We don’t need to tell you how important testosterone is for men.
It is the key to a man’s strength, vitality, and energy.
Excessive amounts of testosterone are lethal of course; having too much testosterone is why so many men die so much earlier than women.
But having healthy testosterone levels is a prerequisite for a man to be fit, muscular, energetic, and confident (to say nothing of having a healthy sex life).
Or to put it another way, a serious testosterone deficiency is known to cause everything from low mood and poor immune system function to low libido and even male impotence.
It’s no wonder then that men today are so interested in elevating their testosterone levels. Anabolic steroid use is on the rise, with more and more men injecting exogenous testosterone to see gains in the gym and the bedroom. Natural testosterone boosters are also becoming increasingly popular; less potent than steroids, these supplements can still positively affect free serum testosterone levels.
But what if we told you that there is an easier way for you to ensure that your test levels are nice and healthy?
Well, there is: just get some sun!
Sunlight exposure dramatically increases the synthesis of Vitamin D in the human body, and Vitamin D has been shown to have a massive effect on testosterone production in men.
By ramping up your Vitamin D levels, you can significantly increase your free serum testosterone levels, thereby promoting strength and muscle gain, a healthy sexual appetite, a positive mood and good energy levels.
Don’t just take our word for it though. Let’s go through the details and explain how all of this works.
We’ll start with a discussion of the relationship between Vitamin D and testosterone. We’ll then show that sun exposure of just 30 minutes per day is sufficient for promoting testosterone levels naturally. The sun does this through two mechanisms; by boosting Vitamin D, and more directly through hormone manipulation. At the end, we’ll talk about how much of a problem this is for men today – spoiler, it’s a big one!
Vitamin D & Testosterone
It’s now pretty certain that Vitamin D has a direct effect on testosterone levels in men. Several studies, such as this one, have found that Vitamin D supplementation leads to a steep rise in free and bioactive testosterone levels in the blood. It is worth quoting the cited study at length:
“Mean circulating 25(OH)D concentrations increased significantly by 53.5 nmol/l in the vitamin D group, but remained almost constant in the placebo group. Compared to baseline values, a significant increase in total testosterone levels (from 10.7 ± 3.9 nmol/l to 13.4 ± 4.7 nmol/l; p < 0.001), bioactive testosterone (from 5.21 ± 1.87 nmol/l to 6.25 ± 2.01 nmol/l; p = 0.001), and free testosterone levels (from 0.222 ± 0.080 nmol/l to 0.267 ± 0.087 nmol/l; p = 0.001) were observed in the vitamin D supplemented group. By contrast, there was no significant change in any testosterone measure in the placebo group. Our results suggest that vitamin D supplementation might increase testosterone levels. Further randomized controlled trials are warranted to confirm this hypothesis.”
Studies such as this trial, published in Clinical Endocrinology in 2010, have replicated these findings quite reliable. The authors of this study concluded:
“Men with sufficient 25(OH)D levels had significantly higher levels of testosterone and FAI and significantly lower levels of SHBG when compared to 25(OH)D insufficient and 25(OH)D-deficient men. In linear regression analyses adjusted for possible confounders, we found significant associations of 25(OH)D levels with testosterone, FAI and SHBG levels”.
The jury isn’t out on this one. The writing is on the wall.
We’ve seen enough robust clinical trials now showing a direct, predictable relationship between Vitamin D administration and elevated testosterone levels.
It isn’t difficult to find these studies. We recommend taking a look at some of the references in the cited papers above. It’s also worth looking at some of the health recommendations of the major public bodies in your country. Most people are in agreement that healthy Vitamin D levels are at least positively correlated with healthy testosterone levels.
So that’s agreed.
But the properties of Vitamin D don’t stop there!
Vitamin D’s Other Functions
Vitamin D acts more like a hormone than a vitamin in the human body.
In fact, Vitamin D is technically classified as a secosteroid, such is its behaviour.
It is an extremely important molecule; it is involved in wide ranging, vital bodily functions, from regulating bone repair to supporting the function of the immune system.
