Risk Factors of Prostate Cancer

Written by Dr. Steve Chaney on . Posted in current health articles, Nutritiion, Vitamins and Health

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.

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Comments (4)

  • Theresa Bankert

    |

    Is there a version #1 of the Myths e-books? The one I downloaded says #2. Just curious.
    Thank you,
    Theresa

    Reply

    • Dr. Steve Chaney

      |

      Dear Theresa,

      Book #1 of the “Myths” eBook series is still in preparation. I’m following the Star Wars model 🙂

      Dr. Chaney

      Reply

  • support prostate health

    |

    Everything is very open with a precise explanation of the challenges.

    It was truly informative. Your site is very helpful.
    Many thanks for sharing!

    Reply

  • omega 3 fatty acids prostate cancer risk

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    Cancer cann often be detected through a rectal examination conducted byy a doctor and through a prostate-specific antigen (PSA)
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Latest Article

Can Plant-based Diets Be Unhealthy?

Posted September 10, 2019 by Dr. Steve Chaney

Do Plant-Based Diets Reduce Heart Disease Deaths?

Author: Dr. Stephen Chaney

 

plant-based diets vegetablesPlant-based diets have become the “Golden Boys” of the diet world. They are the diets most often recommended by knowledgeable health and nutrition professionals. I’m not talking about all the “Dr. Strangeloves” who pitch weird diets in books and the internet. I am talking legitimate experts who have spent their life studying the impact of nutrition on our health.

Certainly, there is an overwhelming body of evidence supporting the claim that plant-based diets are healthy. Going on a plant-based diet can help you lower blood pressure, inflammation, cholesterol and triglycerides. People who consume a plant-based diet for a lifetime weigh less and have decreased risk of heart disease, diabetes, and cancer.

But, can a plant-based diet be unhealthy? Some people consider a plant-based diet to simply be the absence of meat and other animal foods. Is just replacing animal foods with plant-based foods enough to make a diet healthy?

Maybe not. After all, sugar and white flour are plant-based food ingredients. Fake meats of all kinds abound in our grocery stores. Some are very wholesome, but others are little more than vegetarian junk food. If you replace animal foods with plant-based sweets, desserts, and junk food, is your diet really healthier?

While the answer to that question seems obvious, very few studies have asked that question. Most studies on the benefits of plant-based diets have compared population groups that eat a strictly plant-based diet (Seventh-Day Adventists, vegans, or vegetarians) with the general public. They have not looked at variations in plant food consumption within the general public. Nor have they compared people who consume healthy and unhealthy plant foods.

This study (H Kim et al, Journal of the American Heart Association, 8:e012865, 2019) was designed to fill that void.

 

How Was The Study Done?

plant-based diets studyThis study used data collected from 12,168 middle aged adults in the ARIC (Atherosclerosis Risk in Communities) study between 1987 and 2016.

The participant’s usual intake of foods and beverages was assessed by trained interviewers using a food frequency questionnaire at the time of entry into the study and again 6 years later.

Participants were asked to indicate the frequency with which they consumed 66 foods and beverages of a defined serving size in the previous year. Visual guides were provided to help participants estimate portion sizes.

The participant’s adherence to a plant-based diet was assessed using four different well-established plant-based diet scores. For the sake of simplicity, I will include 3 of them in this review.

  • The PDI (Plant-Based Diet Index) categorizes foods as either plant foods or animal foods. A high PDI score means that the participant’s diet contains more plant foods than animal foods. A low PDI score means the participant’s diet contains more animal foods than plant foods.
  • The hPDI (healthy plant-based diet index) is based on the PDI but emphasizes “healthy” plant foods. A high hPDI score means that the participant’s diet is high in healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, coffee and tea) and low in animal foods.
  • The uPDI (unhealthy plant-based diet index) is based on the PDI but emphasizes “unhealthy” plant foods. A high uPDI score means that the participant’s diet is high in unhealthy plant foods (refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts) and low in animal foods.

For statistical analysis the scores from the various plant-based diet indices were divided into 5 equal groups. In each case, the group with the highest score consumed the most plant foods and least animal foods. The group with the lowest score consumed the least plant foods and the most animal foods.

