Vitamin D and Cancer Risk?

Written by Dr. Steve Chaney on . Posted in Vitamin D and Cancer Risk

Does Vitamin D Reduce Cancer Risk?

Author: Dr. Stephen Chaney

 

vitamin d and cancer riskThe relationship between vitamin D and cancer risk is controversial. Some studies suggest that vitamin D reduces cancer risk. In those studies, the risk reduction was strongest for colon cancer, lung cancer, and breast cancer. However, other studies have found no association between vitamin D status and cancer risk.

Most previous studies have been conducted in European and American populations. Very few of the studies have been done in Asian populations. So, the authors of the current study (S. Budhathoki et al, BMJ 2018; 360:k671, doi: 10.1136/bmj.k671 ) focused their attention on the Japanese population.

How Was The Study Done?

vitamin d and cancer risk studyThe data for this study were drawn from the much larger Japanese Public Health Center (JPHC) Study. THE JPHC Study is an ongoing study investigating the role of lifestyle and other factors on the risk of cancer and other diseases. The study began in 1990 and enrolled 140, 420 participants aged 40-59.

All participants in the JPHC study filled out a detailed food frequency questionnaire at the time of entry into the study. A subset of participants also donated blood upon entry into the study for determination of 25-hydroxyvitamin D levels (the most reliable measurement of vitamin D status). It is this subset of participants who formed the basis of the current study.

There were 33,736 participants in this study. Based on plasma 25-hydroxyvitamin D levels at entry into the study, the participants were divided into four groups of around 1000 participants.

  • Group 1 had a median serum 25-hydroxyvitamin D level of 36.9 nmol/L.
  • Group 2 had a median serum 25-hydroxyvitamin D level 48.4 nmol/L.
  • Group 3 had a median serum 25-hydroxyvitamin D level of 56.9 nmol/L.
  • Group 4 had a median serum 25-hydroxyvitamin D level of 72.6 nmol/L.

For reference, the NIH considers < 30 nmol/L to be deficient, 30 to < 50 nmol/L to be insufficient for bone and overall health, > 50 nmol/L to be sufficient, and > 150 nmol/L to be potentially associated with adverse effects. By these criteria, group 1 had insufficient serum levels of 25-hydroxyvitamin D, group 2 was borderline, and groups 3 and 4 had sufficient serum levels of 25-hydroxyvitamin D.

The participants were followed for a total of 19 years. During this time 3301 participants developed cancer. The cancer incidence in groups 2, 3 and 4 were compared to the cancer incidence in group 1 to determine the effect of vitamin D status on cancer risk.

 

Vitamin D and Cancer Risk

 

vitamin d and cancer risk study resultsThe results of the Vitamin D and cancer risk study were:

  • Vitamin D reduced total cancer risk by up to 25%.
  • Vitamin D reduced the risk of liver cancer by up to 55%.
  • Vitamin D reduced the risk of pre-menopausal breast cancer by up to 44%.
  • There was a trend towards reduction of colon, liver, and prostate cancer by vitamin D, but the results did not quite reach significance.
  • There were too few cases for most other cancers to assess whether vitamin D status had any effect.
  • Risk reduction was not linear. Except for liver cancer, risk reduction for group 4 (72.6 nmol/L) was not greater than the risk reduction for group 3 (56.9 nmol/L). The significance of this observation will be discussed below.

The authors concluded: “Our findings support the hypothesis that vitamin D may confer protection against cancer. Nevertheless, the lower risk associated with higher circulating vitamin D concentrations seemed to show a ceiling effect, which may suggest that although maintaining an optimal 25-hydroxyvitamin D concentration is important for prevention of cancer, having a concentration beyond this optimal level may provide no further benefit.”

 

Why Is The Association of Vitamin D And Cancer Risk So Confusing?

 

vitamin d and cancer risk confusionSo why do some studies demonstrate confusing data on Vitamin D and cancer risk?  The “ceiling effect” mentioned by the authors of this study may explain much of the variation in results from previous trials. As I say in my upcoming book, “Slaying The Supplement Myths” , supplementation is most likely to be effective when the subjects are deficient in that nutrient at the beginning of the study. If they are starting with adequate levels of the nutrient, supplementation is unlikely to provide additional benefit.

