April 7, 2017

Director's Letter 
Carole Baggerly 
Director, GrassrootsHealth 

Have you ever wondered 'what do I DO?' with all this information about cancer prevention and vitamin D?

Just this last month, results from a new randomized trial by Lappe et al. were published showing a 30% decrease in incidence and, the editorial that accompanied the paper essentially indicated that it was 'too early to tell', the results were not 'significant' with a P value of only 0.06 (the security that the results have a 94% likelihood of being due to treatment, instead of just happening by chance. The industry target of 5%  is called significant).

There were indeed some expectations that the trial would have shown stronger results, like the Lappe trial of 2007. Why didn't they? Well, one of the biggest reasons was that more people are taking vitamin D now and Dr. Lappe's group had a very small number that started with vitamin D serum levels below 20 ng/ml. (The biggest change occurs in the range from about 20-40 ng/ml.)

My own personal decision is the same--get my serum 25(OH)D level to the range of 40-60 ng/ml! To me, it is foolish not to. The risks of NOT doing that are to have an even greater probability of getting cancer. I've already had that experience, I definitely don't need it again.

Below are some key charts that were in various publications that 'tell the story' to me. Please take a look, let me know how we can further address any questions you have about vitamin D and cancer prevention.  If YOU can make a decision to help prevent cancer with something so simple, I truly hope with all my heart that you will do so. It is our ongoing goal to 'Move Research into Practice' with education about the science and personal testing for your own vitamin D levels.

Please donate today to help us keep providing both education and quality research to you!  We need your help. 

Hopefully yours, 
Carole Baggerly 
Director, GrassrootsHealth 
A Public Health Promotion & Research Organization 
Moving Research into Practice NOW!
  Vitamin D and Cancer
A Review of Randomized Controlled Trials and GrassrootsHealth cancer research 

June 2007

The first randomized controlled trial was done in Nebraska under the direction of Joan Lappe, PhD RN FAAN, at Creighton University. This trial followed 1179 community dwelling women aged 55 or older with good general health for four years. They were randomized into three different groups 
  1. 1400-1500 mg calcium daily (no D)
  2. 1400-1500 mg calcium + 1100 IU vitamin D daily
  3. placebo

Here is the graph showing the fraction of cancer-free participants (1 means no one has cancer) - so with this chart you want the curve to stay as close to 1 as possible.

Click to Print or Enlarge

This analysis takes out the data from year one, on the hypothesis that cancers diagnosed early in the study would have been present, although un-recognized, at the start of the study. The data shows a risk reduction in the vitamin D + calcium group of 77% (P=.005).  This means that there is only a 0.5% chance that the conclusions are due to chance, as opposed to vitamin D + calcium.

April 2016 

For this analysis GrassrootsHealth combined data for women 55 and older from the GrassrootsHealth D*action cohort (N = 1,135, median serum level = 48 ng/ml) and the cohort mentioned above (Lappe 2007, N= 1,169, median serum level = 30 ng/ml) and used the pooled cohort to investigate cancer incidence over time (median = 3.9 years). Combining cohorts gave us a wider range of serum levels, more data, and thus improved statistical power. We looked at all invasive cancers combined, excluding skin cancer.

In our analysis, without adjusting for other risk factors, we found that women with a mean vitamin D serum level greater than or equal to 40 ng/ml had a 71% lower risk of cancer than women with serum levels <20 ng/ml (P=.02). This trend is shown in the chart above, where you can see that the greatest decrease in risk occurred between about 10 - 40 ng/ml. 

March 2017 

Lappe replicated her 2007 study with a larger population - 2303 women - over a 4 year period and a bigger vitamin D dose (2000 IU instead of 1100 IU). This new study did not include a calcium only group, as the first study showed more promise with vitamin D + calcium. 

The study enrolled 2303 women - 1156 in the vitamin D + calcium group and 1147 in the placebo group. When analyzed by treatment group (chart in next article) it showed a 30% reduction.
At GrassrootsHealth, we analyze by serum level, the relevant biological marker for vitamin D. This analysis is found in the supplementary online content of the JAMA article (most news outlets did not receive this chart). 

This analysis concluded that when compared with a vitamin D level of 30 ng/ml, participants with vitamin D level of 55 ng/ml were 35% less likely to get cancer (P=.03)  

It also shows a trend that we are used to seeing - an inverse association between cancer incidence and vitamin D level, meaning that cancer incidence decreases as vitamin D levels increase.
Vitamin D in the News:
Understanding the Headlines

Dr. Lappe's latest research paper was published in the March 28th edition of JAMA. Since that time, due to some specific wording in the paper, there have been headlines around the world such as "Vitamin D, Calcium Supplements Have No Impact On Cancer Rate, New Study Shows," or "Vitamin D pills may not protect against cancer after all." 

These headlines give the impression to readers that there was no reduction in cancer as vitamin D level increased. That is not so.

So why is it being reported this way?

