Monday, September 14, 2009

Bacteria Food and Reflux

If you spend a few minutes on the internet trying to figure out what one with BE should eat, you will likely find a recommendation that you should eat a low fat diet. There are a few reasons why this recommendation is typically made. First, it is thought that high fat meals delay gastric emptying (turns out, high carb meals do too). Second, it is thought that high fat diets result in more bile production (turns out, high carb meals do too). Third, certain kinds of fats may result in more bad bile acids (will do a full post on this soon). Lastly, there is some evidence from epidemiological studies (i.e., the kind of studies that should never be relied upon) that high fat diets are associated with higher rates of esophageal adenocarcinoma.

Before moving on, a quick word about the epidemiological findings. First, these types of studies very often get causality wrong -- for instance, these studies typically also find that high fat/meat/junk-food eaters also die in accidents at higher rates. Nobody thinks that fat causes car crashes, so why assume it causes cancer? These studies provide hypotheses to be checked by more direct methods. If there were valid mechanistic reasons why fat should cause Barrett's esophagus and esophageal cancer, I would be worried. However, the mechanistic reasons discussed above cannot be valid because they also apply to high carbohydrate diets. For example, high carb diets cause more reflux, result in the same amount of bile production, and also delay gastric emptying. So why not focus on carbs?

One idea is that high fat diets worsen the composition of bile acids (i.e., more deoxycholic bile acids). First, I don't think this is the theory behind much of the advice (it's just too esoteric). Second, I would guess that high carb diets do the same thing (though know of no studies on the topic). Lastly, I believe the result depends on what type of fat you're eating. For example, fish oil and coconut oil don't seem to produce more deoxycholic acid while corn oil may. Animal fat may be more risky, but I don't worry for a number of reasons that I will cover in a full post on this topic (coming soon).

Even if these epidemiological studies are detecting something causal in part, perhaps they are just picking up the fact that in a western society, most people who eat high fat diets eat a lot of processed vegetable oils. These bad oils are known to worsen the composition of bile acids (more deoxycholic) and the excess of omega 6 fatty acids found in these bad oils significantly promote inflammation!! Ok, don't eat vegetable oils if you're concerned about the epidemiological studies. I certainly don't, for this and many other reasons. I eat a lot of saturated fat instead. Regarding the effect of a high saturated fat diet on cardiovascular and general health see this, this, and this for a lot of background. From my personal experience, I can tell you that after 6 months on a 70% fat diet (mostly saturated), my HDL went from 41 to 54, my LDL went from 88 to 90, and my triglycerides went from 140 to 62. I also take fish oil and vitamin D daily, which may confound the results to some extent.

What is often ignored, however, is the many ill effects of high-carbohydrate diets. Filling up on sweets, grains, and low-fat yogurt increase bacterial fermentation in the colon. Basically, the bacteria eat what you don't adsorb. Add in a touch of lactose intolerance or fructose malabsorption (problems which many people have without knowing it) and you might end up with irritable bowel syndrome to go along with your Barrett's esophagus. So what's wrong with colonic fermentation from a GERD perspective? It causes it, that's what. High-carb diets over time also open the door to metabolic syndrome, something you don't want, especially if you have Barrett's esophagus.

By eating a very low-carb diet (i.e., meals of all meat or, my favorite, organic heavy whipping cream and whey protein powder), one can prevent GERD, probably by depriving the bacteria of their food. The idea is not to kill the bacteria; after all, the healthy ones protect you from the bad ones. Rather, the idea is to deprive them of the undigested sugars they love to ferment, fermentation which causes you heartburn.

Even though bacteria may play a role in reflux, I still take a probiotic (good bacteria) supplement on most days to make sure the "good" ones are crowding out the "bad" ones. That said, on my diet, I avoid feeding even the good ones very much. To this end, I also avoid prebiotics (polysaccharides that bacteria ferment). People take them to help the probiotics take hold better (by providing food for them). I avoid them completely for the same reason that I generally avoid excess intake of carbohydrates; it is bacteria food that may cause reflux.

This will not be the last post on fat. Indeed some of the concerns listed above, do carry some water with me (though not much). However, even putting the science aside, I just experience less reflux when I eat more fat.

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