As I promised in my last post, I’m back at the drawing board to talk about vitamin D. For those who didn’t read it, my interest in the vitamin D ignited from hearing that it could be a very reliable ally against swine-flu. It turns out the vitamin D protects against a multitude of disease, flu being just one of them many: cancers, multiple sclerosis, diabetes, autism and
“frequent bone fractures, muscle pain and weakness, heart disease, congestive heart failure, hypertension, diabetes, some types of cancer, fibromyalgia, preeclampsia in pregnancy, autoimmune disorders such as rheumatoid arthritis and multiple sclerosis, depression, brain development, migraines, flu, pneumonia, tuberculosis, and periodontal disease” (Collins et al, 2009)
What I’m trying to get at in this post is what predisposes us to vitamin D deficiency (D-ficiency) and what kind of supplements to take. Few reasons why I’m convinced you’d want to know:
- our modern indoor/sunscreened life style increased tremendously the number of D-ficient people during the past years;
- the attention this vitamin is getting continues to be dim, so, unless you show some severe d-ficiency symptoms, this won’t be the first (second or third) thing your doctor will check;
- the recommended daily intake (RDI) is 400 IU/day; that is way too low and it’s behind the current research whilst research itself can’t seem to reach a consensus in terms of a dosage to suit all needs
Before I start diving in more, I want to express my infinite gratitude to all those who are trying to create the swine-flu hysteria and then to sell us a vaccine that is produced hastily from stuff that’s not going to be tested before it’s used! Without them I wouldn’t have read so much about vitamin D, I wouldn’t have take it as seriously as it should be taken. Alright, I’m wiping off my crocodile tears now and continue.
Vitamin D is a generic name that refers to vitamin D2 or vitamin D3. The published literature uses micrograms and IU (international units) to express the concentration. This is the rule: 25 micrograms = 1000 IU. The most accessible and efficient source of D3 is the sun – more exactly D3 is metabolized in the skin when exposed to the sun. Some foods like oily fish (salmon, cod) or sun-dried mushroom are rich in vitamin D (1). I mentioned briefly in The (vitamin) D-day which other foods could be prioritized for a good vitamin D intake. Holick 2008 explains that 100 gr (3.5 ounce) of salmon serving gives you 500-1000 IU (depending on where the salmon lived before it landed on your plate). The winner salmon in the vitamin D category is the wild-caught one or the one farmed in Norway, whereas the one farmed in the US contains as little as 10-25% D3 compared to the champ. Some countries like the US, Sweden and Finland fortify their diary products (milk, yogurt, cheese) with D3.
A bit of history on the fortification of milk with vitamin D: the industrialization of the Northern Europe and Northeastern US brought with it dramatic pollution, which resulted in preventing parents to have their children out in the sun, which resulted in the MAJORITY of children in these areas suffering from rickets (softening of bones potentially causing deformity and fractures), which resulted in the understanding that vitamin D deficiency plays a dramatic role in growth retardation, muscle weakness, skeletal deformities (2), which resulted in trying to supply vitamin D through a common and affordable food (i.e. milk fortification). Unfortunately, this took the wrong turn in the mid 1950’s when the over-fortification of milk in Great Britain resulted in more than 200 cases of infantile hypercalcemia (this disorder causes a whole spectrum of serious conditions that spans from impaired growth to impaired renal function, mental retardation and severe heart conditions). You can find here more details. Now, I’m not any sort of specialist to tell you how much that milk has to be over-fortified to have such dramatic consequences but there’s a paragraph in “Safe Foods for Infants – the regulation of milk, infant formula and other infant foods” by LJ Filer, 1993 (J Nutr) that makes me think it’s not easy to achieve that:
“[…] it must be noted that in 1991 a small interstate dairy in Massachusetts over-fortified its fluid milk with vitamin D resulting in at least seven cases of vitamin D toxicity and one death. Some samples of milk contained 600 times the labeled amount. If uniform distribution of the vitamin D concentrate entering the product had occurred, all products would have contained 65 times [the] label. Investigation of the situation prompted the FDA to survey fluid milk samples from 47 states […] The vitamin D content of 3884 samples indicated that 27% contained >120% of (the amount on the) label”
The point of this detour is that the over-fortification disaster in 1950 caused the milk fortification to be forbidden throughout Europe. Although this story about US still erring dangerously in handling the milk 40 years later, it may be that countries like Sweden and Finland, where btw the sun it’s not usually smiling down on us through the late autumn and winter, can handle better food control and felt more at ease to reintroduce fortification.
Anyway, coming back to the sun, I’ve never heard or read of anybody getting vitamin D intoxication from sun exposure! And, no, I’m not oblivious of the amount of research that is looking at sun exposure and melanoma! What I believe is that some moderate amount of time (some say 20 minutes) spent in the sun – without using a sunscreen – will do a world of good. You can always take a good walk or sit outside with a cup of whatever-something-good before the sun gets too strong. I can’t mention sunscreen without saying that some recent studies have shown that the ingredients in sunscreens have estrogenic effects on cultured breast cancer cells (3) (i.e. in lab experiments the breast cancer cells enjoyed the sunscreen)! And! ..
“The proper application of a sunscreen with a sun protection factor of 15 should absorb 99% of incident UVB photons, resulting in a 99% decrease in production of previtamin D3.” (Holick, 2008)
Fear of the fatal form of skin cancer, malignant melanoma, keeps many people out of the sun. The problem with the theory is that the incidence of melanoma continues to increase dramatically although many people have been completely avoiding the sun for years. We are not saying sunburns are safe, they are not. We are saying that brief, full-body sun exposure may slightly increase your risk of skin cancer but it is a much smarter thing to do than dying of vitamin D deficiency. (from the Vitamin D Council webpage)
Good question but tough to answer! Because there might be no symptoms for years or they are too subtle to spot before you’ve been d-ficient for a long time. They may include softening of bones disorders (rickets in children, osteoporosis in adults), low blood calcium, fatigue, depression, etc. Severe deficiency over a very long period of time may manifest as broken bones or reduced hight. So, how to figure that out before it’s too late?! Well, you may try getting a blood test – for some of us this involves convincing the doctor it is important to do so (not easy, at least in my corner of the world) – and/or think whether your circumstances make you more likely to be D-ficient (4, 7):
– you live at a high or low latitude (say 40 degrees N/S of the equator)
– you’re skin is protected from sun exposure via use of sunscreens, cultural dress, etc and/or you spend very little time outdoors
– you are older than 60 years (at the age of 60 the capacity of the skin to produce vitamin D from sun exposure has dropped to 75% compared to the skin of a teenager)
– you are predisposed to obesity or suffer from malabsorption disorders (Crohn’s disease, celiac disease, and cystic fibrosis)
– you are a nursing mother; that goes also for the infant if the nutrition is exclusively through breastfeeding without vitamin D supplements
What supplements to take?
This question alone gave me headaches for the past 2 weeks! There’s no consensus about the dosage and hence no guidelines either. I guess that for now we have to have the initiative to answer this question each for ourselves. With the total awareness of our current situation: do I live in a place where the sun is a precious site through the winter? (YES!), do I spend most of my time indoors and do I usually put on sunscreen when I’m outside? (YES and NO!), etc… With that in mind you can decide WHEN to supplement (ex, autumn-winter months) and HOW MUCH. Below are some hints that helped me to make up my mind:
1: total body exposure (as in naked) out in the sun (at a 30-40 deg latitude, summer time) for about half an hour results in 10.000 IU (250 microgr) – and this seems to be a natural physiological limit, meaning that by longer exposures the skin won’t produce more vitamin D.
2: studies have tested various concentrations of oral supplements and come up with recommendations anywhere btw 1.000 IU/day and 10.000 IU/day (4, 5). Several studies (clinical trials) showed no adverse effects of a prolonged intake of 10.000 IU/d for adults (9), while the documented cases of toxicity all involve intake of more then 40.000 IU/d (5).
– a clinical trial reported that doses of 800 IU/d reduced reported incidence of colds and flu (Cannell 2008)
– doses of 2000 IU/d, given during one year, eradicated all reports of colds or flu (Cannell 2008)
– Heaney et al 2003 estimated that an intake of 3,000 IU/d of vitamin D is needed to bring 95% of the population out of the D-ficiency range
– there are well explained online recommendations of 4000-5000 IU/d; you can read more at
– 5000 IU/d given to sun deprived older adults over a 1 year period improved bone density (8)
– a comprehensive review from 2006, Epidemic Influenza and vitamin D (10), coming from Dr Cannell who leads The Vitamin D Council group states that:
a) 400 IU/d are INSUFFICIENT to prevent wintertime d-ficiency
b) 600-700 IU/d given as cod liver oil and multivitamin reduced the average number of respiratory infections during Oct-May in a group of 47 children (2 years old on avg) living in NY; “an equivalent dose in a 70kg adult would be about 3500 IU/d”
Note: Norway has the highest vitamin D levels in Europe – which is associated with consuming fish and cod liver oil throughout the year
c) in a Canadian study, 4000 IU/d were administered to endocrinology outpatients for 6 months; this resulted in improved levels of vitamin D and “no side effects other than an improved mood”
Dosage will depend upon age, latitude, season, skin type, body weight, sun exposure and pre-existing 25(OH)D [vitamin D] levels. Some groups – African-Americans, the obese, and the elderly – may require supplementation with 5000 IU/day during winter but less, or none, during the summer to obtain 25(OH)D levels of 50 ng/ml. These studies indicate that ideal daily doses of vitamin D exceed current recommendations by an order of magnitude.
3: make up your mind! Start by accepting that the current vitamin D recommendations are inappropriate and misleading (about 10 times lower than they should be), continue by knowing that vitamin D can help prevent flu, influenza and cancer and decide that you want to be healthy. It’s up to you! And one more thing: it is really up to you!
1. Holick MF. Vitamin D: a D-Lightful perspective. Nutr Rev 2008; 66:S182-94
2. Holick MF. Resurrection of vitamin D deficiency and rickets. J Clin Invest 2006; 116(8):2062-72
3. Klann A, et al. Estrogen-like effects of ultraviolet screen 3-(4-methylbenzylidene)-camphor (Eusolex 6300) on cell proliferation and gene induction in mammalian and amphibian cells. Environ Res 2005;97(3):274-81
4. Collins N, et al. Vitamin D Deficiency: shinning new light on the sun nutrient. Ostomy Wound Manage 2009; 55(4):14,16-7
5. Vieth R. Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety. Am J Clin Nutr 1999; 69(5):842-56
6. Heaney RP, et al. Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol. Am J Clin Nutr. 2003;77(1):204–210.
7. Weggemans RM, et al. Towards an adequate intake of vitamin D. An advisory report of the Health Council of the Netherlands. Eur J Clin Nutr 2009
8. Mocanu V, et al. Long term effects of giving nursing home residents bread fortified with 125 microg (5000 IU) vitamin D(3) per daily serving. Am J Clin Nutr 89(4):1132-7
9. Vieth R. Vitamin D and cancer mini-symposium: the risk of additional vitamin D. Ann Epidemiol 2009; 19(7): 441-5
10. Cannell JJ et al. Epidemic influenza and vitamin D. Epidemiol Infect 2006; 134(6): 1129-40
Other reading resources regarding deficiency symptoms: