Sunscreen - friend or foe?

[Little Rickie]

Eat well and bee healthy. Don't worry about all that crap you read on the internet. Worry and anxiety is worse for you than a little sunscreen.

Sources of Vitamin D
Food
Very few foods in nature contain vitamin D.
The flesh of fatty fish (such as salmon, tuna, and mackerel) and fish liver oils are among the best sources [1,11].
Small amounts of vitamin D are found in beef liver, cheese, and egg yolks. Vitamin D in these foods is primarily in the form of vitamin D3 and its metabolite 25(OH)D3 [12]. Some mushrooms provide vitamin D2 in variable amounts [13,14]. Mushrooms with enhanced levels of vitamin D2 from being exposed to ultraviolet light under controlled conditions are also available.
Fortified foods provide most of the vitamin D in the American diet [1,14]. For example, almost all of the U.S. milk supply is voluntarily fortified with 100 IU/cup [1]. (In Canada, milk is fortified by law with 35–40 IU/100 mL, as is margarine at ≥530 IU/100 g.) In the 1930s, a milk fortification program was implemented in the United States to combat rickets, then a major public health problem [1]. Other dairy products made from milk, such as cheese and ice cream, are generally not fortified. Ready-to-eat breakfast cereals often contain added vitamin D, as do some brands of orange juice, yogurt, margarine and other food products.
Both the United States and Canada mandate the fortification of infant formula with vitamin D: 40–100 IU/100 kcal in the United States and 40–80 IU/100 kcal in Canada [1].
Several food sources of vitamin D are listed in Table 3.
Table 3: Selected Food Sources of Vitamin D [11] Food IUs per serving* Percent DV**
Cod liver oil, 1 tablespoon 1,360 340
Salmon (sockeye), cooked, 3 ounces 447 112
Mackerel, cooked, 3 ounces 388 97
Tuna fish, canned in water, drained, 3 ounces 154 39
Milk, nonfat, reduced fat, and whole, vitamin D-fortified, 1 cup 115-124 29-31
Orange juice fortified with vitamin D, 1 cup (check product labels, as amount of added vitamin D varies) 100 25
Yogurt, fortified with 20% of the DV for vitamin D, 6 ounces (more heavily fortified yogurts provide more of the DV) 80 20
Margarine, fortified, 1 tablespoon 60 15
Liver, beef, cooked, 3.5 ounces 49 12
Sardines, canned in oil, drained, 2 sardines 46 12
Egg, 1 large (vitamin D is found in yolk) 41 10
Ready-to-eat cereal, fortified with 10% of the DV for vitamin D, 0.75-1 cup (more heavily fortified cereals might provide more of the DV) 40 10
Cheese, Swiss, 1 ounce

 

[weatherman]

Two questions -

Do the various sunblock lotions prevent the production of Vitamin D?

How much skin (square inches?) needs to be exposed in order to produce Vitamin D?

1. Unfortunately, yes.
2. Not much. A derm lecture I went to last year mentioned "both hands, for 10 minutes." That sounds kind of low to me, but if you're outside at all with a little exposure, you're likely fine.

It amazes me how many people are vitamin D deficient. One more symptom of nature deficit disorder! I'd bet a buck or two that hikers have a relative risk of, oh, 0.1 or so compared to the general population, unless you only hike at night.

Edit: whoops, others beat me to it.

 

[TEO]

You can get what you need by going for a walk outside in the winter a few days a week.

No, you can't. If you live in the northern United States, one source says North of Atlanta, it is impossible to get vitamin D from sun exposure in the winter.

 

[chipc]

more on vit D

Coincidentally just received this summary of a paper from a well-known vitamin D researcher recommended levels:

http://www.internalmedicinenews.com/newsletter/internal-medicine-news-e-newsletter/singleview40703/healthy-people-don-t-need-vitamin-d-screen-guidelines-say/7936cf6264.html

 

[Little Rickie]

North of Atlanta, it is impossible to get vitamin D from sun exposure in the winter.

That would mean a huge percent of the population isn't getting enough Vit D in the winter?

I would think if you can get sunburn in the winter from UV then you would be getting enough UV for Vit D.

 

[pedxing]

This is an interesting discussion on a couple levels.

For me, the basic lesson is to use sunscreen thoughtfully and strategically and avoid the ultra high potency sunscreens - not need to use 100 SPF when 15 will do.

I'm still pondering the Vitamin-D - calcium - parathyroid information. As a survivor of parathyroid cancer (exceedingly rare) - mentions of parathyroid always get my interest. I take Vitamin D and calcium supplements to avoid excessive activation of parathyroid tissue.

 

[Kevin Rooney]

No, you can't. If you live in the northern United States, one source says North of Atlanta, it is impossible to get vitamin D from sun exposure in the winter.

I've seen that factoid published elsewhere as well, and like Little Rickie, don't put much stock in it either. The latitude of Atlanta is 33 North, and a big chunk of the world's population lives above that latitude. Somehow I think evolution has solved this "problem".

Good thread.

 

[marty]

Well, all this vitamin D stuff is quite confusing. I had my annual physical in November and my doctor told me that my Vitamin D was a bit low. He put me on 400 IU of Vitamin D per day. I had to do a lab test six months later and everything came out normal.

Anyway, I guess I will be staying on the daily Vitamin D pills, although I probably got a serious dose of Vitamin D while hiking Saturday. I did not put adequate sunscreen on top of my bald head and got a serious sunburn. It's all tanned and peeled now.

Marty

 

[DougPaul]

Well, all this vitamin D stuff is quite confusing. I had my annual physical in November and my doctor told me that my Vitamin D was a bit low. He put me on 400 IU of Vitamin D per day. I had to do a lab test six months later and everything came out normal.

Many daily multi-vitamins contain D. Mine, for instance, contains 400 IU. Some calcium tablets also include D. (D is needed for proper utilization of the calcium.)

Doug

 

[TEO]

I've seen that factoid published elsewhere as well, and like Little Rickie, don't put much stock in it either. The latitude of Atlanta is 33 North, and a big chunk of the world's population lives above that latitude. Somehow I think evolution has solved this "problem".

Good thread.

"Season: Vitamin D Winter and latitude

"What latitude you reside at will affect the length of your Vitamin D Winter. Vitamin D Winter is when no vitamin D production is possible due to the atmosphere blocking all UVB. This lasts for several months, with the duration of time increasing as you move further from the equato"

"Angle of the Sun’s rays
"Time of day, season, and latitude all determine the amount of UVB that reaches your skin. When the Sun's rays enter the Earth's atmosphere at too much of an angle, the atmosphere diffuses (blocks) the UVB portion of the rays. This occurs during the early and latter parts of the day, during the winter season (what is called “Vitamin D Winter”), and increases as one moves further away from the equator. A good rule of thumb is: If your shadow is longer than you are tall (an indicator of the oblique angle of the Sun), you are not making much vitamin D."

"Latitudes above 40 degrees north will experience Vitamin D Winter from around November through early March."

Source: Vitamin D Council

 

[Snowflea]

Apparently there's more than Vitamin D at issue. Lots of good info here, probably more than anyone wants to know...

http://breakingnews.ewg.org/2011sunscreen/

http://www.enviroblog.org/2011/05/here-comes-the-sun-what-now-what.html

 

[daxs]

most of the patients I test have low VIT D levels. At this is living in a beach community.

 

[Stan]

I've used SPF 45 for years and, especially with the risk of fair skin, feel that the benefit outweighs the risks of the other things that could go wrong. My only complaint is that it can irritate my eyes if I'm not careful applying it or if perspiration gets it in my eyes.

If you read the labels of many products, most notably food and beverages, you'd have good cause to be even more cautious than with sunscreen. For my money and health, I lean towards natural and organic foods more than any reluctance to protect my skin with sunscreen.

 

[Little Rickie]

"Season: Vitamin D Winter and latitude

"What latitude you reside at will affect the length of your Vitamin D Winter. Vitamin D Winter is when no vitamin D production is possible due to the atmosphere blocking all UVB. This lasts for several months, with the duration of time increasing as you move further from the equato"

"Angle of the Sun’s rays
"Time of day, season, and latitude all determine the amount of UVB that reaches your skin. When the Sun's rays enter the Earth's atmosphere at too much of an angle, the atmosphere diffuses (blocks) the UVB portion of the rays. This occurs during the early and latter parts of the day, during the winter season (what is called “Vitamin D Winter”), and increases as one moves further away from the equator. A good rule of thumb is: If your shadow is longer than you are tall (an indicator of the oblique angle of the Sun), you are not making much vitamin D."

"Latitudes above 40 degrees north will experience Vitamin D Winter from around November through early March."

Source: Vitamin D Council

Sorry I don't believe everything written on the internet. (not you but the plethora of "expert sources" make me question what I should accept as truth)

How would you explain UV sunburn and not getting enough UV to make Vit d?

It's one thing to be short D because you don't go out side and another to say going out side would do no good or wouldn't work.

 

[erugs]

I've used SPF 45 for years and, especially with the risk of fair skin, feel that the benefit outweighs the risks of the other things that could go wrong. My only complaint is that it can irritate my eyes if I'm not careful applying it or if perspiration gets it in my eyes.
QUOTE]

On the rare occasions I use sunscreen (out sailing, for example or snow fields), I don't put it on my forehead if I think the possibility of sweating is there.

 

[DougPaul]

On the rare occasions I use sunscreen (out sailing, for example or snow fields), I don't put it on my forehead if I think the possibility of sweating is there.

If you are on snow or water, you can get a sunburn under your hat from the reflected UV. Add altitude and some have gotten sunburn in their nostrils and/or the roof of their mouths... (Yes, high-altitude climbers need to put sunscreen in their nostrils.)

Doug

 

[TEO]

Sorry I don't believe everything written on the internet. (not you but the plethora of "expert sources" make me question what I should accept as truth)

How would you explain UV sunburn and not getting enough UV to make Vit d?

It's one thing to be short D because you don't go out side and another to say going out side would do no good or wouldn't work.

As I understand it, this is an established, accepted fact. But since you're sceptical, here's another source from the scientific community (that is peer-reviewed):

"In latitudes around 40 degrees north or 40 degrees south (Boston is 42 degrees north), there is insufficient UVB radiation available for vitamin D synthesis from November to early March. Ten degrees farther north or south (Edmonton, Canada) the “vitamin D winter” extends from mid-October to mid-March."

I'm fair-skinned and burn very easily. I also spend my fair share of time in the outdoors. I don't ever recall getting a sunburn in November, December, January, or February. Yet, I've definitely gotten them on similar outings in late-March & April. [Edit to add:] That said, the threshold for vitamin D production and tanning/burning your skin are likely different.

As for how do we then get vitamin D in the winter, the answer is simple: sardines.

 

[Little Rickie]

Maybe some other folks can chime in and tell us if they have gotten or can get sunburn between Nov and Feb in the northern states.

I'm dark haired and usually don't but I can burn.

Love sardines!

 

[sierra]

Personally I have never used sunscreen, even above 14,000ft, Ive only sunburned once in my life. As far as skin cancer, I think cancer is a crap shoot no matter what you do. I know this is not scientific and alot of previous posters seem quite intelligent, but I dont take medication except advil and I never go to the doctors, in fact I havent seen a doctor in 15 years or been to a hospital in 32 years ( for myself). I do not eat processed foods, I hike alot, I drink, smoke, but train and ignore colds and such as things to just deal with. Manmade health remedies are full of crap, so are vitamins and all the other crap people take or are prescribed. The medical field is motivated to get you in and keep you there imo. I read lables, items like sunscreen and such are full of unhealthy man made chemicals, Ill take my chances oh natural.

 

[Kevin Rooney]

Maybe some other folks can chime in and tell us if they have gotten or can get sunburn between Nov and Feb in the northern states.

I'm dark haired and usually don't but I can burn.

Love sardines!

If I spend a sunny winter day above treeline without sunscreen there's a good chance my face will be quite burned between the direct sun, reflected sun and the wind.