While an Institute of Medicine committee has stated that 4000 IU/day is a safe dosage, their recommended minimum daily intake is only 600 IU/day. According to the study in the journal Anticancer Research:
"The supplemental dose ensuring that 97.5 percent of this population achieved a serum 25(OH)D of at least 40 ng/ml was 9,600 IU/d ... Universal intake of up to 40,000 IU vitamin D per day is unlikely to result in vitamin D toxicity."
Meanwhile, during the winter, pre-teen girls especially may need more vitamin D to have healthy bones, according to a separate new study. The research found that teen girls need a vitamin D intake of about 750 IU per day to have levels in their blood that allow for healthy bone growth.
This amount is higher than the U.S. Institute of Medicine's recommendation of 600 IU per day.
"... [W]earing sun block and not spending time outside can cut down on the vitamin D we get from the sun."
This new research confirms what I have been saying for some time now, that Americans simply are not getting enough vitamin D to maintain healthy bones, much less getting enough to fight off the diseases that vitamin D has been shown to cut the risk of in half.
I was one of the first to publicly advocate increasing your vitamin D level. This new study validates the concept that therapeutic doses of up to 40,000 IU a day is unlikely to result in vitamin D toxicity.
It has been my experience that many are still nervous about taking doses larger than 1000 to 2000 units per day. This is unfortunate as most adults without sun exposure will need 6-8,000 units of vitamin D per day to attain healthy vitamin D levels.
Earlier studies have shown that optimizing your vitamin D levels could help you to prevent at least 16 different types of cancer including pancreatic, lung, ovarian, prostate, and skin cancers.
The four major points to remember about vitamin D are the following:
- Your best source for this vitamin is exposure to the sun, without sunblock on your skin, until your skin turns the lightest shade of pink. While this isn't always possible due to the change of the seasons and your geographic location (and your skin color), this is the ideal to aim for. Vitamin D supplementation can fill the gaps during the winter months outside of the tropics, when healthy sun exposure is not an option.
- When you do supplement with vitamin D, you'll only want to supplement with natural vitamin D3 (cholecalciferol). Do NOT use the synthetic and highly inferior vitamin D2, which is the one most doctors will give you in a prescription most of the time unless you ask specifically for D3.
- Get your vitamin D blood levels checked! The only way to determine the correct dose is to get your blood tested since there are so many variables that influence your vitamin D status. I recommend using Lab Corp in the U.S.
The correct test your doctor needs to order is 25(OH)D, also called 25-hydroxyvitamin D, which is the better marker of overall D status. This is the marker that is most strongly associated with overall health.
What is Vitamin D?
Vitamin D is a steroid hormone that influences virtually every cell in your body, and is easily one of nature's most potent cancer fighters. Receptors that respond to vitamin D have been found in nearly every type of human cell, from your bones to your brain.
Your organs can convert the vitamin D in your bloodstream into calcitriol, which is the hormonal or activated version of vitamin D. Your organs then use it to repair damage, including damage from cancer cells and tumors.
Theories linking vitamin D to certain cancers have been tested and confirmed in more than 200 epidemiological studies, and understanding of its physiological basis stems from more than 2,500 laboratory studies, according to epidemiologist Cedric Garland, DrPH, professor of family and preventive medicine at the UC San Diego School of Medicine.
Dr. Garland is widely regarded as the leading epidemiologist on vitamin D and its relation to health. He led one study on vitamin D for cancer prevention and proposed a new model of cancer development -- dubbed DINOMIT-- that is centered on a loss of cancer cells' ability to stick together.
Pre-Teen Girls and Vitamin D
In one of the new studies above, Kevin Cashman, head of the School of Food and Nutritional Sciences at University College Cork in Ireland, found that teen girls need a vitamin D intake of about 750 IU per day to have levels in their blood that allow for healthy bone growth.
Please remember though that the lowest level of vitamin D is needed to help bone growth. Far higher levels are required to get the benefits for treating cancer, heart disease and the many other conditions that vitamin D benefits.
According to Dr. Steven Abrams, professor of pediatrics at the Baylor College of Medicine in Houston:
"It means that below that level that there's a risk that all of the needs for bone health are not being met."
But is 750 IU per day really enough to meet the needs of a growing body?
My Recommendations for Vitamin D Dosing
When you are not able to get healthy, safe, daily sun exposure, the new research referenced in the article above indicates the average efficacious dose of vitamin D for reaching the levels thought to fight disease in study subjects was found to be 9,600 IU per day, well above the rates currently recommended by either the government or even myself.
And that dose only produced blood levels of 40 ng/ml in study subjects, not nearly the level of 60 ng/ml that I currently recommend for optimal disease fighting.
Ideally, it is best to get your vitamin D from sun exposure. However, it's important to realize that sun exposure needs are dependent on numerous factors, such as the color of your skin, your location, age, altitude, and season.
The study above found that daily intakes of vitamin D by adults in the range of 4000-8000 IU were needed to maintain blood levels of vitamin D metabolites in the range needed to reduce by about half the risk of breast cancer, colon cancer, multiple sclerosis, and type 1 diabetes.
So, although these recommendations may put you closer to the ballpark of what most people likely need, it is simply impossible to make a blanket recommendation that will cover everyone's needs. For instance, the lighter your skin, the more vitamin D you will produce from sun exposure, and the closer you live to the equator, the more vitamin D the sun on your skin will produce.
