This is really getting confusing. Experts at the Institute of Medicine of the National Academy of Sciences set recommended dietary requirements of nutrients. For vitamin D, the agency has recommended 200 IU (international units) per day up to age 50, 400 IU per day to age 70, and 600 IU per day for individuals over 70. They also set an upper limit of 2,000 IU that's considered the most a person should safely take to avoid vitamin D toxicity. Vitamin D3 is the kind to look for.
The recommended intakes are based on levels needed to prevent rickets, but 15 nutrition experts consider the guidelines outdated and called for an urgent overhaul in an editorial in the March edition of the American Journal of Clinical Nutrition. They complained that the guidelines give the public the impression that they are receiving enough vitamin D when an overwhelming amount of research indicates they are not. They even called the current dietary requirement a joke! but did not identify new limits. However, vitamin D advocates suggest the recommendation should be increased to 1,000 IU and perhaps as high as 2,000 IU. They also say the upper limit for daily intake could safely be set at 10,000 IU.
Research suggests vitamin D helps regulate cell growth and differentiation, the process that determines what a cell becomes. This is important in cancer. Cells should change normally, such as the way skin cells form throughout life, and not proliferate wildly to produce a malignant tumor. Vitamin D may inhibit cells from growing and dividing and may kill tumor cells in some cases. It may also cause cancer cells to change into more mature, harmless cells.
As such, vitamin D is seen both as a protectant against cancer and as a potential treatment.
I think that this is interesting: hundreds of patients were tested in the Buffalo area, and 70% of them were found to be deficient in vitamin D! African-Americans and other people with dark skin, as well as residents of regions that receive less sun, produce less vitamin D and experience higher cancer rates.
I read where one doctor said individuals should take low-cost supplements and have their vitamin D level regularly measured, like cholesterol, to make sure they are not getting too much.
I became interested in Vitamin D3 when I read that it helps with depression. I have been living for the last 12 years in northern Germany, where (until global warming changed our weather patterns this year) we normally have mostly gray dismal weather all year long. I had been getting Seasonal Affective Disorder every winter when we lived in sunny California, and when we moved here, the depression started lasting longer and longer until one year it didn't lift until August. I've been taking 36 micrograms (1500 IU) of vitamin D3 daily for a couple of years now. I no longer have suicidal depressions. I plan on upping that to 48 micrograms (2000 IU) when we switch to daylight saving time in the fall.
Based on my readings in the scientific literature, it appears that Vitamin D3 is, as you say, way too low in most of the population. And it is important for so many of our bodily functions.
I consume a lot of milk products, including powdered milk. I noticed when we moved here to Germany that there was no mention on the carton or box of fortifying the milk with Vitamin D, as we see in America. I looked up nutritional information on both the American USDA government site and in my nutritional information book for foods in Germany -- and, sure enough, milk isn't fortified here.
Since I don't go out in the sun because I burn easily, I just wasn't getting ANY Vitamin D. So now that I discovered the supplement I'm doing MUCH better in many areas of my life.
I too think that the recommendations for RDA as well as for the upper limits are way too low.
Thanks, I'm actually taking 2,000 IU now most days, but do want to get my blood checked just to make sure that is OK. I remember when I was a child, I sometimes heard this expression: the melancholy Swedes. I wonder if the northern latitude and lack of vitamin D from the sun in Sweden has been a contributing factor in this alleged depression of the Swedes, not just the culture or outlook of the people there.
Hardy, re: what you said about northern latitidues, etc. -- MS is also more prevalent in cetain geographic areas with less year-round sun. Recently, there been evidence that supports that D3 may be helpful for MS; that's why I'm taking it. Most of what I've seen about the potential benefits for different conditions has been is specifically about D3.
I've been supplementing my calcium that has D in it with 800 mg. of D3 a day. That's not based on anything scientific; just that it "feels right" to me, but I do plan to eventually consult with a nutritionist about everything I'm taking.
Naturally, D3 can be found in the following foods, although of course you won't be getting the dose we're talking about: green peppers, citrus fruits and juices, strawberries, tomatoes, broccoli, turnip greens and other leafy greens, sweet and white potatoes.
I live in MA and 2 yrs ago test came back LOW Vit D levels. Dr recommended 800 UI. Recently she increased it to 1500 - 2000 based on the fact that the government is going to change it's standards on Vit D3.
I also read an article last Nov. Vit D has anti-biotic values also and used to be used for that before penicillin was developed...(Can't remember the magazine but if you do a check under my user name it's in the thyroid thread somewhere.)
My endiocrinologist did a blood test on my to check my levels of Vitamin D and I came back in the low end of "normal" but he told me that's all changing now and told me to start supplementing with 1000 mg of vitamin D, no matter how much dairy I eat. I've been taking it for maybe a year now, and really can't tell much of a difference in my body aches or depression...but I guess it can't hurt.