Calcium and Breast Cancer Prevention

Written by Dr. Steve Chaney on . Posted in Calcium and Breast Cancer, Supplements and Health, Vitamins and Health

Author: Dr. Stephen Chaney

 

calcium and breast cancerIs there a connection between calcium and breast cancer prevention?  There has been lots of confusion about calcium supplements lately. Just a few years ago most health professionals were recommending calcium supplementation for women to prevent osteoporosis. Now that recommendation has become controversial. That’s because some studies have suggested that increasing calcium intake doesn’t actually prevent osteoporosis. Other studies have suggested that calcium supplementation may actually cause heart disease.

As if all this wasn’t confusing enough, the latest headlines are claiming that increased calcium intake will reduce breast cancer risk. What are we to believe about the value of calcium for our health? Should we take that calcium supplement we threw away out of the trash can and start using it again?

I have previously evaluated the studies behind the previous headlines and debunked the headlines. For example, I reported that previous studies suggesting that calcium supplementation might increase heart attack risk were followed by a much larger, better designed study showing that, if anything, calcium supplementation actually decreases heart attack risk in Do Calcium Supplements Increase Heart Attack Risk?. I also reported that the study claiming calcium supplements did not prevent osteoporosis was fatally flawed in Do Calcium Supplements Prevent Bone Fractures?.

Now it is time to evaluate the study behind the latest calcium headline. Is this headline myth or is it true?  What is the connection between calcium and breast cancer.

 

Calcium and Breast Cancer Risk Reduction

calcium reduces breast cancer riskThis study (Hidayat et al, British Journal of Nutrition, 116: 158-166, 2016) was a meta-analysis of 11 previous clinical studies published between 2002 and 2013 with a total of 872,895 women subjects which measured calcium intake and breast cancer. Follow up ranged from 7 to 25 years in these studies, during which time 26,606 of the women developed breast cancer.

Dietary plus supplemental calcium intake was determined at the beginning of each study using either a 24-hour diet recall or a food frequency questionnaire. Calcium intakes ranged from 203 mg/day to 1,750 mg/day.

In short this was a very large and well done study. Because of the large number of subjects and the large number of cancer cases, this study had the sensitivity to detect even small effects of calcium on breast cancer risk – something that was not possible in previous studies. In addition, the investigators were able to conduct a dose-response evaluation of the effect of calcium and breast cancer risk reduction. This was also had not been possible in previous studies.

When the women with the highest calcium intakes were compared to the women with the lowest calcium intakes:

  • Calcium reduced breast cancer risk by 8%.
  • The effect was much larger for premenopausal women than postmenopausal women:
  • Calcium reduced breast cancer risk by 25% in premenopausal women.
  • Calcium reduced breast cancer risk by 6% in postmenopausal women.
  • The dose response effect was fairly linear over the entire dose range with a 2% decreased risk of breast cancer for every 300 mg/day increase in calcium intake.

 

What Does This Study Mean For You?

As I said in the beginning, when you read the headlines proclaiming that increasing your calcium intake could decrease your breast cancer risk, you probably had two questions:

Is it true?  The answer appears to be yes. This was a very large, very well done study and it showed there is a connection between calcium and breast cancer risk reduction. It was capable of detecting even small effects of calcium on breast cancer risk – something that previous studies simply could not do.

Does it matter?  Here the answer is more complicated. If you’re a postmenopausal woman, increased calcium intake only decreases your risk of breast cancer by 6%.  If you are a premenopausal woman, increased calcium intake decreases your risk of breast cancer by a more robust 25%. However, in both cases you should think of calcium as only one component of a holistic approach to reducing breast cancer risk – something I’ll discuss in more detail below.

Now that you know the answer to those two questions you probably have a third question:

How much calcium do I need?   That’s pretty simple. The calcium DV for adults is 1,000 mg/day, increasing to 1,200 mg/day for women over 50.

How Can You Reduce Breast Cancer Risk?

In a previous article Preventing Osteoporosis,  I reported that while calcium supplementation alone had only a very modest effect on reducing osteoporosis risk, it played an important role as part of a holistic bone-healthy lifestyle. The role of calcium in reducing breast cancer risk is no different.

Most experts estimate that between 30 and 60% of breast cancer cases could be prevented by diet and lifestyle changes. In addition to calcium, both the Mayo Clinic  and the American Cancer Society make the following recommendations for reducing breast cancer risk:

  • calcium supplementsLimit or avoid hormone therapy. This is the single most important step you can take to reduce breast cancer risk.
  • Eat a plant-based diet with plenty of fresh fruits and vegetables, whole grains, legumes and nuts. Use fats in moderation and choose healthy fats such as olive oil and omega-3 fats. Limit the amounts of red meat and processed meats.
  • Control your weight.
  • Be physically active.
  • Don’t smoke
  • Limit alcohol intake.
  • Avoid exposure to radiation and environmental pollution.
  • Breast feed.

