Should Cancer Patients Avoid Raw Fruits and Vegetables?

Back in the 1960s, a patient isolator unit was developed for cancer patients undergoing chemotherapy. Because our immune system cells were often caught in the friendly fire, up to 50% of cancer patients died of infections before they could even complete the chemo because their immune systems had become so compromised. So, a bubble boy-like contraption was developed. The patient was shaved, dipped in disinfectant, rinsed off with alcohol, rubbed with antibiotic ointment into every orifice, and placed on a rotating regimen of a dozen of the most powerful antibiotics they had. Procedures were performed through plastic sleeves on the sides of the unit, and everything in and out had to be sterilized and passed through airlocks. So, the patient wasn’t allowed any fresh fruits or vegetables.

People went crazy cooped up in these bubble-like units, with 38% even experiencing hallucinations. Fifteen years later the results were in: it simply didn’t work. People were still dying at the same rate, so the whole thing was scrapped—except the diet. The airlocks and alcohol baths were abandoned, but they continued to make sure no one got to eat a salad.

Neutrophils are white blood cells that serve as our front line of defense. When we’re immunocompromised and don’t have enough neutrophils, we’re called “neutropenic.” So, the chemotherapy patients were put on a so-called neutropenic diet without any fresh fruits and vegetables. The problem is there’s a glaring lack of evidence that such a neutropenic diet actually helps (see my video Is a Neutropenic Diet Necessary for Cancer Patients?).

Ironically, the neutropenic diet is the one remaining component of those patient isolator unit protocols that’s still practiced, yet it has the least evidence supporting its use. Why? The rationale is: there are bacteria in salads, bacteria cause infections, immunocompromised patients are at increased risk for infections, and therefore, no salad. What’s more, they were actually glad there aren’t any studies on this because it could be way too risky to give a cancer patient an apple or something. So, its continued use seems to be based on a ‘‘better safe than sorry’’ philosophy.

The problem is that kids diagnosed with cancer are already low in dietary antioxidants, so the last thing we should do is tell them they can’t have any fresh fruit or veggies. In addition to the lack of clinical evidence for this neutropenic diet, there may be some drawbacks. Restricting fruits and vegetables may even increase the risk of infection and compromise their nutritional status.

So, are neutropenic diets for cancer patients “reasonable prudence” or “clinical superstition”? Starting in the 1990s, there was a resurgence of research when greater importance was placed on the need to “support clinical practice with evidence.”

What a concept!

Three randomized controlled trials were published, and not one supported the neutropenic diet. In the biggest study, an all-cooked diet was compared to one that allowed raw fruits and veggies, and there was no difference in infection and death rates. As a result of the study, the principal investigator at the MD Anderson Cancer Center described how their practice has changed and now everyone is allowed to eat their vegetables—a far cry from “please don’t eat the salads” 31 years earlier. 

Today, neither the Food and Drug Administration, the Centers for Disease Control and Prevention, nor the American Cancer Society support the neutropenic diet. The real danger comes from pathogenic food-poisoning bacteria like Campylobacter, Salmonella, and E. coli. So we still have to keep patients away from risky foods like undercooked eggs, meat, dairy, and sprouts. At this point, though, there really shouldn’t be a debate about whether cancer patients should be on a neutropenic diet. Nevertheless, many institutions still tell cancer patients they shouldn’t eat fresh fruits and veggies. According to the latest survey, more than half of pediatric cancer doctors continue to prescribe these diets, though it’s quite variable even among those at the same institution.

Why are doctors still reluctant to move away from the neutropenic diet? There are several reasons why physicians may be hesitant to incorporate evidence-based medicine into their practices. They may have limited time to review the literature. They’d like to dig deep into studies, but simply don’t have the time to look at the evidence. Hmm, if only there was a website… 🙂

Bone marrow transplants are the final frontier. Sometimes it’s our immune system itself that is cancerous, such as in leukemia or lymphoma. In these cases, the immune system is wiped out on purpose to rebuild it from scratch. So, inherent in the procedure is a profound immunodeficiency for which a neutropenic diet is often recommended. This has also had never been tested—until now.

Not only did it not work, a strict neutropenic diet was actually associated with an increased risk for infection, maybe because you don’t get the good bugs from fruits and vegetables crowding out the bad guys in the gut. So not only was the neutropenic diet found to be unbeneficial; there was a suggestion that it has the potential to be harmful. This wouldn’t be the first time an intervention strategy made good sense theoretically, but, when put to the test, was ultimately ineffective.

