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

Does Protein Supplement Timing Matter?

Posted May 15, 2018 by Dr. Steve Chaney

How Do You Gain Muscle Mass & Lose Fat Mass?

Author: Dr. Stephen Chaney

 

protein supplement timingMost of what you read about protein supplements on the internet is wrong. That is because most published studies on protein supplements:

  • Are very small
  • Are not double blinded.
    • Both the subjects and the investigators knew who got the protein supplement.
  • Are done by individual companies with their product.
    • You have no idea which ingredients are in their product are responsible for the effects they report.
    • You have no idea how their product compares with other protein products.
    • There is no standardization with respect to the amount or type of protein or the addition of non-protein ingredients.

Because of these limitations there is a lot of misleading information on the benefits of protein supplements timing and maximal benefit. Let’s start by looking at why people use protein supplements. Let’s also look at what is generally accepted as true with respect to the best supplement timing.

There are 4 major reasons people consume protein supplements:

  • Enhance the muscle gain associated with resistance training: In this case, protein supplements are customarily consumed concurrently with the workout.
  • Preserve muscle and accelerate fat loss while on a weight loss diet: In this case, protein supplements are customarily consumed with meals or as meal replacements.
  • Provide a healthier protein source. In this case, protein supplements are customarily consumed with meals in place of meat protein.
  • Prevent muscle loss associated with aging or illness. There is no customary pattern associated with this use of protein supplements.

How good are the data supporting the customary timing of protein supplementation? The answer is: Not very good. The timing is based on a collection of weak studies which do not always agree with each other.

The current study  (J.L. Hudson et al, Nutrition Reviews, 76: 461-468, 2018 ) was designed to fill this void in our knowledge. It is a meta-analysis that compares all reasonably good studies that have looked at the effect of protein supplement timing on weight gain or loss, lean muscle mass gain, fat loss, and the ratio of lean muscle mass to fat mass.

How Was The Study Done?

The authors started by doing a literature search of all studies that met the following criteria:

  • The study was a randomized control trial with parallel design. This means that study contained a control group. It does not mean that the investigators or subjects were blinded with respect to which subjects used a protein supplement and which did not.
  • The subjects were engaged in resistance training.
  • The study lasted 6 weeks or longer.
  • Reliable methods were used to measure body composition (lean muscle mass and fat mass).
  • The subjects were healthy and at least 19 years old.
  • There was no restriction on the food the subjects consumed.

The authors started with 2074 published studies and ended up with 34 that met all their criteria. They then separated the studies into two groups – those in which the protein supplements were used with meals and those in which the protein supplements were used between meals.

Both groups were diverse.

  • Group 1 included subjects who consumed their protein supplement with their meal and those who consumed their protein supplement as a meal replacement.
  • Group 2 included subjects who consumed their protein supplement concurrent with exercise (usually immediately after exercise) and those who consumed their protein supplement at a fixed time of day not associated with exercise.

Does Protein Supplement Timing Matter?

 

protein supplement timing workoutsBecause the individual studies were very diverse in the way they were designed, the authors could not calculate a reliable estimate of how much lean muscle mass was increased or fat mass was decreased. Instead, they calculated the percentage of studies showing an increase in lean muscle mass or a decrease in fat mass.

When the authors compared protein supplements consumed with meals versus protein supplements consumed between meals:

  • Weight gain was observed in 56% of the studies of protein supplementation with meals compared to 72% of the studies of protein supplementation between meals. In other words, protein supplements consumed with meals were less likely to lead to weight gain than protein supplements consumed between meals.
  • An increase in lean muscle mass was observed in 94% of the studies of protein supplementation with meals compared to 90% of the studies of protein supplementation between meals. In other words, timing of protein supplementation did not matter with respect to increase in muscle mass.
  • A loss of fat mass was observed in 87% of the studies of protein supplementation with meals compared to 59% of the studies of protein supplementation between meals. In other words, protein supplements consumed with meals were more likely to lead to loss of fat mass.
  • An increase in the ratio of lean muscle mass to fat mass was observed in 100% of the studies of protein supplementation with meals compared to 87% of the studies of protein supplementation between meals. In short, protein supplements consumed with meals were slightly more likely to lead to an increase in the ratio of lean muscle mass to fat mass.

The following seem to suggest protein supplement timing matters:

The authors pointed out that their findings were consistent with previous studies showing that when protein supplements are consumed with a meal they displace some of the calories that otherwise would have been consumed. Simply put, people naturally compensate by eating less of other foods.

