“I figure if I keep my spirit in shape, the bones will take care of themselves.” (1)

Do you have any idea what I would give to know that my bones would take care of themselves? To know that even in an aging body, my bones would remain strong, solid and dense. To trust that my bones would keep me upright and fearless in my choice of physical activities.

A lot. I’d give A LOT.

The possibility of weakened bones is a concern for ALL women, yet for those of us who’ve experienced breast cancer, the onset of cancer treatment-induced bone loss (CTIBL) is a real threat. (2)

Any of the following can lead to a loss of bone density: (3)

  • Aromatase Inhibitors
  • Chemotherapies
  • Oophorectomy
  • Medically shutting down the ovaries
  • Corticosteroids

If previously you’ve undergone or currently are receiving any of these treatments, your doctor has likely told you about their impact on increasing risk for fractures, compromising bone mineral density, and osteoporosis.

For example, let’s say you’re postmenopausal and take AI’s. Did your doctor tell you that regardless of which AI you take, the loss of bone mineral density is twice as high compared to healthy postmenopausal women? (4)

If she/he hasn’t, print this post out and use it to initiate a discussion on bone health at your next visit.

Not only the treatments, but the disease of breast cancer itself presents challenges to skeletal integrity. I invite you to read on to learn more about dietary and nutritional options that may minimize and/or contain potential damage.

May is National Osteoporosis Month, the perfect time for a bone health primer.

I polled readers for questions on nutrition, fitness, osteoporosis risk and breast cancer. The wonderful responses I received helped shape this overview of diet, food, nutrition and supplements.

As a heads up, this is an ENORMOUS topic, well beyond the scope of a single blog post. I’ll hit the highlights, sharing what I think is most important for you to know.

My May 24 post covers FITNESS and bone health, so be sure to give it a read when it becomes available.

Absorption and Supplementation

Calcium is the most abundant mineral in your body. More than 99% of calcium is found in your bones.

“Food first” is good advice for getting calcium to your bones, but since most women are likely to get inadequate amounts of calcium from food, there can be room for supplementation.

But do you even need a calcium supplement? What kind and how much should you take?

To help you determine that, let’s first look at other considerations for calcium intake, and your body’s ability to “keep” it.  

If you intentionally aim to eat the daily recommended amount of calcium, you’re off to a good start.

How much is “recommended” depends on which guideline you use. The National Institutes of Health recommends you get the following amount from food: (5)

  • 19-50 years; 1,000 mg/day
  • 51-70 years; 1,200 mg/day

Researchers at Harvard suggest that although the 1,000-1,200 mg/day guidelines are probably adequate for women, the need may be not quite that high. They submit that more emphasis needs to be placed on exercise and adequate Vitamin D intake. Simply increasing the amount of calcium doesn’t equate to increased bone density and prevention of fractures. (6)

When tallying the amount of calcium you eat in a day, you must consider absorption. Your body absorbs only about 30% of the total amount you eat, and that amount varies depending on what types of foods you choose. (5)

Here’s what 30% absorption looks like in real life:

  • You add one cup of plant-based milk to your morning smoothie. There’s 300 mg of calcium in that one cup. A 30% absorption rate means only 90 mg sticks around to go to work in your body.

Other factors that affect calcium absorption include:

  • Amount Consumed
    • As calcium intake increases, absorption “efficiency” decreases.
  • Age
    • Absorption decreases to 15-20% in adulthood and continues to decrease with age.
  • Vitamin D Intake
    • Improves absorption.
  • Phytic Acid and Oxalic Acid
    • These components are found naturally in some plant foods. They “bind” to calcium and inhibit its absorption, but the extent to which they affect absorption varies.

There are three forms of calcium supplements:

  • Calcium carbonate
    • Naturally derived
    • Refined
  • Chelated calcium (citrate)

Which is best for you depends on your particular needs.

It’s recommended to not “over” supplement with calcium (no more than 1,000 mg per day). Split dosage to only 500 mg at one time.

Absorption is highest in a dosage ≤500 mg. (7)

One research study I found suggests that for women undergoing breast cancer treatment, even supplementation isn’t enough to prevent a reduction in bone mineral density. (8)

While this study looked at results from 16 trials, it’s not the final word. If you’re unsure whether or not to add a supplement, meet with a dietitian to review and assess your individual dietary requirements.

Dairy

Growing up, it may have been strongly encouraged (demanded?) that you drink milk to build strong bones. It’s the message I always got. Even when studying for my nutrition degree, I learned that eating adequate dairy meant adequate calcium for bone health.

