In Post-Menopausal Women, 'the Sunshine Vitamin' is One to Watch
By: Cathy Cram,
SparkPeople Blogger
1/25/2012 10:00 AM
: 23 comments
: 11,171 Views
Vitamin D is a hot topic in nutrition, and one that's become a focus in menopausal bone health. There are two forms of the vitamin, D2 and D3 (cholecalciferol), with D3 the form best metabolized by the body. Vitamin D is found in foods such as fish, eggs, fortified milk and the old remedy, cod liver oil.
Although this nutrient is found in foods, the greatest source for obtaining vitamin D is through the skin. When bare skin is exposed to ultraviolet light, it synthesizes vitamin D3 that is then stored in the liver. You only need 10-15 minutes of sun exposure during peak sun hours (between 10 a.m. and 2 p.m. in most locations) during the summer months to produce up to 10,000 IUs of the nutrient. After that short exposure you can continue with safe sun habits and slather on a broad-spectrum sunscreen.
How much vitamin D do you need? According to SparkPeople's resident dietitian, Becky Hand: In the last few years, many experts and health organizations urged the Institute of Medicine to revisit the DRI set for vitamin D and re-evaluate the latest research. After a thorough review, the recommendations for vitamin D did go up by two or threefold in some age groups. The current Recommended Dietary Allowance for vitamin D (as of November 2010) is:
Read more: How to Get Your Daily Dose of Vitamin D
Current research on vitamin D and its role in health suggests that there may be a correlation between low blood levels of this nutrient and the development of diseases such as osteoporosis, some cancers, diabetes, cardiovascular disease, hypertension and even obesity and depression. There are estimates that up to one half of all Americans are deficient in this vitamin, with an increased risk of deficiency in people who have one or more of these risk factors:
Postmenopausal women should determine their vitamin D blood level by having their healthcare provider order the 25-hydroxy vitamin D test. If your test level is under 32 mg per milliliter (some healthcare providers consider numbers higher that this to be in the low/deficient range), you are considered deficient and supplementation of the vitamin and follow up testing is needed.
There's conflicting medical discussion regarding what constitutes a deficient, low or normal level of vitamin D, as well as what is a safe and effective supplement dose. Many healthcare providers feel that the current guidelines for what constitutes normal 25-hydroxy vitamin D level and recommended daily intake are outdated and need revision.
A prospective cohort study of 72,000 post-menopausal women in the U.S. reported that the women who took in at least 600 IU/day of vitamin D3 (via diet and supplement) had a 37% decreased risk of osteoporotic hip fracture than the women who consumed less than 140 IU/day.
The data increasingly suggests that the threshold level of vitamin D3 daily intake needs to be at least 700-800 IUs, with several studies finding similar threshold levels needed for bone protection. Of interest, when vitamin D3 supplements were discontinued in study participants, bone density gains were lost within two years.
The steps to determining your optimal daily vitamin D requirement are:
Do you track your vitamin D intake? (You can easily track it on the SparkPeople Nutrition Tracker.) Do you know if you're getting an adequate amount of vitamin D? Have you ever been tested?
Although this nutrient is found in foods, the greatest source for obtaining vitamin D is through the skin. When bare skin is exposed to ultraviolet light, it synthesizes vitamin D3 that is then stored in the liver. You only need 10-15 minutes of sun exposure during peak sun hours (between 10 a.m. and 2 p.m. in most locations) during the summer months to produce up to 10,000 IUs of the nutrient. After that short exposure you can continue with safe sun habits and slather on a broad-spectrum sunscreen.
How much vitamin D do you need? According to SparkPeople's resident dietitian, Becky Hand: In the last few years, many experts and health organizations urged the Institute of Medicine to revisit the DRI set for vitamin D and re-evaluate the latest research. After a thorough review, the recommendations for vitamin D did go up by two or threefold in some age groups. The current Recommended Dietary Allowance for vitamin D (as of November 2010) is:
- Ages 1-70: 600 IU (International Units) daily
- Ages 71 and older: 800 IU daily
- Tolerable Upper Intake Level: ages 9 and up: 4000 IU daily
Read more: How to Get Your Daily Dose of Vitamin D
Current research on vitamin D and its role in health suggests that there may be a correlation between low blood levels of this nutrient and the development of diseases such as osteoporosis, some cancers, diabetes, cardiovascular disease, hypertension and even obesity and depression. There are estimates that up to one half of all Americans are deficient in this vitamin, with an increased risk of deficiency in people who have one or more of these risk factors:
- Dark skinned
- Live in northern latitudes
- Over the age of 50
- Post-menopausal
- A diet low in foods containing vitamin D
- Fat malabsorption syndromes
- Obesity
- Inflammatory bowel disease
Postmenopausal women should determine their vitamin D blood level by having their healthcare provider order the 25-hydroxy vitamin D test. If your test level is under 32 mg per milliliter (some healthcare providers consider numbers higher that this to be in the low/deficient range), you are considered deficient and supplementation of the vitamin and follow up testing is needed.
