Do Calcium Supplements Increase Heart Attack Risk?

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

 

Calcium Confusion

Author: Dr. Stephen Chaney

 cardiovascular-disease

Should you avoid calcium supplements? Do calcium supplements increase heart disease risk? If you’ve been reading some of the recent headlines in magazines, newspapers and current health articles, that’s exactly what you might think.

And, after years of telling us that calcium supplements may be important for bone health, even some doctors are now recommending that their patients avoid calcium supplements. So what’s the truth? What should you believe?

Calcium Confusion

While some headlines and blogs have been telling you to avoid “killer calcium” supplements at all cost, the actual literature on the subject is much more confusing. Some studies claim that taking over 1,000 mg of supplemental calcium is associated with a slight (20-24%) increase in heart attack risk (Bolland et al, BMJ, 341: c3691, 2010; Bolland et al, BMJ 342: d2040, 2011; Xiao et al, JAMA Internal Medicine, 173: 639-646, 2013). Other studies find no association between supplemental calcium intake and heart attack risk or decreased heart attack risk (Lansetmo et al, J Clin Endocrinol Metab, 98: 3010-3018, 2013; Wang et al, Am J Cardiovasc Drugs, 12:105-116, 2012).

Why the confusion? It turns out that most of these studies had some significant limitations – particularly the studies reporting increased heart attack risk. For example:

  • Some studies were too small or the follow-up was too short. As a consequence the total number of cardiovascular deaths was so small that it was difficult to have confidence in small differences between the group supplementing with calcium and the one that was not supplementing.
  • Some of the papers represented a re-analysis of the data from studies that were actually designed to measure whether calcium supplements decreased risk of bone fracture, not whether they increased the risk of cardiovascular death. That is a concern because it means that cardiovascular deaths were not systematically recorded at the time the studies were performed.

And when studies like that are poorly designed, you end up with some pretty bizarre findings. For example:

  • One study reported that calcium supplementation increased the risk of heart attack only in women who were using no calcium supplements prior to the study. A second study by the same authors reported that calcium supplementation increased heart attack risk only women who were taking calcium supplements prior to the study. Obviously, both studies couldn’t be correct.
  • One study has reported that calcium supplementation increases heart attack risk in women, but not in men. Another study reports that calcium supplementation increases heart attack risk in men, but not in women. A third study claims that calcium supplementation reduces cardiovascular death in women, but not in men. Again, all of those studies can’t be true.

Are you confused yet? If so, I have good news for you. The definitive study on calcium supplements and heart attack risk in humans has just been published.

 

Do Calcium Supplements Increase Heart Attack Risk?

A group of scientists from Brigham and Women’s Hospital in Boston and Harvard University analyzed the relationship between supplemental calcium use and cardiovascular disease in 74,245 women with no previous history of heart disease who were enrolled in the Nurses’ Health Study (Paik et al, Osteoporosis International, doi: 10.1007/s00198-014-2732-2, 2014). This was a very well designed study that avoided the flaws of the previous studies. For example:

  • There were a large number of women in the study (74,245) and a long follow-up (24 years). As a consequence there were a large number of adverse cardiovascular events (2,709 deaths and 1,856 strokes). This allowed for a very precise statistical comparison of calcium supplement users and non-users.
  • This study was designed to measure cardiovascular disease and cardiovascular deaths
  • This study was also designed to measure calcium intake. In fact, calcium intake was measured every 4 years.

The results were pretty clear cut:

  • Women taking >1,000 mg of supplemental calcium/day had an 18% decrease in cardiovascular deaths.
  • Women taking >1,000 mg of supplemental calcium/day had a 29% decrease in cardiovascular disease.
  • When they looked at total calcium intake (dietary and supplemental) women consuming >2,000 mg/day had an 18% decrease in cardiovascular deaths compared to women consuming <500 mg/day (about the average dietary intake for American women).
  • It didn’t make any difference whether the women were at high or low risk of heart disease (smokers versus non-smokers, high blood pressure versus normal blood pressure, high cholesterol versus normal cholesterol, heart healthy diet or poor diet, pre- or post-menopause, etc)
  • It also didn’t make any difference if the women started supplementing with calcium during the last 4 years of the study or had been supplementing with calcium for 24 years. The results were essentially the same.

 

The Bottom Line

1)     You can ignore the “Killer Calcium” headlines and the warnings that taking calcium supplements will increase your risk of heart disease. The definitive study for women has just been published, and it shows that >1,000 mg/day of supplemental calcium reduces your risk of cardiovascular disease by 29% and cardiovascular death (primarily heart attacks) by 18%.

2)     The definitive study for men has not yet been published, but it is likely that the results will be similar to those for women.

3)     On the other hand, there is clear evidence that calcium intake in the 1000 to 1300 mg per day range (the current RDA recommendations) decreases the risk of osteoporosis, and osteoporosis can significantly decrease quality of life and even lead to increased mortality. Most people aren’t getting enough calcium in their diet. For these people appropriate calcium supplementation is clearly advantageous.

4)     Finally, as I discuss in my book “The Myths of the Naysayers” (available for free to subscribers of “Health Tips From the Professor”), some poorly designed calcium supplements could indeed have the potential to increase heart disease risk. My recommendation is to make sure that your calcium supplement contains 800 to 1200 IU of vitamin D per day plus RDA levels of the other nutrients needed for bone formation (vitamin C, vitamin K, magnesium, zinc, copper and manganese).

 

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)

  • Helen

    |

    Thank you for this professional and timely information you provide. Most appreciative of your work and effort.

    How does one get your book re: Naysayers?

    HTG

    Reply

    • Dr. Steve Chaney

      |

      Dear Helen,

      When you go to https://www.healthtipsfromtheprofessor.com and register to receive my health tips on a weekly basis you will receive an email with instructions on how to receive your free Naysayers eBook.

      Dr. Chaney

      Reply

  • sharry zacharia

    |

    Thank you for clearing the confusion on CA intake and heart disease.

    Reply

  • Mary Ahrens

    |

    thank you Dr. Chaney for simplifying the results for each of these studies! It’s incredibly helpful!

    Reply

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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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