Vitamin D is not a vitamin per se. It’s actually classed as a hormone – a hormone that can increase a man’s testosterone and balancing women’s estrogen levels.
Furthermore, Vit-D helps your body to fight off diseases and metabolize energy from the foods you eat. Not only that, but it’s also important for calcium absorption, and much more which I’ll discuss below:
Table of Contents
What is Vitamin D?
As previously discussed, vitamin D is a group of fat-soluble secosteroids (a type of steroid) responsible for increasing the absorption of calcium, magnesium, and phosphate within the body. (I)
It’s linked to numerous biological effects such as; hormone regulation and the metabolism of the foods we eat. Without enough vitamin D, you could incur symptoms of fatigue, a low sex drive, a foggy brain, and a general feeling of unwellness.
There are numerous varieties of vitamin D – from D1, D2, D3 and so on. However, in humans, the most important compounds in this group are vitamin D3 (also known as cholecalciferol) and vitamin D2 (ergocalciferol). (II)
Cholecalciferol and ergocalciferol can be ingested from particular foods – and in supplement form. They both mimic what our bodies create when sunlight interacts with the skin – hence their popularity.
Vitamin D Discovery
Vitamin D was first discovered in 1922 by Elmer McCollum, who first began his tests on dogs with rickets. He fed the dogs modified cod liver oil. And, after putting the dogs under x-rays, he found the bone formation in the animals improved – thus discovering the cure for rickets. (III)
While we now know vitamin D to be a hormone, it was actually named as a vitamin at the time of its discovery as this vitamin ‘D‘ hadn’t yet been allocated to any known compound.
The discovery of vitamin D proved a valuable cure for rickets in children across America, which throughout the 1920s most children in the United States suffered from this condition: Rickets is a condition where the bones fail to form correctly due to poor calcium absorption.
The discovery of vitamin D and its ability to improve calcium absorption was groundbreaking at the time. It was at this point, fortified foods such as milk, cereals, bread etc, were loaded with vitamin D. (IV) This, coupled with a higher protein and dairy diet relieved the population of rickets.
Most Used Forms Of Vitamin D
So, which vitamin D is the best for us? The types of vitamin D we’re most concerned with are vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol).
These two forms of vitamin D can be found in foods and made in the body once the skin is exposed to sunlight. Vitamin D2 and D3 are easily available for our body to absorb and create – making them, the most important types of vitamin D for us as humans.
Apart from natural sunlight, vitamin D3 is derived from three main sources – fish oil, sheep lanolin and lichen, a plant-based source. (V) Sheeps fur you say? Yes, that’s right, the sheep’s fur is boiled down and put through a chemical process that mimics vitamin D3. (VI)
Vitamin D2 is made from yeast or other plant matter such as mushrooms. Many experts believe that D2 is not well absorbed or utilized by the body due to its source – from plants.
This means, vitamin D2 it’s not the type of vitamin D the body makes naturally, which makes it a less popular choice. Vitamin D3, on the other hand, is the closest we can get in supplemental form to receive the full benefits. The body can convert D2 to D3, but it may not be as efficient, especially if you’re trying to correct a vitamin D deficiency. (VII)
How Much Vitamin-D Do You Need?
We cover more on the ideal dosages later in the article, along with how you can improve ingestion and absorption – but to quickly summaries: Most people can supplement with as little as 300 IU (International Units) per day and see good results.
As a general rule, we need anywhere between 300 – 1200 IU per day for optimum health. (VIII) How much vitamin D you need will depend on several factors such as stress, sickness, age, and geographical location (sunlight restrictions).
Benefits of Vitamin D
Vitamin D increases ‘expression of the tyrosine hydroxylase gene in adrenal medullary cells’. This, in turn, affects the ‘synthesis of neurotrophic factors, nitric oxide synthase, and glutathione’s’. This clarifies that vitamin D is a viable option for enhanced performance. But in the real world, what does this mean?
This means that vitamin D holds the ability to improve the functioning of the mitochondria and nitric oxide production.
It’s the mitochondria’s ability to create more energy within the body, where it’s known as ‘powerhouse‘ of energy production. (IX) The more mitochondria you have available, the more energy you’re going to have.
As for nitric oxide, this helps the body to shuttle more oxygen to the muscle and brain, especially during an intense activity such as sprinting or even endurance events.
