Vitamin D and prostate cancer: a strong set of recommendations

A new review makes some strong recommendations regarding the impact of serum levels of 25-hydroxyvitamin D — also known as 25(OH)D — and its metabolites and the effects on risk for several forms of cancer (including aggressive forms of prostate cancer).

We should be clear up front, however, that these recommendations are based primarily on epidemiological and observational data. Only one randomized clinical trial has ever substantiated the clinical impact of 25(OH)D on risk for or progression of any type of cancer, as far as we are aware. That trial, by Lappe et al., was in post-menopausal women, and therefore excluded any patient with prostate cancer. Furthermore, that trial compared vitamin D + calcium supplementation to calcium supplementation alone.

The entire article, by Garland et al., is available on line for interested readers (but you do have to register as a member of the OncologySTAT web site to access the full article). Here are the most critical points made in the review, with particular emphasis on prostate cancer:

  • High serum levels of 25(OH)D are associated with lower incidence rates of many common cancers (including colon, pancreatic, and aggressive forms of prostate cancer).
  • People living at or higher than 30° latitude north or south of the equator — or who have a predominantly indoor lifestyle — are at high risk for many types of cancer because of the high prevalence of vitamin D deficiency.
  • In the United States and Canada, each year, raising the minimum year-round serum level of 25(OH)D to between 40 and 60 ng/ml is projected to prevent
    • 58,000 new cases of breast cancer
    • 49,000 new cases of colon cancer
    • 75 percent of the deaths from these diseases
  • In addition, raising the minimum year-round serum level of 25(OH)D to between 40 and 60 ng/ml is projected to reduce case fatality rates (mortality rates) of patients who have breast, colon, and prostate cancer by 50 percent.
  • There are no known, “unreasonable” risks from a daily intake of 2,000 IU/d of vitamin D3, or from a year-round serum level of 40 to 60 ng/ml of 25(OH)D.

We should note immediately that nearly everyone in the US and Canada lives north of latitude 30°N . Only those living in southern Florida and the southern tip of Texas (Corpus Christi, Laredo, Brownsville) live south of latitude 30°N.

The specific recommendations made in the review are that

  • Vitamin D3 (cholecalciferol) should be used as the primary form of vitamin D supplement as opposed to vitamin D2 (ergocalciferol) because cholecalciferol is the normal product of biosynthesis of vitamin D in humans and is believed to be more effective in humans (at least in higher doses).
  • The recommended adequate intake of vitamin D3 is a minimum of 2,000 to 4,000 IU/d.
  • The minimal upper limit of vitamin D3 is 5,000 IU/d (but some specialists recommend up to 10,000 IU/d).

There is an implicit recommendation that we should all be tested to see if our serum 25(OH)D levels are at least 40-60 ng/ml, and preferably higher.

Now the one thing that is still not clear to this author is at what age we must start to maintain such 25(OH)D levels in our blood stream if we are to have effective impact on cancer prevention. In other words, will starting at age 50 have the same impact as starting at age 25? Something tells me that that is not the case, and that truly effective prevention  strategies of this type have to be in place for a lifetime — but we don’t have the data to make that determination.

What’s the bottom line here? Well, vitamin D is generally good for you, will certainly prevent the age-old problem of rickets (a disease commonly observed in undernourished children), and — at least at the minimum levels suggested in this review — and has minimal risk for adverse events (primarily rare cases of hypercalcemia).

Can we make a guarantee to a 50-year-old man today that if he abides by the above recommendations that it will reduce his risk of death from prostate cancer? No we can’t. But it will probably improve his health generally — especially if he also exercises regularly and follows a “heart-healthy diet.”

4 Responses

  1. According to my oncologist, Las Vegas is a great place to live for D3. Still I take the supplement. The problem with over-exposure to the sunlight is risk of another cancer — skin cancer. Skin cancer is very common in Las Vegas. Limiting direct sunlight and supplementation with D3 is best!

    Just my thought…

  2. Sorry, I think you confused rickets and scurvy. (Citrus and vitamin — common problem with a diet of salt beef and biscuit. The term “limey” for British Sailors came from the lime juice stores taken on board when this was discovered.) Otherwise, great article.

  3. You’re absolutely correct. I did. Mea culpa. Comes from trying to do too much too fast!

    I have duly corrected the article above.

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