In contrast, the authors stated that previous studies have shown that when foods, especially liquid foods, are consumed as snacks (between meals), people are less likely to compensate by reducing the calories consumed in the next meal.

The others concluded: “Concurrently with resistance training, consuming protein supplements with meals, rather than between meals, may more effectively promote weight control and reduce fat mass without influencing improvements in lean [muscle] mass.”

What Are The Limitations Of The Study?

Meta-analyses such as this one, are only as good as the studies included in the meta-analysis. Unfortunately, most sports nutrition studies are very weak studies. Thus, this meta-analysis is a perfect example of the “Garbage In: Garbage Out (GI:GO)” phenomenon.

For example, let’s start by looking at what the term “protein supplement” meant.

  • Because the studies were done by individual companies with their product, the protein supplements in this meta-analysis:
    • Included whey, casein, soy, bovine colostrum, rice or combinations of protein sources.
    • Were isolates, concentrates, or hydrolysates.
    • Contained various additions like creatine, amino acids, and carbohydrate.
  • As I discuss in my book, Slaying the Food Myths, previous studies have shown that optimal protein and leucine levels are needed to maximize the increase in muscle mass and decrease in fat mass associated with resistance exercise. However, neither protein nor leucine levels were standardized in the protein supplements included in this meta-analysis.
  • Previous studies have shown that protein supplements that have little effect on blood sugar levels (have a low glycemic index) are more likely to curb appetite. However, glycemic index was not standardized for the protein supplements included in this meta-analysis.

protein supplement timing workout peopleIn short, the conclusions of this study might be true for some protein supplements, but not for others. We have no way of knowing.

We also need to consider the composition of the two groups.

  • Protein supplements used as meal replacements are more likely to decrease weight and fat mass than protein supplements consumed with meals. Yet, both were included in group 1.
  • Some studies suggest that protein supplements consumed concurrent with resistance exercise are more likely to increase muscle mass than protein supplements consumed another time of day. Yet, both are included in group 2. We also have no idea whether the meals with protein supplements in group 1 were consumed shortly after exercise or at an entirely different time of day.

This was the most glaring weakness of the study because it was completely avoidable. The authors could have grouped the studies into categories that made more sense.

In other words, there are multiple weaknesses that limit the predictive power of this study.

What Can We Learn From This Study?

Despite its many limitations, this study does remind us that protein supplements do have calories. This is of relatively little importance for people whose primary goal is to increase lean muscle mass.

However, most of us are using protein supplements to lose weight or to increase our lean mass to fat mass ratio. Simply put, we are either trying to lean out (shape up) or lose weight. And, we want to lose that weight primarily by getting rid of excess fat. For us, calories do matter. With that in mind:

  • If we are consuming a protein supplement immediately after exercise or between meals we probably should make a conscious effort to reduce our daily caloric intake elsewhere in our diet.
  • Alternatively, we could consume the protein supplement with a meal, but time the meal so it occurs shortly after exercise.

 

The Bottom Line:

 

A recent study looked at the optimal timing of protein supplements consumed by subjects who were engaged in resistance exercise. Specifically, the study compared protein supplements consumed with meals versus protein supplements consumed between meals on weight, lean muscle mass, fat mass, and the ratio of lean muscle mass to fat mass. The study reported:

  • Protein supplements consumed with meals were less likely to lead to weight gain than protein supplements consumed between meals.
  • Timing of protein supplementation did not matter with respect to increase in muscle mass.
  • Protein supplements consumed with meals were more likely to lead to loss of fat mass.
  • Protein supplements consumed with meals were slightly more likely to lead to an increase in the ratio of lean mass to fat mass.

The authors pointed out that their findings were consistent with previous studies showing that when a protein supplement was consumed with a meal it displaces some of the calories that would have been otherwise consumed. Simply put, people naturally compensate by eating less of other foods.

In contrast, the authors said that previous studies have shown that when foods, especially liquid foods, are consumed as snacks (between meals), people are less likely to compensate by reducing the calories consumed in the next meal.

As discussed in the article above, the study has major weaknesses. However, despite its many weaknesses, this study does remind us that protein supplements do have calories. This is of relatively little importance for people whose primary goal is to increase lean muscle mass.

However, for those of us who are using protein supplements to lose weight or to increase our lean mass to fat mass ratio, calories do matter.  With that in mind:

  • If we are consuming a protein supplement immediately after exercise or between meals we probably should make a conscious effort to reduce our daily caloric intake elsewhere in our diet.
  • Alternatively, we could consume the protein supplement with a meal, but time the meal so it occurs shortly after exercise.

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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