Where Should You Get Your Calcium?

Many experts recommend that you get your calcium only from food. Is that the best advice?  I always like to start with food as the source of essential nutrients, but in the case of calcium that usually isn’t sufficient. Here are some facts to ponder:

  • Plain, nonfat yoghurt is the calcium champion, with an 8 ounce serving supplying 42% of the DV (the calcium DV = 1,000 mg/day). However, most yoghurt cups in the market these days are 4 ounces or less.
  • Milk and a few cheeses supply around 30% of the DV. However, many people can’t or don’t consume the 3 or more servings needed to reach the DV.
  • Green leafy vegetables are often mentioned as another good food source. However, a serving of them only provides around 10% of the DV, and many leafy greens contain oxalates which decrease calcium absorption.
  • Beyond that,  most food sources of calcium supply only 1-8% of the DV for calcium. If you don’t drink lots of milk, you need to be a dietitian with an advanced degree to figure out how to get enough calcium from foods alone.
  • If that isn’t bad enough, many foods contain substances that interfere with calcium absorption. In addition to the oxalates in leafy greens, these substances include phytates from whole grains, phosphate from sodas, and saturated fat from red meats.

 

Experts often also recommend getting calcium from calcium fortified foods such as calcium fortified orange juice. That can help you reach the recommended calcium intake, but in my opinion calcium-fortified foods are likely to be more expensive and no better than regular foods plus a calcium supplement.

I recommend getting as much calcium as possible from food and adding a calcium supplement for the rest. Here are my tips on calcium supplementation:

  • If you do use a calcium supplement, make sure it is complete. Don’t just settle for calcium and vitamin D. At the very least you will want your supplement to contain magnesium and vitamin K. I personally recommend that it also contain zinc, copper, and manganese as well.
  • Your calcium supplement will be best utilized if taken between meals.
  • Your calcium supplement will be best utilized if you don’t take more than 500 mg at a time.
  • In most cases there is no need for more than the DV of calcium.

Let’s review the connection between calcium and breast cancer risk reduction.

 

The Bottom Line

  • A recent study has shown that increasing calcium intake reduces the risk of breast cancer. The effect of calcium intake on breast cancer risk was much greater for premenopausal women (25% risk reduction) than it was for postmenopausal women (6% risk reduction).
  • While the effect of calcium alone on breast cancer risk was relatively modest,  it is likely to be an important component of a holistic approach for reducing breast cancer risk.  Additional recommendations of the Mayo Clinic and American Cancer Society for reducing breast cancer risk are contained in the article above.
  • While many experts recommend getting your calcium from food alone, a careful analysis of food sources of calcium clearly shows how difficult that is for most people.
  • Calcium supplements are a safe and effective way to make sure you are getting the calcium you need. In the article above, I describe the optimal design of a calcium supplement and how to take a calcium supplement for optimal utilization.

 

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 (1)

  • douglas

    |

    Gracias muy interesante, se lo dificil que es obtener el calcio en los alimentos cuando se es algo vegetariano-

    Reply

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Latest Article

What Is The Planetary Diet?

Posted May 21, 2019 by Dr. Steve Chaney

Is Your Diet Destroying The Planet?

Author: Dr. Stephen Chaney

 

Earth Day has come and gone, but you are still committed to saving the planet. You save energy. You recycle. You drive an electric car. But is your diet destroying the planet?

This is not a new question, but a recent commission of international scientists has conducted a comprehensive study into our diet and its effect on our health and our environment. Their report (W. Willet et al, The Lancet, 393, issue 10170, 447-492, 2019 ) serves as a dire warning of what will happen if we don’t change our ways. I touched on this report briefly in a previous issue of “Health Tips From The Professor,” What Is The Flexitarian Diet , but this topic is important enough that it deserves an issue all its own.

The commission carefully evaluated diet and food production methods and asked three questions:

  • Are they good for us?
  • Are they good for the planet?
  • Are they sustainable? Will they be able to meet the needs of the projected population of 10 billion people in 2050 without degrading our environment.

The commission described the typical American diet as a “lose-lose diet.” It is bad for our health. It is bad for the planet. And it is not sustainable.

In its place they carefully designed their version of a primarily plant-based diet they called a “win-win diet.”  It is good for our health. It is good for the planet. And, it is sustainable.