The health outcomes measured in this study were heart disease events, heart disease deaths, and all-cause deaths. Again, for the sake of simplicity, I will only include 2 of these outcomes (heart disease deaths and all-cause deaths) in this review. The data on deaths were obtained from state death records and the National Death Index. (Yes, your personal information is available on the web even after you die.)

 

Do Plant-Based Diets Reduce Heart Disease Deaths?

plant-based diets reduce heart deathsThe participants in this study were followed for an average of 25 years.

The investigators looked at heart disease deaths over the 25 years and compared people with the highest intake of plant foods to people with the highest intake of red meat and other animal foods. The results were:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, coffee and tea) had a 19-32% lower risk of dying from heart disease than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods (refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts) had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

When the investigators looked at all-cause deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had an 11-25% lower risk of dying from any cause than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

What Else Did The Study Show?

The investigators made a couple of other interesting observations:

  • The association of the overall diet with heart disease and all-cause deaths was stronger than the association of individual food components. This underscores the importance of looking at the effect of the whole diet on health outcomes rather than the “magic” foods you hear about on Dr. Strangelove’s Health Blog.
  • Diets with the highest amount of healthy plant foods were associated with higher intake of carbohydrates, plant protein, fiber, and micronutrients, including potassium, magnesium, iron, vitamin A, vitamin C, folate, and lower intake of saturated fat and cholesterol.
  • Diets with the highest amount of unhealthy plant foods were associated with higher intake of calories and carbohydrates and lower intake of fiber and micronutrients.

The last two observations may help explain some of the health benefits of plant-based diets.

 

Can Plant-Based Diets Be Unhealthy?

plant-based diets unhealthy cookiesNow, let’s return to the question I asked at the beginning of this article: “Can plant-based diets be unhealthy?” Although some previous studies have suggested that unhealthy plant-based diets might increase the risk of heart disease, this study did not show that.

What this study did show was that an unhealthy plant-based diet was no better for you than a diet containing lots of red meat and other animal foods.

If this were the only conclusion from this study, it might be considered a neutral result. However, this result clearly contrasts with the data from this study and many others showing that both plant-based diets in general and healthy plant-based diets reduce the risk of heart disease deaths and all-cause deaths compared to animal-based diets.

The main message from this study is clear.

  • Replacing red meat and other animal foods with plant foods can be a healthier choice, but only if they are whole, minimally processed plant foods like whole grains, fruits, vegetables, nuts, legumes, coffee and tea.
  • If the plant foods are refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts, all bets are off. You may be just as unhealthy as if you kept eating a diet high in red meat and other animal foods.

There is one other subtle message from this study. This study did not compare vegans with the general public. Everyone in the study was the general public. Nobody in the study was consuming a 100% plant-based diet.

For example:

  • The group with the highest intake of plant foods consumed 9 servings per day of plant foods and 3.6 servings per day of animal foods.
  • The group with the lowest intake of plant foods consumed 5.4 servings per day of plant foods and 5.6 servings per day of animal foods.

In other words, you don’t need to be a vegan purist to experience health benefits from adding more whole, minimally processed plant foods to your diet.

 

The Bottom Line

A recent study analyzed the effect of consuming plant foods on heart disease deaths and all-cause deaths over a 25-year period.

When the investigators looked at heart disease deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had a 19-32% lower risk of dying from heart disease than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

When the investigators looked at all-cause deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had an 11-25% lower risk of dying from any cause than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

The main message from this study is clear.

  • Replacing red meat and other animal foods with plant foods can be a healthier choice, but only if they are whole, minimally processed plant foods like whole grains, fruits, vegetables, nuts, legumes, coffee and tea.
  • If the plant foods are refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts, all bets are off. You may be just as unhealthy as if you kept eating a diet high in red meat and other animal foods.

A more subtle message from the study is that you don’t need to be a vegan purist to experience health benefits from adding more whole, minimally processed plant foods to your diet. The people in this study were not following some special diet. The only difference was that some of the people in this study ate more plant foods and others more animal foods.

For more details on the study, read the article above.

 

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.

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