Is vitamin D really a cure-all, and how should we get our fix?
theguardian.com
theguardian.com
One question: blind or double blind? Does the distributor also not know which product is being given to the patient?
I look forward to the results!
From anecdotes, the correlation studies, and my personal experience, I believe the results will be positive. If the results show otherwise, I'll accept it and try to understand why I was wrong.
Moreover, even in cases with low Vitamin D, where medical professionals are unsure if treatment with Vitamin D would be beneficial at all (in this case: for osteoporosis prevention)[2].
Finally, recent randomised, double-blind clinical trial (n=5108) assessed if monthly administration of a high dosage (100.000 IU) of Vitamin D for more than a year would in any way prevent cardiovascular disease, and found no benefit in patients receiving treatment or placebo after a 3.3 year follow-up period[3]. Another study (n=2303, 4-year long, 2000 IU/d), testing the efficacy of Vitamin D to prevent cancer, actually suggests that low dose of Vitamin D is may increase cancer.[4]
Taken together, I hope that this helps illustrate how 'making a prediction' or 'expecting a certain result' is neither scientifically ethical, nor possible, given the controversial results in the literature so far.
[1] https://www.ncbi.nlm.nih.gov/pubmed/21395958
[2] http://www.nejm.org/doi/pdf/10.1056/NEJMcp1009570
[3] https://jamanetwork.com/journals/jamacardiology/article-abst...
Another Swedish study, non immigrant related, found a pattern of higher autism rates among children whose 3rd trimester was during winter. For illustration - brain formation during 3rd trimester - http://www.brainfacts.org/-/media/Brainfacts2/Archives/Artic...
Do you have another source for the statement in the first paragraph?
"increasing chances" and "necessarily leading to" are 2 different things. Consider for example smoking and cancer - among people who smoke the same amount of tobacco some will get cancer, some will not. That doesn't falsify the fact that smoking increases the chances of the cancer.
You link is actually enough here. From your link :
"Results: Between 12 and 17 mothers from the different groups accepted to participate, both groups of mothers of Somali origin had significantly lower values of 25-hydroxyvitamin D compared with Swedish mothers. "
So, i'm not sure what of the 2 well established facts you are arguing against :
1. Somalis in Sweden have very low D
2. Somali children born in Sweden have much higher autism rate.
Of course correlation isn't necessarily causation, yet the correlation (both - between populations as well as inside the Somali mothers population) is clearly stated in your link (have you read it yourself?) :
"Conclusion: Our findings of low vitamin D levels in Somali women entail considerable consequences in a public health perspective. The observed tendency, i.e. the lowest values in mothers of Somali origin with a child with autism was in the predicted direction, supporting the need for further research of vitamin D levels in larger samples of Somali mothers of children with and without autism."
1. Yes, Somalis in Sweden have very low D. That is quite obvious [from Table 1] after winter.
2. Yes, Somali children born in Sweden have higher rate (according to this study: 17 in 2437 [0.7%] for Somali background, 484 in 250565 [0.19%] for non-Somali): http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8749.2008....
However we should also consider the effect of other compounding factors about parents coming from Somali.
Here: https://link.springer.com/article/10.1007/s10803-017-3232-z
"Results lend support to previous studies that found higher rates of ASD intellectual disability in children of immigrants from low human resource index countries compared to other groups."
coming from Somali also means coming from a low human resource index country. all kinds of air/water pollutants and chemicals/pesticides might be at play -together with- vitamin D deficiency.
Vitamin D effect itself is hard to isolate from just this. Further studies need additional data about these other factors (air pollution, exposed chemicals etc)
>coming from Somali also means coming from a low human resource index country. all kinds of air/water pollutants and chemicals/pesticides might be at play -together with- vitamin D deficiency.
>Vitamin D effect itself is hard to isolate from just this.
If anything, your link confirms vitamin D theory even more :) What is the most common trait for all these low human resource index countries? They are closer to equator, i.e darker skin of the population.
https://en.wikipedia.org/wiki/List_of_countries_by_Human_Dev...