Prevents cardiovascular diseases
Low levels of vitamin D have been linked to a number of diseases and conditions such as low blood levels, which are connected to an increased risk of heart diseases, and also cardiovascular diseases.
“Several epidemiological studies have suggested that individuals with low blood levels of vitamin D have increased risks of heart disease, stroke, hypertension, and diabetes.” (X)
The thought process is that vitamin D acts as a receptor in cells throughout the vascular system. Many cells types, but those, in particular, are the vascular smooth muscle cells, endothelial cells, and cardiomyocytes (cardiac muscles) which produce calcitriol, the natural molecule that binds to others as a vitamin D receptor.
What’s the role of calcitriol? Calcitriol helps the vascular system to remain strong and healthy, where it prevents the build-up of coagulation and, at the same time, help with anti-inflammatory benefits.
Improves bone health
As we’ve already discussed, vitamin D is vital for the absorption of calcium throughout the body. Without enough vitamin D present, then calcium cannot be used to form or strengthen bones.
This makes vitamin D ideal for not only for the elderly and young but also athletes who put their bodies under strenuous activities on a regular basis.
A Wikipedia article on vitamin D refers to a study that; “In 2011 an IOM [Institute of Medicine] committee concluded a serum 25(OH)D level of 20 ng/ml (50 nmol/L) is needed for bone and overall health.”
The article continued to suggest that ‘overshooting’ on the dosage of vitamin D may be necessary to establish adequate serum levels: “The dietary reference intakes for vitamin D are chosen with a margin of safety and ‘overshoot’ the targeted serum value to ensure the specified levels of intake achieve the desired serum 25 (OH) D levels in almost all persons.” (XI)
Stimulates testosterone production
Studies have proven that the male reproductive tract has “been identified as a target tissue for vitamin D.” In light of this information, the Department of Internal Medicine set out a study which took 200 healthy men and put them through a vitamin D supplement regimen for one year.
“Two hundred Healthy overweight men undergoing a weight reduction program who participated in a randomized controlled trial were analyzed for testosterone levels.”
After the study was complete, the results came back with an overall increase in testosterone levels. To summarises these results, there was a rise in testosterone from 10.7 ± 3.9 nmol/l, to 13.4 ± 4.7 nmol/l by the end of the trial.
These results many sounds complicated to understand – it basically means that their testosterone levels increased by almost 50%. (XII)
Vitamin D and Rickets
As previously discussed, children and some adults throughout early history suffered from conditions such as rickets, and Osteomalacia (mainly found in adults).
Osteomalacia is a disease that is created form the result of low vitamin D levels, which affects the skeletal strength and formation of bone mass – much like rickets.
Low Vitamin D Symptoms: “softening of the bones, leading to bending of the spine, bowing of the legs, proximal muscle weakness, bone fragility, and increased risk for fractures.” (XIII)
The question is; ‘why did children and adults have low levels of vitamin D in the first place?‘ It’s because adults and children often spent their time indoors in Central AmericaCentral America post World War II, working in factories, or in education – where the amount of sunlight needed for calcium formation wasn’t readily available. (XIV)
This, coupled with a diet that was insufficient in vitamin D resulted in a large population experiencing the side effects of vitamin D deficiency. Therefore, this is when fortified foods made their way into mainstream society throughout America.
Low Vitamin D – Who’s at Risk?
Nowadays, the world population (compared to previous generations) minimally suffer from low vitamin D levels to the extent where conditions such as rickets are caused.
But, there are still some cases where we may find ourselves in need of vitamin D support, either in a supplement, or sunlight form which we’ll discuss below.
Low levels of vitamin D have also been linked to;
- Respiratory infections
- Lack of appetite
- Poor physical strength
- Low mental performance
Let’s run through some of the most common ways people might fall into the category of having low levels of vitamin D.
Main Reasons For Vitamin D Deficiency
People who live in the northern hemisphere are more at risk of becoming deficient in vitamin D. This is due to the lack of sunlight throughout the winter months. However, supplementing with vitamin D can rectify this.
In countries such as Norway, during the Polar Nights which lasts from November to January, the sun doesn’t rise at all – making it difficult to get enough vitamin d. (XV) Therefore, families eat large amounts of fish which contain vitamin D – this keeps them healthy throughout the dark winter months.