There's conflicting medical discussion regarding what constitutes a deficient, low or normal level of vitamin D, as well as what is a safe and effective supplement dose. Many healthcare providers feel that the current guidelines for what constitutes normal 25-hydroxy vitamin D level and recommended daily intake are outdated and need revision.
A prospective cohort study of 72,000 post-menopausal women in the U.S. reported that the women who took in at least 600 IU/day of vitamin D3 (via diet and supplement) had a 37% decreased risk of osteoporotic hip fracture than the women who consumed less than 140 IU/day.
The data increasingly suggests that the threshold level of vitamin D3 daily intake needs to be at least 700-800 IUs, with several studies finding similar threshold levels needed for bone protection. Of interest, when vitamin D3 supplements were discontinued in study participants, bone density gains were lost within two years.
The steps to determining your optimal daily vitamin D requirement are:
- Have your 25-hydroxy vitamin D tested.
- Discuss your results and treatment options with your healthcare provider.
- Follow up with additional testing if you tested low and modify your vitamin D intake if your test level hasn't increased to recommended levels.
Do you track your vitamin D intake? (You can easily track it on the SparkPeople Nutrition Tracker.) Do you know if you're getting an adequate amount of vitamin D? Have you ever been tested?
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Comments
YES, the blood test is expensive....and I hope to see it become standard with the CBC in the future!
I live in Arizona, and wear the best sun screen all over, which means even here LESS Vitamin D in the blood stream.
I plan to get my levels done again, soon.... - 1/26/2012 3:15:47 PM
wikipedia.org/wiki/Vitamin_D - 1/26/2012 12:05:18 PM
Your doctor can run a simple blood test to determine if you are deficient.
I require considerably higher supplementation - based on blood tests that I had run every six months when I first started the supplements. I now get tested annually. - 1/26/2012 7:19:50 AM
Good questions, but I do want to stress that for many people, it's unrealistic to be able to obtain adequate vitamin D from sun exposure. I focused more on vitamin D3 supplementation, since all the studies on this vitamin have used oral vitamin D supplements. The link to Becky Hand's article on vitamin D included in my blog provides more information on how to get your recommended amount from sun exposure:
"Sunlight is an excellent source of vitamin D. It is free and abundant. The ultraviolet B (UVB) rays from the sun convert a precursor into vitamin D, which becomes 25-hydroxyvitamin D in the liver and is then activated to 1, 25-hydroxyvitamin D in the kidneys. A person sitting outside in a bathing suit in New York City gets more vitamin D in 20 minutes than from drinking 200 glasses of milk. In fact, many experts suggest getting 10 minutes of unprotected sun on the arms and face or arms and legs, three times weekly and before applying sunscreen. But getting vitamin D from the sun isn't that simple. UVB rays vary greatly depending on latitude, cloud cover, time of year and time of day. Above 42 degrees north latitude, the sun’s rays do not provide sufficient D from November through February, for example. Remember too, that UVB rays do not penetrate glass or sunscreen with a sun protection factor (SPF) of 8 or more. The elderly, people who spend all or most of their time indoors, and people with darker skin also produce less vitamin D. Talk to your health care provider about unprotected sun exposure; not everyone in the scientific community thinks that even a little sun is a good idea, because of the risk of skin cancer."
As I noted, it's difficult to obtain adequate levels of vitamin D via sun exposure during winter months in northern latitudes. If you're unable to use the guidelines of exposure of arms or legs during summer months, then the recommendation for you would be to take an oral supplement of vitamin D. There aren't any clear guidelines on how much skin exposure is needed outside of what Becky and I provided, so taking a supplement would ensure you're getting your daily requirement. - 1/25/2012 2:46:39 PM
I'm an avid gardener but was very surprised to learn that my Vit. D. levels were extremely low despite time spent in the garden. After bringing them up to normal I can definitely tell the difference. - 1/25/2012 2:15:30 PM
a) How much of your body do you need to expose to direct sunlight to get the benefits? What did the subjects do in the study? Were they exposing just their faces, their arms and faces? Wearing bikinis? Naked? My doctor said it's not enough to expose just your face and neck if you're just going for 10-15 minutes once a week. He said exposing my arms (sleeveless or short sleeved shirt) or legs (shorts or knee length skirt) plus my face/neck would be about right. That's something I can do in the summer by taking a coffee break outside.
2) But what do you do if a) it's winter; or b) it's not mid-day; or c) you don't want to expose large expanses of skin to the sun? What would be a helpful guide there? if I walk to and from work (30 minutes total per day) during daylight hours but at 8 am and 5 pm and I'm just exposing my face and neck, am I getting enough if I do this 5 days a week?
3) And realistically, who is going to go sit outside in the middle of the day and then put on sunscreen? I put it on before I leave home, not while sitting on a park bench.
I look to Spark to convert scientific studies into practical tips. While there are some good tips in this article (e.g., about getting tested etc), the guidance on how to get Vitamin D from sunlight isn't specific enough to be helpful. - 1/25/2012 1:38:26 PM
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