Why Did Doctors Keep Prescribing Cancer?

We’ve known about the role of estrogen in breast cancer going back to the 1800s, when surgical removal of the ovaries seemed to help in some cases. Ovaries were said to send out “mysterious” influences to the rest of the body, which were identified as estrogen in 1923. The medical profession jumped on this discovery and started injecting menopausal women by the thousands, and it was said that “[t]he ‘shot’ gives a ‘respectable’ hook on which to hang the visit to the doctor…” Soon, there were pills and patches, and medical journals like the Journal of the American Medical Association regaled doctors with ads I feature in my video How Did Doctors Not Know About the Risks of Hormone Therapy? on how they can “help the women to happiness by simply prescribing estrogen” and, “[w]hen women outlive their ovaries…,” there is Premarin.

As far back as the 1940s, concerns were raised that this practice might cause breast cancer, noting it would have been nice to figure this out before we started dosing women en masse. But breast cancer risk didn’t seem to matter as much, because heart disease was the number-one killer of women, reviews concluded, and because women taking hormones appeared to have lower heart attack rates, which would outweigh any additional breast cancer. However, women taking estrogen tended to be of a higher socioeconomic class, exercised more, and engaged in other healthy lifestyle changes like consuming more dietary fiber and getting their cholesterol checked. So, maybe that’s why women taking estrogen appeared to be protected from heart disease. Perhaps it had nothing to do with the drugs themselves. Despite the medical profession’s “enthusiasm for estrogen replacement therapy,” only a randomized clinical trial could really resolve this question. We would need to divide women into two groups, with half getting the hormones and half getting a placebo, and follow them out for a few years. There was no such study…until the 1990s, when the Women’s Health Initiative study was designed.

Wait a second. Why did it take the bulk of a century to decide to definitively study the safety of something prescribed to millions of women? Perhaps because there had never been a female director of the National Institutes of Health until then. “Just three weeks after being named NIH Director in 1991, [Bernadine Healy] went before Congress to announce, ‘We need a moon walk for women.’ That ‘moon walk’ took the form of the Women’s Health Initiative, the most definitive, far-reaching clinical trial of women’s health ever undertaken in the United States.”

The bombshell landed in summer 2002. There was so much more invasive breast cancer in the hormone users that they were forced to stop the study prematurely. What about heart disease? Wasn’t that supposed to balance things out? The women didn’t just have more breast cancer—they had more heart attacks, more strokes, and more blood clots to their lungs.

The news that women treated with hormone replacement therapy “experienced higher rates of breast cancer, cardiovascular disease, and overall harm has rocked women and physicians across the country.” Estrogen started out as the most prescribed drug in America before the study, but, after, the number of prescriptions dropped immediately and, within a year, so did the incidence of breast cancer in the United States.

The most important question about this story is why were we all so surprised? There had been “decades of repeated warnings” about the risks of cancer. In fact, the reason breast cancer patients had so much trouble suing the pharmaceutical company was that “the drugs have contained warning labels for decades.” And, with that disclosure, surely any reasonable physician would have included it in their risk and benefit discussions with their patients, right? It’s like the warning labels on packs of cigarettes. If you get lung cancer now, you should have known better. And, so, if you were on hormone replacement therapy and got breast cancer, don’t blame the drug company. They warned you about the risks, right there in the fine print.

Why didn’t more doctors warn their patients? Even after the study came out, millions of prescriptions continued to be dispensed. That’s a lot of cancer in our patients we caused, wrote one doctor. “How long will it take us to discard the financial gains, to admit that we are harming many of our patients, and to start changing our prescription habits?”

“Why did this practice continue in the face of mounting evidence of harm?” Well, it is a multibillion-dollar industry. “Despite an overwhelming amount of evidence to the contrary, many physicians still believe that estrogenic hormones have overall health benefits,” a “non-evidence-based perception [that] may be the result of decades of carefully orchestrated corporate influence on medical literature.” Indeed, “[d]ozens of ghostwritten reviews and commentaries published in medical journals and supplements were used to promote unproven benefits and downplay harms of menopausal hormone therapy…” PR companies were paid to write the articles that were then passed off as having been written by some expert.

