Up to 85 percent of all Americans have vitamin D levels that are too low.
Cancer cells and vitamin D
Instead of differentiating into normal cells, cancer cells divide so rapidly they do not turn into the specialized cells needed by the body. Instead they divide forever overwhelming the host with nonfunctional cancer cells.
Vitmain D3 helps regulate cell growth and differentiation. It also increases the self destruction of damaged cells, while at the same time reducing the growth of new blood vessels cancer cells need to spread.
Studies on vitamin D
A study by Dr. William Grant, internationally recognized research scientist and vitamin D expert, found that about 30 percent of cancer deaths – which amounts to two million worldwide and 200,000 in the United States – could be prevented each year with higher levels of vitamin D.
A large 2007 study supported a protective effect of dietary vitamin D on premenopausal breast cancer risk.
The findings of a 2008 study strongly suggested that post-menopausal women with a higher blood level of vitamin D had less breast cancer.
Additionally, another study presented at an American Society of Clinical Oncologists meeting found that breast cancer patients deficient in vitamin D were 94 percent more likely to have their cancer spread. However, low levels of vitamin D may be the result of disease related inflammation, not the cause.
Even though several previous studies had shown higher blood levels of vitamin D correlated with a 50 percent reduction in breast cancer risk, a large 2014 Lancet meta-analysis found no evidence of reduced cancer risk with vitamin D supplementation.
Sources of vitamin D
Food sources of vitamin D include cod liver oil, fish, dairy products, and egg yolk. However, the conversion of vitamin D to its active form can be inhibited by overconsumption of animal foods and high blood calcium levels.
Since the human body was designed to produce vitamin D in response to sunlight, 20 minutes of sun exposure without sun screen is the best way to get your “D”. Just make sure you never get burned. A study by UC San Diego researchers confirmed that UVB sun exposure was inversely associated with breast cancer rates.
Unfortunately, since the amount of sun reaching most of the U.S. is insufficient for less than half of the year, some supplementation may be necessary. Ask your doctor about taking a vitamin D supplement.
Only supplement with natural vitamin D3 (not the synthetic, highly inferior and more expensive vitamin D2 often covered by insurance). D2 does not work nearly as well.
How much D3 to take
Even though the RDA for vitamin D is 600 IU, some experts recommend getting 1,000 IU or even more. According to a 2010 study by Dr. Creighton Garland, from UC San Diego Moores Cancer Center: “daily intakes of vitamin D by adults in the range of 4000-8000 IU are needed to maintain blood levels of vitamin D metabolites.”
If you take vitamin D supplements, periodic blood tests must be done to make sure you are getting enough D3, but not too much.
Checkout Dr. Mercola’s article for more tips on vitamin D and cancer prevention.
DCIS Redefined 
Excellent article. Thank you. I’ve been a Vitamin D advocate for a decade. But I have learned from experience that Vitamin D, taken in pill form, must be accompanied by certain partner compounds in order for us to benefit fully (or even to protect us from harm). Here is a good article from Dr Mercola, with this excerpt:
“Vitamins D and K: ‘The Gatekeeper and the Traffic Cop’
One of the undisputed benefits vitamin D provides for you is improved bone development by helping you ABSORB calcium. This is not news — we have known about vitamin D and the absorption of calcium for many decades.
But there is new evidence that it is the vitamin K (specifically, vitamin K2) that directs the calcium to your skeleton, while preventing it from being deposited where you don’t want it — i.e., your organs, joint spaces, and arteries. A large part of arterial plaque consists of calcium deposits (atherosclerosis), hence the term “hardening of the arteries.”
Vitamin K2 activates a protein hormone called osteocalcin, produced by osteoblasts, which is needed to bind calcium into the matrix of your bone. Osteocalcin also appears to help prevent calcium from depositing into your arteries.
You can think of vitamin D as the gatekeeper, controlling who gets in, and vitamin K as the traffic cop, directing the traffic to where it needs to go.
Lots of traffic — but no traffic cop — means clogging, crowding, and chaos everywhere!
In other words, without the help of vitamin K2, the calcium that your vitamin D so effectively lets in might be working AGAINST you — by building up your coronary arteries rather than your bones.
There is even evidence that the safety of vitamin D is dependent on vitamin K, and that vitamin D toxicity (although very rare with the D3 form) is actually caused by vitamin K2 deficiency.”
A personal story: As noted, I’ve taken D3 supplements for many years (not megadoses, just ~2000 iu per day to keep my levels at 40-60 ng/ml). But 2 years ago, I began seeing artery thickening on routine scans. (I’m 52.) My Dr was puzzled, as arterial disease is not in my history or family history, and I’m a fitness nut. After one year of antioxidants and other unsuccessful remedies, Vitamin K2 (MK7) supplements and magnesium chloride gel (transdermal) were the key to a normal scan once again.
Thank you again and good health to all!
Kay
Here is the article.
http://articles.mercola.com/sites/articles/archive/2011/03/26/the-delicate-dance-between-vitamins-d-and-k.aspx
Kay, thanks for all the info regarding vitamin K2 and the article link! 🙂 Donna