Does suntan lotion prevent the development of vitamin D, in humans?

YES!

SPF blocks UVB rays. If you aren’t getting tan or burnt you aren’t getting D.

According to this article, the skin needs a very small dosage of UVB rays to produce vitamin D, and even with sunscreen an adequate supply is created.

Theoretically yes but practically, in real life, it doesn’t make any difference to vitamin d production.

@LostInParadise Tell that to all the Floridians with significant vitamin D deficiency. We get sun every day just running errands, but most of us wear sunscreen every day to not burn or cancer concerns. I don’t know who that study tested, or how long people were in the sun, but it does not sound like any of the studies I’ve read nor my experience living in Florida and almost everyone I know is D deficient. It sounds like it’s just pushing to use sunscreen. The article does not have a footnote or link to any studies it is citing.

Everyone should get their D tested, especially people of all skin colors who have very little or no tan.

If your skin goes pink you are damaging your skin. Nobody needs to tan. Depending on how sensitive your skin is to sunlight and how strong the sun is where you live, 10–30 min a day, 5 days a week would be fine and for this amount of sun exposure, you wouldn’t want or need sunscreen. A walk in the mid-day sun, (11am to 3pm) in short sleeves. We can also get vit D from food we eat. Oily fish, eggs and a number of fortified foods like cereal and milk and now, non-milk alternatives. I love a good sardine on toast. A person in a swimsuit with ginger colouring in a water park in New Orleans or on a beach in Australia is going to get a painful burn in 30 minutes, so again. It depends on where you live depends on how direct the sunlight is and if you have fair colouring, err on the side of caution. Sunburns are horrible. A person living in a high latitude, where winter months are dark) will need to supplement their diet. All this being said without looking at metabolic reasons a person can’t generate vit D from sunlight. Vitamin D is a hormone that a healthy body can produce from rather complicated process through the skin, using sunlight, but there are things that can reduce or stop that production. There are also diseases that preclude the taking of large amounts of vit D supplements. There is no risk of over production from sun exposure, due to the processes involved. It is advised not to take more than 100μg of vitamin D a day, as it could be harmful.

@sorry I take about 7,000–8,000 IU a day to stay in normal range. I know a ton of people like me. The only way to know is to get a test. I live in Florida. Parts of my body are exposed to the sun daily.

@JLeslie , Thanks for the info. I was not aware that so many Floridians had a vitamin D deficiency.

Here’s just a small study of a few hundred people in Miami, some participants even take some D supplements. Depending the time of year and gender deficiency was found in 20–40% (I’m rounding) of participants. https://academic.oup.com/jcem/article/90/3/1557/2836809

I tend to be more deficient than my husband. He’s darker (so more natural protection) and theoretically I should be absorbing D more readily than him since I’m extremely pale, but he winds up higher in D, because he doesn’t need to worry about sunscreen to avoid being burned or wrinkled like I do.

FYI: My dermatologist told me that tanned skin is injured skin. She scolds me when she see a tan line anywhere on my naked body during yearly skin exams.

Dermatologists have been slicing and dicing on every aspect (including between my toes and my scrotum) of my skin since I was a kid. The only part of my body that sees sun light is my face, neck and hands. I lay on the sunscreen thick.

I get by on taking 4000 IUD’s in capsules per day of vitamin D.

Anything over 4000iu of vitamin D a day is considered hazardous to the health. 2000iu a day is the upper levels of what most people can tolerate without side effects.

The recommended (US) daily dose for adults is between 600–800 iu.

I’ll just say again, get you blood tested. That’s how you figure out how much D you need, or if you don’t need it at all. Don’t guess. Don’t just pop pills. Get your calcium checked periodically to make sure it isn’t high if you are going to take a large amount if D.

@Lightlyseared Doctors prescribe 50,000 IU once a week all the time. I’ve been taking it for years.

When I was taking 2,000 a day I was deficient.

@gondwanalon That keeps you in normal range?

@JLeslie Do you have an underlying health condition with your hormones/endocrine system? (if you don’t mind me asking such a personal question)

@sorry Only hypothyroid, but I take meds for it. Why do ask?

Just curious have you had your vitamin D tested?

@JLeslie I think that you are right about the importance of monitoring vitamin D levels. I’ve never had my blood tested for vitamin D level. If I asked my doctor to test my vitamin D, then I’d expect him to ask, “Do you have vitamin D deficiency symptoms?”. In the past I asked him to do a basic metabolic panel and a CBC and he said that he needs symptoms. Vitamin D deficiency symptoms are pretty vague (fatigue, infractions, body aches and pains). I have no vitamin D deficiency symptoms.

@gondwanalon: My doctor told me a few years ago that there are often no symptoms of a low D level. He said you don’t know until your bones start breaking, your back breaks, etc. I usually have my D checked when I have my annual blood work.

Coincidentally, I was visiting a friend who told me she broke her back doing normal housework. I asked her what happened, and she told me the details. She told me when she was at the doctor afterwards to deal with the broken back, she found out that her D level was very low. It made me realize that what my doctor told me was accurate. I have D gummies which I try to remember to take on a regular basis. I say “try” because just like he said, I don’t feel like I have any symptoms but just like my friend, you may not know until it’s too late.

@JLeslie… that makes sense. Hypothyroidism seems to block the process of turning sunshine into vitamin D, so I sort of guessed that you had some endocrine problem. You do still seem to take an excessive amount, but as long as your doctor is monitoring your calcium levels and you’re not having symptoms of toxicity, it’s all good. Hypercalcemia from too much vit D weakens bones, more efficiently as too little vit D does. And yes, I have regular blood tests as part of my job and living where I do. I prefer to eat my vitamins in the form of food but the vit D pills are always in the cupboard.

@gondwalan It would not surprise me at all if your doctor initially refused to test your D because as you said you don’t have symptoms. However, if at least 30% of the population is deficient, there’s a really good chance you might be, especially if you have no tan lines.

A lot of older doctors don’t believe D is a problem or worth testing, and refuse to believe the new normal range is legitimate.

I think women are much more at risk. Our face lotion and make-up tends to block UVB absorption so we don’t even get exposure on our face, while men at least usually get that unless they have facial hair protecting their skin. Also, men tend to have shorter hair and I see more men in shorts than women, so a little more sun on their neck and legs. Especially men who work outdoors. I’m not including people under 18 in that generalization, just talking about adults.

@sorry Maybe it does have some effect, but I know a lot of people who don’t have endocrine issues who still need to take 6,000–8,000 a day to stay up between 40 and 50. Ever think that maybe lack of D or other vitamins or minerals might be causing the endocrine problems? Maybe the you are looking at the egg, but it’s really the chicken.

You have regular “blood tests” but do they test your D? I know a lot of people who say their doctor always checks their blood and everything is fine, and then if they actually bother to look at their lab work, D was never tested.

@sorry I’m not a doctor I’m a patient who has dealt with this for years, and I’m not telling anyone to take anything. In fact just the opposite. All I’m suggesting to people is to get a simple test done next time they get blood drawn if they haven’t had their D checked before.

You’re not going to make me feel bad or stop suggesting it, because I have helped people find out they are deficient multiple times. Many times I have had doctors and nutritionists say in the US it’s unlikely to be deficient because we have fortified food (I realize you are not in the US) and that’s completely wrong as proven by statistics in many studies done here.

There are a lot of people taking high doses like me, prescribed by their doctors, based on blood tests, it’s not guessing.

I warned jellies to check calcium for two reasons. First to make sure there is no underlying parathyroid problem or tumor before taking a lot of D. Plus, to check calcium while taken the higher doses of D to make sure calcium doesn’t rise from that.

Vitamin D helped me immensely, I was barely able to exercise, and my doctor said she sees it over and over again. I really didn’t think it would help. Now, I know a lot of people like me. I also know people who have low D and don’t have any symptoms.

Possibly, it is helping my heart and bones too, I hope so. I’m high risk for heart disease, I like to think the D is putting the calcium in my bones not in my arteries and other soft tissues. I might get a cardiac calcium scan, I’m still deciding if I want to take on the radiation.

If you’re a doctor that’s great, we love having medical professionals here.

Looks like I have to development a vitamin D related disease before my doctor will test my vitamin D blood levels. Of course I could lie and say that I have symptoms related to vitamin D definitely. That’s pretty sad. I know that doctors have their hands tied up by the insurance companies to save money but in some cases like vitamin D testing being proactive might save money. Could save getting hip replacement surgery from low vitamin D related bone loss.

@gondwanalon Vitamin D you can get tested without a doctor, but the thing is, it is important to test calcium also, because a parathyroid tumor can do wonky things to D and calcium levels.

My FIL had normal D levels and high calcium. About once a year for a few years I reminded him when he goes to the doctor to ask about a parathyroid test, but my inlaws don’t like to listen to me. Although, when they are sick they call me.

One day my MIL shows me his tests over time, and five years before his parathyroid had been tested and abnormal. and then the doctor never tested it again! His calcium remains high, probably clogging his arteries and who knows what other damage. So frustrating.

He started with a new doctor, so hopefully that other doctor tested his parathyroid again. It might not be high enough to do something about, I really don’t know, but I think it probably should be monitored.

@JLeslie Do you mean a parathyroid GLAND can do wonky things to D and calcium levels?

Calcium is part of a basic metabolic panel (BMP). That plus a CBC are routinely tested. Easy to get those tested. Too bad some of us have to present to the doctor with vitamin D deficiency symptoms or lie about it in order to get our blood vitamin D level determined.

@gondwanalon What I know is a parathyroid tumor can cause blood serum calcium to be high.

What I don’t know (I’d have to research it) is how a parathyroid tumor or parathyroid problem might effect the D levels. Maybe @sorry knows.

A long time ago I saw a study about vitamin D level having a relationship to parathyroid function when I was reading up for myself, but I just don’t know enough about the science. The researcher implied that this was partly the reason why the normal range for D was raised.

My calcium is always in normal range so I never worried about a parathyroid problem for myself. I get a CMP and CBC done about twice a year for various reasons.

I’m really curious about the relationship of D and cholesterol. D3 is synthesized through cholesterol, but there have been studies giving people high doses of D to see if it lowers cholesterol, and it looks like it doesn’t. Although, there is some conflicting information and interesting correlations on the matter. Every so often I Google for new research. I try to stick to PubMed and JAMA etc. It’s hard with vitamin information, because there is a ton of vitamin articles from “health” magazines that are possibly on point, but just as easily could be garbage, which I know you know.

@JLeslie A parathyroid tumor sounds like a very serious condition that would likely give symptoms (they look similar to vitamin D deficiency symptoms). Bummer.