hormone that increases the expression of many genes, up to 5 per cent of all human genome!
Getting the sunshine vitamin from the sun
We have written about this topic in this article on sun exposure, but let’s have a quick recap. When sunlight reaches your skin it hits the cholesterol molecules transforming them into a precursor of vitamin D, which then gets fully activated in the liver and the kidneys.
For a healthy Caucasian, a 20-minute summer sunbathing at around 35 degrees latitude at midday would produce enough vitamin D to last for a week. This is a very general estimate that varies greatly depending on your age, skin type, altitude and genetics.
Being a fat-soluble vitamin, it can be easily stored in the body, it has a serum half-life of 2-3 weeks. Its production in the skin is limited to 10,000-20,000 IU each day. Once serum levels reach 60 ng/mL, any excess is inactivated, which means you can’t overdose on vitamin D through sun exposure (the preferred range by the government agencies is 30-50 ng/mL). Thanks, Mother Nature!
You do have to get direct sunlight on your skin - car and office windows don’t count as they absorb most of the UVB radiation responsible for the production of vitamin D. The same goes for sunscreens.
Health benefits
Vitamin D has numerous indispensable roles in the body including anti-inflammatory effects and a role in many metabolic processes (i.e. supporting normal insulin production). Low vitamin D levels have been associated with obesity, insulin resistance, and type 2 diabetes.
Vitamin D is important for bone health and several studies link its low blood levels with an increased risk of fractures in older adults.
Animal and laboratory studies have found that vitamin D can inhibit the development of tumours and slow the growth of existing tumours including those from the breast, ovary, colon, prostate, and brain.
Immune and inflammatory cells that play a role in cardiovascular disease conditions like atherosclerosis are regulated by vitamin D. The vitamin also helps to keep arteries flexible and relaxed, which in turn helps to control high blood pressure.
Inadequate vitamin D levels and UVB exposure (along with a person’s genetic background) have been identified to increase the risk of multiple sclerosis and type 1 diabetes.
Vitamin D is incredibly important for the immune system. Its levels are lowest in the winter months and many reports of cough, cold, or upper respiratory tract infection have been linked to vitamin D deficiency. It is also now established that it plays an important role in reducing the severity of Covid-19 symptoms.
The Vitamin D and Omega 3 trial, a randomized double-blind placebo-controlled trial following more than 25,000 men and women ages 50 and older, found that taking vitamin D supplements (2,000 IU/day) for five years reduced the incidence of autoimmune diseases (including rheumatoid arthritis, psoriasis, and autoimmune thyroid diseases like Hashimoto’s thyroiditis, Graves’ disease) by about 22%, compared with a placebo.
Serotonin (an important neurotransmitter responsible for mood, emotions, appetite, and digestion) can’t cross the brain-blood barrier to enter the brain. It is tryptophan, the amino acid we get from food, that does that and then gets converted into serotonin in the brain. This conversion is enabled by vitamin D.
Lastly, a smaller study on vitamin D-deficient African Americans found that supplementing with 4,000 IU per day to bring their levels back to normal reversed their epigenetic aging by 3 years. A study in mice confirmed a link between increased aging and severe vitamin D deficiency.
Supplementation
Many experts believe blood levels of vitamin D should fall in the 30-50 ng/mL range.
Correcting vitamin D deficiency through food is not possible. Your best bet is adequate sun exposure, although even that becomes increasingly inefficient as you age. So, the next solution is supplementation.
Measuring your levels before and after supplementation is very important. Supplementing with 1,000 IU per day will raise your blood levels by around 5 ng/mL. So if you want to get from 20 ng/mL to 40 ng/mL (and you don’t have any metabolic issues that would prevent absorption) you would need at least 4,000 IU per day.
Vitamin D3 is usually recommended as a supplement although many fortified foods might contain vitamin D2. Supplementing with D3 tends to raise blood concentrations of the vitamin more and sustains those levels longer than D2.
Steroid hormones like vitamin D are slow-acting, so the time of day when you take supplements doesn’t really matter. Being fat-soluble, taking it with a meal can enhance its absorption.
How much is enough?
The recommended dietary allowance (RDA) for vitamin D is 600 IU (or 15 mcg) per day for adults under age 70 and 800 IU (or 20 mcg) per day for adults over age 70.
Yet, in the opinion of most experts, these numbers are far too low. The world-renowned biomedical researcher Dr Rhonda Patrick suggests it is really hard to overdose on vitamin D3. She recommends a daily intake of 2000-4000 IU, and according to her, studies have shown that you would have to consume hundreds of thousands of IUs on a daily basis to start experiencing dangerous negative effects.
Around one per cent of the population has a gene mutation that prevents them from the efficient conversion of vitamin D3 into the active form. They have higher all-cause mortality and respiratory-related and cancer-related mortality. They often need to supplement with doses as high as 30,000 IU per day.
Conclusion
Fearing sun exposure can be a dangerous habit since the sun is literally our source of life. Just like plants, we use sunlight to grow and be healthy and happy.
Safely spending enough time outside in the sun is our best bet to maintain adequate vitamin D levels, yet, depending on your location and age, it might be really hard in winter. This is why regular monitoring of this important hormone and supplementing when necessary is crucial for our health and longevity.
First, let nature do what it does best. Only when necessary and unavoidable, a bit of science can help you get back on track.
Resources and further reading/listening:
https://www.youtube.com/watch?v=XcvhERcZpWw
https://www.nature.com/articles/s41430-020-0558-y