What now? “Gynecologists must switch allegiance from eminence-based to evidence-based medicine.” In other words, they must consider what the science says and not just what some so-called expert says. It’s been said that the “current culture of gynecology encourages the dissemination of health advice based on advertising rather than science.”

“Women were placed in the way of harm by their physicians, who acted as unsuspecting patsies for the pharmaceutical companies.” If we really wanted to prevent heart attacks in women, simple lifestyle behaviors can eliminate more than 90 percent of heart attack risk. So, instead of being Big Pharma’s pawns, “recommending a healthful diet, increased exercise, and smoking cessation would truly benefit women’s health.”


The whole Premarin debacle speaks to the importance of putting purported therapies to the test (see, for example, Do Vitamin D Supplements Help with Diabetes, Weight Loss, and Blood Pressure?), as well as to the power of Big Pharma (Eliminating Conflicts of Interest in Medical Research), medical community collusion (American Medical Association Complicity with Big Tobacco), and my most series on mammograms.

What about Plant-Based Bioidentical Hormones and Soy Phytoestrogens for Menopause Hot Flashes? Check out the videos to find out.

In general, patients (and doctors) tend to wildly overestimate the efficacy of pills and procedures. See Why Prevention Is Worth a Ton of Cure and The Actual Benefit of Diet vs. Drugs.

Medical care, in general, may be the third leading cause of death in the United States. See How Doctors Responded to Being Named a Leading Killer.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

The Best Source of Resistant Starch

Resistant starch wasn’t discovered until 1982. Before that, we thought all starch could be digested by the digestive enzymes in our small intestine. Subsequent studies confirmed that there are indeed starches that resist digestion and end up in our large intestine, where they can feed our good bacteria, just like fiber does. Resistant starch is found naturally in many common foods, including grains, vegetables, beans, seeds, and some nuts, but in small quantities, just a few percent of the total. As I discuss in my video Getting Starch to Take the Path of Most Resistance, there are a few ways, though, to get some of the rest of the starch to join the resistance.

When regular starches are cooked and then cooled, some of the starch recrystallizes into resistant starch. For this reason, pasta salad can be healthier than hot pasta and potato salad can be healthier than a baked potato, but the effect isn’t huge. The resistant starch goes from about 3 percent up to 4 percent. The best source of resistant starch is not from eating cold starches, but from eating beans, which start at 4 or 5 percent and go up from there.

If you mix cooked black beans with a “fresh fecal” sample, there’s so much fiber and resistant starch in the beans that the pH drops as good bacteria churn out beneficial short-chain fatty acids, which are associated both directly and indirectly with lower colon cancer risk. (See Stool pH and Colon Cancer.) The more of this poopy black bean mixture you smear on human colon cancer, the fewer cancer cells survive.

Better yet, we can eat berries with our meals that act as starch blockers. Raspberries, for example, completely inhibit the enzyme that we use to digest starch, leaving more for our friendly flora. So, putting raspberry jam on your toast, strawberries on your corn flakes, or making blueberry pancakes may allow your good bacteria to share in some of the breakfast bounty.

Another way to feed our good bacteria is to eat intact grains, beans, nuts, and seeds. In one study, researchers split people into two groups and had them eat the same food, but in one group, the seeds, grains, beans, and chickpeas were eaten more or less in a whole form, while they were ground up for the other group. For example, for breakfast, the whole-grain group got muesli, and the ground-grain group had the same muesli, but it was blended into a porridge. Similarly, beans were added to salads for the whole-grain group, whereas they were blended into hummus for the ground-grain group. Note that both groups were eating whole grains—not refined—that is, they were eating whole foods. In the ground-grain group, though, those whole grains, beans, and seeds were made into flour or blended up.