It is very well established epidemiological fact that darker skin immigrants have noticeably lower vitamin D in higher altitudes (i.e where the higher developed countries are that they immigrate into).
If by "theory" you mean "low vitamin D -> autism", you're reading science wrong (by only using correlation when reasoning about it). You have to control for other factors in Somali population. That's how you do proper research. In its current form, as the researchers themselves point out, this says that a future study is needed.
Let me repeat: you might be entirely right but "this correlation supports the theory better" is not scientific evidence. It's just a hint to direct research.
As I said, if they find Swedish mothers with really low vitamin D and compare with Swedish mothers with high vitamin D, that would say a lot more.
It was pretty eye-opening (and alarming) when I read it.
In short: While Vitamin D is great for everyone, your body will begin lacking in vitamins A and K because of the effects of D (too much of a good thing, essentially). It's all about finding the right balance for yourself.
Snippet from the closing:
1. Get enough vitamin D… but not too much. Doses of around 1,000 IUs per day — even as high as 2,000 IUs a day in the winter months when you’re not exposed to much sunlight — are likely safe. Especially when other key nutrients are included, such as vitamin K, vitamin A, and magnesium. You can ensure you are getting enough of these by taking a quality multi-vitamin.
2. Support vitamin D’s work Remember that other nutrients act together with vitamin D. Consume a wide variety of minimally processed foods to help get vitamin D’s nutritional colleagues such as magnesium, vitamin A, and vitamin K.
Eat your greens and fermented foods. Dark leafy greens — such as kale, spinach, or Swiss chard — are good sources of vitamin K1. They’re also high in dietary magnesium. Fermented veggies such as sauerkraut along with eggs, meats (especially organ meats such as liver) and fermented/aged cheeses are good sources of vitamin K2.
Eat the rainbow. The carotenoid form of vitamin A is found in colorful fruits and veggies. Eggs, butter, full-fat dairy (such as cheese) and organ meats are also great sources of the active retinol form of vitamin A.
Keep your intestinal flora happy and healthy. Vitamin K conversion happens in the GI tract. So eat plenty of fermented foods and prebiotic fiber, consider a probiotic supplement, and avoid antibiotics unless absolutely necessary (research has found that broad-spectrum antibiotics can reduce K production by up to 75%).
Review all medications and supplements with your doctor and/or pharmacist. Many medications, such as corticosteroids like Prednisone, weight loss drugs like Orlistat, cholesterol-blocking drugs like statins, and/or high blood pressure drugs like thiazide diuretics can disrupt the delicate balance of vitamin and mineral regulation in the body. Make sure you know all the side effects and interactions of any medications (or “healthy” supplements) you are taking.
2,000 IU is not a high level of Vitamin D. That's a medium-to-low level of Vitamin D. 20,000 IU is high.
Most people can very safely take 5,000 IU and won't come even remotely close to seeing negative health consequences. Quite the opposite, studies have suggested you may need that level of VitD intake just to get up to a healthy blood reading, especially if you have low sunlight exposure.
The old RDA guidelines have increasingly been shown to be a scientific embarrassment over the last 20 years.
Since then I've periodically stayed on s 10k IU supplement three times a week. That's just over the counter.
I do also get my D3 levels checked annually as well, as should anyone with a diagnosed deficiency.
I was getting acupuncture, began excercising more, eating more veggies, and dealt with the factors that were bringing about my depression.
There is very little conclusive evidence that suggests probiotics are actually useful. In the EU and USA companies are not able to claim health benefits from them legally.
Some good studies cited on the Wikipedia article: https://en.wikipedia.org/wiki/Probiotic#Scientific_reviews_a...
I was prescribed some a year or so ago when I was on some heavy antibiotics. Reading that article still makes it look like efficacy is pretty minor. Since it doesn’t really hurt to take it why not?
