Immune Health
Vitamin D is Toxic and Unnecessary!
Vitamin D is an important hormone that supports our immune system – and it's safer than often claimed. Discover why daily supplementation in winter makes sense.
Immune Health
Vitamin D is an important hormone that supports our immune system – and it's safer than often claimed. Discover why daily supplementation in winter makes sense.
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The topic of Vitamin D has been extensively and very controversially discussed in recent years. It's promoted as an absolute miracle cure just as often as it's warned against.
If by now you no longer know what or whom to believe, then read on. But above all: stick with it, even if you can't hear the words "Vitamin D" anymore. ;-)
Vitamin D is undisputably an important substance in our bodies. More precisely, it's actually a hormone, because unlike vitamins, we can produce hormones ourselves. With Vitamin D, this happens through the uptake of UV-B radiation by the skin. In our latitudes, however, this can only occur from March to October. For about two months now, your body hasn't been able to synthesize Vitamin D.
If someone now brings up, "Wait, but we store Vitamin D in fatty tissue," they'll be disappointed. All of that has been calculated via studies. Even fully stocked Vitamin D stores—that is, after plenty of sunbathing in the summer—keep us adequately supplied for at most one to two months. But only if we actively mobilize fats from fatty tissue cough, cough.
There's therefore a good reason why studies consistently show that only a minority of adults achieve adequate Vitamin D supply year-round. In Switzerland, the picture is no different.¹ Those who read the studies carefully, for example Rabenberg et al. 2015, will find that people at comparable geographic latitudes fail to reach the conservatively set thresholds of serum 25(OH) levels of 50 nmol/l (= 20 ng/ml) year-round – and up to 80-90% of the population isn't adequately supplied in winter.² That's striking!
So highest time to supplement with Vitamin D. Or? Far from it.
Everyone knows the headlines that warn of the "serious consequences" of Vitamin D supplementation. Yes, Vitamin D can be harmful in excessively high doses(!) Just like anything else. Remember: The dose makes the poison. Overdosed Vitamin D can lead to disruptions in calcium metabolism and bring unpleasant symptoms.
And yes: We also advocate gradually adjusting to the appropriate Vitamin D dose. You don't have to start with high doses right away. Meeting the need in the range of 1000-5000 IU – and this can be very individual within this dose range – is usually enough to benefit from Vitamin D.
How safe Vitamin D really is was demonstrated in the esteemed journal JAMA Network Open just last year.³ A meta-analysis of randomized controlled trials in children aged 0-6 years concluded:
"Vitamin D supplementation in dose ranges of 1200 to 10,000 IU/day and single doses up to 600,000 IU can be well tolerated in infants and young children."
Compared to the control group, there was simply no serious side effect – such as the famous hypercalcemia – under high-dose Vitamin D in children. For comparison: The conventional recommended intake at this age is about 500 IU per day.
Studies in adults also showed that Vitamin D supplementation over a period of more than 3 years led to neither kidney stones nor pathologically elevated calcium levels. ⁴
Okay, okay, Vitamin D is actually very safe. But what about infections? You repeatedly read in the press that Vitamin D is unnecessary and doesn't protect against infections.
On this topic as well, let me recapitulate: Vitamin D regulates well over 1000 genes, that is, at least 5% of the entire human genome. Vitamin D thereby regulates a multitude of genes that affect immune function. Well documented for decades.
Seems to be a matter of belief again: Believe the gloomy journalist without biology knowledge, or the world's best(!) journal in the field of endocrinology and metabolism? Let's listen.
A meta-analysis that evaluated 46 high-quality human studies with 76,000 people on the topic of infection prevention through Vitamin D, and was published in the renowned journal The Lancet Diabetes & Endocrinology ⁵, highlights three important points under which Vitamin D can actually prevent respiratory infections:
Then Vitamin D reduces the risk of respiratory infections by 20-30%. For a single substance in the interplay of our lifestyle factors, that's quite a lot!
Vitamin D is safe and protects us. The rule is: avoid deficiency in winter. Even if we want to raise our Vitamin D levels faster with somewhat higher dosages, we're essentially running no risk of developing serious side effects.
At this point, we want to mention once more that Vitamin D alone is of course not enough to get us through the winter infection-free. Much more is needed here, for example: exercise, sauna bathing/cold thermogenesis, plenty of high-quality protein, adequate selenium levels, more Vitamin C, zinc, and so on.
Let's go!
(1) Robert Koch Institute (2016). Vitamin D status of adults in Germany. doi:10.17886/RKI-GBE-2016-036.
(2) Rabenberg, M.* et al*. (2015) 'Vitamin D status among adults in Germany – results from the German health interview and Examination Survey for adults (DEGS1)', BMC Public Health, 15(1). doi:10.1186/s12889-015-2016-7.
(3) Brustad, N. et al. (2022) 'Safety of high-dose vitamin D supplementation among children aged 0 to 6 years', JAMA Network Open, 5(4). doi:10.1001/jamanetworkopen.2022.7410.
(4) Malihi, Z. et al. (2019) 'Monthly high-dose vitamin D supplementation does not increase kidney stone risk or serum calcium: Results from a randomized controlled trial',* The American Journal of Clinical Nutrition*, 109(6), pp. 1578–1587. doi:10.1093/ajcn/nqy378.
(5) Jolliffe, D.A. et al. (2021) 'Vitamin D supplementation to prevent acute respiratory infections: A systematic review and meta-analysis of aggregate data from randomised controlled trials', The Lancet Diabetes & Endocrinology, 9(5), pp. 276–292. doi:10.1016/s2213-8587(21)00051-6.
