Nutritiion

Risk Factors of Prostate Cancer

by

Vitamin D Deficiency?

Author: Dr. Stephen Chaney

Vitamin D

Is vitamin D deficiency one of the risk factors of prostate cancer? What if something as simple as maintaining optimal vitamin D status could decrease your risk of prostate cancer? There is a lot of indirect evidence suggesting that vitamin D deficiency might affect your risk of developing prostate cancer. For example:

  • Prostate cancer incidence and vitamin D deficiency parallel each other. Both are highest in northern latitudes, in African American men, and in older men.
  • Prostate cancer mortality rates are highest for patients diagnosed in the winter and at Northern latitudes.

However, clinical studies looking at the correlation between 25-hydroxy vitamin D (the biologically active form of vitamin D in the blood) and prostate cancer incidence have been inconsistent. Because of this there has been considerable controversy in the scientific community as to whether or not there was any correlation between vitamin D deficiency and prostate cancer.

Vitamin D Deficiency and Cancer

That’s what makes the recent headlines suggesting that vitamin D is associated with decreased risk of aggressive prostate cancer so interesting. Does this study show low vitamin D to be one of the risk factors of prostate cancer? Have the conflicting data on vitamin D deficiency and prostate cancer finally been resolved or is this just another case of dueling headlines? Let’s start by looking at the study itself.

This study (Murphy et al, Clinical Cancer Research, 20: 2289-2299, 2014) enrolled 667 men, aged 40-79 (average age = 62), from five urology clinics in Chicago over a four year period. These were all men who were undergoing their first prostate biopsy because of elevated serum PSA levels or an abnormal DRE (that’s doctor talk for digital rectal exam – the least favorite part of every guy’s physical exam). The clinics also drew blood and measured each patient’s 25-hydroxy vitamin D level at the time of the prostate biopsy.

This study had a number of important strengths:

  • It was conducted at a northern latitude. Because of that 41.2% of the men in this study were vitamin D deficient (<20 ng/ml) and 15.7% were severely vitamin D deficient (<12 ng/ml). That’s important because you need a significant percentage of patients with vitamin D deficiency to have any chance of seeing an effect of vitamin D status on prostate cancer risk.
  • The study had equal numbers of African American and European American men. That’s important because African American men have significantly lower 25-hydroxy vitamin D status and significantly higher risk of prostate cancer than European American men.
  • All of the men enrolled in the study had elevated PSA levels or abnormal DREs. That’s important because it meant that all of the men enrolled in the study were at high risk of having prostate cancer. That made the correlation between vitamin D status and prostate cancer easier to detect.
  • This was the first study to correlate 25-hydroxyvitamin D levels with prostate biopsies at the time of biopsy. That’s important because it allowed the investigators to distinguish between aggressive tumors (which require immediate treatment and have a higher probability of mortality) and slow growing tumors (which may simply need to be monitored).

The results were pretty dramatic:

  • In African American men vitamin D deficiency (<20 ng/ml) was associated with an increased risk of prostate cancer diagnosis at time of biopsy.
  • In both European American and African American men severe vitamin D deficiency (<12 ng/ml) was associated with increased risk of aggressive prostate cancer diagnosis at time of biopsy.

The authors concluded: “Our work supports the hypothesis that 25-hydroxy vitamin D is a potential biomarker that plays a clinically significant role in prostate cancer, and it may be a useful modifiable risk factor in the disease”.

That’s “science speak” for “adequate vitamin D status may help prevent prostate cancer” or “low vitamin D may indeed be one of the risk factors of prostate cancer.”

VitaminD-smashes-cancer

Why Have Some Studies Failed To Find A Correlation Between Vitamin D Deficiency and Prostate Cancer?

The authors of the current study had an interesting hypothesis for why some previous studies have not seen an association between vitamin D status and prostate cancer risk. When you compare all of the previous studies, the strongest correlations between vitamin D deficiency and prostate cancer were the studies conducted at northern latitudes, in African American men, or focusing on aggressive prostate cancer as an end point.

That offers a few clues as to why other studies may have failed to find a link between vitamin D status and prostate cancer risk. For example:

  • The clue that the correlation between vitamin D deficiency and prostate cancer risk was strongest at northern latitudes and with African American men suggests that you need to have a significant percentage of subjects with deficient or very deficient levels of 25-hydroxy vitamin D before you can see a correlation. Other studies may have failed to show a correlation simply because most of the men in the study had normal vitamin D status.
  • The clue that the correlation is strongest for aggressive prostate cancer is more subtle. The authors hypothesized that prostate cancer develops over a lifetime. If that is the case, measuring vitamin D deficiency at the time of diagnosis may not represent the lifetime vitamin D status. The vitamin D status could have decreased because the men were older or had become overweight, or the vitamin D status could have changed simply because they moved from one geographical location to another.

In contrast, the progression from benign to aggressive prostate cancer is generally short term, so it would be affected by the most recent vitamin D status. If that is the case, then the vitamin D status measured at the time of diagnosis may more accurately reflect the vitamin D deficiency that affected the aggressiveness of the cancer.

 

The Bottom Line

1)     The latest study suggests that vitamin D deficiency (<20 ng/ml serum 25-hydroxy vitamin D) may significantly increase the risk of prostate cancer. The correlation between low vitamin D status and prostate cancer risk is strongest for African American men.

2)     The study also suggests that severe vitamin D deficiency (<12 ng/ml serum 25-hydroxyvitamin D) may significantly increase the risk of aggressive prostate cancer in both African American and European American men.

3)     This is a very well done study, and it is consistent with many, but not all, of the previous studies. Clearly more research needs to be done. Future research should be focused on high risk subjects and subjects with low vitamin D status so that the correlation between vitamin D status and prostate cancer risk can be adequately tested.