In their publication they refer to their diet as the “universal healthy reference diet” (What else would you expect from a committee?). However, it has become popularly known as the “Planetary Diet.”

I have spoken before about the importance of a primarily plant-based diet for our health. In that context it is a personal choice. It is optional.

However, this report is a wake-up call. It puts a primarily plant-based diet in an entirely different context. It is essential for the survival of our planet. It is no longer optional.

If you care about global warming…If you care about saving our planet, there is no other choice.

How Was The Study Done?

The study (W. Willet et al, The Lancet, 393, issue 10170, 447-492, 2019 ) was the report of the EAT-Lancet Commission on Healthy Diets from Sustainable Food Systems. This Commission convened 30 of the top experts from across the globe to prepare a science-based evaluation of the effect of diet on both health and sustainable food production through the year 2050. The Commission included world class experts on healthy diets, agricultural methods, climate change, and earth sciences. The Commission reviewed 356 published studies in preparing their report.

 

Is Your Diet Destroying The Planet?

When they looked at the effect of food production on the environment, the Commission concluded:

  • “Strong evidence indicates that food production is among the largest drivers of global environmental change.” Specifically, the commission reported:
  • Agriculture occupies 40% of global land (58% of that is for pasture use).
  • Food production is responsible for 30% of global greenhouse gas emissions and 70% of freshwater use.
  • Conversion of natural ecosystems to croplands and pastures is the largest factor causing species to be threatened with extinction. Specifically, 80% of extinction threats to mammals and bird species are due to agricultural practices.
  • Overuse and misuse of nitrogen and phosphorous in fertilizers causes eutrophication. In case you are wondering, eutrophication is defined as the process by which a body of water becomes enriched in dissolved nutrients (such as phosphates from commercial fertilizer) that stimulate the growth of algae and other aquatic plant life, usually resulting in the depletion of dissolved oxygen. This creates dead zones in lakes and coastal regions where fish and other marine organisms cannot survive.
  • About 60% of world fish stocks are fully fished and more than 30% are overfished. Because of this, catch by global marine fisheries has been declining since 1996.
  • “Reaching the Paris Agreement of limiting global warming…is not possible by only decarbonizing the global energy systems. Transformation to healthy diets from sustainable food systems is essential to achieving the Paris Agreement.”
  • The world’s population is expected to increase to 10 billion by 2050. The current system of food production is unsustainable.

When they looked at the effect of the foods we eat on the environment, the Commission concluded:

  • Beef and lamb are the biggest contributors to greenhouse gas emissions and land use.
  • The concern about land use is obvious because of the large amount of pasture land required to raise cattle and sheep.
  • The concern about greenhouse gas emissions is because cattle and sheep are ruminants. They not only breathe out CO2, but they also release methane into the atmosphere from fermentation in their rumens of the food they eat. Methane is a potent greenhouse gas, and it persists in the atmosphere 25 times longer than CO2. The single most important thing we can do as individuals to reduce greenhouse gas emissions is to eat less beef and lamb. [Note: grass fed cattle produce more greenhouse gas emissions than cattle raised on corn because they require 3 years to bring to market rather than 2 years.]
  • In terms of energy use beef, lamb, pork, chicken, dairy and eggs all require much more energy to produce than any of the plant foods.
  • In terms of eutrophication, beef, lamb, and pork, all cause much more eutrophication than any plant food. Dairy and eggs cause more eutrophication than any plant food except fruits.
  • In contrast, plant crops reduce greenhouse gas emissions by removing CO2 from the atmosphere.

 

What Is The Planetary Diet?

In the words of the Commission: “[The Planetary Diet] largely consists of vegetables, fruits, whole grains, legumes, nuts, and unsaturated oils. It includes a low to moderate amount of seafood, poultry, and eggs. It includes no or a very low amount of red meat, processed meat, sugar, refined grains, and starchy vegetables.”

When described in that fashion it sounds very much like other healthy diets such as semi-vegetarian, Mediterranean, DASH, and Flexitarian. However, what truly distinguishes it from the other diets is the restrictions placed on the non-plant portion of the diet to make it both environmentally friendly and sustainable. Here is a more detailed description of the diet:

  • It starts with a vegetarian diet. Vegetables, fruits, beans, nuts, soy foods, and whole grains are the foundation of the diet.
  • It allows the option of adding one serving of dairy a day (It turns out that cows produce much less greenhouse emissions per serving of dairy than per serving of beef. That’s because cows take several years to mature before they can be converted to meat, and they are emitting greenhouse gases the entire time).
  • It allows the option of adding one 3 oz serving of fish or poultry or one egg per day.
  • It allows the option of swapping seafood, poultry, or egg for a 3 oz serving of red meat no more than once a week. If you want a 12 oz steak, that would be no more than once a month.