The first time I read about “non-dairy” and/or “milk-free” diets? I couldn’t believe there was such a thing.

Turns out, it’s definitely possible to get enough calcium without eating dairy. But I’m getting ahead of myself.

One of the most common questions I get regarding a healthy breast cancer diet is whether or not it’s safe to eat dairy.

My response lies in considering the many compounds in dairy: calcium, casein, fat (in high-fat products), lactose, and dairy as a whole.

But before I get to that, let me say this.

In the breast cancer world, dairy is a controversial food and a hot-button topic. Dairy is often portrayed as a food villain responsible for causing and driving breast cancer.

Maybe you’ve heard about hormones, casein, or IGF (insulin-like growth factor.) Maybe you don’t know why dairy is “bad” for you, only that you “heard” you should avoid it.

As a reminder, there’s no single food – including dairy – that causes or cures breast cancer. The pattern of your diet (what you eat day in and day out, all year round) speaks to the healthfulness of a breast cancer diet.

And let’s not forget, there’s liquid and solid dairy. There’s yogurt, milk, kefir. Different animals produce different milks to make a wide variety of cheeses. The variety of animal feed may or may not contribute to the final cheese or milk product. This may in turn impact the way dairy food “works” in your body versus your neighbor.

It’s not a black or white issue.  

I’m pretty sure you’ve formed your own opinion about dairy, solidly staking your claim somewhere along the love it/hate it spectrum. Remember, your opinion about dairy’s “safety and healthfulness” re: breast cancer is not the same as your personal preference for or against dairy foods.

Let’s say you love, love, love double-cream Brie cheese (personal preference). And yet, the mere fact that it’s dairy freaks you out, because you heard dairy is “bad” for breast cancer (opinion.)

You’re entitled to both your opinion and your food preferences. I respect both. But, my mission is to help people use food to elevate their health and optimize healing.

I meet people where they are. I don’t strong arm anyone into a pattern of eating that may be backed by science, yet contains absolutely no foods they enjoy.

What would be the point of that? I work with people to find a delicious middle ground.

So if you enjoy dairy, eat it. If you’re lactose-intolerant, have a milk allergy, or simply don’t like dairy, don’t eat it.

What I would encourage you to not do, is confuse opinion with nutrition science. Below I share what we know at the time of this writing about dairy and breast cancer. Please do me a favor and share this information with those who aren’t familiar with the science, yet opine the danger of dairy to all who will listen. It helps make my job easier!

Dairy Foods (total dairy and milk intakes)

The American Institute for Cancer Research (AICR) and World Cancer Research Fund (WCRF) Continuous Update Project (CUP) Third Expert Report is used for making recommendations for (overall) cancer prevention.

There are 10 Cancer Prevention Recommendations in the report. Because of limited evidence, a specific recommendation for or against dairy is not included.

The report does contain a section highlighting the specific findings on breast cancer and dairy. It outlines its findings separately for pre and postmenopausal breast cancer. (9)

  • Premenopause: The evidence suggesting that consumption of dairy products decreases the risk of premenopausal breast cancer is limited.
  • Postmenopause: The evidence for an association was considered to be limited, and no conclusion was possible.

Definition of “limited, suggestive.” Evidence is inadequate to permit a judgement of a probable or convincing causal (protective) relationship, but is suggestive of a direction of effect. This judgement generally doesn’t justify making recommendations.

Casein

It’s possible to have a casein allergy. But is it possible casein causes breast cancer? (10)

Casein is the main protein in milk; there are four subtypes. You may have heard or read to avoid dairy because it contains casein, which is connected to breast cancer.

Googling “casein and breast cancer” can yield all sorts of terrifying results. “The Dangers of Dairy” popped up in a couple of my searches.

In combing the scientific literature, I found no research to support the casein = breast cancer claim. In fact, I found one study indicating that one of the casein subtypes found in human breast milk functions as a suppressor of breast cancer tumor growth and metastasis. Although this piece of research was conducted using cell lines and animal models, the findings are the polar opposite of what hyped-headlines would have us believe. (11)

Lactose

I found no research to support lactose (naturally occuring milk sugar) as a cause of breast cancer. In fact, one systematic review and meta-analysis indicated that dairy and its various compounds is inversely (the opposite) associated with the risk of developing breast cancer. (12)

Fat

Reducing dietary fat, especially saturated fat, doesn’t necessarily lead to reduced risk for breast cancer. However, keeping the total fat in your overall dietary pattern on the low side may help keep your weight stable. Maintaining a healthy weight is protective in reducing risk of recurrence. High-fat dairy products are calorie-dense, meaning they have more calories than lower-fat varieties. Including both high and low-fat dairy in your diet is a good approach to weight management and potentially reducing risk. (13, 14)

Calcium

Remember, calcium is found in many foods other than dairy. This research outcome speaks to CALCIUM in the diet, regardless of the food origin. (9)

  • Premenopause: The evidence suggesting that diets high in calcium decrease the risk of breast cancer is limited.
  • Postmenopause: The evidence suggesting that diets high in calcium decrease the risk of breast cancer is limited.