While that statement seems to be obvious, many previous studies have ignored the beginning nutritional status. Some have not measured 25-hydroxyvitamin D levels at the beginning of the study. Others have measured starting 25-hydroxyvitamin levels but have not considered the starting levels in interpretation of their data.

Group 1 in the current study clearly had inadequate 25-hydroxyvitamin D levels. That may be why the groups with sufficient 25-hydroxyvitamin D levels showed a reduction in risk. The low baseline 25-hydroxyvitamin D is logical because most of Japan lies north of the United States, so sun exposure is less. In addition, the authors stated that food fortification and supplementation with vitamin D is much less in Japan than the US. In contrast, the baseline 25-hydroxyvitamin D status in many US studies is significantly higher.

The authors did a thorough analysis of previous studies. In general, studies with a low baseline level of 25-hydroxyvitamin D showed a reduction in cancer risk by vitamin D. Studies with a higher baseline level of 25-hydroxyvitamin D showed no effect.

This analysis does not permit a definitive conclusion, but it clearly defines how future studies should be designed. Simply put, to reliably test whether vitamin D reduces cancer risk, the experiment must be designed in such a way that the baseline 25-hydroxyvitamin D level is in the inadequate range. Otherwise, there is no reason to expect that higher levels of 25-hydroxyvitamin D will confer any benefit.

 

The Bottom Line:

 

A recent study looked at the effect of vitamin D status (serum 25-hydroxyvitaminD levels) on cancer risk. The study reported:

  • Vitamin D reduced total cancer risk by up to 25%.
  • Vitamin D reduced the risk of liver cancer by up to 55%.
  • Vitamin D reduced the risk of pre-menopausal breast cancer by up to 44%.
  • There was a trend towards reduction of colon, liver, and prostate cancer by vitamin D, but the results did not quite reach significance.
  • There were too few cases for most other cancers to assess whether vitamin D status had any effect.
  • Risk reduction was not linear. Except for liver cancer, risk reduction for group 4 (72.6 nmol/L) was not greater than the risk reduction for group 3 (56.9 nmol/L).

The authors concluded: “Our findings support the hypothesis that vitamin D may confer protection against cancer. Nevertheless, the lower risk associated with higher circulating vitamin D concentrations seemed to show a ceiling effect, which may suggest that although maintaining an optimal 25-hydroxyvitamin D concentration is important for prevention of cancer, having a concentration beyond this optimal level may provide no further benefit.”

The “ceiling effect” mentioned by the authors of this study may explain much of the variation in results from previous trials.

For more details, 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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Comments (4)

  • Kathleen-Marie

    |

    It’s important if we are taking a calcium supplement to be sure we are also getting adequate vitamin D from diet (mushrooms, eggs, fish), sunshine on the exposed skin midday in the summer, or our D3 supplementation. Especially for diets high in vitamin A, D is important too. All possibly affecting the cancer and disease prevention quality of circulating D2/3 in the bloodstream. It’s important to remember that vitamin D is a hormone precursor, or has hormone like affects on metabolism in general as well. In the animal world — reindeer moving North due to hotter temperatures (which means more suffocating flies in their nostrils), the reindeer are beginning to suffer from D deficiencies, even getting rickets and not being able to stand up well as babies. Wise vets and Laplanders have been putting a lot of lichen (which is also what our birds eat in the winter as source for D supplementation) in reindeer feeding areas. It’s so important for good immune function! I notice backyard birds eating lichen on rainy days perching on fallen tree branches around my feeders. Chimpanzes and other research and zoo animals also need D supplementation in their “chow” feed, along with fresh veggies and roots, to keep well and happier.

    Reply

  • Mary Butler

    |

    It asked me if chrome could access all of my files etc and I said no…so it didn’t download.

    Reply

  • Laura Nokes Lang

    |

    Thank you for letting us know the good news about eggs. I have always enjoyed eggs and usually have at least one a day. Now I know I’m not killing myself doing that, I feel better.

    Reply

  • Caroline

    |

    Dr., unfortunately I have seen women young and over age 55 with super low BP and that is dangerous. I chew on two REAL licorice pieces on the days my BP is too low and I am over 80 and I get back my energy and brain working well. I do take the OmegaGuard and sell a lot of it, thank goodness. But then I still have some trust left in Shaklee.

    Reply

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Latest Article

Does Magnesium Optimize Vitamin D Levels?