And the microbiome is so vast that it’s hard to influence on the long term. With a very strong probiotic you get 5 * 10^10 bacteria (of which most die in the stomach and small intestine), but at the same time you have 3.8 * 10^13 native bacteria settled and accustomed to your body, feeding on the sugar you have just eaten. You need a lot of those tablets to have a meaningful impact.
Just like a great body, a great microbiome gets made in the kitchen. AFAIK dietary changes work way faster than popping probiotics. With the exception that you are missing certain strains (eliminated by antibiotics?), which should be replaced.
I try to be cautious with vitamins. It appears that taking them in pill form might not be safe. I switched to a high-nutrient diet that focuses on getting nutrients from food wherever possible.
Some examples of cases where vitamins that are beneficial in food form might be dangerous in extracted form:
Vitamin E and the Risk of Prostate Cancer: https://jamanetwork.com/journals/jama/fullarticle/1104493
Dietary Supplements and Mortality Rate in Older Women: https://jamanetwork.com/journals/jamainternalmedicine/fullar...
Death Stalks Smokers in Beta-Carotene Study: https://www.webmd.com/smoking-cessation/news/20041130/death-...
I'm not a fan of multivitamins that go crazy over the RDA unless I know the RDA number is way too low to begin with (like in Vitamin D's case). It's also an especially bad idea to go crazy over RDA with fat-soluble vitamins, because those are the ones that are stored in your body for longer periods of time. At least the water-soluble ones come out when you pee, but I think there's some new evidence that even some of those is stored or at least it may not be a good idea to "mega-dose" on them.
But I agree about trying to get your vitamins from your diet in general.
Here is some more reading:
* Enough Is Enough: Stop Wasting Money on Vitamin and Mineral Supplements http://annals.org/aim/fullarticle/1789253/enough-enough-stop...
* Vitamin B.S. https://www.theatlantic.com/health/archive/2015/02/vitamin-b...
* Experts: Don't Waste Your Money on Multivitamins https://www.webmd.com/vitamins-and-supplements/news/20131216...
* The Case Against Multivitamins Grows Stronger https://www.npr.org/sections/health-shots/2013/12/17/2519558...
* A Scientist Debunks The 'Magic' Of Vitamins And Supplements https://www.npr.org/sections/health-shots/2013/07/23/2045251...
Testing is really the only way to know how much you should be taking
I took the blood test for Vitamin D (25-hydroxy) and I was something around 7, where the desired number is more like 20-50. Started taking 10k-20k IU of Vitamin D per day (plus K and also a range of other daily vitamins added at the same time), as well as a 4 or 8 dose course of demodex over 2-3 weeks, and both problems were resolved within a month. Apparently low D causes the cornea to sag so the lens itself is out of shape and thus astigmatic.
We tried all sorts of drops and cleaning regimes to no avail. She went for another blood test and learned her Vitamin D levels were through the roof (somewhere around 90+). She immediately stopped the Vitamin D supplements and after a few weeks, all her eye issues were gone!
Goes to show we definitely need some good studies examining long-term Vitamin D intake.
Some people get adequate amounts just from "regular food", others (like me) need extra large doses to keep up, especially during the winter months.
And then there's people like your wife who go through the roof if they see a supplement at the store :D
Goes to show that the recommended level of it are about right.
4,000 IU is the upper limit. 2K is high.
You can synthesize 1000 IU from 10 minutes in the sun if... you're young, have light skin (of which most is visible), don't wear sunscreen, it's the middle of the day & summer, and you're lying down to get roasted.
4,000 IU is equivalent to getting burnt to a crisp.
You are very unlikely to develop excess vitamin D unless you supplement more than 10,000 per day for months, and typically not even then unless you exceed 40,000 per day via supplements. https://www.vitamindcouncil.org/about-vitamin-d/am-i-getting...
Additionally, if you supplement or take K2 with vitamin D, the risks are substantially mitigated (Vitamin D adds calcium ions to things, K2 takes them out).