What happened? Those on the intact whole-grain diet “resulted in a doubling of the amount excreted compared to the usual diet and produced an additional and statistically significant increase in stool mass” compared with those on the ground whole-grain diet, even though they were eating the same food and the same amount of food. Why? On the whole-grain diet, there was so much more for our good bacteria to eat that they grew so well and appeared to bulk up the stool. Even though people chewed their food, “[l]arge amounts of apparently whole seeds were recovered from stools,” but on closer inspection, they weren’t whole at all. Our bacteria were having a smorgasbord. The little bits and pieces left after chewing transport all this wonderful starch straight down to our good bacteria. As a result, stool pH dropped as our bacteria were able to churn out so many of those short-chain fatty acids. Whole grains are great, but intact whole grains may be even better, allowing us to feed our good gut bacteria with the leftovers.

Once in our colon, resistant starches have been found to have the same benefits as fiber: softening and bulking stools, reducing colon cancer risk by decreasing pH, increasing short-chain fatty acid production, reducing products of protein fermentation (also known as products of putrefaction), and decreasing secondary bile products.

Well, if resistant starch is so great, why not just take resistant starch pills? It should come as no surprise that commercial preparations of resistant starch are now available and “food scientists have developed a number of RS-enriched products.” After all, some find it “difficult to recommend a high-fiber diet to the general public.” Wouldn’t be easier to just enrich some junk food? And, indeed, you now can buy pop tarts bragging they contain “resistant corn starch.”

Just taking resistant starch supplements does not work, however. There have been two trials so far trying to prevent cancer in people with genetic disorders that put them at extremely high risk, with virtually a 100-percent chance of getting cancer, and resistant starch supplements didn’t help. A similar result was found in another study. So, we’re either barking up the wrong tree, the development of hereditary colon cancer is somehow different than regular colon cancer, or you simply can’t emulate the effects of naturally occurring dietary fiber in plant-rich diets just by giving people some resistant starch supplements.

For resistant starch to work, it has to get all the way to the end of the colon, which is where most tumors form. But, if the bacteria higher up eat it all, then resistant starch may not be protective. So, we also may have to eat fiber to push it along. Thus, we either eat huge amounts of resistant starch—up near the level consumed in Africa, which is twice as much as were tried in the two cancer trials—or we consume foods rich in both resistant starch and fiber. In other words, “[f]rom a public health perspective, eating more of a variety of food rich in dietary fibre including wholegrains, vegetables, fruits, and pulses [such as chickpeas and lentils] is a preferable strategy for reducing cancer risk.”


What’s so great about resistant starch? See my video Resistant Starch and Colon Cancer.

I first broached the subject of intact grains in Are Green Smoothies Bad for You?.

Why should we care about what our gut flora eats? See Gut Dysbiosis: Starving Our Microbial Self.

Did I say putrefaction? See Putrefying Protein and “Toxifying” Enzymes.

Berries don’t just help block starch digestion, but sugar digestion as well. See If Fructose Is Bad, What About Fruit?.

The whole attitude that we can just stuff the effects into a pill is a perfect example of reductionism at work. See Reductionism and the Deficiency Mentality and Why is Nutrition So Commercialized? for more on this.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

The Answer to a Colon Cancer Mystery

Colorectal cancer is the third most common cause of cancer death in the world. Thankfully, the good bacteria in our gut take the fiber we eat and make short-chain fatty acids, like butyrate, that protect us from cancer. We take care of them, and they take care of us. If we do nothing to colon cancer cells, they grow. That’s what cancer does. But if we expose the colon cancer cells to the concentration of butyrate our good bacteria make in our gut when we eat fiber, the growth is stopped in its tracks. If, however, the butyrate stops, if we eat healthy for only one day and then turn off the fiber the next, the cancer can resume its growth. So, ideally, we have to eat a lot of fiber-rich foods—meaning whole plant foods—every day.

What about the populations, like those in modern sub-Saharan Africa, where they don’t eat a lot of fiber yet still rarely get colon cancer? Traditionallly. they used to eat a lot of fiber, but now their diet is centered around highly refined corn meal, which is low in fiber—yet they still have low colon cancer rates. Why? This was explained by the fact that while they may be lacking protective factors like fiber, they are also lacking cancer-promoting factors like animal protein and fat. But are they really lacking protective factors?

If you measure the pH of their stools, the black populations in South Africa have lower pH, which means more acidic stools, despite comparable fiber intakes. That’s a good thing and may account for the lower cancer rates. But, wait a second. Low colon pH is caused by short-chain fatty acids, which are produced by our good bacteria when they eat fiber, but they weren’t eating any more fiber, suggesting there was something else in addition to fiber in their diets that was feeding their flora. And, indeed, despite low fiber intake, the bacteria in their colon were still churning out short-chain fatty acids like crazy. But if their bacteria weren’t eating fiber, what were they eating? Resistant starch. “[T]he method of cooking and eating the maize [corn] meal as a porridge results in an increase in resistant starch, which acts in the same way as fiber in the colon,” as a prebiotic, a food for our good bacteria to produce the same cancer-preventing, short-chain fatty acids.

As I discuss in my video Resistant Starch and Colon Cancer, “[r]esistant starch is any starch…that is not digested and absorbed in the upper digestive tract [our small intestine] and, so, passes into the large bowel,” our colon, to feed our good bacteria. When you boil starches and then let them cool, some of the starch can recrystallize into a form resistant to our digestive enzymes. So, we can get resistant starch eating cooled starches, such as pasta salad, potato salad, or cold cornmeal porridge. “This may explain the striking differences in colon cancer rates.” Thus, they were feeding their good bacteria after all, but just with lots of starch rather than fiber. “Consequently, a high carbohydrate diet may act in the same way as a high fiber diet.” Because a small fraction of the carbs make it down to our colon, the more carbs we eat, the more butyrate our gut bacteria can produce.

Indeed, countries where people eat the most starch have some of the lowest colon cancer rates, so fiber may not be the only protective factor. Only about 5 percent of starch may reach the colon, compared to 100 percent of the fiber, but we eat up to ten times more starch than fiber, so it can potentially play a significant role feeding our flora.

So, the protection Africans enjoy from cancer may be two-fold: a diet high in resistant starch and low in animal products. Just eating more resistant starch isn’t enough. Meat contains or contributes to the production of presumed carcinogens, such as N-nitroso compounds. A study divided people into three groups: one was on a low-meat diet, the second was on a high-meat diet including beef, pork, and poultry, and the third group was on the same high-meat diet but with the addition of lots of resistant starch. The high-meat groups had three times more of these presumptive carcinogens and twice the ammonia in their stool than the low-meat group, and the addition of the resistant starch didn’t seem to help. This confirms that “exposure to these compounds is increased with meat intake,” and 90 percent are created in our bowel. So, it doesn’t matter if we get nitrite-free, uncured fresh meat; these nitrosamines are created from the meat as it sits in our colon. This “may help explain the higher incidence of large bowel cancer in meat-eating populations,” along with the increase in ammonia—neither of which could be helped by just adding resistant starch on top of the meat.

“[T]he deleterious effects of animal products on colonic metabolism override the potentially beneficial effects of other protective nutrients.” So, we should do a combination of less meat and more whole plant foods, along with exercise, not only for our colon, but also for general health.


This is a follow-up to my video Is the Fiber Theory Wrong?.

What exactly is butyrate? See:

For videos on optimizing your gut flora, see:

Interested in more on preventing colon cancer? See:

If you’re eating healthfully, do you need a colonoscopy? Find out in Should We All Get Colonoscopies Starting at Age 50?.

When regular starches are cooked and then cooled, some of the starch recrystallizes into resistant starch. For this reason, pasta salad can be healthier than hot pasta, and potato salad can be healthier than a baked potato. Find out more in my video Getting Starch to Take the Path of Most Resistance.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: