Dietary fiber: Cancer cure—or cause?

The colon is an amazing part of anatomy. It’s really a complex ecosystem within the body. Inside, its contents act as a growth medium for both intestinal bacteria and colonic cells. This growth medium, in turn, is influenced extensively by “host conditions.” Primarily, the foods you eat.

For the most part, this colonic ecosystem adapts to whatever you throw at it (or into it, as the case may be). But there are limits to its flexibility. And pushing those limits can result in some serious consequences—like cancer and other diseases.

Of course, on the flip side of that coin, there must also be specific substances that offer a protective effect in the colonic ecosystem. And, for decades, fiber has been the most widely accepted colon protector.

But beware—fiber is more complicated than you’ve been led to believe…

The major source of fiber that’s wreaking havoc on your health

The idea that a high-fiber diet lowers cancer risk first attracted attention back in 1971. All because one British pathologist named Denis Parsons Burkitt proposed that the reason Africans were at low risk of colon cancer was because their diets were high in fiber.

This hypothesis is attractive, but has actually proven to be problematic…

In the previous article on cholesterol myths, I mentioned how large amounts of fat weren’t part of a “normal” human diet among our ancestors. But neither was a diet high in grains. Which, today, are considered a major source of fiber.

Grains weren’t a part of a typical human dietary pattern until about 10,000 years ago (which is relatively recently in the overall history of the human species on this planet).

And archaeologists have shown how this move toward a more grain-based diet has actually created dietary problems. Most notably, it has completely altered the “feast or famine” situation our ancestors lived by.

All feast, no famine

Today, we live in a constant “feast” environment. And while that sounds like a good thing, it’s not. We need the balancing effect of “famine” (or at least fasting). Constant exposure to so much food—and food so different from what human bodies originally adapted to—can have some extremely negative consequences on your health.

During “feasts,” cell proliferation (the growth and spread of cells) in the intestines increases. This can actually have a disease-promoting effect. After all, unhealthy cells will spread as much as healthy cells.

Normally, this increased growth and spread would be negated during times of famine, as an energy- conserving mechanism.

But since most of us no longer experience periods of famine, our capacity to adapt has all but disappeared. Leading to obesity, chronically high G.I. hormone levels, and, again, elevated colonic cellular proliferation.

In other words, high intake of fiber in the form of grains results in increased risk of cancer.

This may explain why there hasn’t been any real evidence of lower cancer rates in the popular macrobiotic diet. The high-fiber content may perhaps be counter- productive.

It also explains why the association between “dietary fiber” and colon cancer has produced mixed findings. And why even the interpretations of the existing data aren’t consistent.

Fiber is a common constituent in the foods that consistently appear to prevent cancer. But it isn’t the only protective factor.

The whole package

What has never been clearly recognized by the NIH or statistical research is the most consistent finding in diet and cancer. And it’s not a high intake of fiber. At least, not by itself.

It’s a high intake of fiber- containing fruits and vegetables in general that lowers risk of cancer. And not just in the colon—but a wide variety of cancer sites.

Hundreds of studies looking at the role of vegetable and fruit intake in relation to cancer reveal a very consistent picture of lower risk in association with higher consumption. And these effects simply cannot be linked solely to the foods’ fiber content. Fiber may just be a “proxy” for other protective nutrients.

Given the consistency of high fruit and vegetable intake as protective against cancer, and the opposite effect of grains, it’s obvious that fiber itself isn’t the answer.

But why waste time, money, and resources debating which nutrient (or even which food) is most crucial?

A better, simpler way to get the cancer protection you need

Fruits and vegetables contain a wide variety of substances besides vitamins and minerals that have anticancer properties. Phenols, isothiocyanates, flavonoids, indoles, lignans, etc. have all proven their anti-cancer potential in studies.

But it isn’t really possible to provide required dosage estimates for these “non-nutrient” substances. Government food tables certainly don’t provide this information.

In fact, most of the relevant analyses needed to determine these values haven’t even been done. Besides, it’s likely that whole classes of beneficial constituents of fruits and vegetables still remain to be identified.

So rather that grasping at straws, waiting for scientists to separate every nutrient in a particular vegetable or fruit, and test it for its potential effects, why not make it easy on yourself? Simply eat more of them in general.

Fruits and vegetables are “purpose-fitted” packages of required nutrients for humans.

After all, humans evolved in the presence of plants, not just nutrients. And people eat foods, not nutrients.


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