The eye doctor, who has a journal article somewhere about this, is Dr. James McMillan, of Medina Eye (in Bellevue, WA). Expensive ($400 for a visit), but great care.
The explanatory arguments are more than sufficient: skin colour corresponds to the availability of sunlight - with the exception of dark-skinned Inuits who maintain a fish based diet - which indicates the importance of vitamin D to survival.
Only in the modern era do we now spend more time inside than outside, which could be an explanation for increasing incidence of diseases.
As for this ridiculous quote:
> And as Adrian Martineau, clinical professor of respiratory infection and immunity at Queen Mary University of London, points out, even in the summer, “sunshine isn’t going to be the answer, especially because there is an associated risk of skin cancer.”
No, sunshine is the answer. The risk of skin cancer is elevated if you get sunburnt, if you expose your pale skin suddenly to the sun in the height of summer. Nobody is suggesting you do that. Build up a tan gradually throughout the year, follow common sense.
This is very common skin cancer myth that can be debunked by few minutes of googling.
Any change in your natural skin color is a sign of skin damage and that damage is cumulative. Getting a tan is a sign of damage. Total UV dose you build up over time, rather than getting sunburnt, matters most (Sunburn is used as a proxy for skin cancer risk because it is related to individual sun sensitivity and UV exposure).
UV radiation is complete carcinogen. It's both a mutagen and a non-specific damaging agent. It's both tumor initiator and a tumor promoter. Three most common types of skin cancer are basal cell carcinoma (BCC) , squamous cell carcinoma (SCC) and malignant melanoma. Chronic cumulative exposure is associated with BCC and SCC and melanoma with sunburns and childhood exposure but melanoma may develop through multiple pathways.
Do you have a source for that? A source that compares people from further North living in the Mediterranean region compared to further North for skin cancer?
the CDC on US Skin Cancer Rates By State: https://www.cdc.gov/cancer/skin/statistics/state.htm - if you squint there sure is a general north-south gradient, with LESS skin cancer in the South. Also note that "Melanoma is much more common among non-Hispanic whites than people of other races and ethnicities. More than 9 out of 10 cases of melanoma are diagnosed in non-Hispanic whites."
Forbes on "skin cancer hotspots of the world": https://www.forbes.com/2008/07/28/skin-cancer-hotspots-forbe...
relevant excerpt: "Studies have shown that while there is generally an increase in the incidence of melanoma as latitude decreases (closer to the equator), mortality from melanoma is four to six times higher in Nordic countries than in Mediterranean countries, according to the WHO." It then goes on to talk about cultural differences that essentially boil down to "people raised in sunny places get taught strategies for dealing with lots of sun".
You could probably find better studies, this is just five minutes of searching.
Cancer is essentially triggered by damage to cellular DNA which results in a “pathological” strand. That strand then multiplies throughout our bodies through cell regrowth with the pathological DNA.
Sun light “flips the dice” with our skin cell DNA, among just generally harming our skin. Some people go their whole lives without any pathological DNA damage, and others not so much.
The skin cells of Caucasians have little to no natural defense to the sun’s rays.
Add as an anecdote: I saw a documentary with a girl born without any pigment (I think?). I forget the exact specifics. But she has to walk around in a 100% UV blocking hood and completely covering draped clothing when the sun is out. If any UV touches her skin she will get cancer then and there. She had a hole in the fabric of one of her hoods as a toddler and they had to do things to counteract that (I think they cut away that skin).
1: http://www.traditionalmusic.co.uk/folk-song-lyrics/Mad_Dogs_...
What makes you assume that they don't?
Burden of cancer in the Eastern Mediterranean Region, 2005–2015: findings from the Global Burden of Disease 2015. https://link.springer.com/article/10.1007/s00038-017-0999-9
Please don't do this. Almost nothing is trivially googleable. For instance, the pages I'm reading say a tan is equivalent to about 2-3 SPF, which isn't a huge amount of protection (it corresponds to a 50-66% reduction in UV exposure). However, I'm not sure how to compare that 2-3 SPF to sunscreen measurements. SPF measurements for sunscreen are based on using something 4 teaspoons, or 1/3rd of a bottle per usage. No one I know does that.