4)     This is another example of why I recommend that you have your serum 25-hydroxy vitamin D level measured on a regular basis and that you aim to keep it in the normal range (20-80 ng/ml). Some experts believe that 30-80 ng/ml is optimal.

5)     If you are African American, overweight, live in northern latitudes or it is winter, you may need supplemental vitamin D3. 1,000 – 4,000 IU/day of vitamin D3 is generally considered to be safe. If higher amounts are needed to normalize your 25-hydroxy vitamin D levels I recommend that you consult your physician for the appropriate dose.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Are MultiVitamins a Waste of Money?

by

The Multivitamin Controversy You Never Heard About

Author: Dr. Stephen Chaney

money-waste Are multivitamins a waste of money?  You probably saw the recent headlines telling you that “the experts” have concluded that multivitamins are a waste of money. The article (Gualler et al., Annals of Internal Medicine, 159: 850-851, 2013) that generated all of the headlines was an editorial, which means it was an opinion piece, not a scientific study. It represented the opinion of five very prominent doctors, but it was, at the end of the day, just their opinion.

At the time I pointed out fallacies of their arguments in a “Health Tips From the Professor” article (MultiVitamins-Waste Money?). But, what do I know? I have only published 114 papers in peer reviewed journals and two book chapters on nutrition.

It turns out that I’m not the only expert who feels this way. Five very prominent experts recently published rebuttals concluding that the authors of the original editorial ignored “decades of nutrition research and diet monitoring of the U.S. population to reach this misleading conclusion” (Frei et al, Annals of Internal Medicine, 160: 807-809, 2014).

Who Are These Experts?

Before I share what these experts said, I should probably share their qualifications:

Balz Frei, PhD

  • Distinguished Professor of Biochemistry & Biophysics & Director of the Linus Pauling Institute, Oregon State University
  • 203 publications

Bruce N. Ames, PhD

  • Director of the Nutrition & Metabolism Center, Children’s Hospital Oakland Research Institute
  • 540 publications

Jeffrey B. Blumberg, PhD

  • Professor, Freidman School of Nutrition Science and Policy and Director of the Antioxidants Research Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University
  • >300 publications

Walter C. Willet, MD, DrPH

  • Chair of the Department of Nutrition, Harvard School of Public Health
  • 1,422 publications

Thomas R. Friberg, MD, MS

  • Professor of Ophthamology and Director of the Medical & Surgical Retinal Division of the University of Pittsburg School of Medicine
  • Principle investigator for the AREDS and AREDS II clinical studies.
  • 134 publications

As you can see, these are not just your run of the mill scientists. They are the top experts in the field.

 

Are You Wasting Your Money On Multivitamins?

Are multivitamins a waste of money?   What did these experts say?

  1. They started by pointing out that few people in the United States follow the USDA dietary guidelines, and “consequently, most people in the United States even in cities like Raleigh, Durham, and Chapel Hill are not well nourished”. Specifically:
  • 93% of U.S. adults don’t get enough vitamins D & E from their diet.
  • 71% of U.S. adults don’t get enough vitamin K from their diet.
  • 61% of U.S. adults don’t get enough magnesium from their diet.
  • 50% of U.S. adults don’t get enough calcium and vitamin A from their diet.
  1. They also pointed out that adequate intake of micronutrients is essential for normal body function and to support good health. Specifically:
  • Vitamins A, D, iron and zinc are required for normal immune function
  • Folic acid is required for neurological development. For example, “A multivitamin supplying folic acid dramatically decreases the risk of neural tube defects and is recommended for women of childbearing age.”
  • The AREDS and AREDS II studies have established the value of supplementation in preventing vision loss due to age-related macular degeneration.
  1. They pointed out that largest (15,000 male physicians) and longest (13 years) randomized, placebo controlled trial of a multivitamin (the Physician’s Health Study II) showed a:
  • 8% reduction in cancer incidence and a 12% reduction in cancer deaths
  • 9% reduction in cataract formation
  1. Finally, they pointed out that the claims that supplement use might actually increase mortality were overemphasized. Specifically:
  • The claims that high dose vitamin E increase mortality have been refuted by subsequent studies. I have discussed that in detail in my eBook, “The Myths of the Naysayers” (available for free to all subscribers of “Health Tips From the Professor”).
  • Only 1.1% of the U.S. population consumes more than the recommended upper limit for vitamin A (10,000 IU/day).
  • The only warning that actually holds up is that smokers should avoid high dose beta-carotene.
  • More importantly, all of those concerns involved high dose individual supplements. There is no evidence for any risk from taking a daily multivitamin.

In summary, the experts concluded: “Taking a daily multivitamin and mineral supplement not only helps fill known nutritional gaps in the diet of most persons in the United States (thereby ensuring normal body function and supporting good health), but may have the added benefit of helping to reduce the risk for chronic disease.”

 

The Bottom Line

1)     Are multivitamins are a waste of money?  No.  That was simply the opinion of one group of experts. Other experts have come to the exact opposite conclusion.

2)     Of course, it was only the negative opinion that made the headlines. Somehow the opinion that multivitamins are valuable for most Americans never got the attention of the press.

3)     According to the experts mentioned in this article, multivitamins play an important role in filling well documented nutrition gaps in the U.S. population, assuring normal body function and helping preserve good health. There is evidence that they may have a modest role in reducing the risk for chronic diseases, and there is no evidence that multivitamin supplements increase the risk of mortality.

4)     Of course, you shouldn’t expect miracles from your multivitamin. It’s not going to help you leap tall buildings in a single bound. Your multivitamin should just be one small part of your holistic health program of diet, exercise, weight control and supplementation.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

 

Health Tips From The Professor