As we get older, we might tend to avoid sunlight in fear of attracting skin cancer. Because of this, there’s a chance of not getting enough sunlight as required to create vitamin D. Also, the elderly may become weaker as they age, which could also limit their ability to venture outdoors.
Low cholesterol medication will introvertly cause a drop in vitamin D levels. This is due to the way our bodies create vitamin D, which is through a process that uses cholesterol that’s stored throughout the body. (XVI) So, those who have low cholesterol due to a ‘low cholesterol diet’, or insufficient calories, for example, could be deficient in vitamin D.
If you have issues with your digestion or liver, there might be a restriction in the way your body produces and uses vitamin D. (XVII) Bile, which is secreted in the liver assists your body in creating vitamin D. So, if you are on medication such as antibiotics (which cause gut issues), could lead to reduced vitamin D levels.
If there are too many stress receptors activated in the body, you could end up blocking the body’s ability to absorb vitamin D. Cortisol is a major cause of vitamin loss. (XVIII)
Poor sleeping patterns, bad food choices, and other phycological and physiological issues that when left unattended, will cause a whole host of health issues not just the loss of vitamin D.
How To Increase Vitamin D Levels
Getting Vitamin D From The Sun
The most common way to get vitamin D is from the sun. This happens in a process via the synthesis of cholecalciferol. This is created in the skin using cholesterol that we have stored in the body.
For example, this process only happens once our skin is exposed to sunlight. This is why people who have low exposure to sunlight, are often the ones with lower levels of vitamin D – such as those who work indoors or live in the northern hemisphere.
Chemical Process of Vitamin D Production Within The Body
For vitamin D to be synthesized in the body, it needs an enzymatic conversion (hydroxylation) to happen. Once this enzymatic conversion has taken place (which is processed in the skin, liver, and kidneys) vitamin D can then be activated and used throughout the body.
This all happens when the body’s skin interacts with ultraviolet B light (UVB). The body uses cholesterol (7 – dehydrocholesterol) to form vitamin D3 once sunlight is present.
Before vitamin D can be used throughout the body, it first needs to pick up oxygen from the liver, more specifically, oxygen and hydrogen molecules to become 25-hydroxyvitamin D, or 25 (OH) D. (XIX)
Vitamin D then travels to the kidneys on its final journey before being released throughout the body. There, it picks up additional molecules (again in the form of oxygen and hydrogen) to become 1,25 dihydroxy vitamin D.
Scientists refer to this as vitamin 1,25(OH)2D, (or calcitriol) but most of us simply know it as vitamin D.
Where Can You Find Vitamin D?
Apart from getting vitamin D from the sun, you can find vitamin D in supplementation form and also some food groups. Here’s a list of most common food sources containing vitamin D:
- Dark green leafy vegetables
- Calcium-fortified foods such as cereals and juices
- Egg yolks
- Beef Liver
Ideal Vitamin D Dosages
The recommended amount of daily vitamin D is 600 IU (International Units) per day. However, as the most natural source of vitamin D is from the sun, this is the best recommendation. Ideally, 20-30 per day in the sun twice per week is the ideal amount.
The upper ‘safe‘ tested limit of vitamin D is 4,000 IU per day. However, large dosages should be avoided unless otherwise stared by your healthcare provider.
As the ideal dosage recommendations vary depending on age, current health, and where you live in the world – it’s always best to have a test done to determine if you are deficient in vitamin D. For most people, upwards of 1000 IU’s per day may be taken without concerns regarding side effects.
“Watch your numbers. If you’re taking a vitamin D supplement, you probably don’t need more than 600 to 800 IU per day. Which is adequate for most people. Some people may need a higher dose, however, including those with a bone health disorder and those with a condition that interferes with the absorption of vitamin D or calcium, says Dr. Manson. Unless your doctor recommends it, avoid taking more than 4,000 IU per day, which is considered the safe upper limit.” (XX)
How Long Does Vitamin D Stay In Your System For?