This is obviously very different from the way most Americans currently eat. According to the Commission:

  • “This would require greater than 50% reduction in consumption of unhealthy foods, such as red meat and sugar, and greater than 100% increase in the consumption of healthy foods, such as nuts, fruits, vegetables, and legumes.”
  • “In addition to the benefits for the environment, “dietary changes from current diets to healthy diets are likely to substantially benefit human health, averting about 10.8-11.6 million deaths per year globally.”

What Else Did The Commission Recommend?

In addition to changes in our diets, the Commission also recommended several changes in the way food is produced. Here are a few of them.

  • Reduce greenhouse gas emissions from the fuel used to transport food to market.
  • Reduce food losses and waste by at least 50%.
  • Make radical improvements in the efficiency of fertilizer and water use. In terms of fertilizer, the change would be two-fold:
    • In developed countries, reduce fertilizer use and put in place systems to capture runoff and recycle the phosphorous.
    • In third world countries, make fertilizer more available so that crop yields can be increased, something the Commission refer to as eliminating the “yield gap” between third world and developed countries.
  • Stop the expansion of new agricultural land use into natural ecosystems and put in place policies aimed at restoring and re-foresting degraded land.
  • Manage the world’s oceans effectively to ensure that fish stocks are used responsibly and global aquaculture (fish farm) production is expanded sustainability.

What we can do: While most of these are government level policies, we can contribute to the first three by reducing personal food waste and purchasing organic produce locally whenever possible.

What Does This Mean For You?

If you are a vegan, you are probably asking why the Commission did not recommend a completely plant-based diet. The answer is that a vegan diet is perfect for the health of our planet. However, the Commission wanted to make a diet that was as consumer-friendly as possible and still meet their goals of a healthy, environmentally friendly, and sustainable diet.

If you are eating a typical American diet or one of the fad diets that encourage meat consumption, you are probably wondering how you can ever make such drastic changes to your diet. The answer is “one step at a time.”  If you have read my books “Slaying The Food Myths” or “Slaying the Supplement Myths,”  you know that my wife and I did not change our diet overnight. Our diet evolved to something very close to the Planetary Diet over a period of years.

The Commission also purposely designed the Planetary Diet so that you “never have to say never” to your favorite foods. Three ounces of red meat a week does not sound like much, but it allows you a juicy steak once a month.

Sometimes you just need to develop a new mindset. As I shared in my books, my father prided himself on grilling the perfect steak. I love steaks, but I decided to set a few parameters. I don’t waste my red meat calories on anything besides filet mignon at a fine restaurant. It must be a special occasion, and someone else must be buying. That limits it to 2-3 times a year. I still get to enjoy good steak, and I stay well within the parameters of the Planetary diet.

Develop your strategy for enjoying some of your favorite foods within the parameters of the Planetary Diet and have fun with it.

The Bottom Line

 

Is your diet destroying the planet? This is not a new question, but a recent commission of international scientists has conducted a comprehensive study into our diet and its effect on our health and our environment. Their report serves as a dire warning of what will happen to us and our planet if we don’t change our ways.

The Commission carefully evaluated diet and food production methods and asked three questions:

  • Are they good for us?
  • Are they good for the planet?
  • Are they sustainable? Will they be able to meet the needs of the projected population of 10 billion people in 2050 without degrading our environment.

The Commission described the typical American diet as a “lose-lose diet.”  It is bad for our health. It is bad for the planet. And it is not sustainable.

In its place they carefully designed their version of a primarily plant-based diet they called a “win-win diet.”  It is good for our health. It is good for the planet. And, it is sustainable.

In their publication they refer to their diet as the “universal healthy reference diet” (What else would you expect from a committee?). However, it has become popularly known as the “Planetary Diet.”

The Planetary Diet is similar to other healthy diets such as semi-vegetarian, Mediterranean, DASH, and Flexitarian. However, what truly distinguishes it from the other diets is the restrictions placed on the non-plant portion of the diet to make it both environmentally friendly and sustainable (for details, read the article above).

I have spoken before about the importance of a primarily plant-based diet for our health. In that context it is a personal choice. It is optional.

However, this report is a wake-up call. It puts a primarily plant-based diet in an entirely different context. It is essential for the survival of our planet. It is no longer optional.

If you care about global warming…If you care about saving our planet, there is no other choice.

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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