Posted February 12, 2019 by Dr. Steve Chaney

The Case For Holistic Supplementation

Author: Dr. Stephen Chaney

 

Does magnesium optimize vitamin D levels?

magnesium optimize vitamin dOne of the great mysteries about vitamin D is the lack of correlation between vitamin D intake and blood levels of its active metabolite, 25-hydroxyvitamin D. Many people who consume RDA levels of vitamin D from foods and/or supplements end up with low blood levels of 25-hydroxyvitamin D. The reason(s) for this discrepancy between intake of vitamin D and blood levels of its active metabolite are not currently understood.

Another great mystery is why it has been so difficult to demonstrate benefits of vitamin D supplementation. Association studies show a strong correlation between optimal 25-hydroxyvitamin D levels and reduced risk of heart disease, cancer, and other diseases. However, placebo-controlled clinical trials of vitamin D supplementation have often come up empty. Until recently, many of those studies did not measure 25-hydroxyvitamin D levels. Could it be that optimal levels of 25-hydroxyvitamin D were not achieved?

The authors of the current study hypothesized that optimal magnesium status might be required for vitamin D conversion to its active form. You are probably wondering why magnesium would influence vitamin D metabolism. I had the same question.

The authors pointed out that:

  • Magnesium status affects the activities of enzymes involved in both the synthesis and degradation of 25-hydroxyvitamin D.
  • Some clinical studies have suggested that magnesium intake interacts with vitamin D intake in affecting health outcomes.
  • If the author’s hypothesis is correct, it is a concern because magnesium deficiency is prevalent in this country. In their “Fact Sheet For Health Professionals,” the NIH states that “…a majority of Americans of all ages ingest less magnesium from food than their respective EARs [Estimated Average Requirement]; adult men aged 71 years and older and adolescent females are most likely to have low intakes.” Other sources have indicated that magnesium deficiency may approach 70-80% for adults over 70.

If the author’s hypothesis that magnesium is required for vitamin D activation is correct and most Americans are deficient in magnesium, this raises some troubling questions.

  • Most vitamin D supplements do not contain magnesium. If people aren’t getting supplemental magnesium from another source, they may not be optimally utilizing the vitamin D in the supplements.
  • Most clinical studies involving vitamin D do not also include magnesium. If most of the study participants are deficient in magnesium, it might explain why it has been so difficult to show benefits from vitamin D supplementation.

Thus the authors devised a study (Q Dai et al, American Journal of Clinical Nutrition, 108: 1249-1258, 2018 ) to directly test their hypothesis.

 

How Was The Study Designed?

magnesium optimize vitamin d studyThe authors recruited 180 volunteers, aged 40-85, from an ongoing study on the prevention of colon cancer being conducted at Vanderbilt University. The duration of the study was 12 weeks. Blood was drawn at the beginning of the study to measure baseline 25-hydroxyvitamin D levels. Three additional blood draws to determine 25-hydroxyvitamin D levels were performed at weeks 1, 6, and 12.

Because high blood calcium levels increase excretion of magnesium, the authors individualized magnesium intake based on “optimizing” the calcium to magnesium ratio in the diet rather than giving everyone the same amount of magnesium. The dietary calcium to magnesium ratio for most Americans is 2.6 to 1 or higher. Based on their previous work, they considered an “ideal” calcium to magnesium ratio to be 2.3 to 1. The mean daily dose of magnesium supplementation in this study was 205 mg, with a range from 77 to 390 mg to achieve the “ideal” calcium to magnesium ratio. The placebo was an identical gel capsule containing microcrystalline cellulose.

Two 24-hour dietary recalls were conducted at baseline to determine baseline dietary intake of calcium and magnesium. Four additional 24-hour dietary recalls were performed during the 12-week study to assure that calcium intake was unchanged and the calcium to magnesium ratio of 2.3 to 1 was achieved.

In short this was a small study, but it was very well designed to test the author’s hypothesis.

 

Does Magnesium Optimize Vitamin D Levels?

 

does magnesium optimize vitamin d levelsThis was a very complex study, so I am simplifying it for this discussion. For full details, I refer you to the journal article (Q Dai et al, American Journal of Clinical Nutrition, 108: 1249-1258, 2018).

