A D-angerous D-eficit
vitamin D and its mysteriesA few days ago I discussed about vitamin D with my sister-in-law who is an anesthesiologist and deals with pain therapy: she is convinced that it is important to fill this deficiency in the treatment of chronic pain refractory to medical therapy. In fact, calcitriol, or vitamin D, is an extraordinary molecule.
What is vitamin D?The term vitamin, takes up the root of vital, or something that is necessary for the human body because it cannot produce it independently. Erroneously vitamin D was included in this group. Calcitriol or 1,25 (OH) 2D3-1, 25dihydroxyvitamin D 3, is formed from cholesterol, so we all have the possibility of forming them in sufficient quantities. The problem is its activation as we will see later. Human DNA contains about 2700 binding sites for calcitriol, so we could say that it has a vital function throughout the body. Most know its role in maintaining bone health (its deficiency causes rickets in children and osteoporosis in adults). But its deficiency also has a decisive role in the pathogenesis of extra-skeletal diseases such as asthma, heart failure, autoimmune diseases (Chron’s disease, ulcerative colitis, multiple sclerosis). It acts with an anti-proliferative, anti-inflammatory immunosuppressant effect.1 So my sister-in-law has every reason to give vitamin D as a complement in pain therapy.
Where is vitamin D found?The sources of vitamin D can be endogenous, therefore produced by our body starting from the activation of UVB rays, or made through the diet. There are 2 types of D vitamins in foods:
Vitamins D3: animal cholecalciferol Vitamin D2 ergocalciferol of vegetable origin
Foods that contain vitamin D are not very numerous (egg yolk, fatty fish, fish liver oil and liver), so in some USA and Canada countries above all, there are fortified foods such as milk and yougurt. Among the vegetable sources, we will find some mushrooms that can contain vitamin D but only if they have been exposed to the sun and in small quantities. Exposure to UV rays (we will call UVR-from UV radiation), is a fundamental moment to convert the precursor of vitamin D -7dehydrocholesterol that is accumulated in the sebaceous glands in pro-vitamin D-calcitriol. (Photo activation) Hence the age-old question that arises every time we insist on the importance of sun exposure. The sun is important for our life and our health, we will not exist without it (as indeed there would be no life form). The point is to understand that for the aforementioned activation 10 minutes of exposure per day are sufficient for the lightest skin types (those with light hair and eyes) up to an hour for black skin. The rays are those perpendicular to the surface of the earth, or to the latitude in which I write, those of midday. For this reason, I suggest my patients drink coffee after lunch on the terrace. The exposed surface must be abundant (arms, legs), the face alone is not enough and in any case I strongly advise against sunbathing without a sunscreen. The use of solar filters is much discussed in relation to the possible limitation of the activation of vitamin D. Sunscreens absorb:
SPF 15 93% of UVA and UVB SPF 50+ 99% of UVA and UVB
So several studies show that since the protection is never complete and because most of the population is not adequately protected – spreading 2 mg of cream per cm3 (about 30 g for the whole body), and at least every 2 hours – we can activate the necessary amount of vitamin D also using a good SPF15 filter.2 Avoid burns at all costs. Melanoma is an aggressive skin cancer that can grow subtly and be lethal. The World Health Organization (WHO) estimates that every year 60,000 deaths are caused by malignant skin tumors such as melanoma and 90% of them are related to UVR.3 Since I am not a dermatologist, I strongly recommend the articles of these brilliant doctors who created the myskin.it platform, the attached article talks about sunburn and false myths about tanning. Please, read it. https://www.myskin.it/editoriale/7-falsi-miti-abbronzatura-esposizione-solare So, returning to our vitamin D, a fair-skinned person, produces 20,000 IU of vitamin D by walking on the beach for 20 minutes. To compare a large portion of salmon or sardines, it could contain about 1000 IU.