So it is a fine science trying to figure out how much vitamin D your body is able to produce naturally. You really need to be your own vitamin D level sleuth, and I suggest you do the necessary work, because this is truly one of the most powerhouse vitamins available for your health, and one that and the majority of people currently are deficient.
The only way to truly optimize your own vitamin D levels are to work with your doctor taking the 25 OH D test and then supplement with a dose somewhere in the range of 5000-40,000, and retest your blood levels after a few months of supplementation.
According to the study above entitled "Vitamin D Supplement Doses and Serum 25-Hydroxyvitamin D in the Range Associated with Cancer Prevention":
"Studies indicate that intake of vitamin D in the range from 1,100 to 4,000 IU/d and a serum 25-hydroxyvitamin D concentration [25(OH)D] from 60-80 ng/ml may be needed to reduce cancer risk. Per 1000 IU/day, 10 ng/ml rise starting at 10 ng/ml; only 8 ng/ml rise starting at 30 ng/ml; only 5 ng/ml rise starting at 50 ng/ml."
This means a law of diminishing returns applies to vitamin D supplementation, as after 30ng/ml the amount your blood level vitamin D rises is LESS with each further increase of 1000 IU. This is why doses approaching 10,000 IU may be necessary to fight cancer for people with already low blood levels of vitamin D.
For children below the age of 5 I recommend 35 IU per pound per day and for pregnant women I recommend anywhere from 5,000 to 10,000 IU per day. But again, there really is no "right" amount unless you take the time to have your blood levels checked.
And I certainly wouldn't recommend more than 40,000 IU per day for anyone at this time, especially without monitoring your blood level of vitamin D.
Optimal Vitamin D Levels Explained
The "normal" 25-hydroxyvitamin D lab range is between 20-56 ng/ml. As you can see from this discussion, this conventional range is really a sign of deficiency, and is too broad to be ideal.
In fact, your vitamin D level should not be below 32 ng/ml, and any levels below 20 ng/ml are considered serious deficiency states, increasing your risk of cancer and autoimmune diseases like multiple sclerosis and rheumatoid arthritis, just to name a few.
The OPTIMAL value that you're looking for is 50-65 ng/ml and for those with diseases probably 60-85 ng/ml. Remember that if you were in the sun nearly every day with large amounts of your skin exposed and not taking any oral vitamin D, your level would be around 100 ng/ml.
This range applies for everyone: children, adolescents, adults and seniors.
Keeping your level in this range, and even erring toward the higher numbers in this range, is going to give you the most protective benefit. And the way you maintain your levels within this range is by getting tested regularly -- say two to four times a year in the beginning, and adjusting your vitamin D intake accordingly.
Astaxanthin as an Internal Sunscreen
Too much sun exposure can be just as much of a problem as too little, but you want to avoid commercial sunscreens at all costs, as they put harmful chemicals into your bloodstream that can cause potential health risks far outweighing the gains of blocking out the good UVB rays in the first place.
Astaxanthin has recently jumped to the front of the line in terms of its status as a "supernutrient," becoming the focus of a large and growing number of peer-reviewed scientific studies. One of the benefits of astaxanthin that has piqued the interest of researchers is its ability to protect your skin from the sun, and thereby reduce the signs of aging.
Cyanotech Corporation funded a study through an independent consumer research laboratory to measure the skin's resistance to both UVA and UVB light, before and after astaxanthin supplementation.
The result was that in only two weeks of taking 4mg per day, subjects showed a significant increase in the amount of time necessary for UV radiation to redden their skin.
Animal studies lend further evidence to astaxanthin's effects as an internal sunscreen.
Consider the following:
- In 1995, hairless mice were fed various combinations of astaxanthin, beta-carotene and retinol for four months. After irradiation, astaxanthin alone or in combination with retinol was substantially effective in preventing photoaging of the skin (as measured by markers for skin damage
- In a 1998 study with rats, astaxanthin was found to be 100 times stronger than beta-carotene and 1000 times stronger than lutein in preventing UVA light-induced oxidative stress.
The Journal of Dermatological Science published a study in 2002 that found astaxanthin is able to protect against alterations in human DNA induced by UVA light exposure.
So supplementing with astaxanthin is something you want to consider to maximize your body's internal ability to fight damage from the sun while you are getting safe sun exposure to optimize your vitamin D levels.
Astaxanthin is certainly a better sunscreen option than most commercial sunscreens, which I do not recommend.
How to Further Optimize your Vitamin D Levels
Having your doctor check your vitamin D levels is certainly the best step to take in your quest to use this vitamin to its full potential as an anti-cancer, anti-disease hormone. And getting good quality and safe sun exposure on a daily basis is also a step in the right direction.
Other steps you can take to maximize your vitamin D levels while protecting yourself from sun damage:
- If you really need some form of sun protection because you're outside for extended periods of time, either use light clothing to cover exposed areas, or look for safer, natural sunscreen products that contain no petrochemicals, which you can likely find in your local health food store.
- Another excellent resource is the EWG's "Skin Deep Report," where you can find out which brands of sunscreens are free from toxic chemicals.
- My book Dark Deception, goes into FAR more details about vitamin D and sunlight.
- Eat plenty of foods that provide superior levels of vitamin D including fresh wild salmon, sardines, shrimp, raw milk and raw eggs.
- Use a safe indoor tanning bed during times when outdoor sun exposure is limited.
For a comprehensive list of resources about vitamin D, please see this previous article. And pre-teen girls, who need to be concerned about growing strong bones, need even more vitamin D than has been previously recommended.