What is vitamin D and what does it do?
Vitamin D is essential for our health. Its main functions include helping to maintain healthy bones and supporting the normal function of the immune system.
According to the Spanish Society of Family and Community Medicine, this vitamin is directly linked to strong bones, as it increases calcium absorption in the intestine. It also plays an important role in muscle, nervous system and immune function.
Despite this, vitamin D deficiency remains a concern, as it affects a large proportion of the population.
You may already be familiar with some of these points, but you may not know that medicinal mushrooms are among the best natural sources of vitamin D. Here, we explain why.
TYPES OF VITAMIN D
First of all, it is important to distinguish between two main forms of vitamin D, both of which require processing by the liver and kidneys to become biologically active
Ergocalciferol (D2)
This form is primarily derived from non-animal sources. It is obtained through foods that contain it, such as medicinal mushrooms, and more specifically through food supplements made from them, either in powder or extract form.
Cholecalciferol (D3)
Unlike D2, this form is produced in the skin following exposure to UV radiation. It can also be obtained through the diet, mainly from foods of animal origin.
Foods rich in vitamin D
According to several publications, very few foods naturally contain the ‘sunshine vitamin’. These include oily fish such as salmon, tuna and mackerel, as well as certain vegetables and, importantly, fungi and mushrooms.
In this context, studies using vitamin D2 derived from fungi and mushrooms have shown an increase in 25(OH)D, the circulating form of vitamin D, in clinical trials involving healthy individuals who were deficient during the winter months. After two weeks, serum 25(OH)D levels were significantly higher in the group that consumed mushroom-derived vitamin D than in the placebo group..
Source: Cardwell, G.; Bornman, J.F.; James, A.P.; Black, L.J. A Review of Mushrooms as a Potential Source of Dietary Vitamin D. Nutrients 2018, 10, 1498.
Fruit, vegetables and medicinal mushrooms
Based on the study cited above and the preceding graph, there is no longer any doubt: medicinal mushrooms are a good source of vitamin D. Maitake and Pleurotus ostreatus are among the most notable examples. They all contain B-group vitamins, vitamins C and E, as well as vitamin D precursors.
Quality of vitamin D sources
Mushrooms can be an exceptional source of vitamin D when they are grown sustainably using non-invasive methods, in accordance with organic production and certification standards, and exposed to sunlight. Like us, they need UV radiation to synthesise this vitamin properly.
Lee’s research group (Lee G. et al., 2009) studied the nutritional and therapeutic differences between Shiitake mushrooms grown with and without UV exposure. The findings showed that Shiitake grown under optimal UV conditions had significantly higher levels of vitamin D and calcium than Shiitake grown indoors.
How to increase vitamin D levels quickly
It is estimated that between 80% and 90% of the body’s vitamin D stores come from exposure to sunlight. At our latitudes, exposing the face and arms to the sun for between 5 and 15 minutes, preferably around the middle of the day, may be enough to help maintain adequate vitamin D levels.
However, this is only a general estimate. In addition to latitude and time of day, factors such as air pollution and cloud cover can also affect vitamin D synthesis.
Symptoms of vitamin D deficiency
As mentioned above, the ‘sunshine vitamin’ should, strictly speaking, be considered a prohormone, as it is converted into a metabolite that acts as a steroid hormone. This hormone is essential for maintaining skeletal homeostasis by regulating calcium and phosphorus levels (DeLuca et al., 1990).
For this reason, vitamin D plays a central role in skeletal mineralisation and, consequently, in maintaining healthy bones throughout life.
BONES AND THE IMMUNE SYSTEM
Rickets and softening of the bones are among the consequences of vitamin D deficiency. Low blood levels of this vitamin have also been associated with a range of chronic conditions, including cardiovascular disease, diabetes, autoimmune disorders, cancer and other conditions affecting the nervous system, such as depression.
Numerous studies have identified antiproliferative and pro-apoptotic properties, as well as potential antimetastatic activity, in cancers such as breast and kidney cancer.
This potential antitumour activity has attracted clinical interest. However, vitamin D is not used therapeutically for this purpose because of its marked effect on calcium metabolism. Direct administration at supraphysiological doses can induce hypercalcaemia.
