All about vitamin D
Vitamin D is not actually a single vitamin, rather it is a family of fat soluble vitamins known as secosteroids. A secosteroid has a molecular structure akin to a steroid, the difference being it has a broken ring. Secosteroids are a subclass of steroids.
Classification appears to be somewhat of an opinion as some bodies refer to it as a vitamin while others call it a hormone.
Technically, it is a hormone because of its steroid like structure and because its synthesis and actions are active in several areas of the body.
As a result of its metabolic pathways and effects on sex hormone binding globulin, vit D has been shown to positively influence natural testosterone. Zinc absorbtion is enhanced in the presence of Vit D, and combining the two further enhances natural testosterone.
This is exactly why we added both as ingredients in our premium testosterone booster DNA Lean Test-FX.
The vitamin D family includes:
- D1 (ergocalciferol with lumisterol, 1:1)
- D2 (ergocalciferol [made from ergosterol])
- Vit D3 (cholecalciferol [made from 7-dehydrocholesterol in the skin])
- D4 (22-dihydroergocalciferol)
- D5 (sitocalciferol [made from 7-dehydrositosterol])
Although there are several different forms the two most relevant to human nutrition
are vitamin D2 and particularly vitamin D3.
Functions of Vitamin D
Vitamin D plays a vital role in maintaining human health. It is largely responsible for
improving the absorption of essential minerals such as magnesium, zinc, iron and in particular
calcium and phosphorus. Data from studies show that it is crucial for maintaining healthy bones and
teeth because of its effects on calcium and mineral absorption. It is especially important for
maintaining normal and healthy bone development in preadolescent children.
Vit D also serves many other important mechanisms for supporting optimal health. Multifacted research exploring the functions and effects upon various organs, metabolic responses and diseases, have uncovered a complex array of interactions. Endocrine functions, brain and cognitive health, inflammation, cardio vascular disease and atherosclerosis, are all affected by this vitamin. Its effects have been found to be so vast, it has been evidenced that vitamin D is known to influence over 200 genes highlighting links to diseases.
Importance of Vitamin D on health
A deficiency of vitamin D can lead to serious health risks, low levels have been directly linked to diabetes, hypertension, autoimmune diseases and cancer. Severe deficiencies may lead to diseases such as:
Positive effects of Vitamin D on Testosterone
In men, 97% of testosterone is produced by the testes, with only 3% being produced by the
adrenal glands. Vitamin D receptors are present in the testes which suggests that this vitamin does
have some action on endogenous testosterone.
Endocrinologists and other branches of science are
currently trying to understand the exact processes of how it affects and interacts with endgenous testosterone levels. Although the exact mechanism of vit D’s influence on testosterone is not yet fully understood, results of studies do show that there is a direct correlation between vitamin D and testosterone.
Vitamin D may reduce SHBG increasing free circulating testosterone
The majority proportion of endogenous testosterone is bound to SHBG (Sex Hormone Binding
Globulin). Testosterone bound to SHBG remains unavailable to bind to androgenic receptors and
induce its anabolic effects. Essentially all testosterone bound to SHBG is dormant, having no
biological effect. Reducing SHBG increases freely “available” testosterone pools, meaning more testosterone is bio-available, ergo the effects of testosterone are more pronounced. Data from various human studies indicate that Vitamin D is significantly associated with total testosterone and sex hormone-binding globulin.
Best food sources of vitamin D
There are few foods that contain vit D let alone contain it in abundance, this is why dietary food sources are a contributing factor toward deficiency or sufficiency. Here are some of the best food sources:
- Wild oily fish (non farmed)
- Butter from 100% grass fed cows
- Egg yolks from pastured hens
Farmed fish and produce from grain fed cows do not naturally have the same vit
D content unless artificially fortified.
Sunlight and vitamin D3 synthesis
Vitamin D3 is synthesised in the skin via exposure to sunlight. Ultra violet rays (UVB radiation) from the sun catalyse the photochemical conversion of provitamin D3 into vitamin D3. The amount of exposure to sunlight significantly affects Vitamin D3 levels. For example, indoor oriented lifestyles can increase the risk of deficiency due to lack of natural UV rays, resulting in a reduction of the dermal synthesis of Vitamin D3. The bottom line is lack of sunlight can lead to a deficiency. The best way to counter low exposure to sunlight is to consume foods from above list and/or use a supplement.
Plant based vitamin D and plant sterols
It was once thought that plants did not contain vitamin D, however various studies have led to the discovery of vitamin D in plants. Data shows that animals grazing on specific types of plants are known to develop calcium intoxication similar to that caused by consuming too much vitamin D. Scientists believe this phenomenon to be caused by vitamin D3 or a metabolite of vitamin D3 contained in the plants that stimulate calcium absorption.
The plant kingdom is estimated to have around 260,000 different species of plants, each with
their own unique properties and genetic make-up. Many species of plants contain some very
interesting phytochemicals, some of these phytochemicals are known as sterols. A sterol or
phystosterol, in chemistry, is known as a steroid alcohol. Sterols are a sub class of steroid
hormones and are structurally very similar to vit D; sterols are precursors of vit D. It
is widely thought that plants containing provitamin D3 (a precursor to vitamin
D3) are able to synthesise vit D3 via photochemical conversion from
exposure to UV rays from sunlight.
Nutrients are passed down the food chain
When trying to incorporate high quality dietary sources of vit D into your nutritional plan,
it is important to note that not all foods are equal. For example, wild salmon are free to feed
on their natural diet of squid and other smaller fish, eels, and shrimp. Wild Sockeye salmon
almost exclusively feed on plankton and as such are a great source of vit D. Ultimately salmon acquire their vitamin D through phytoplankton and marine plants, whether it be from directly eating these plants or by consuming other smaller creatures such as krill who feed off these nutrient rich plants. Farming fish and deviating from their natural diet to that of low grade, low nutrient, man made food pellets, significantly lowers the nutrient quality of the actual fish.
Vitamin D deficiency
Although there are many different symptoms of deficiency, there is currently only one way to accurately determine a deficiency. This can only be done via a blood test, which is commonly known as a vitamin D test. A deficiency is generally recognised if levels of Calcifediol 25(OH)D are measured below 30 ng/ml. Check out the Vitamin D council for more information on on vitamin D levels.
Insufficiency or deficiency – what’s the difference?
Insufficiency and deficiency differ only by degree and appear to be a matter of opinion. A blood level of Calcifediol 25(OH)D between 20-30 ng/mL is recognised by the Vit D council as a deficiency, yet according to the endocrine society, its an insufficiency. Opinions aside, a blood level of Calcifediol 25(OH)D ranging between 20-30 ng/mL is too low and poses an increased risk of disease.
Vit D is imperative for maintaining optimal health and also for preventing disease. Furthermore it is a potent ergonomic sporting aid due to its positive influence on testosterone. High quality dietary sources are rare and therefore it is of great importance to regularly consume foods such as wild salmon that are naturally high in vitamin D. Furthermore exposure to sunlight stimulates the biosynthesis of D3 and is a contibuting factor in maintaining a healthy level. All things considered, I’d recommend supplementing daily with at least 1000iu as a preventive measure against Insufficiency and deficiency.
Article by Paul Jenkins CEO and founder of DNA Lean®
DNA Lean. (2017). Vitamin D: Discover how it can increase testosterone (FAST). [online] Available at: https://www.dna-lean.co.uk/blog/vitamin-d-increases-testosterone/
[Accessed 17 Jan. 2017].