The abstract, or summary of the paper, is often all that people see unless they subscribe to the journal or pay for the paper. In the abstract to this paper it states

"Conclusions and Relevance - Among healthy postmenopausal older women with a mean baseline serum 25-hydroxyvitamin D level of 32.8 ng/ml, supplementation with vitamin D3 and calcium compared with placebo did not result in a significantly lower risk of all-type cancer at 4 years. Further research is necessary to assess the possible role of vitamin D in cancer prevention."

When a layman reads this text, it can be understood to mean that there wasn't a meaningful reduction in risk - or that the vitamin D + calcium group did not have fewer cancers than the placebo group. However, this is not true.

"Significance" in scientific research terms is a computation done during data analysis to evaluate the strength of the evidence. It is also called the P-value. In this paper it was reported as such (from the results section of the abstract)

"A new diagnosis of cancer was confirmed in 109 participants, 45 (3.89%) in the vitamin D + calcium group and 64 (5.58%) in the placebo group (difference, 1.69% [95% CI, -0.06% to 3.46%]; P=.06)."

The P-value is a probability, it is a percentage. In this calculation the P-value was .06, which means that there is a 6% chance that this result (30% reduction in cancer in the vitamin D + calcium group) was due to chance - not the actual treatment. In a different wording, that means you are 94% sure it was NOT chance! The scientific community has agreed that P=.05 or less is an accepted amount for study results to have "significance" and anything higher than P=.05 is "not statistically significant." There is no middle ground, it is black or white. 


When you are making a decision for public health, is 94% 'enough'? 

Year 1 data usage

On page 7 of the paper, under 'Post Hoc Analyses,' when participants who withdrew from the study or developed cancer within the first 12 months were excluded from analysis, the study reports a 35% reduction in cancer in the vitamin D + calcium group compared to the placebo group with a P-value of .047 - it was statistically significant! 
Why would we take out year 1 data? This chart explains it well if you are a visual person. For the two groups, the first year, cancer incidence was almost identical. You can see the yellow and blue lines are on top of each other. After a year they start to separate. 

Why would it be useful to remove a year's worth of data? If you can imagine a cancer diagnosis during the first year of the study - was it due to what they did that year? It is likely that those cancers diagnosed in the first year of study would not have had the time to be affected by vitamin D + calcium. In Lappe's first cancer study she analyzed it the same way, excluding the first year of data in the final analysis. 

Analysis by Serum Level

If you are reading this newsletter you probably already agree that vitamin D levels need to be tested - that two people taking 2000 IU vitamin D per day may have drastically different blood levels. We have shown that using your data

For this study if you analyze by serum level, using all the data - not excluding year 1 - this is what the graph looks like (and is found in the supplemental content). 

Where would you want your vitamin D level to be? On the left or the right side of this graph?

Analyzed by serum level, the data showed that participants with a vitamin D level of 55 ng/ml were 35% less likely to get cancer as compared to those with a vitamin D level of 30 ng/ml, with..... a P value of .03 - it was statistically significant!

Vitamin D supplementation in the placebo group

To enroll in the study you needed to be a post-menopausal woman, independently living, 55 years or older, who responded to a recruitment mailing. 

First of all you can imagine the population to respond would be one that cared about their health and whether supplements were helpful for a disease free life.

Secondly, since the US RDA for that population is between 600 - 800 IU/day vitamin D (600 IU/day for ages 50 - 70, 800 IU/day for those over 70), and a participant would not know whether or not they were in the treatment arm or the placebo arm - they were allowed to supplement with vitamin D up to 800 IU/day. 

In addition, there was a high average vitamin D measurement at the start of the trial (33 ng/ml) - which means there was not a big difference in vitamin D levels between the placebo and treatment arms. That is why analysis by vitamin D level is so important - it is not only how much they are taking, but what serum level they achieved that matters.


ALL these studies have shown a reduction in incidence of cancers (from 30% to 77%).

ALL these studies have show a very good confidence rating, from < .005 to .06. 

What actions should be taken?

This data tells us the probability of cancer reduction is high for public health.  We also know that vitamin D is safe, inexpensive and easily available. What decision will you make?

What is the cost of NOT taking vitamin D to achieve a serum level between 40 and 60 ng/ml?

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Vitamin D status in a rural postmenopausal female population
Joan M. Lappe, et al.
The Journal of the American College of Nutrition
October 2006

Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial
Joan M. Lappe, et al.
American Journal Clinical Nutrition
June 2007

Serum 25-Hydroxyvitamin D Concentrations ≥40 ng/ml are Associated with >65% Lower Cancer Risk: Pooled Analysis of Randomized Trial and Prospective Cohort Study
Sharon L. McDonnell, et al.
April 2016

Effect of Vitamin D and Calcium Supplementation on Cancer Incidence in Older Women - A Randomized Clinical Trial
Joan Lappe, et al.
Journal of American Medical Association
March 28, 2017

Want more information on vitamin D and cancer?

Our new web site is search-able. In the upper right click on the magnifying glass and enter 'cancer' or 'breast cancer'. 

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