Vitamin D is widely recognized for its fundamental importance in the mineralization of bones and teeth. However, not everyone is aware of its crucial role in the optimal health of the hair follicle, which directly affects the health of our precious hair.
What is Vitamin D?
Vitamin D belongs to the group of fat-soluble vitamins , which means that it requires the presence of fats to be dissolved and assimilated. There are five forms of vitamin D, but the most bioavailable to the human body are D2 and D3 .
Vitamin D2 , known as ergocalciferol , is of plant origin and can only be obtained through food.
Vitamin D3 , or cholecalciferol , is the form naturally present in mammals and is up to 100 times more active than ergocalciferol.
This vitamin is produced directly by the skin, which, thanks to exposure to sunlight, transforms the precursor 7-dehydrocholesterol (derived from cholesterol) into cholecalciferol.
It is important to note that vitamin D is not stored in the liver and the amount obtainable from food is quite limited. Production occurs mainly in the skin through exposure to the sun.
Cholecalciferol has a structure very similar to that of a steroid hormone; for this reason, many scientists tend to consider it more of a hormone than a classic vitamin.
Vitamin D and Hair
If you have landed on this page, it is likely that you are particularly interested in what vitamin D can offer in the trichological field. Therefore, let’s start right away with the highlights:
- Since it is produced through the skin, its receptor, known as VDR , is also present in hair follicles. This receptor is expressed during the late stages of anagen and during catagen . Vitamin D3 would therefore play a crucial role in initiating anagen, the active phase of the hair’s life cycle.
- Although the levels of this vitamin are not considered among the causes of androgenetic alopecia , its presence is extremely important for the health of the hair follicle. A vitamin D deficiency can certainly lead to strong hair loss due to an alteration of the hair cycle.
- Interestingly, rickets , the main symptom associated with low levels of this vitamin, is often accompanied by alopecia. Although it is not androgenetic alopecia, it is clear that vitamin D has a correlation with hair health, as demonstrated by a study conducted at the University of Cleveland .
- Another study, conducted at the University of Seoul (Korea), is rather complex for the layman. However, in simple terms, it shows that the VDR receptor has a decreased expression in follicles affected by alopecia areata and alopecia universalis , highlighting once again how vitamin D is involved in the hair growth process.
- Finally, vitamin D is one of the main parameters monitored by dermatologists during a trichological visit in case of hair loss.
Other Functions of Vitamin D
While our focus is primarily on hair, it is important to recognize that vitamin D performs a number of essential functions in our bodies. Here is an overview of the main functions:
- It regulates the absorption of calcium in the intestine, ensuring that our body can make the best use of this vital mineral.
- Mineralization : Vitamin D enables the mineralization of bones through the deposition of calcium and phosphorus in bone tissue and teeth. This is certainly the function for which vitamin D is best known.
- Regulation of the immune response : The VDR receptor has been confirmed to be present on virtually all cell types of our immune system, including T lymphocytes , B lymphocytes , and macrophages . The presence of this receptor indicates that vitamin D is essential for the proper functioning of these cells.
Obviously, we cannot go into this topic in detail, as it would require several pages.
Vitamin D and Testosterone
Several studies, such as those available on PubMed , highlight a correlation between low vitamin D levels and low testosterone levels .
An interesting study conducted by the University of Graz in Austria administered a dosage of 3332 IU per day of cholecalciferol to 54 men, with remarkable results: a significant increase in testosterone was observed, in addition to the restoration of vitamin D levels.
It is understandable that many readers of this article may be concerned about the idea of an increase in testosterone, since this hormone is involved, albeit indirectly, in the onset of androgenetic alopecia . However, it is important to emphasize that a correct level of testosterone is essential for men to feel good sexually and muscularly.
Furthermore, it is important to remember that the increase in testosterone induced by any vitamin D supplementation always remains within physiological limits. To be clear, it is not a question of injecting anabolic steroids!
Foods that contain it
Vitamin D from food is of secondary importance, since, as we have seen, most of its production occurs through exposure to the sun . However, foods in which it is present essentially include the following:
- Liver
- Fish oils
- Fatty fish such as salmon and sardines
- Eggs (specifically the yolk )
- Milk
- Full fat cheeses
- Butter
- Some varieties of mushrooms (the latter, however, contain ergocalciferol , since they are of vegetal origin)
Reference Values
Vitamin D levels can be monitored with simple and inexpensive 25(OH)D blood tests . A deficiency is defined as a level lower than 20 ng/ml , an insufficiency if the blood levels are between 20 and 30 ng/ml , and a sufficiency above 30 ng/ml of blood.