One of the most important functions of Vitamin D is facilitating the absorption of calcium and phosphorous in the human digestive tract. Without sufficient levels of Vitamin D, you wont be able to obtain all the calcium and phosphorous you need from your food. This will mean weak bones, poor cognitive function, and high blood pressure (and that’s just for starters).
There is also evidence to suggest that Vitamin D interacts with insulin; researchers have suggested that it may have some effect on the risk of developing diabetes. This literature review seems to indicate that Vitamin D deficiency may be a risk factor for the development of diabetes, although the authors stress that much more work is needed.
So vitamin D isn’t just something you need to consider if you’re looking to maximize testosterone levels.
Vitamin D deficiency is known to raise the risk of developing osteoporosis, along with other bone disorders (e.g risk of fractures). It causes calcium and phosphorous deficiencies, and it might elevate your risk of developing diabetes.
But where does the sun come in?!
The Sun & Vitamin D
We’ll cut right to the chase here and explain why the sun is your best source of Vitamin D.
There is a naturally-occurring form of cholesterol in your skin called 7-dehydrocholesterol.
When ultraviolet (UV) light hits your skin, a reaction begins which converts 7-dehydrocholesterol into cholecalciferol. This cholecalciferol is then transported to your liver, where it undergoes another reaction, before finally arriving at your kidneys where it is turned into its final form: 1,25-dihydroxyvitamin D or 25(OH)2D.
This is the form of Vitamin D that we’re familiar with; it’s the stuff found in supplements, and it’s the stuff that our bodies use to carry out all the vital bodily functions mentioned above.
So your body is perfectly capable of making its own Vitamin D.
It just needs exposure to the UV rays of the sun.
But how much?
It turns out, not much at all. Current thinking is that just 30 minutes of sun exposure between the hours of 10am and 3pm (obviously varying depending on location and time of year) two to three times per week is all you need.
Vitamin D is fat-soluble, so you can store it. A quick hour burst in the sunshine will give you enough Vitamin D for you to draw on for the next few days.
That’s not much to ask!
However, if your goal is to maximize health, physical performance and testosterone production, you probably aren’t interested in what the ‘basic requirements’ are; after all, you probably don’t want to be like everyone else if you’re reading this article!
We think it’s good to set yourself a goal of spending at least an hour outside with direct sun exposure every single day. You don’t need to be in blazing sunshine; being outside – even under thin cloud – should do the trick.
But if you live in a northern place, chances are this isn’t going to be feasible for you during the winter months.
If you live in northern Germany, Denmark, the UK, Scandinavia, Canada or the northern US, you probably need to take a Vitamin D supplement through the darkest months of the year.
Either than, or you should try to eat some of the foods high in Vitamin D on a regular basis if you know that you aren’t getting enough sun. Food high in Vitamin D are foods that provide a lot of animal fat (as it is a vitamin stored in fat).
These foods include:
- Oily fish (herring, sardines, etc)
- Egg yolk
Obviously, some of these foods aren’t ideal, as they’re very high in cholesterol. So eat them in moderation, vary them up, and do your best to get some sun. A supplement is probably preferable to eating lots of egg yolks every day!
How Much Of A Problem Is Vitamin D Deficiency?
Vitamin D deficiency is a serious problem in the northern hemisphere.
Obviously, the prevalence of a vitamin D deficiency depends on the threshold used to define “deficiency”. There is no obvious bottom – no point at which levels go from “great” to “dire”.
But we can look at the threshold used by various studies.
If we use 30ng/mL as our threshold, then we get a deficiency rate of 69% in the United States.
And that’s one of the higher thresholds!
In northern Europe, then we get epidemiology rates varying from 50% to 70% in the winter months. The problem is exacerbated by the modern working environment; an office, usually with few windows.
We’ve already shown that low levels of Vitamin D are correlated with various negative health outcomes, from the increase in bone fractures to the development of diabetes and osteoporosis.
The ideal solution would be for these people to spend more time outdoors, or to eat more fresh oily fish. But until we can make that happen, supplementation is probably preferable to rising rates of these serious diseases!