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

Should You Avoid Sugar Completely?

Posted October 24, 2017 by Dr. Steve Chaney

Is It The Sugar, Or Is It The Food?

Author: Dr. Stephen Chaney

 

Should we avoid sugar completely?  Almost every expert agrees that Americans should cut down on the amount of sugar we are consuming. However, for some people this has become a “sugar phobia”. They have sworn that “sugar shall never touch their lips”. Not only do they avoid sugar sweetened sodas and junk food, but they also have become avid label readers. They scour the label of every food they see and reject foods they find any form of sugar listed as an ingredient. Is this degree of sugar avoidance justified?

 

Should We Avoid Sugar to Keep it From Killing Us?

 

Let me add some perspective:

  • If you just take studies about the dangers of sugar at face value, sugar does, indeed, look dangerous. Excess sugar consumption is associated with increased risk of obesity, diabetes, and heart disease. However, when you look a little closer, you find that most of these studies have been done by looking at the correlation of each of these conditions with sugar sweetened beverage consumption (sodas and fruit juices).

A few studies have looked at the correlation of obesity and disease with total “added sugar” consumption. However, 71.6% of added sugar in the American diet comes from sugar sweetened beverages and junk food. None of the studies have looked at the sugar from healthy foods like fruits, vegetables, and whole grains. That’s because there is ample evidence that these foods decrease the risk of obesity, diabetes, and heart disease.

  • For example, if apples had a nutrition label, it would list 16 grams of sugar in a medium 80 calorie apple, which corresponds to about 80% of the calories in that apple. The sugar in an apple is about the same proportion of fructose and glucose found in high fructose corn syrup. Apples are not unique. The nutrition label would read about the same on most other fruits. Does that mean you should avoid sugar from all fruits? I think not.

Avoid Sugar or Avoid Certain Foods

 

avoid sugar from junk foodsThe obvious question is: “Why are the same sugars, in about the same amounts, unhealthy in sodas and healthy in fruits?” Let’s go back to those studies I just mentioned—the ones that are often used to vilify sugars. They are all association studies, the association of sugar intake with obesity and various diseases.

The weakness of association studies is the association could be with something else that is tightly correlated with the variable (sugar intake) that you are measuring. Could it be the food that is the problem, not the sugar?

If we look at healthy foods (fruits, vegetables, whole grains) they are chock full of vitamins, minerals, phytonutrients, fiber, and (sometimes) protein. Fiber and protein slow the absorption of sugar into the bloodstream. As a result, blood sugar levels rise slowly and are sustained at relatively low levels for a substantial period of time.

In sodas there is nothing to slow the absorption of blood sugar. You get rapid rise in blood sugar followed by an equally rapid fall. The same is true of junk foods consisting primarily of sugar, refined flour and/or fat.  Avoid sugar from those types of foods.

Another consideration is something called caloric density. Here is a simple analogy. I used to explain the concept of caloric density to medical students in my teaching days. There are about the same number of calories in a 2-ounce candy bar and a pound of apples (around 278 in the 2-ounce candy bar and 237 in a pound of apples). You can eat a 2-ounce candy bar and still be hungry. If you eat a pound of apples you are done for a while. In this example, the 2-ounce candy bar had a high caloric density (a lot of calories in a small package). Perhaps a more familiar terminology would be the candy bar was just empty calories.

Are Sodas and Junk Foods Killing Us?

avoid sugar from candyPutting all that together, you can start to understand why the foods the sugars are in are more important than the sugars themselves. When you consume sugars in the form of sugar sweetened beverages or sugary junk foods, your appetite increases. We don’t know for sure whether it is the intense sweetness of those foods, the rapid increase and fall in blood sugar, or the high caloric density (lots of calories ina small package) that makes us hungrier. It doesn’t matter. We crave more food, and it isn’t usually fruits, vegetables, and complex carbohydrates we crave. It’s more junk. That sets in motion a predictable sequence of events.

