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Beware of Health Headlines Warning You of Increased or Decreased Risk!

Updated: Jun 4

I just came across a recently released study that assessed the long-term health outcomes of calcium and vitamin D supplementation in post-menopausal women, specifically on cardiovascular mortality and cancer mortality.


At first glance, the results as described seem straightforward enough: there was a 7% increase in CVD mortality risk over a 22 year-period, and a 6% decrease in cancer

Source: Annals of Internal Medicine mortality risk. So one would think, equal risk and benefit, right?


Not exactly. The risk conversation in medical research is an interesting and complex one. Results are expressed as risk differences because it is supposedly easier for the average person to understand. But it's never that simple, and this can actually be deceiving. In my opinion, headlines do a disservice because this is how overreactions can happen. As you can see from the headline below, these nuances are rarely detectable unless you look deeper.


First, is this percent risk significant from a statistical perspective? i.e., was it different enough to stand out from the other group? This is rarely evident from the headline.


But more importantly, is this percent risk difference meaningful? Is it enough for a practitioner to change how they prescribe because the risk is now considered different enough for their patient population? And is it meaningfully different for you, the patient? Does it change how they view their risk-to-benefit ratio now? Source: Medical News Today


For example, a 10% decrease in risk for a baseline population of 100 is an absolute reduction of 10 cases (starting risk was low). But a 10% decrease in risk for a baseline population of 1,000,000 is an absolute reduction of 100,000 cases. Which is more meaningful from a population perspective? Yea. The latter.


A real-life example of over-reactions is when the WHI (world health initiative) study came out in the early 2000s that concluded that hormone therapy increased the risk of breast cancer and endometrial cancer, then hormone prescriptions plummeted overnight. With no other tools in doctors' toolkits for women, all of a sudden women suffering from menopause symptoms or just entering menopause were now helpless, and the conversation on menopause was relegated to the Dark Ages: nothing was said about it for about 20 years. But what the study funders failed to promote was the magnitude of the benefits that women were receiving from hormone therapies, and how that stacked up against the magnitude of the new risks.


Until multiple new analyses came out clarifying the results and parsing out which populations actually benefitted and which ones did not, and also put into perspective what the risk increase in cancer was. Basically, breast cancer is scary and the most common type of cancer in women, but cardiovascular disease and osteoporosis are way more common and deadly, and hormone therapy shows a benefit for those (debatable for CVD) as well as large benefits in quality of life and menopause symptoms, so the (small) increase in breast cancer risk at a population level did not outweigh the benefits to other health aspects. So slowly, medical societies have updated their guidelines, and health providers are restarting to prescribe hormones for menopause symptoms. (see Dr Jen Gunter, MD's book, The Menopause Manifesto)


Don't get fooled into making the same mistake by misinterpreting science headlines. Here's how to work through analysing the implications of this particular study, that you can apply to other studies.


1: Is this a New Finding, or Has it Been Known Already? What is New About It?

Is Calcium & Vit D Supplementation a Known Risk?

It's been long known that calcium supplementation can increase the risk of kidney stones and some cardiovascular events (here). It seems like Vitamin D doesn't have the negative effects that calcium does.


Now we have an updated long-term analysis of the existing data (we're talking 22 years out), and it seems like supplementation of calcium and Vitamin D is confirmed to increase CVD risk, BUT to lower cancer risk. In the earlier analysis, there was no change to cancer risk.


2: Understand What the Current Guidelines Are for Said Topic.

What are the Current Calcium and Vitamin D Guidelines for Menopause? And Why?

The benefits of calcium and Vitamin D are considered important for bone health. In the earlier mentioned WHI study, supplementation was found to reduce the risk of hip fractures by up to 30%, and reduced hip bone loss. The benefits were especially noticeable for older women (over age 60).


Considering that hip fractures are extremely common (300,000 in the US every year hospitalized for hip fractures), are primarily experienced in women (75% of hip fractures are in women), and are associated with greater mortality (3-month mortality rate after hip fracture surgery in assisted living facility was 25%); it seems to make sense to try to prevent hip fractures by protecting bone health with supplementation, despite the other risks.


Guidelines say to focus on dietary sources (i.e. food) of calcium and vitamin D as much as possible, and to supplement only up to 500mg of calcium. Some people seem to accumulate more calcium in their arteries than others, and that may be a test that can get done in terms of urine excretion, but I don't know much about that.


3: Is the New Finding Clinically Meaningful? How Large of a Population Impact Are We Talking About?

How many lives were lost prematurely due to increased CVD risk, and how many lives were saved due to decreased cancer risk?


Consider the size of the cancer population "saved" (7% risk reduction):

  • Out of 36,282 post-menopausal females in this post-hoc analysis, there were 1817 vs. 1943 deaths from cancer (colorectal, breast, and total cancer) in the 2 respective groups (supplementation vs none). That's a total of 3,760, or 10% of women who died from cancer over a period of 22 years.

  • So the 7% decrease in cancer deaths may sound like a lot, but we're really talking about 126 fewer cancer deaths out of a population of 36,282 women, which is 0.3%.

  • If we translate that to the general population, in Ontario for example, we have an estimated 3.7 million women over 45, then an estimated 11,000 lives could be "saved" over a period of 22 years from the calcium and vitamin D supplementation, or 500 annual cancer deaths.

  • Just for context, we have around 15,000 annual female deaths from cancer in Ontario.


