Fighting colorectal cancer with calcium

Tissue? I Hardly Know You!

Calcium intake is a powerful preventive against colorectal cancer.

That’s a bold statement, but with study after study we’re seeing that it appears to be true.

In the e-Alert “Counting the Ways” (6/24/04), I told you about research at the Dartmouth-Hitchcock Medical Center that showed how high calcium intake may significantly lower the risk of advanced polyps developing into cancer. That study indicated that calcium supplements (apart from dietary sources) provide effective protection against advanced polyps.

Now a new study from the University of Minnesota confirms those earlier results, while shedding new light on the value of supplementing with calcium. But as we’ll see, there are important guidelines that everyone who uses calcium supplements needs to be aware of.

To protect and defend

Researchers at the University of Minnesota (UM) used data collected from more than 45,000 women who completed National Cancer Institute food frequency questionnaires. None of the women had a history of colorectal cancer at the outset of the study.

In addition to tracking dietary sources of calcium, the researchers separated the subjects into four groups according to their intake of supplementary calcium:

  • Zero calcium supplement intake: more than 25,400 subjects
  • Zero to 400 mg daily: more than 9,400 subjects
  • 401 to 800 mg daily: more than 4,100 subjects
  • More than 800 mg daily: more than 6,200 subjects

Diet, supplement intake and medical records were followed for an average of 8.5 years. During that time, 482 women developed colorectal cancer.

As published in the January issue of Cancer Epidemiology, Biomarkers and Prevention, the UM team reported three key results:

  • Compared with low calcium consumption (from either diet or supplements), subjects who consumed between 400 and 800 mg of calcium per day from any source reduced their risk of colorectal cancer by about 25 percent
  • When calcium intake was more than 800 mg per day, colorectal cancer risk was reduced by more than 45 percent
  • Women who consumed large amounts of calcium from BOTH dietary and supplemental sources had the greatest protection against colorectal cancer

These results, combined with earlier research (such as the Dartmouth-Hitchcock trial of more than 900 men and women), would indicate that high calcium intake also acts as a preventive against colorectal cancer in men.

Dynamic duo

Both the UM and Dartmouth-Hitchcock studies illustrate the importance of including plenty of calcium-rich foods in your diet, such as salmon, cabbage, kale, and yellow, green, or waxed beans.

In the Dartmouth-Hitchcock study, subjects also took 1,200 mg of calcium carbonate daily. In the e-Alert “Absorbing it All” (4/19/04), HSI Panelist Allan Spreen, M.D., noted that calcium carbonate is the most common, most readily available and least expensive type of calcium supplement. But the carbonate form does have two drawbacks: It’s not as well absorbed as some other inorganic forms of calcium, and it binds the most acid.

The latter problem presents a potential plus, as well as a minus. Some scientists believe that calcium’s ability to bind acids may be the very reason it protects against cancer. But binding digestive acids may also result in poor absorption of nutrients and indigestion. So if a 1,200 mg supplement of calcium is taken daily, along with good sources of calcium in the diet, keep an eye out for digestive problems, which can usually be managed by adjusting the dosage of the supplement.

In addition, Dr. Spreen notes that, “Calcium is not found in nature (in edible form) without magnesium, and they therefore should always be given together.”

Foods that are high in magnesium include leafy green vegetables, whole grains, bananas, apricots, meat, beans, and nuts.

Added prevention

And as long as we’re on the subject of protecting the colon with supplements, I should also mention folate.

A 2002 study – also published in Cancer Epidemiology, Biomarkers, and Prevention – showed that those with a family history of colon cancer may cut their risk by as much as 50 percent with a supplement of 400 micrograms of folate daily. In addition to supplements, spinach and asparagus provide good sources of folate.

Whether or not you and your doctor decide that calcium and folate supplements are right for you, keep in mind one more important preventive measure: Ask your doctor about arranging for a colonoscopy, which is recommended every three to five years for everyone over the age of 50; especially those with a family history of colon cancer.


and another thing

It’s time for a confession: I may be living outside the law.

I had a cold last week and my husband brought home a box of Kleenex Anti-Viral tissues. They seemed to work just as well as normal tissues. I’m not sure how effective the “moisture-activated” viral-killing middle layer really is, but I figured it couldn’t do any harm.

How naive I was back then!

One evening when my congestion was charging back with a vengeance (Can someone please tell me why colds turn nasty when the sun goes down?), I reached for a tissue and for the first time noticed these words printed on the box: “See directions.”

Directions? For tissues? I thought everyone learned how to use tissues the same way: Your mom holds one up to your face and says, “Blow!” Most of us master the technique after just one lesson.

Of course, I HAD to check to see what these “directions” were all about. So I flipped the box over and found – not directions – but a warning: “It is a violation of federal law to use this product in a manner inconsistent with its labeling.”

My blood ran cold.

That very morning my cat had coughed up a hairball on the carpet. I pulled a tissue out of the box, and instead of placing it over my nose in a manner consistent with the labeling, I used it to pick up the hairball!

A possible violation of federal law!

And I’d been doing this sort of thing all day long! I wiped some moisture off the bathroom counter with an Anti-Viral tissue. I rubbed a smudge off a picture frame. And possibly the worst violation of all: I cleaned my sunglasses!

Out of curiosity (and guilt!) I called the 800 number on the tissue box to inquire about exactly what might constitute tissue use inconsistent with the labeling. A nice woman at Kimberly-Clark (the maker of Kleenex) couldn’t answer my question, so asked me to hold. A moment later she came back and explained that while there’s nothing in the Anti-Viral tissue that might be harmful, the tissues shouldn’t be used for cleaning up spills or to remove makeup.

I had a sense that she probably couldn’t walk me through the federal laws that forbid these activities, so I didn’t press the issue. But maybe I should have. I don’t really want to look up and see my photo on a wanted poster the next time I’m standing in line at the post office with a runny nose.

To Your Good Health,

Jenny Thompson
Health Sciences Institute