Further research is nevertheless needed to establish clear links between vitamin D and the development of certain conditions.
The sunshine vitamin
Vitamin D3 is synthesised several hours after exposure to sunlight. When sun exposure is prolonged, vitamin D levels are regulated by melanin production, the main factor competing with vitamin D3 synthesis.
This mechanism allows the body to regulate excessive production during extended periods of sun exposure.
Our health depends on maintaining a balanced level of sun exposure. Excessive, unprotected exposure can damage genetic material and trigger carcinogenic processes, while increased pigmentation can reduce vitamin D3 production by up to 50-fold (Clements et al., 1992).
Conversely, complete protection prevents UV radiation from reaching the dermis, entirely inhibiting the main pathway through which vitamin D, a hormone with antitumour properties, is synthesised.
Vitamin D: frequently asked questions
1. What is the relationship between vitamin D and COVID-19?
Even before the emergence of SARS-CoV-2, researchers were studying the relationship between vitamin D and the body’s response to viruses and bacteria. Since the pandemic, the number of studies in this area has increased significantly.
More recently, the potential anti-inflammatory role of vitamin D in relation to the influenza virus has been highlighted, and some recommendations have also been made for patients with COVID-19.
Beyond these recent findings concerning the immune system, vitamin D deficiency has also been associated with rickets in children and osteomalacia, or softening of the bones, in adults.
2. Why is vitamin D considered a prohormone?
Vitamin D is produced in the skin following exposure to sunlight. Its structure is then modified in the liver and kidneys to form the active hormone.
Adequate vitamin D levels, insufficiency and deficiency
- Adequate levels: blood concentrations of 25(OH)D between 30 and 70 ng/ml.
- Insufficiency: levels below 20 ng/ml.
- Deficiency: levels below 10 ng/ml.
Consequences of vitamin D insufficiency
Vitamin D insufficiency can contribute to the development of osteopenia and osteoporosis, conditions characterised by a progressive loss of bone mass.
Consequences of prolonged vitamin D deficiency
Prolonged vitamin D deficiency can cause rickets in growing children and osteomalacia in adults. The most common symptoms include bone pain, particularly in the pelvis, spine and ribs.
Foods containing significant amounts of vitamin D
- Salmon
- Mackerel
- Tinned sardines
- Tuna
- Eggs
- Fortified milk
- Fungi and mushrooms
What is the minimum recommended daily intake of vitamin D?
- For those under 18: 600 IU per day.
- For those aged 18 and over: 800 IU per day.
Possible signs of vitamin D deficiency
- Bone pain
- Bone deformities, particularly in the chest
- Low levels of calcium or phosphorus in the blood
- Osteoporosis and fractures
In summary…
- Despite the number of daylight hours in our country, a recent study reports that 75% of the population may have low vitamin D levels, rising to 80% among young people.
- Vitamin D is linked to immune system function, mental wellbeing, bone health and the incidence of certain viral infections.
- Maintaining adequate vitamin D levels helps support normal immune function, contributes to the growth and development of healthy bones, and helps preserve mental wellbeing.
- Looking for a natural supplement containing vitamin D? At Hifas da Terra, we developed Cocovit D3 + K2, a daily supplement designed to support the body’s natural defences, formulated with bioactive compounds from some of the most extensively studied medicinal mushrooms.
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Referencias
- La insuficiencia de vitamina D es una epidemia mundial, que afecta a más de la mitad de la población
- Déficit de vitamina D
- https://ods.od.nih.gov/pdf/factsheets/VitaminD-DatosEnEspanol.pdf
- https://medlineplus.gov/spanish/vitaminddeficiency.html
- https://portal.guiasalud.es/wp-content/uploads/2021/07/pa_10_avalia-t_vitamina-d-1.pdf
- https://www.semfyc.es/grupos/nutricion-y-vitamina-d/
- Cardwell, G.; Bornman, J.F.; James, A.P.; Black, L.J. A Review of Mushrooms as a Potential Source of Dietary Vitamin D. Nutrients 2018, 10, 1498. https://doi.org/10.3390/nu10101498
- European Journal of Clinical Nutrition (2011) 65, 965-971; doi:10.1038/ejcn.2011.53.