Limiting factors of vitamin D intake1. Latitude
The further one moves away from the equator, the weaker the effective radiation will be, decreasing the zenith angle, that is, the angle at which solar radiation strikes the earth. To give an example, by living in Miami you will have enough sun to produce vitamin D all year long, at the latitudes of Stockholm there will be sufficient rays only during 5 months a year. The geographical distribution of some types of cancer would demonstrate a greater incidence at the northern latitudes and a decrease approaching the equator.42. Season
As for latitude, solar radiation will be much less effective during the winter months when the sun is lower in the sky (or further away from the earth). To evaluate the effectiveness of the radiation you are taking, I advise you to follow the rule of Kerley’s shadow: if the shadow is shorter than your body, you are probably activating vitamin D, if the shadow is much longer than yours body means that the sun’s rays are low and therefore will not have sufficient power.3. Age
With age the amount of is dehydrocholesterol decreases and therefore decreases the substrate from which to form vitamin D. 4. Shadow
Living in sunny cities but always remaining in the shadow of skyscrapers or buildings, always staying inside without going out (school, work, prison, etc.) prevents the cutaneous activation of vitamin D.5. Skin Colore
The color of the skin is proportional to the melanin content, the darker the more it has. Melanin works by increasing the absorption of UVB radiation and acts as a competitor for 7-dehidrocolesterol. So darker skins need longer exposure to produce adequate amounts of vitamin D. But be careful, this does not mean being safe from sunburn and skin cancer.6. Religion and worship
As for those who live inside, even veiled women are at high risk of vitamin D deficiency, so I suggest finding a house with at least one terrace and sun exposure at least in a domestic environment. Some women then have the absolute cult of white skin like the Japanese (probably dating back to the geisha figure and to personal care); they also avoid the sun as the devil but the deficiency risk remains high (but they still have a fantastic skin!).7. Obesity
Overweight people more frequently have a vitamin D deficiency. The mechanism by which this occurs could be at different levels. It appears that since vitamin D is a fat-soluble molecule its metabolites are sequestered at the level of the abundant adipose tissue of overweight people. Since the first stage of activation of vitamin D occurs in the liver thanks to cytochrome P450, where there is a fatty liver, this reaction will occur with some difficulties. Furthermore, people who are overweight due to motor handicap or exposure to shame tend to avoid life in the open air.8. Drugs
Some types of drugs decrease the action of vitamin D, including: cortisone, anticonvulsants, HIV therapy, antifungal agents such as ketonazole.
SHOULD I TAKE VITAMIN D AS A SUPPLEMENT?Vitamin D deficiency is quite widespread in the world, it is estimated that around 1 billion people are in deficit.6 A meta-analysis study published in 2007 shows that vitamin D supplementation decreases mortality.7 To verify a deficiency it is necessary to perform a blood test: 25 (OH) D or 25-hydroxyvitamin D. Adequate values are above 30 mg / L. This would require a daily administration of 1000 IU / day or 25 mcg can be a good starting point.8,9 But it all depends on the latitude in which we live, on the color of our skin, on genetics and on our lifestyle. In the first instance, I would recommend a dosage through a blood test, if necessary I would suggest daily supplementation. But also and above all a change in lifestyle, doing activities outside, exposing oneself to the sun with due precautions, eating in a balanced way.
|Age||Adequate intake µg||Maximal limit tolerable|
|From 0-1 years||5||25|
|From 1-50 years||5||50|
|Over 50 years||10||50|
|Over 75 years||15||50|
 Feldman D, Vitamin D: biology,actions, and clinical implications Osteoporosis, chapter 13, 2013 Elsevier
 Farrerons et al. Clinically prescribed sunscreen (sun protection factor 15) does not decrease serum vitamin D concentration sufficiently either to induce changes in parathyroid function or in metabolic markers. Br J Dermatol 1998; 139(3):422-427
 Lucas R et al, Solar ultraviolet radiation :global burden of disease from solar ultarviolet radiation. Geneva: World Health Organization 2006.
 Grant WB. An estimate of premature cancer morbidity in the U.S. due to inadequate doses of solar ultraviolet-B radiation. Cancer 2002; 94:1867-75 4 Holick MF,Photobiology of vitamineD .Accademic Press 2011
 Holick MF, Vitamin D deficiency. N Engl j Med ; 2007 Jul 19;35è(3):266-81.Review
 Autier P, Gandini S. Vitamin D supplementation and total mortality: A meta-analysis of randomized controlled trials. Arch Intern Med. 2007;167:1730–7. [PubMed: 17846391]
 Vieth R. Vitamine D supplementation, 25-hydroxyvitamin D concentrations, and safety; Am J Clin Nutr. 1999 May;69(5):842-5§. review
 Harvard School of Public Health Nutrition Source. Vitamin D and health. [Last accessed on 2010 Aug]
. Available from: vitamind