Vitamin D, the best supplement of winter?

Is Vitamin D the best supplement you can use at this time?

For those who live in Portugal, it is easy to achieve good levels of Vitamin D in summer.

In the winter?

Not at all.

While in summer we have a climate conducive to achieving good values of this vitamin, in winter the sun appears less, and with less intensity.

The days are also shorter and the probability of a failure increases significantly.

This is where vitamin D supplementation comes in.

What is Vitamin D?

Vitamin D is one of 24 micronutrients essential to humans, and can be ingested or synthesized by the skin.

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While in hot times it is easy to achieve good vitamin D levels, in winter the story changes.

The body produces this vitamin through cholesterol, but needs sun exposure to do so.

If there is no sun exposure, you need to ingest it through food, or supplementation.

Unfortunately, it is difficult to achieve good values of this vitamin through food.

Vitamin D-fortified milk typically provides about 30 IU per 100 ml.

The egg yolk?

Less than 50 IU.

Salmon, depending on their cultivation, can reach 300/400 IU, and sardines can reach approximately 200 IU.

Basically, relying solely on food to achieve good vitamin D levels is not a good strategy and you'll see why.

vitamin D

What does Vitamin D do?

Vitamin D influences immense processes in the human body.

It is associated with the immune system and a reduction in the likelihood of contracting certain health problems.

It is also essential for bone health and plays an important role in well-being, with low levels of this vitamin being associated with symptoms of bad mood and depression.

As if that were not enough, it is also very important for the hormonal system, with a strong influence on testosterone levels.

Does Vitamin D Increase Testosterone?

Testosterone is one of the main hormones when it comes to gaining muscle mass and losing fat.

High levels lead to more strength and muscle mass, low levels lead to increased fat, little energy and difficulty gaining muscle.

In winter, vitamin D levels go down, after all, the sun goes on vacation.

When Vitamin D levels are low, Testosterone levels drop.

When Vitamin D supplementation is introduced in people with low levels of this vitamin, Testosterone values go up.

Vitamin D and Testosterone

In a study of 2,299 participants, all of them men, measured the values of Vitamin D, Testosterone and SHBG.

In addition, they also examined whether androgen levels varied seasonally.

That is, they checked whether in the summer these values are higher and whether in winter they are lower, or not.

The results?

Men with sufficient Vitamin D values had significantly higher testosterone and androgen levels compared to those with insufficient values of this vitamin.

In addition, SHBG levels were also significantly lower in those with sufficient Vitamin D compared to the rest.

To finish, the time of year when testosterone levels were higher?


Vitamin D Supplementation

In another study of 54 healthy but overweight men, Testosterone levels were measured while doing a weight reduction program.

For one year, 31 of them received 3,332 IU of Vitamin D per day, while 23 did not.

At the beginning of the study, both groups had low Vitamin D levels (below 20 ng/mL) and testosterone levels were also low.

The group that used Vitamin D, unsurprisingly, saw their Vitamin D levels increase.

However, it was not only the levels of this vitamin that increased.

The group that used Vitamin D supplementation saw their total testosterone increase by about 25%, their bioactive testosterone by 19% and free testosterone by 20%.

On the other hand, the group that did not use supplementation had no significant changes in any of these areas.

vitamin D supplementation

Recommended doses

The recommended daily dose of Vitamin D in Portugal is only 200 IU.

This is an extremely low value(1), especially given the amount of factors that can influence the levels of this vitamin in the body.

In Germany(2) and the United States(3), the recommended daily dose was recently changed to 800 IU.

But after all we are in Portugal, a country with a much warmer climate than Germany.

We don't need as much Vitamin D as they do, do we?


In 2005, a study(4) was conducted to evaluate vitamin D levels in the South Florida population.

South Florida, in which the largest city is Miami, is located in the United States, and enjoys a tropical climate, that is, immense sunshine throughout the year.

For this, data were collected from 212 people, both men and women, at the end of the winter period.

The results?

38% of men and 40% of women have insufficient values of this vitamin.

Vitamin D Miami

Optimal doses

Recommended doses serve as a minimum value to avoid serious health problems.

That doesn't mean they're the ideal doses.

The ideal minimum value in the body is 20 ng/mL, and the recommended is around 30 ng/mL of 25(OH)D.

These values are obtained through analysis, so if you want to know your values accurately, you should measure the levels of 25(OH)D.

There are several factors that influence vitamin D levels in the body, and therefore it is impossible to suggest a perfect value for all people.

However, the main factor is undoubtedly sun exposure.

A person living in Sweden needs to ingest more amounts of this vitamin than someone living in the Canaisa.

What dose do I use then?

You should ingest at least 1000 IU of Vitamin D3 per day, and always with a meal with some fat.

However, to reach the ideal values, especially in winter, the intake must be higher.

Between 2000 and 4000 IU of Vitamin D3 per day is an interesting value for the majority of the population.

You can also calculate an approximate value using your body weight by multiplying your current weight by a value between 20 and 60 IU.

In addition to sun exposure, factors such as skin tone, the use of sunscreens(5) and latitude influence the conversion of this vitamin in the body.

Darker skin tones require increased sun exposure and the use of sunscreens reduces vitamin D production in the body.

Finally, you must not exceed 10 000 IU.

Moving from an insufficient level of this vitamin to an adequate level leads to an increase in Testosterone.

This does not mean that by using more you will get higher levels of this hormone.

You should seek to achieve and maintain optimal levels of Vitamin D, not excessive and harmful levels.

In addition, these values are for healthy people, so if you have a health problem, you should always be informed first about your specific case.

What supplement should I use?

First of all, you should opt for a Vitamin D3 supplement and not D2, as the body uses it more efficiently.

Then you should take into account the amount you want to use and the price.

Two good options are Myprotein and Prozis products.

If you want to use only 1000 IU daily, Prozis Foods Vitamin D3 is a good bet.

It costs 6,99€ the pack of 120 capsules and has a cost of 6 cents for each with 1000 IU.

You can find the product here and with the code GVIRTUAL you can also get 10% discount.

Myprotein's offer not only presents a larger amount per capsule but also a more interesting price.

It costs 9,49€ and brings 180 capsules, with 2500 IU each.

The cost per capsule is 5 cents and paid 2 cents per 1000 IU.

You can find the product here and you can also get a discount on this page.

vitamin D capsules


Vitamin D plays an important role in several processes in the body, and the hormonal system is one of them.

Basically, in winter it is easy to drop levels of this vitamin to insufficient values, and correcting this will increase your Testosterone.

Hence the importance of this supplement this season.

Not only will it help you in the gym, but also outside it, with lots of benefits in various areas.

Already in the summer, although it is equally important to have good levels of this vitamin in the body, you can easily reach them through sun exposure, which makes their supplementation in many cases unnecessary.

So is Vitamin D the best supplement of winter?


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