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, vitami

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=9709864645088550922 https://scholar.google.com/scholar?cluster=97098646450885509... [2] https://scholar.google.com/scholar?cluster=10953625923154745587 https://scholar.google.com/scholar?cluster=10953625923154745... [3] http://www.brynmawrdermatology.com/wp-content/uploads/2015/03/c58be9ca65b2fbc14d13947b6c6be676.jpg http://www.brynmawrdermatology.com/wp-content/uploads/2015/0... [4] https://i.redd.it/kr2knqhn88ey.png https://i.redd.it/kr2knqhn88ey.png [5] https://scholar.google.com/scholar?cluster=18414347133842843143 https://scholar.google.com/scholar?cluster=18414347133842843... [5 Fig 3] https://pubs.rsc.org/image/article/2019/PP/c8pp00343b/c8pp00343b-f3_hi-res.gif https://pubs.rsc.org/image/article/2019/PP/c8pp00343b/c8pp00... [6]https://scholar.google.com/scholar?cluster=3949939436296520932 https://scholar.google.com/scholar?cluster=39499394362965209... [7] https://www.ewg.org/sunscreen/report/the-trouble-with-sunscreen-chemicals/ https://www.ewg.org/sunscreen/report/the-trouble-with-sunscr... [8] https://oceanservice.noaa.gov/news/sunscreen-corals.html https://oceanservice.noaa.gov/news/sunscreen-corals.html [9] https://www.ewg.org/sunscreen/report/the-trouble-with-sunscreen-chemicals/ https://www.ewg.org/sunscreen/report/the-trouble-with-sunscr...