However, an optimal dosage is considered to be between 40 and 60 ng/ml , while above 150 ng/ml toxic levels are reached, with the possibility of overdose symptoms , which you will see later.
The minimum amount the human body needs to stay healthy is 200 IU per day of vitamin D; in general, 3-4000 IU per day can be taken through supplements .
It may seem like a lot, but remember that exposing yourself to the sun in the summer in a swimsuit can produce up to 20,000 IU in just half an hour. Furthermore, recent studies show that it is possible to safely take up to 10,000 IU per day.
Shortage
Too low levels of vitamin D lead to a real hypovitaminosis , the consequences of which can be quite serious, as we can see below:
- In children , deficiency can lead to rickets , a disease that affects the skeleton and can cause deformities or weakness of the bones.
- In adults , it manifests itself in the form of osteomalacia , characterized by muscle and bone pain.
- Abdominal pain may occur .
- In older adults , deficiency may contribute to problems with osteoporosis and reduced bone density.
- Alterations in the hair’s life cycle may occur , with possible effluvia , as we have seen in the previous paragraphs.
Overdose
Given the low presence of vitamin D in foods, it is highly unlikely to have problems from excess vitamin D from this source, just as there are no known cases of overdose due to excessive exposure to the sun. It is instead possible to create imbalances through excessive intake of specific supplements .
Symptoms can range from simple nausea and abdominal pain to more serious cases of hypercalcemia , nephrocalcinosis (common kidney stones), and soft tissue calcification . To combat these problems related to excess calcium, it may be useful to combine it with vitamin K2 .
How much should you stay in the sun?
It is now well known that proper sun exposure is essential for the production of vitamin D. However, many have wondered: “How much time should I spend in the sun?”
To give a general idea, it can be said that a minimum exposure time to sunlight during the summer of about 20 minutes per day , with at least 5% of skin exposed , allows to produce a sufficient serum concentration of vitamin D.
Additionally, just 15 to 30 minutes of bathing suit exposure can generate between 10,000 and 20,000 IU of vitamin D.
It is important to note that any excess cholecalciferol produced will not be wasted, but will be stored in adipose tissue to be used when needed.
Absorption limitations
Sometimes, even with optimal sun exposure and adequate dietary intake, deficiencies can occur due to limited absorption. Causes may include:
- Climatic : living at latitudes far from the equator, where solar radiation is reduced, involves risks of poor exposure .
- Cloudy areas : Adverse weather conditions can limit vitamin D production.
- Advanced age : In older people, absorption is significantly reduced, often due to poor sun exposure.
- Using high protection creams or sunscreens : these can reduce the skin’s ability to synthesize vitamin D.
- Dark skin color : The increased amount of melanin can reduce the synthesis of vitamin D.
- Obesity : High levels of body fat can bind fat-soluble cholecalciferol, preventing it from being used.
Supplementing Vitamin D
If a blood test reveals a deficiency , your doctor may prescribe a vitamin D supplement to restore the correct levels in your blood.
It can be taken orally or, in cases of malabsorption , through intramuscular injections .
This article is not intended to be an advertisement for vitamin D supplements, but rather a guide to the characteristics of this important element, with a specific focus on hair . Therefore, I will limit myself to a quick summary.
Basic
Its composition consists of cholecalciferol (in quantities that vary depending on the dosage) combined with refined olive oil , which guarantees maximum absorption of this fat-soluble vitamin.
Because vitamin D is stored by the human body, it is not necessary to take it daily . Typically, weekly , monthly , or even quarterly doses are prescribed if using the 300,000 IU injectable format .
Over-the-counter supplements
While it is important to have a doctor check for any vitamin D deficiencies , if for any reason you do not want to take Dibase , you are on vacation and have no way of getting a prescription, you find it inconvenient to take it by drops or injection, or whatever the reason, you can find several capsule products both in pharmacies and online that may be right for you.
Since the unit of measurement is usually International Units (IU) , but many vitamin D supplements list dosages in micrograms (mcg) , it may be helpful to know that 1 mcg = 40 IU.
At the end of this long article, we have seen the very important functions that vitamin D performs in our body. Involving such a broad spectrum, it actually behaves more like a hormone (and, if you remember, we explained that it also has the chemical structure).
It regulates functions ranging from the musculoskeletal system to the immune and endocrine systems . Furthermore, as we have seen, it also plays a fundamental role in the health of our beloved hair.
So, in my opinion, it is a wise idea to check your levels of this vitamin through blood tests and have your dermatologist evaluate whether it is the case to start supplementing it.
Personally, I regularly supplement it in the autumn-winter period , then suspend it in spring and summer , and in the last 3 years the values have always been normal.