On top of that, as a very pale person, I find that I don't get sunburnt because I put on SPF 15 and it's not strong enough--I get sunburnt when I don't reapply the SPF 50 after sweating for a few hours.
Or even better, trivially googling Basal Cell Carcinoma gets me to wikipedia which says that it's unclear if sunscreen even affects your risk of BCC. I probably shouldn't trust wikipedia, but that's what you're telling me to do when you say "it's easy to google for".
Short story: I'm still willing to believe that you're right. You clearly know more than I do about the subject. But "just google it" is not typically helpful.
What I meant is to google basic public health information provided by national health authorities and international health organizations. They usually give a balanced view. For example, it's not beneficial to avoid going outside or not doing outdoor activities because they have other health benefits that outweigh skin cancer risk. Tanned skin is damaged skin but maybe you should accept the risk not avoid getting some tan.
For example:
https://www.surgeongeneral.gov/library/calls/prevent-skin-ca...
[0] I do use sunscreen, but between getting in the water, uneven application or whatever else, I end up with part of my body burning a fraction on the time.
Do we have increasing incidence of diseases? [citation needed]
I see little reason for evolution to favor long lives. Setting offspring early and living long enough to support your offspring sure. But beyond that returns are quickly diminishing.
The idea that it's natural to live a long healthy life is very romantic, but hardly realistic.
Even if the numbers did increase, most of the time this is due to improved detection, or shifting age distributions, ie. an older population will necessarily have more health issues.
Is exactly the term I was looking for :)
I feel like some of the love people have for: natural medicine, organic food, natural coloring, flavors and preservatives are somewhat similar... Granted there are environmental benefits to some of it for sure.
Other than what you say about older people, it is pure conjecture to say that "most of the time" these are the causes.
It's quite possible that diseases suspect of being due to vitamin D deficiency are up, but evidence to that effect needs to be cited.
I'm not convinced that we have higher incidence of diseases today, than we did 50 years ago. At least not when you correct for age, and population size, etc. Maybe diabetes is up, but... still evidence is good.
As a Finn, I have found that the natives really don't want to hear that most of the country is on the same latitudes as Alaska.
As for your question, well... <snark value="11">I did.</snark> Wonderful ice breaker in pubs, btw. "I moved to London for the weather."
I don't think so.
'The body needs sunlight to produce the vitamin' okay. But now i say: '15 Minutes of sunlight a day is enough for your body'.
What now?
Where is your study saying how much sunlight is relevant? And if it makes sense to supplement? And what are the dangners of too much?
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2873840/
After reviewing over 1300 article titles and evaluating 270 articles in detail, we pooled ORs from 51 independent study populations for “ever” sunburned and risk of cutaneous melanoma. Among these, 26 studies reported results from dose-response analyses. Dose-response analyses were examined using both fixed-effects models and Bayesian random-effects models.
Results:
An increased risk of melanoma was seen with increasing number of sunburns for all time-periods (childhood, adolescence, adulthood and lifetime). In an attempt to understand how risk between life-periods compares, we also report these same linear models on a scale of 5 sunburns per decade for each life-period. The magnitude of risk for 5 sunburns per decade is highest for adult and lifetime sunburns.
Conclusions:
Overall, these results show an increased risk of melanoma with increasing number of sunburns during all life-periods, not just childhood. Prevention efforts should focus on reducing sunburns during all life-periods.
The medical community also seems to think that 20 ng/ml is when the deficiency starts, when in reality it's more like 40. Some studies have shown that you can see benefits upwards of 60 ng/ml. Other research has shown that Vitamin D helps with sleep in the 60-80 ng/ml range.
I've seen many people on Reddit say that their blood tests level came out at 5-10. That's crazy. Get your 25(OH)D level checked.