[Of course this assumes many many things which are not necessarily the case, and this is meant as a thought exercise only (e.g. the study population mirrors the general population, US based is applicable to Canada based, no change in the future to cancer mortality from other factors, no change to population size, adherence to treatment, etc.)]


On the other hand consider the size of the CVD population with premature death (6% risk increase):

  • Out of 36,282 post-menopausal females in this post-hoc analysis, there were 2621 vs. 2420 deaths from cardiovascular disease in the 2 respective groups (supplementation vs none). That's a total of 5,041 or 14% of women who died from CVD over a period of 22 years.

  • So the 6% increase in CVD deaths was actually 201 more CVD deaths out of a population of 36,282 women, which is 0.55%.

  • Again, translating this to our estimated 3.7 million women over 45 in Ontario, this means an additional 20,350 women could die prematurely from taking calcium supplements over a 22-yr period, or 925 more deaths annually.

  • For context, in Canada around 36,400 women died in 2022 of diseases of the circulatory system. This means an estimated 12,375 women die in Ontario of heart disease every year (~Ontario makes up 34% of Canadian population).


4: How Does the New Risk Compare to the Known Benefits?

How many lives are saved every year from bone complications due to supplementation?


Now, to go back to the original reason calcium supplements are given in the first place: bone health. This study found a small benefit for long-term cancer outcomes, but the initial known benefits were really for bone health, to prevent hip fractures and bone loss resulting in osteoporosis or osteopenia.


We saw earlier that hip fractures in the elderly, especially women, are very common, and mortality rates are significantly higher.

  • in Ontario, there are 13,000 hip fractures every year, and 20% result in mortality within 1 year. Also important, another 20% will be admitted to long-term care as a result, and less than half can return to walking independently, all of which increase costs and burden to caregivers etc., not to mention decrease independent living and quality of life.

  • 30% reduction in hip fractures over a period of 7 years (from earlier study results, or here) would mean in Ontario terms, 27,300 hip fractures avoided out of a total 91,000 fractures over a 7-yr period, or 3,900 avoided yearly.

  • That's around 780 fewer deaths resulting from hip fractures plus 780 fewer long-term care admissions, and maybe around 1,500 fewer individuals losing independent mobility. There is also a significant burden on the healthcare system, long-term care, caregivers, not to mention a huge social wellbeing impact on the individual who loses mobility from a hip fracture (and a huge financial cost as well for long-term care), that could be avoided.


Table 1: Comparing the Known Benefits to New Risks of Calcium & Vit D Supplementation


Cancer risk

CVD risk

Hip fracture risk

No. of Ontario annual deaths/ incidents

15,000

12,375

13,000

No. of Ontario women impacted annually

500 fewer deaths annually

925 more deaths annually

3,900 fewer fractures, 780 fewer deaths & LTC each

Source: NEJM bone health WHI study, Canadian Cancer Statistics, Statistics Canada, Statistica, Health Quality Ontario, and my own calculations


[And this does not include other limitations of the study, which were that this was an observational study (not a prospective one) and the authors did not control for other lifestyle factors such as exercise (esp. weight bearing exercise), or eating more healthy, or smoking, or drinking alcohol, or more stressed, or taking other medications, etc. (although they did look at concomitant hormone therapies and osteoporosis medications but this didn't seem to have much impact).


5: Draw Your Conclusion for Yourself

What does that mean for you?


Do the additional new risks/benefits outweigh the existing known benefits/risks? That would depend on whether you are a health practitioner or not, and also what type of health condition you deal with every day. For example, a geriatric specialist might see a lot more osteoporosis morbidity and decide that that is what matters more than the potential impact to other health risks. But for a heart specialist they might decide that this is enough to stop prescribing. For an oncologist working with women, they may decide that it's a good enough reason to recommend it.


Does that mean you should start or stop your calcium supplementation? Well, ask yourself the following questions:

  • Are you more likely to develop osteoporosis (does it run in your family), cardiovascular risk, or cancer? Your individual risk factor should influence your personal risk to benefit ratio.

  • Are you already getting enough calcium and vitamin D? It's supplementation that seems to be a problem potentially, not dietary calcium. Can you get more from diet and sunshine?

  • Are you already doing everything you can to protect your bone mass and make you fall-proof? Like strength training, agility training, balance training, quitting smoking, reducing alcohol, eating more protein, etc.? If you're not sure what more you could do, get some support from a professional. (And by the way lifestyle habits to improve bone health are also the same ones that will improve heart health and reduce cancer risk!)

  • Are you eligible for hormone therapy? Some hormone therapies can help reduce the risk of osteoporosis. Work with your healthcare provider.

  • Are you open to using other safe supplements to improve bone health?  Creatine and collagen have both been shown recently to improve some bone health and other health markers long-term in older adults.


Applying this to other study results, you can ask yourself similar questions to understand how this applies to you, and what other interventions you're already doing or could implement realistically in your life that could reduce your health risks.


Now you're ready to interpret any science headline that comes your way. The most important thing to remember is, don't take the numbers you see at face value, ask yourself, what is the bigger context and is it meaningful? And what else can I do to lower my risks?


Let me know if you found this useful!


Sarah Lussier is a Menopause Health Mediator and Strategist, and a personal trainer, Women's Coaching Specialist (pending) and a Menopause Coaching Specialist. Her background is health economics which is why she loves to nerd out in the weeds and understanding data but more importantly how it impacts our behavior to improve our health.


If you are looking for support in lifestyle routine accountability or evidence-based lifestyle tips to improve your health, or in health navigation and literacy for menopause health, contact her at sarah@accountablemeno.com.



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