The Keto Diet: Good Or Bad For Intestinal Cancer?

The science is clear, and the answer is “yes”:

There are two intestines inside of you

You know this, of course. A small intestine and a large intestine. Sometimes it’s easy to get confused which is which, because the small intestine is much longer than the large intestine and by virtue of this also has the greater surface area, but it’s easy to remember at least that there are two of them.

Researchers (Dr. Jessica Shay et al.) investigated the effect of the ketogenic diet on cancers of the intestines, and found:

• Good news: the ketogenic diet has been found to decrease the risk of cancer of the colon (large intestine)
• Bad news: the ketogenic diet has been found to increase the risk of cancer of the small intestine

This latter is particularly important to note, because small intestinal cancers have been increasing in recent decades, especially in people with inherited conditions such as familial adenomatous polyposis (FAP).

That said, the mechanism by which this happens is so far only proven in mice (because it’s difficult to do ethically do RCTs of this kind in humans, which means observational studies that can’t prove causality, and also having to wait a lot longer for data because humans live a lot longer than mice).

The mechanism, by the way, is that the ketogenic diet increased fatty acid oxidation, activating PPAR proteins, which stimulated intestinal stem cells to divide more rapidly.

In case this wasn’t clear, yes that does mean that the effects were not caused by ketone bodies such as β-hydroxybutyrate (BHB), but rather, they were driven by how intestinal cells metabolized large amounts of dietary fat. This is an important thing to know since the ketogenic diet works by drastically reducing carbohydrates, the body burns fat instead of glucose for energy, producing ketone bodies such as BHB and acetoacetate.

And, we must nevertheless underline: it’s still very keto-specific, rather than being “just” a matter of the fat alone, because mice on the ketogenic diet developed small intestinal tumors at rates similar to or even higher than mice fed the obesogenic high-fat, high-calorie diet, despite not gaining weight.

Since chemistry continues to be chemistry regardless of species, and those proteins exist in humans too, there is no known reason why this shouldn’t apply to humans also, it’s just, scientists can’t and won’t claim things that aren’t outright proven (and neither can/will we).

You can read the paper in full, here: Ketogenic diet mediates intestinal tumorigenesis through lipids not ketones

These anticancer and (in the other intestine) carcinogenic properties aren’t the only pros and cons of keto, so we’ll link to our main article about other pros and cons, here: Ketogenic Diet: Burning Fat Or Burning Out?

We will also, before moving on, mention a few relevant things we’ve written about since that article, including:

• How To Dodge The “Keto Flu” ← this is about the unwanted symptoms of being ketosis, something that is a goal in the ketogenic diet, those less favorable symptoms including bad breath, weight loss, appetite loss, increased fatigue and irritability, digestive issues, and insomnia
• Why Keto Fat Loss Doesn’t Work So Well For Women ← short version is that in response to a drop in carbohydrate intake (even if made of for with fat, calorie-wise) estrogen tries to save us from starving by prioritizing fat storage to outlast the famine we are obviously experiencing
• The Diets & Supplements That Can Mess Up Your Skin ← keto is in the #1 spot here

Want a more generally healthier diet?

We recommend the Mediterranean diet, which is generally considered the “gold standard” of healthy diets.

See also: Four Ways To Upgrade The Mediterranean

(the above is about keeping to the Mediterranean diet, while tweaking one’s choices within it for a specific extra health focus such as an anti-inflammatory upgrade, a heart-healthy upgrade, a gut-healthy upgrade, and a brain-healthy upgrade)

However, if you’d like a more comprehensive overview of what various diets might do for you, then here you go:

Which Diet? Top Diets Ranked By Experts ← a panel of 69 doctors and nutritionists examine the evidence for 38 diets, and score them in 21 categories (e.g. best for weight loss, best for heart, best against diabetes, best for the liver, etc).

Take care, and enjoy!