The most significant finding was that magnesium supplementation did affect blood levels of 25-hydroxyvitamin D. However, the effect of magnesium supplementation varied depending on the baseline 25-hydroxyvitamin D level at the beginning of the study.

  • When the baseline 25-hydroxyvitamin D was 20 ng/ml or less (which the NIH considers inadequate), magnesium supplementation had no effect on 25-hydroxyvitamin D levels.
  • When the baseline 25-hydroxyvitamin D was 20-30 ng/ml (which the NIH considers the lower end of the adequate range), magnesium supplementation increased 25-hydroxyvitamin D levels.
  • When the baseline 25-hydroxyvitamin D level approached 50 ng/ml (which the NIH says may be “associated with adverse effects”), magnesium supplementation lowered 25-hydroxyvitamin D levels.

The simplest interpretation of these results is:

  • When vitamin D intake is inadequate, magnesium cannot magically create 25-hydroxyvitamin D from thin air.
  • When vitamin D intake is adequate, magnesium can enhance the conversion of vitamin D to 25-hydroxyvitamin D.
  • When vitamin D intake is too high, magnesium can help protect you by lowering 25-hydroxyvitamin D levels.

The authors concluded: “Our findings suggest that optimal magnesium status may be important for optimizing 25-hydroxyvitamin D status. Further dosing studies are warranted…”

 

What Does This Study Mean For You?

magnesium optimize vitamin d for youThis was a groundbreaking study that has provided novel and interesting results.

  • It provides the first evidence that optimal magnesium status may be required for optimizing the conversion of vitamin D to 25-hydroxyvitamin D.
  • It suggests that optimal magnesium status can help normalize 25-hydroxyvitamin D levels by increasing low levels and decreasing high levels.

However, this was a small study and, like any groundbreaking study, has significant limitations. For a complete discussion of the limitations and strengths of this study I refer you to the editorial (S Lin and Q Liu, American Journal of Clinical Nutrition, 108: 1159-1161, 2018) that accompanied the study.

In summary, this study needs to be replicated by larger clinical studies with a more diverse study population. In order to provide meaningful results, those studies would need to carefully control and monitor calcium, magnesium, and vitamin D intake. There is also a need for mechanistic studies to better understand how magnesium can both increase low 25-hydroxyvitamin D levels and decrease high 25-hydroxyvitamin D levels.

However, assuming the conclusions of this study to be true, it has some interesting implications:

  • If you are taking a vitamin D supplement, you should probably make sure that you are also getting the DV (400 mg) of magnesium from diet plus supplementation.
  • If you are taking a calcium supplement, you should check that it also provides a significant amount of magnesium. If not, change supplements or make sure that you get the DV for magnesium elsewhere.
  • I am suggesting that you shoot for the DV (400 mg) of magnesium rather than reading every label and calculating the calcium to magnesium ratio. The “ideal” ratio of 2.3 to 1 is hypothetical at this point. A supplement providing the DV of both calcium and magnesium would have a calcium to magnesium ratio of 2.5, and I would not fault any manufacturer for providing you with the DV of both nutrients.
  • If you are taking high amounts of calcium, I would recommend a supplement that has a calcium to magnesium ratio of 2.5 or less.
  • If you are considering a magnesium supplement to optimize your magnesium status, you should be aware that magnesium can cause gas, bloating, and diarrhea. I would recommend a sustained release magnesium supplement.
  • Finally, whole grains and legumes are among your best dietary sources of magnesium. Forget those diets that tell you to eliminate whole food groups. They are likely to leave you magnesium-deficient.

Even if the conclusions of this study are not confirmed by subsequent studies, we need to remember that magnesium is an essential nutrient with many health benefits and that most Americans do not get enough magnesium in their diet. The recommendations I have made for optimizing magnesium status are common-sense recommendations that apply to all of us.

 

The Case For Holistic Supplementation

 

magnesium optimize vitamin d case for holistic supplementationThis study is one of many examples showing that a holistic approach to supplementation is superior to a “magic bullet” approach where you take individual nutrients to solve individual problems. For example, in the case of magnesium and vitamin D:

  • If you asked most nutrition experts and supplement manufacturers whether it is important to provide magnesium along with vitamin D, their answer would likely be “No”. Even if they are focused on bone health, they would be more likely to recommend calcium along with vitamin D than magnesium along with vitamin D.
  • If your doctor has tested your 25-hydroxyvitamin D levels and recommended a vitamin D supplement, chances are they didn’t also recommend that you optimize your magnesium status.
  • Clinical studies investigating the benefits of vitamin D supplementation never ask whether magnesium intake is optimal.

