Hacker News Reader

Comment by bdickason | Hacker News Reader

Thanks for sharing. I skimmed the article looking for a specific set of info but may have missed it: how do bodies naturally/organically generate vitamin D and can that be sufficient or are supplements necessary? (E.g. I surf 5 days a week with sunscreen and go for walks regularly. Will I have enough vitamin D or should I supplement?)

View on HN

Straight forward blood tests will tell you where you are at. Get a test, get your answer.

I would hazard a guess that significant outdoor exposure would be enough, but I am not a doctor in any sense.

Also, depending on your level of sun exposure and possible deficiency, you should probably supplement MUCH more than what has been usual for decades.

You will find a max of 1000 IU and many supplements at daily doses way lower than that (300 - 700 IU). This is likely wrong:

"Since all-disease mortality is reduced to 1.0 with serum vitamin D levels ≥100 nmol/L, we call public health authorities to consider designating as the RDA at least three-fourths of the levels proposed by the Endocrine Society Expert Committee as safe upper tolerable daily intake doses. 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." [1]

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5541280/

Some of this really depends on where you live, how well you reapply sunscreen, and things like this.

I wound up at the doctor a couple years ago and my levels were really low. For some background, I'm from Indiana and moved to Norway. I got levels up, and was instructed to supplement from September through May. During the summer, I was told I could go outside for a minimum of 15 minutes a day so long as I had enough exposed skin - more than just my face. During the winter, there simply isn't enough sun.

Folks in other locations get different advice. It might change where you are at and with your current activity levels. Surfing may or may not give your skin enough exposure to the sun, depending on your suit. I'd suggest simply going to the doctor and getting levels tested if it worries you.

Try to eat salmon every other day during the winter months. There are other foods, but not that many. Personally, I love salmon, but if you hate fish then milk and eggs is really the only other option unless you want to supplement daily.

http://www.whfoods.com/genpage.php?tname=nutrient&dbid=110

Seriously, I'll just follow the doctor's advice, thanks. Changing from supplements is seriously not worth the health risks for me (I found out since then that I have MS, and it is important not to get low).

I'm in Norway, and fish is everywhere. I do eat it, but am mostly vegetarian. I do eat eggs and dairy quite often. It isn't enough: And it isn't just me, but many Norwegians have to take a supplement even though people will teach kids to eat plenty of fish for health reasons. Heck, as an immigrant, we were advised to take supplements during the winter since daylight is not only short in duration but also in intensity - I just didn't follow it at first. I'm lucky to be living in a time when I can take chewable tablets - cod liver oil is more traditional.

Does it matter if the salmon is canned? Right before the lockdown my wife bought something like 50 cans of wild caught canned salmon from Costco and I'd love a good reason to convince my family to eat it all now. Sounds like salmon patties of egg + salmon fried up might be a vitamin D superfood.

I would love to have that much salmon! With the high price per can, it sounds like she spent a fortune.

I've looked it up and it seems like canned salmon has the same amount of vitamin D.

It has a non-zero Vit-D but watch out for mercury.

I'm not a doctor but I've read a few articles on vitamin D.

> how do bodies naturally/organically generate vitamin D

Avoiding the biochemistry details, vitamin D is produced exposing skin to 280-315 nm (short UVB) radiation [1].

> I surf 5 days a week with sunscreen and go for walks regularly. Will I have enough vitamin D or should I supplement?

The UV radiation depends on [1]:

   Seasons
   Time of the day
   Latitude
   Altitude
   Ozone
   Aerosol and pollution

The production of Vitamin D depends on physiological factors such [2]:

    Age
    Skin type
    Fat absorption
    Obesity

And, of course, the amount of exposed skin and sun sunscreen usage.

According to [2], the required time for a fair skinned Australian achieve "synthesis of 1000 IU of vitamin D with one side of the hands, arms and neck (11% of the body) exposed to the sun (0.455 MED)" on winter at a few AUS cities:

    Darwin: 8 min
    Townsville: 11 min
    Brisbane: 17 min
    Perth: 17 min
    Sidney: 9 min
    Adelaide: 32 min
    Melbourne 43 min

For more details check [2].