Calcium-Rich Foods

You already know that dairy foods are excellent sources of dairy. Here’s a (partial) list of plant foods to add. (15)

Table 1: Calcium Content of Selected Vegan Foods
Food Amount Calcium (mg)
Blackstrap molasses 2 Tbsp 400
Plant milks, calcium-fortified 8 ounces 100-450
Tofu, processed with calcium sulfate* 4 ounces 200-434
Tofu, processed with nigari* 4 ounces 130-400
Calcium-fortified orange juice 8 ounces 350
Commercial soy yogurt, plain 6 ounces 300
Collard greens, cooked 1 cup 268
Turnip greens, cooked 1 cup 197
Tempeh 1 cup 184
Kale, cooked 1 cup 177
Soybeans, cooked 1 cup 175
Mustard greens, cooked 1 cup 165
Bok choy, cooked 1 cup 158
Tahini 2 Tbsp 128
Navy beans, cooked 1 cup 126
Okra, cooked 1 cup 124
Almond butter 2 Tbsp 111
Almonds, whole 1/4 cup 94
Broccoli, cooked 1 cup 62
*Read the label on your tofu container to see if it is processed with calcium sulfate or nigari.

Foods That Interfere with Calcium Absorption

Earlier I mentioned that certain compounds in plant foods may inhibit calcium absorption. Phytic acid and oxalic acid bind to calcium and can contribute to reduced absorption rates. (16)

The extent to which these compounds affect absorption varies. Aim to eat a variety of foods, and the interaction will likely have little or no nutritional consequence. (5)

Examples of foods with phytic acid

  • Wheat bran
  • Wheat germ
  • Barley
  • Beans
  • Legumes
  • Lentils
  • Millet
  • Nuts
  • Oats
  • Seeds
  • Soybeans

Examples of foods with oxalic acid

  • Spinach
  • Collard greens
  • Sweet potatoes
  • Rhubarb
  • Beans

Take-Aways

While this post is full of information, it’s not exhaustive. Perhaps I’ll revisit this topic again in future. Tell me in the comments below whether or not that would be helpful!

Here are the main points:

  • We absorb approximately 30% of the calcium in our diet.

  • Women need 1,000 mg – 1,200 mg calcium per day (dependent on age.)

  • Calcium supplements can help fill dietary gaps. Meet with a registered dietitian to determine whether your diet has a “calcium gap.”

  • Split the dosage of calcium supplements, morning and evening. Take only 500 mg at once.

  • Dairy and breast cancer research findings are not yet robust enough to guide dietary recommendations, and haven’t provided a pro/con position.

  • Eat a variety of foods to help support calcium absorption.

 

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SOURCES

  1. Quote by Rita Moreno
  2. Cancer Treatment and Bone Health
  3. Cancer and Osteoporosis
  4. Breast Cancer and Osteoporosis – Management of Cancer Treatment-Induced Bone Loss in Postmenopausal Women with Breast Cancer
  5. Calcium Fact Sheet for Health Professionals
  6. What You Need to Know About Calcium
  7. ConsumerLab. Independent testing of health and nutritional products. Subscription required.
  8. Calcium and vitamin D supplementation and loss of bone mineral density in women undergoing breast cancer therapy
  9. Diet, nutrition, physical activity and breast cancer.
  10. Casein Allergy Overview
  11. The milk protein α-casein functions as a tumor suppressor via activation of STAT1 signaling, effectively preventing breast cancer tumor growth and metastasis
  12. The Association between Dairy Intake and Breast Cancer in Western and Asian Populations: A Systematic Review and Meta-Analysis
  13. Go PINK and RED
  14. Low-Fat Dietary Pattern and Breast Cancer Mortality in the Women’s Health Initiative Randomized Controlled Trial
  15. Calcium in the Vegan Diet
  16. Reduction of phytic acid and enhancement of bioavailable micronutrients in food grains