According to Adam Cloe Ph.D./M.D
“One study, published in a 2008 issue of The American Journal of Clinical Nutrition, found that patients given a single dose of 100,000 international units of cholecalciferol, a form of vitamin D, had elevated levels of calcidiol in their blood for 84 days on average. (XXI)
Their finding suggests that vitamin D can remain in the system for quite some time. What time-frame, all depends on a number of health-related questions such as medication, current weight and lifestyle factors etc.
How Long Until Vitamin D Begins To Work?
If you are supplementing with vitamin D every day. It’s suggested that it will take on average one month before you begin to feel the full benefits. (XXII) However, in some cases, it may be shorter or longer depending on multiple health factors, which can be assessed by your doctor.
How to increase the absorption of vitamin D?
As vitamin D is naturally a fat-soluble vitamin, it’s best taken with a moderate amount of fat to see the best results. This doesn’t mean, however, that you should indulge in fatty foods while taking vitamin D in the hope to increase absorption.
Instead, you should look to consume roughly 11g of fat when supplementing with vitamin D to get the most out of your supplemental program. The science behind taking fat with vitamin D relates to two things;
First, the absorption rate, and secondly, the amount of time you can store vitamin D in the body. (XXIII)
Can You Take To Much Vitamin D – Side Effects?
Believe it or not, you can actually take too much vitamin D. However, you’d have to take very large dosages for it to have a negative effect.
The term that’s used to distinguish whether or not people have taken too much of a particular vitamin is Hypervitaminosis:
“Hypervitaminosis is a condition of abnormally high storage levels of vitamins, which can lead to toxic symptoms. … Toxicities of fat-soluble vitamins can also be caused by a large intake of highly fortified foods, but natural food rarely delivers dangerous levels of fat-soluble vitamins.”
So, how much do you need to take to get onto this hypervitaminosis state? This depends on the individuals current level of vitamin D balance within the body.
To avoid this, it’s best to steer clear of extremely large dosages of up to 60,000 international units (IU) a day of vitamin D for several months, which has been shown to cause toxicity. (XXIV)
How Vitamin D is Made in Supplement Form?
Vitamin D is made in a few different ways in supplement form. You can find it in animal and also plant sources.
Plant Sources of Vitamin D
Lichen – Lichen is typically what you’ll find in vegan-friendly vitamin D supplements. This comes from plant sources that grow like fungi on trees and rocks.
They are cultivated and exposed to high levels of UVB light to help the plant absorb as much vitamin D as possible. (XXV)
Then, once processed, and put into supplement form, the benefits of vitamin D3 can be received thanks to the exposure to UV light.
This process also happens with mushrooms, where they are ground into a fine powder (after numerous chemical processes). And then added to supplements.
Therefore, vitamin D 3 from Lichen is popular among vegetarians and vegans as it comes from plants – making it a more sustainable option. (XXVI)
Animal Sources of Vitamin D
Fish Oils – Fish oil capsules are a common way people like to take vitamin D3 as it contains healthy amounts of this important vitamin/hormone.
Sheep Fur – Sheep wool contains a waxy substance called lanolin, which has the compounds necessary to be turned into vitamin D3. (XXVII)
For example, the wool is sheared and is then chemically altered in the lab to produce vitamin D3. This is also known as cholecalciferol. This mimics what we as humans create once our skin is exposed to sunlight using cholesterol.
Sport Nutrition Expert Recommendation?
Vitamin D, is it for you? Will it increase your performance? Boost your health and fight fatigue?
Whether or not you decide to use vitamin D will depend on your current state of health. And other factors such as geographical location, stress levels, or physical activity to name a few.
In summary, would I recommend using vitamin D?
If you fall into any of the ‘deficiency‘ categories mentioned throughout this article, then I would consider using vitamin D with a healthy fat source. These can be nuts, avocados, or fish oils, for example, to help improve the results. However, to make sure, get in touch with your doctor to see if you’re low in this important hormone called vitamin D.
There’s a lot of benefits to using vitamin D, from sports performance, hormone improvements, and general health and well-being.
This makes vitamin D a great option for not just athletes who deplete their energy stores, but most people who work and spend a lot of time indoors.
Suggested dosages range between 300 IU to 1000 IU per day. However, to determine the actual amount you need will largely depend on test results obtained by a doctor.
However, if you feel lethargic, and you don’t eat enough vitamin D containing foods. Or you don’t get daily sunlight skin exposure, then a vitamin D supplement could be just what you’re looking for.