That’s because most doctors and nutrition experts still think of nutrients as “magic bullets.” I cover holistic supplementation in detail in my book “Slaying The Supplement Myths.”  Other examples that make a case for holistic supplementation that I cover in my book include:

  • A study showing that omega-3 fatty acids and B vitamins may work together to prevent cognitive decline. Unfortunately, most studies looking at the effect of B vitamins on cognitive decline have not considered omega-3 status and vice versa. No wonder those studies have produced inconsistent results.
  • Studies looking at the effect of calcium supplementation on loss of bone density in the elderly have often failed to include vitamin D, magnesium, and other nutrients that are needed for building healthy bone. They have also failed to include exercise, which is essential for building healthy bone. No wonder some of those studies have failed to find an effect of calcium supplementation on bone density.
  • A study reported that selenium and vitamin E by themselves might increase prostate cancer risk. Those were the headlines you might have seen. The same study showed Vitamin E and selenium together did not increase prostate cancer risk. Somehow that part of the study was never mentioned.
  • A study reported that high levels of individual B vitamins increased mortality slightly. Those were the headlines you might have seen. The same study showed that when the same B vitamins were combined in a B complex supplement, mortality decreased. Somehow that observation never made the headlines.
  • A 20-year study reported that a holistic approach to supplementation produced significantly better health outcomes.

In summary, vitamins and minerals interact with each other to produce health benefits in our bodies. Some of those interactions we know about. Others we are still learning about. When we take high doses of individual vitamins and minerals, we create potential problems.

  • We may not get the full benefit of the vitamin or mineral we are taking because some other important nutrient(s) may be missing from our diet.
  • Even worse, high doses of one vitamin or mineral may interfere with the absorption or enhance the excretion of another vitamin or mineral. That can create deficiencies.

The same principles apply to our diet. I mentioned earlier that whole grains and legumes are among the best dietary sources of magnesium. Eliminating those two foods from the diet increases our risk of becoming magnesium deficient. And, that’s just the tip of the iceberg. Any time you eliminate foods or food groups from the diet, you run the risk of creating deficiencies of nutrients, phytonutrients, specific types of fiber, and the healthy gut bacteria that use that fiber as their preferred food source.

The Bottom Line

 

A recent study suggests that optimal magnesium status may be important for optimizing 25-hydroxyvitamin D status. This is one of many examples showing that a holistic approach to supplementation is superior to a “magic bullet” approach where you take individual nutrients to solve individual problems. For example, in the case of magnesium and vitamin D:

  • If you asked most nutrition experts and supplement manufacturers whether it is important to provide magnesium along with vitamin D, their answer would likely be “No.”  Even if they are focused on bone health, they would be more likely to recommend calcium along with vitamin D than magnesium along with vitamin D.
  • If your doctor has tested your 25-hydroxyvitamin D levels and recommended a vitamin D supplement, chances are he or she did not also recommend that you optimize your magnesium status.
  • Clinical studies investigating the benefits of vitamin D supplementation never ask whether magnesium intake is optimal. That may be why so many of those studies have failed to find any benefit of vitamin D supplementation.

I cover holistic supplementation in detail in my book “Slaying The Supplement Myths” and provide several other examples where a holistic approach to supplementation is superior to taking individual supplements.

In summary, vitamins and minerals interact with each other to produce health benefits in our bodies. Some of those interactions we know about. Others we are still learning about. Whenever we take high doses of individual vitamins and minerals, we create potential problems.

  • We may not get the full benefit of the vitamin or mineral we are taking because some other important nutrient(s) may be missing from our diet.
  • Even worse, high doses of one vitamin or mineral may interfere with the absorption or enhance the excretion of another vitamin or mineral. That can create deficiencies.

The same principles apply to what we eat. For example, whole grains and legumes are among the best dietary sources of magnesium. Eliminating those two foods from the diet increases our risk of becoming magnesium deficient. And, that’s just the tip of the iceberg. Any time you eliminate foods or food groups from the diet, you run the risk of creating deficiencies.

For more details about the current study and what it means to you 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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