vitamin D

Vitamin D, the best winter supplement?

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 the summer. In the winter? Not really. While in summer we have a climate conducive to achieving good levels of this vitamin, in winter the sun appears less, and with less intensity. The days also get shorter and the probability of failure increases significantly. This is where Vitamin D supplementation comes in.

What is Vitamin D?

Vitamin D is one of the 24 essential micronutrients for humans, and can be ingested or synthesized by the skin. While in hot seasons it is easy to achieve good levels of Vitamin D, in winter the story changes. The body produces this vitamin through cholesterol, but it 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 obtain good amounts of this vitamin through diet. Milk fortified with this Vitamin normally provides around 30 IU per 100 ml. The egg yolk? Less than 50 IU. Salmon, depending on its cultivation, can reach 300/400 IU, and sardines approximately 200 IU. Basically, relying solely on food to obtain good levels of this vitamin is not a good strategy and you will 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 low mood and depression. As if that weren't 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, levels of this vitamin drop, 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 rise.

Vitamin D and Testosterone

In a study with 2299 participants, all of them men, the values of Vitamin D, Testosterone and SHBG. In addition, they also examined whether androgen levels showed seasonal variation. In other words, they checked whether these values are higher in summer and whether they are lower in winter, or not. The results? Men with sufficient levels of Vitamin D had significantly higher Testosterone and androgen levels compared to those with insufficient levels of this vitamin. Furthermore, SHBG levels were also significantly lower in those who had sufficient Vitamin D compared to the rest. Finally, what time of year were Testosterone levels highest? August.

Vitamin D supplementation

In another study of 54 healthy but overweight men, their testosterone levels were measured while they were on a weight loss program. For a 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 supplementation, unsurprisingly, saw their Vitamin D levels increase. However, it was not just the levels of this vitamin that increased. The group that used Vitamin D supplementation saw their total testosterone increase by approximately 25%, their bioactive testosterone by 19% and free testosterone by 20%. The group that did not use supplementation did not have significant changes in any of these areas. vitamin d testosterone

Recommended doses

The recommended daily dose in Portugal is just 200 IU. This is an extremely low value(1), especially considering the number 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, right?


In 2005, a study(4) was carried out to evaluate Vitamin D levels in the population of South Florida. South Florida, where the largest city is Miami, is located in the United States, and enjoys a tropical climate, that is, lots of sunshine throughout the year. For this purpose, data was collected from 212 people, both men and women, at the end of the winter period. The results? 38% for men and 40% for women have insufficient levels of this vitamin. Vitamin D supplement

Optimal doses

The recommended doses serve as a minimum value to avoid serious health problems. This does not mean that they are ideal doses. The ideal minimum value in the body is 20 ng/mL, with the recommended value being around 30 ng/mL of 25(OH)D. These values are obtained through analysis, and therefore, if you want to know your values accurately, you must measure your 25(OH)D levels. There are several factors that influence Vitamin D levels in the body, and therefore it is impossible to suggest a perfect value for everyone. However, the main factor is undoubtedly sun exposure. A person living in Sweden needs to ingest greater amounts of this vitamin than someone living in the Canaries.

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 ideal values, especially in winter, your 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, 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 sunscreen(5) and latitude influence the conversion of this vitamin in the body. Darker skin tones need greater sun exposure and the use of sunscreens reduces the production of Vitamin D in the body. Finally, you should not exceed 10,000 IU.


Going 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 achieve higher levels of this hormone. You should aim to achieve and maintain ideal levels of Vitamin D, not excessive and harmful levels. Furthermore, these values are for healthy people, so if you have a health problem, you should always inform yourself first regarding your specific case. Ideally, you should always do tests to find out your levels of this vitamin. Ideal and simple too. Just ask any doctor when you go for analysis to add this assessment, or simply do it yourself at any analysis clinic asking for an assessment of Vitamin D levels. This allows you to personalize your Vitamin D supplementation, instead of going by guesswork. .

Vitamin D Supplements

First of all, you should opt for a Vitamin D3 supplement and not D2, as the body uses it more efficiently. Then, you must take into account the quantity you want to use and the price. Here are two products with a good price/quality ratio. You also have the Myprotein offer, with 2500 IU per capsule, but for 10.99? brings with it 180 capsules. Finally, do you have Vitamin D3 from Zumub, which with 2000 IU per capsule and a value of 4.99? for 120 capsules, it is also an excellent bet. You can also use the code GVIRTUAL and get a discount of 10% on your entire order. Is available here. Whatever your choice, you will certainly be well served. vitamin d in capsules


Vitamin D plays an important role in several processes in the body, the hormonal system being one of them. Basically, in winter it is easy to drop the levels of this vitamin to insufficient levels, and correcting this will increase your Testosterone. Hence the importance of this supplement this season. It will not only help you in the gym, but also outside of it, as the benefits of vitamin D are immense. In summer, although it is equally important to have good levels of this vitamin in your body, you can easily reach them through sun exposure, which makes supplementation unnecessary in many cases. So, is Vitamin D the best winter supplement? Possibly.


What is vitamin D?

Vitamin D is an essential nutrient for maintaining bone and immune system health. Furthermore, it plays an important role in the absorption of calcium by the body.

What are the benefits of vitamin D?

Vitamin D can help strengthen bones, prevent diseases such as osteoporosis, reduce the risk of certain types of cancer, and improve immune system function.

How to get vitamin D naturally?

Sun exposure is the main source of vitamin D. Spending about 15 to 30 minutes a day in the sun, with arms and legs exposed, can help the body produce vitamin D. Additionally, foods such as fatty fish, eggs and dairy products also are good sources.

What are the symptoms of vitamin D deficiency?

Common symptoms of vitamin D deficiency include muscle weakness, fatigue, bone pain, depression, and impaired immune system. It can also affect hormone levels, such as testosterone.

What are the risks of vitamin D overdose?

Vitamin D overdose can lead to excessive calcium accumulation in the body, causing problems such as nausea, vomiting, muscle weakness and kidney damage.

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