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(III) Wolf, and George. “Discovery of Vitamin D: The Contribution of Adolf Windaus.” OUP Academic, Oxford University Press, 1 Oct. 2004. (source)
(IV) “Vitamin D-Lightful: Surprising Facts about Fortification.” Dairy MAX – Your Local Dairy Council, 5 May 2017. (source)
(V) Björn, L O, and T Wang. “Vitamin D in an Ecological Context.” International Journal of Circumpolar Health, U.S. National Library of Medicine, Jan. 2000. (source)
(VI) Wells, Christine, and Laura Schults. “Vitamin D and Lanolin.” Gentle World Header Image, 13 Feb. 2016. (source)
(VII) Tripkovic, Laura, et al. “Comparison of Vitamin D2 and Vitamin D3 Supplementation in Raising Serum 25-Hydroxyvitamin D Status: a Systematic Review and Meta-Analysis.” The American Journal of Clinical Nutrition, American Society for Nutrition, June 2012. (source)
(VIII)How Much Vitamin D Should You Take For Optimal Health? (source)
(IX) Vitamin D proven to boost energy – from within the cells. (source)
(X) Shapses, Sue A, and JoAnn E Manson. “Vitamin D and Prevention of Cardiovascular Disease and Diabetes: Why the Evidence Falls Short.” JAMA, U.S. National Library of Medicine, 22 June 2011. (source)
(XI) “Vitamin D.” Wikipedia, Wikimedia Foundation, 18 May 2019. (source)
(XII)Effect of Testosterone Treatment on Adipokines and Gut Hormones in Obese Men on a Hypocaloric Diet. (source)
(XIII) “Osteomalacia.” Wikipedia, Wikimedia Foundation, 20 Jan. 2019. (source)
(XIV) Zhang, Mingyong, et al. “‘English Disease’: Historical Notes on Rickets, the Bone-Lung Link and Child Neglect Issues.” Nutrients, MDPI, 15 Nov. 2016. (source)
(XV) Harvard Health Publishing. “Time for More Vitamin D.” Harvard Health, www.health.harvard.edu/staying-healthy/time-for-more-vitamin-d. (source)
(XVI) “Eating for Lower Cholesterol.” Eating for Lower Cholesterol | HEART UK – The Cholesterol Charity. (source)
(XVII) Tran, Bich, et al. “Effect of Vitamin D Supplementation on Antibiotic Use: a Randomized Controlled Trial.” The American Journal of Clinical Nutrition, U.S. National Library of Medicine, Jan. 2014. (source)
(XVIII) Quraishi, Sadeq A, and Carlos A Camargo. “Vitamin D in Acute Stress and Critical Illness.” Current Opinion in Clinical Nutrition and Metabolic Care, U.S. National Library of Medicine, Nov. 2012. (source)
(XIX) “Vitamin D.” Wikipedia, Wikimedia Foundation, 18 May 2019. (source)
(XX) Harvard Health Publishing. “Taking Too Much Vitamin D Can Cloud Its Benefits and Create Health Risks.” Harvard Health. (source)
(XXI) Cloe, Adam. “How Long Does a Daily Dose of Vitamin D Stay in Your System?” Healthy Eating | SF Gate, 7 Dec. 2018. (source)
(XXII) Kennel, Kurt A, et al. “Vitamin D Deficiency in Adults: When to Test and How to Treat.” Mayo Clinic Proceedings, Mayo Foundation for Medical Education and Research, Aug. 2010. (source)
(XXIII) Examine.com. “How Much Fat Do I Need to Absorb Vitamin D?” Examine.com, Examine.com, 28 Mar. 2017 (source)
(XXIV) Katherine Zeratsky, R.D. “Vitamin D Toxicity: What If You Get Too Much?” Mayo Clinic, Mayo Foundation for Medical Education and Research, 7 Feb. 2018(source)
(XXV) What is vitamin D toxicity, and should I worry about it since I take supplements? (source)
(XXVI) “Hot Ingredient: The First Vegan Society Certified Vitamin D3.” Garden of Life, 7 Aug. 2017. (source)
(XXVII) Wells, Christine, and Laura Schults. “Vitamin D and Lanolin.” Gentle World Header Image, 13 Feb. 2016. (source)