  • We overeat. Those excess calories are stored as fat and we become obese. [Note: The low carb enthusiasts will tell you our fat stores come from carbohydrates alone. That is incorrect. All excess calories, whether from protein, fat, or carbohydrate, are stored as fat.]
  • It’s not just the fat you can see (belly fat) that is the problem. Some of that fat builds up in our liver and muscles. This sets up an unfortunate sequence of metabolic events.
  • The fat stores release inflammatory cytokines into our bloodstream. That causes inflammation. Inflammation increases the risk of many diseases including heart disease and cancer.
  • The fat stores also cause our cells to become resistant to insulin. That reduces the ability of our cells to take up glucose, which leads to hyperglycemia and type 2 diabetes. [Note: The low carb enthusiasts will tell you carbohydrates cause type 2 diabetes. That is also incorrect. It is our fat stores that cause insulin resistance and type 2 diabetes. Our fat stores come from all excess calories, not just excess calories from carbohydrates.]
  • Insulin resistance also causes the liver to overproduce cholesterol and triglycerides and pump them into the bloodstream. That increases the risk of heart disease.
  • Sugar sweetened beverages and sugary junk foods also displace healthier foods from our diet. That leads to potential nutrient shortfalls that can increase our risk of many diseases.

However, none of this has to happen. The one thing that every successful diet has in common is the elimination of sodas, junk foods, fast foods and convenience foods. You should avoid sugar from those foods as much as possible. Once you eliminate those from your diet,you significantly enhance your chances of being at a healthy weight and being healthy long term.

 

What About Protein Supplements And Similar Foods?

Of course, the dilemma is what you, as an intrepid label reader, should do about protein supplements, meal replacement bars, or snack bars. They are supposed to be healthy, but the label lists one or more sugars. Even worse, the sugar content is higher than your favorite health guru recommends.  So, should you avoid sugar from supplements and the like?

In this case, a more useful concept is glycemic index, which is a measure of the effect of the food on your blood sugar levels. Healthy foods like apples may have a high sugar content, but they havea low glycemic index.

avoid sugar and consume protein to slow absorbptionThe same is true for the protein supplements and bars you are considering. Rather than looking at the sugar content, you should be looking for the term “low glycemic” on the label. That means there is enough fiber and protein in the food to slow the absorption of sugar into the bloodstream and stabilize your blood sugar levels.

What Does This Mean For You?

Don’t misunderstand me. I am not advocating for unlimited consumption of sugar. We should work on ways to avoid sugar or reduce the amount of sugar in our diet. On the other hand, we don’t need to become so strict that we and our family need to eat foods that taste like cardboard. We also don’t want to replace natural sugars with artificial sweeteners. I have warned about the dangers of artificial sweeteners previously.

We can go a long way towards reducing sugar by just eliminating sodas, other sugar sweetened beverages, junk foods, fast foods, convenience foods, and pastries from our diet. When considering fast foods and convenience foods, we should check the label for hidden sugar. For example, some Starbucks drinks are mostly sugar. When considering foods that are supposed to be healthy, we should look for the term “low glycemic” on the label.

So we don’t have to avoid sugar completely, but we should reduce sugar from sugar sweetened beverages and junk food.

 

The Bottom Line

 

We need to keep warnings about the dangers of sugar in perspective:

  • The studies showing that sugar consumption leads to obesity, diabetes, and heart disease have all been done with sodas and junk foods.
  • Many fruits have just as much sugar as a soda. They also contain about the same proportion of fructose and glucose as high fructose corn syrup. Yet we know fruits are good for us.
  • Diets rich in fruits, vegetables and whole grains decrease our risk of obesity, diabetes, and heart disease.
  • That is because the sugar in whole foods is generally present along with fiber and protein, which slows the absorption of sugar and prevents the blood sugar spikes we get with sodas and junk foods.
  • In the case of prepared foods like protein supplements, you should look for “low glycemic” on the label rather than sugar content. Low glycemic means that there is enough fiber and protein in the product to slow the absorption of sugar and prevent blood sugar spikes.
  • Don’t misunderstand me. I am not advocating for unlimited consumption of sugar. We should all work on ways to avoid sugar from junk foods or to reduce the amount of sugar in our diet. On the other hand, we don’t need to become so strict that we and our family need to eat foods that taste like cardboard. We also don’t want to replace natural sugars with artificial sweeteners.
  • We can go a long way towards reducing sugar by just eliminating sodas, other sugar sweetened beverages, junk foods, fast foods, convenience foods, and pastries from our diet. When considering fast foods and convenience foods, we should check the label for hidden sugar. When considering foods that are supposed to be healthy, we should look for the term “low glycemic” on the label.

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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