Some of the studies that have shown "no improvement" from Vitamin D saw that result mainly because they were still prescribing far too little Vitamin D (yet still higher than the RDA).
10,000 IU may be necessary just to maintain your level. However, you also have to keep in mind that you won't be getting D only from the supplement, so throughout the year you should actually increase your Vitamin D level as you get more sun exposure. Meanwhile the 10,000 IU (which by the way is "only" 250 micrograms) will maintain those high levels. Then, in the second year, you may further increase your Vitamin D level as you once again get more exposure in the sunny days. So you should check your Vitamin D at least after a year, to ensure your levels aren't too high. After you're stabilized you should need around 5,000-7000 IU, but it's really dependent on each person's needs, so you'll have to figure out on your own through trial and error.
However, you also need to keep in mind that not everyone uses Vitamin D as efficiently. You may have undiscovered gallbladder issues for instance, or your gut bacteria is not well balanced, or your stomach doesn't have enough acid, or you're not taking Vitamin D with enough fat, and all of these factors which could impact how easily you're absorbing Vitamin D.
This is part of the reason why the FDA can't just recommend "everyone should take 10,000 IU". Plus, people of color need much more Vitamin D, so if the FDA recommends everyone 2,000 IU as a higher minimum, that may still not be enough for them.
https://www.youtube.com/watch?v=v3pK0dccQ38&feature=youtu.be...
https://www.youtube.com/watch?v=xF24xmJQK1k
https://www.foundmyfitness.com/vitamin-d
https://www.vitamindcouncil.org/i-tested-my-vitamin-d-level-...
Also, as others have mentioned, there is such a thing as too much - taking too much can affect the balance of your other vitamin levels. There was a nice trial on beta-carotene which showed it increasing mortality which was very unexpected, but made sense once people understood the biochemical pathways better.[2]
[1] http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD007470...
https://www.ncbi.nlm.nih.gov/pubmed/27764518
"In the central nervous system (CNS) the main proteins of myelin are proteolipid protein (PLP), myelin basic protein (MBP), myelin oligodendrocyte glycoprotein (MOG) and CNPase.
[...]
The mice were treated by cuprizone for five weeks in order to induce demyelination.
[...]
a significant increase in the MOG and CNPase expression was seen in vitamin D injected group as compared to SHAM and control groups. It is concluded that vitamin D plays a role in the process of remyelination by increasing MOG and CNPase expression in the cortex."
Meta-analysis suggests that supplementation in vitamin-D deficient populations does not reduce cancer, fractures, cardiovascular problems or all cause mortality (http://www.sciencedirect.com/science/article/pii/S2213858713..., https://academic.oup.com/jcem/article/96/7/1931/2833735).
One limitation of this research is that most studies are done with fairly low doses (700-800 IU is common). However, those few studies that look at higher doses (5000-1000IUs) you don't necessarily see any better signs. On the contrary, there is some evidence that high doses seem to be associated with e.g. higher risk of falls and fractures in elderly patient populations (https://jamanetwork.com/journals/jama/fullarticle/185854, https://jamanetwork.com/journals/jamainternalmedicine/fullar...).
>A statistical error in the estimation of the recommended dietary allowance (RDA) for vitamin D was recently discovered; in a correct analysis of the data used by the Institute of Medicine, it was found that 8895 IU/d was needed for 97.5% of individuals to achieve values ≥50 nmol/L. Another study confirmed that 6201 IU/d was needed to achieve 75 nmol/L and 9122 IU/d was needed to reach 100 nmol/L.
>The largest meta-analysis ever conducted of studies published between 1966 and 2013 showed that 25-hydroxyvitamin D levels <75 nmol/L may be too low for safety and associated with higher all-cause mortality, demolishing the previously presumed U-shape curve of mortality associated with vitamin D levels....
>This could lead to a recommendation of 1000 IU for children <1 year on enriched formula and 1500 IU for breastfed children older than 6 months, 3000 IU for children >1 year of age, and around 8000 IU for young adults and thereafter. Actions are urgently needed to protect the global population from vitamin D deficiency.
There is a U-shaped association between vitamin D concentrations and total mortality[1], inflammatory markers[2], etc. but more studies are needed[3] to be sure.
--
[1]: Plasma vitamin D and mortality in older men: a community-based prospective cohort study. https://www.ncbi.nlm.nih.gov/pubmed/20720256
[2]: Association between serum vitamin D concentrations and inflammatory markers in the general adult population. https://www.ncbi.nlm.nih.gov/pubmed/24928661
[3]: Do studies reporting ‘U’-shaped serum 25-hydroxyvitamin D–health outcome relationships reflect adverse effects? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4951179/
Vitamin D may reduce the risk of some cancers: https://www.nhs.uk/news/cancer/vitamin-d-may-reduce-risk-som...
Vitamin D is ambivalent: as said in the article, it helps calcium absorption so if you're too low on vitamin D you might be too low on calcium and thus have frequent cramps and what not. But if you're a little too high on vitamin D and consume your fair share of calcium, then calcium absorption could be too high and you'll end up with premature atherosclerosis and other vascular issues.
Interestingly, I've managed to avoid getting a seasonal cold this year unlike most of my coworkers and friends, and my guess is that the D3/K2 has helped with that because I haven't changed much else.
It’s not just anecdotal, it’s bad reasoning. You can’t prove that your supplement prevented you from getting sick. Maybe you were immune to whatever was going around. Maybe you didn’t touch your face at the right times. Maybe you washed your hands really well. There are thousands of possible explanations, and it’s misleading and wrong to attribute it to some random supplement.
Please stop doing that. It’s the same reasoning people use when they say that they prayed and God answered. Just because B happens after A doesn’t mean that A caused B; it just means B happened after A.
This is where you committed a fallacy for a change. Next time be more careful! With this kind of thinking you'd rule out any causality.
So by the logic of the other children of the parent I should quit my vitamin D supplementation, and probably avoid friends that take Vitamin D. ;-)
https://www.ted.com/talks/richard_weller_could_the_sun_be_go...
Recommended watching - there is more to sunlight than Vitamin-d.
In addition, you should be out with some skin exposed - more than just your face - for at least 15 minutes a day during daylight hours. In some areas, this makes it somewhat prohibitive during winter and you still might need supplements.
Go outside more. Take 15 min with your shirt off in the sun. In some areas of the world this can be a true challenge, but cold exposure has its own benefits. It will boost mood, improve eyesight, and process vit D. Skin cancer is real, but unless you are getting burnt to the point of peeling or blisters, there is virtually zero risk as an adult. A good tan won't make you look like a lifelong smoker. Just beware akward tanlines, and curious neighbors when trying to eliminate said tanlines.
(The UK is at the same latitude as Vancouver)
"There is no such thing as a healthy suntan. Any change in your natural skin color is a sign of skin damage. Evidence suggests tanning greatly increases your risk of developing skin cancer. The increase in skin pigment called melanin, which causes your skin to tan, is a sign of damage. Once skin is exposed to UV radiation, it increases the production of melanin in an attempt to protect the skin from further damage. The increase in melanin may cause your skin tone to darken over the next 48 hours."
Additionally, I'm too far north for this to do enough. December days are only 4-5 hours long. If I work a normal first shift, I'd have to do this during my half hour lunch or I'd miss daylight completely... plus the fact that the sun isn't strong enough to give me enough benefits.
Now, the good news: It isn't all bad advice. I had low vitamin D this winter, and felt pretty sick. The doctor's advice once I'm done with my 3-months of prescription vitamins: From September through April, I need to take a supplement. 20IU a day. The rest of the year, I need to be out in the daylight for 15 minutes a day, with at least arms exposed (not just my face). It isn't that one needs their shirt off, just skin exposure. This is quite doable.