A note about sunscreen:

The most common screening agent and their attenuation/absorbance spectrum can be seen on [3, 4]. Note: Only a few of them absorbs UVA radiation, and most of them have downside:

- Avobenzone: is not photostable, it degrades when exposed to the sun. Figure [5 Fig.3 a] compares the degradation with and without glutatione to stabilize (note: glu has a sulfurs smells and is expensive). Another alternative is ubiquinone [6] (also expensive). In pratice they are stabilized with octocrylene and bemo-trizinol.

- Menthyl anthranilate: Wikipedia article has one line. Found only 2 products with this sunscreen.

- Oxybenzone: Banned in few place. It is "detected in nearly every American", "Weak estrogen, moderate anti-androgen; associated with altered birth weight in human studies" [7].

- Zn/Ti Oxide: White cast. Nano sized particle can harm marine life [8], offer poor UVA protection [9] and can cause lung damage when inhaled [9].

In summary. Sunscreen works better at blocking the spectrum needed to produce vitamin D (UVB) than the spectrum that penetrate deeper and does most DNA damage (UVA).

I've been looking for an UVA blocker. But with no luck. I might get one of from a compounding pharmacy, but I reckon an commercial product would have better quality and price.

[1] https://scholar.google.com/scholar?cluster=97098646450885509...

[2] https://scholar.google.com/scholar?cluster=10953625923154745...

[3] http://www.brynmawrdermatology.com/wp-content/uploads/2015/0...

[4] https://i.redd.it/kr2knqhn88ey.png

[5] https://scholar.google.com/scholar?cluster=18414347133842843...

[5 Fig 3] https://pubs.rsc.org/image/article/2019/PP/c8pp00343b/c8pp00...

[6]https://scholar.google.com/scholar?cluster=39499394362965209...

[7] https://www.ewg.org/sunscreen/report/the-trouble-with-sunscr...

[8] https://oceanservice.noaa.gov/news/sunscreen-corals.html

[9] https://www.ewg.org/sunscreen/report/the-trouble-with-sunscr...

> I've been looking for an UVA blocker. But with no luck.

You must not have searched much:

"Tinosorb S and Tinosorb M UVA filters, developed by BASF, appear to be much stronger and less affected by exposure to light than avobenzone" [1]

> I might get one of from a compounding pharmacy, but I reckon an commercial product would have better quality and price.

Blame the FDA, and stop caring by ordering EU, Korean or Japanese sunscreen from amazon.com

[1] https://www.ewg.org/sunscreen/report/does-europe-have-better...

>Avoiding the biochemistry details, vitamin D is produced exposing skin to 280-315 nm (short UVB) radiation.

Could we then just have a bracelet that had a diode that emits that specific wavelength of light and that way have our body constantly produce vitamin D?

The UVB radiation also does DNA damage, causes redness and tans. Exposing a small area to large cumulative radiation doesn't sound like a good idea. I don't know if this would be physiological possible.

But you are onto something. Since we spend most of the day inside, maybe installing a DLP projector* with UVB light over the monitor could provide an optimal amount of radiation. The DLP could be used to avoid the eye area.

By the way, russia had a full body approach:

https://www.nationalgeographic.com/photography/photo-of-the-...

* I'm not sure if DLP mirrors reflects UVB.

I guess if we had light bulbs that emited that light it could provide the normal amount of exposure that's needed, or even adjustable to suit your needs, quite in interesting idea indeed!

I'm not a doctor, but my doctor told me when I asked that excess Vitamin D passes through your body harmlessly, so there's basically no reason not to supplement if you're worried you aren't getting enough.

While any level someone might usually consider supplementing (such as 2000-10000IU daily) should be safe, Vitamin D toxicity is a real thing at higher levels of intake. See: https://www.healthline.com/nutrition/how-much-vitamin-d-is-t...

According to the comment thread involving devaboone Vitamin D toxicity isn't inherently due to the Vitamin D, but the impact that it has on blood calcium levels.

I don't think this is true and if you a tendency to form calcifications an excess of vitamin D might be a bad idea.

Reply on news.ycombinator.com