A high fiber diet boosts immunotherapy for cancer. Melanoma patients had a five-fold greater chance of responding to immune checkpoint drugs when they had a diverse gut microbiome. This could explain why some people respond so well to these drugs, while so many others do not.

Woman eating dietary fiber boosts immunotherapy
A relaxing healthy breakfast at home, eating whole grains, berries and yogurt

Key Findings

According to Christine Spencer, PhD, a Houston research scientist:

“We found that patients eating high-fiber diets were about five times as likely to respond to anti-PD1 checkpoint blockade immunotherapy…most likely due to changes in their gut microbiome.

“The gut microbiome plays a big role in moderating the immune system, so the idea that we could potentially change the microbiome—whether by diet or other means—to improve response to immunotherapy treatment is really exciting.”

Spencer works at M.D. Anderson Cancer Center, Houston, with support from the foundation of Sean Parker, a Facebook billionaire. Her full report will be presented in late March 2019 at the annual meeting of the American Association for Cancer Research (AACR). But it is already making waves.

Prof. Elizabeth M Jaffee of Johns Hopkins University, Baltimore, has commented:

“Patients and healthy individuals can also be empowered through their diet to control cancer development and influence their response to therapies.”

Are Probiotics Dangerous?

In a previous post, I recommended that people take probiotic supplements. I AM NOW WITHDRAWING THAT RECOMMENDATION. Spencer’s recent scientific findings show that fiber boosts immunotherapy, but that probiotic supplement use does not, at least in this one study.

In fact, in a counter-intuitive finding, the use of probiotics was associated with a worse response to immune checkpoint drugs. The reason is not explained, but it may be that some commercial probiotics overwhelm the GI tract with one or two kinds of bacteria, whereas it is microbiome diversity is key.

Of course, this contradicts what we previously thought about the effect of these supplements. It may turn out that this negative effect is just an accidental finding. But at this point it is too soon to make a reliable recommendation about which, if any, probiotic supplements might be beneficial. So it is better not to take probiotic supplements, but to rely on diet–which means unsweetened yogurt, whole grains, fruit (especially berries), and psyllium seed husks.

Also, this study confirms that antibiotic use is also associated with a weakened immune response.

Baseball, Hot Dogs and Apple Pie

People will tell you to eat “lots of fruit and vegetables.” But that can also be problematical. Such diets can also raise your blood sugar into the abnormal range. And most people have no idea what a huge problem this is. For, to quote the Los Angeles Times:

“Baseball, hot dogs, apple pie and … diabetes. That’s right. The metabolic condition is about as American as you can get.”

As of 2015, according to U.S. government statistics, more than 100 million American adults were living with diabetes or pre-diabetes. That means 9.4% of the adult population had diabetes, and another 33.9% had pre-diabetes. Among seniors, almost half (48.3%) of the population had pre-diabetes.

So even if you want to make sure that your intake of fiber boosts immunotherapy, you still may need to be cautious about eating unlimited amounts of sugar, honey, grains, fruits and root vegetables such as potatos. However, by contrast, wheat and oat bran and psyllium seed husks will NOT raise your blood sugar to any great degree. And they are extremely inexpensive.

Back to Crackers!

Once again, my suggestion is to bake up a batch of “Ralph’s Superior Seed Crackers.” I add wheat bran and psyllium husks to my crackers, to aid digestion. I just purchased some oat bran from the food coop to add to my next batch.

One ounce of wheat or oat bran contains 12 grams of fiber. Wheat bran mainly contains insoluble fiber, while oat bran has abundant soluble fiber. Since we do not yet have details on which kind of fiber is most beneficial, you can help yourself by taking both.

Is Fiber One Okay?

To make sure that their intake of fiber will boost their immune system, some people might be tempted to eat a commercial high-bran cereal. However, many of these products contain sugar or artificial sweeteners, or other undesirable ingredients. For instance, according to the label, regular Fiber One contains corn fiber, modified wheat starch, guar gum, added color, cellulose gum, salt, baking soda, and aspartame. Who needs all that stuff?

Soluble corn fiber may sound great, but beware. It may has negative health effects and, despite the name, is not in the same class at all as wheat or oat bran.

Beans and Berries

Beans of all kinds are of course another great source of fiber, but avoid the kind that are sweetened. These are sure to mightily raise your blood sugar, especially if you are among the many with diabetes or prediabetes.

But berries, especially raw raspberries and blackberries, are another good source of fiber–about 8 grams to the cup.

These latest findings about how to make immunotherapy more effective are very exciting. These “immuno” drugs are very expensive and in high doses can be toxic. Despite all that, most people do not respond to them. But some of those who do are getting months or even years more survival. So the critical question is, why do some people respond so well, while many do not. We now may have the answer. It’s a gut feeling.

Dr. Moss discusses a high fiber diet and immunotherapy in this video.