Unfortunately, there’s an inertia in medicine that can result in medical practice that is at odds with the available evidence. Sometimes this disconnect can have devastating consequences. See, for example, Evidence-Based Medicine or Evidence-Biased? and The Tomato Effect.

The reason it is so important to straighten out the neutropenic diet myth is that fruits and vegetables may actually improve cancer survival:

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 Food Safety Risk of Organic versus Conventional

The stated principles of organic agriculture are “health, ecology, fairness, and care,” but if you ask people why they buy organic, the strongest predictor is concern for their own health. People appear to spend more for organic foods for selfish reasons, rather than altruistic motives. Although organic foods may not have more nutrients per dollar (see my video Are Organic Foods More Nutritious?), consumption of organic foods may reduce exposure to pesticide residues and antibiotic-resistant bacteria.

Food safety-wise, researchers found no difference in the risk for contamination with food poisoning bacteria in general. Both organic and conventional animal products have been found to be commonly contaminated with Salmonella and Campylobacter, for example. Most chicken samples (organic and inorganic), were found to be contaminated with Campylobacter, and about a third with Salmonella, but the risk of exposure to multidrug-resistant bacteria was lower with the organic meat. They both may carry the same risk of making us sick, but food poisoning from organic meat may be easier for doctors to treat.

What about the pesticides? There is a large body of evidence on the relation between exposure to pesticides and elevated rate of chronic diseases such as different types of cancers, diabetes, neurodegenerative disorders like Parkinson’s, Alzheimer’s, and ALS, as well as birth defects and reproductive disorders—but these studies were largely on people who live or work around pesticides.

Take Salinas Valley California, for example, where they spray a half million pounds of the stuff. Daring to be pregnant in an agricultural community like that may impair childhood brain development, such that pregnant women with the highest levels running through their bodies (as measured in their urine) gave birth to children with an average deficit of about seven IQ points. Twenty-six out of 27 studies showed negative effects of pesticides on brain development in children. These included attention problems, developmental disorders, and short-term memory difficulties.

Even in urban areas, if you compare kids born with higher levels of a common insecticide in their umbilical cord blood, those who were exposed to higher levels are born with brain anomalies. And these were city kids; so, presumably this was from residential pesticide use.

Using insecticides inside your house may also be a contributing risk factor for childhood leukemia. Pregnant farmworkers may be doubling the odds of their child getting leukemia and increase their risk of getting a brain tumor. This has led to authorities advocating that awareness of the potentially negative health outcome for children be increased among populations occupationally exposed to pesticides, though I don’t imagine most farmworkers have much of a choice.

Conventional produce may be bad for the pregnant women who pick them, but what about our own family when we eat them?

Just because we spray pesticides on our food in the fields doesn’t necessarily mean it ends up in our bodies when we eat it, or at least we didn’t know that until a study was published in 2006. Researchers measured the levels of two pesticides running through children’s bodies by measuring specific pesticide breakdown products in their urine. In my video, Are Organic Foods Safer?, you can see the levels of pesticides flowing through the bodies of three to 11-year-olds during a few days on a conventional diet. The kids then went on an organic diet for five days and then back to the conventional diet. As you can see, eating organic provides a dramatic and immediate protective effect against exposures to pesticides commonly used in agricultural production. The study was subsequently extended. It’s clear by looking at the subsequent graph in the video when the kids were eating organic versus conventional. What about adults, though? We didn’t know… until now.

Thirteen men and women consumed a diet of at least 80% organic or conventional food for seven days and then switched. No surprise, during the mostly organic week, pesticide exposure was significantly reduced by a nearly 90% drop.

If it can be concluded that consumption of organic foods provides protection against pesticides, does that also mean protection against disease? We don’t know. The studies just haven’t been done. Nevertheless, in the meantime, the consumption of organic food provides a logical precautionary approach.

For more on organic foods:

For more on the infectious disease implications of organic versus conventional, see Superbugs in Conventional vs. Organic Chicken. Organic produce may be safer too. See Norovirus Food Poisoning from Pesticides. Organic eggs may also have lower Salmonella risk, which is an egg-borne epidemic every year in the US. See my video Who Says Eggs Aren’t Healthy or Safe?

More on Parkinson’s and pesticides in Preventing Parkinson’s Disease With Diet.

Those surprised by the California data might have missed my video California Children Are Contaminated.

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: