Got the Blues? Try Onions & Grapefruit!

OK, onions and grapefruit together isn’t appetizing, but eating more high-fiber foods like these, and maybe some butter, might help, according to new research.

You’ve heard for ages that diets high in fiber can reduce your risk for stroke, hearty disease, cancer, hypertension, and all sorts of chronic health problems.  In addition to all the above benefits, mounting evidence is telling us that a high fiber diet can improve brain health. 

This recent review looked at a wide body of research and concluded that compounds produced by healthy gut bacteria, especially a compound called butyric acid, may positively impact our brains.  Some of the research they reviewed involved only rats, but much of it looked at the impact of high-fiber diets on human behavior, and they found a reduction of anxiety and an improved ability to focus and multitask when there were more healthy bacteria present in the gut. 

An even more recent study that analyzed human gut bacteria found that people reporting a low quality of life and/or depression had different bacteria in their colon than people who had normal mental health and were happier.  The bacteria don’t impact our mental health directly, because they stay in the colon, but the compounds they produce do make it into the circulation and appear to positively impact our brain health.

Fiber: Why eat it if we can’t digest it? 

Fiber: you can’t digest it & you probably need more of it

When we eat, we’re not just feeding ourselves, we’re also feeding the bacteria in our colons, and high-fiber foods like oat and wheat bran, beans, and pretty much most fruits and veggies, promotes the growth of good bacteria.  That’s what makes high-fiber foods PRE-biotic. 

Undigested fiber sails past the small intestine, landing in our colon, where beneficial bacteria see fiber as an all-you-can-eat buffet.  When they’re through with it, they’ve produced beneficial by-products called short-chain fatty acids.  The three main ones are:

  • Acetic acid (think vinegar),
  • Propionic acid, and
  • Butyric acid (also called butyrate).

Butyric acid is getting attention because of its diverse biological functions in our bodies outside of the colon.  A lot of the benefits noted in the studies above have been attributed to butyrate, to the point that its potential health impact shouldn’t be ignored. 

3-4% of butter is butyric acid,
but better sources abound

You CAN Believe It’s Butter

High fiber foods aren’t the only way to increase the butyric acid in your colon.  There are some naturally-occurring sources of butyrate, such as probiotic foods like yogurt and kefir, that can increase strains of bacteria that produce butyrate. 

One of the largest single natural sources of butyrate is butter.  It’s true – butter contains about 4% butyric acid.  I’m not advocating eating more butter, and there are better ways to help get butyric acid into the gut.  Including fermented dairy foods, however, is definitely worthwhile for so many nutritional reasons.

The Fine Print

Ironically, people with irritable bowel and other gastrointestinal conditions are often advised to be on a “low-FODMAP” diet that eliminates many high-fiber foods that good bacteria use to produce butyric acid.  No worries – there are still lots of fruits and vegetables you can eat.  Stick to your prescribed diet and as your condition improves, just add FODMAP foods back into your diet as advised.  Kate Scarlata, RDN, is an outstanding registered dietitian who specializes in the FODMAP diet has tons of info on her website.   

Cut-to-the-Chase Conclusions

The point here is that the gut does communicate with the brain in very specific ways, and these may be influenced by the type and amounts of various strains of bacteria – both good ones and negative ones. Most people only get about 12-14 grams of fiber daily, and we should be eating twice that amount, according to US Dietary Guidelines.

Aim to gradually eat more fruits, vegetables, whole grain breads and cereals, and beans (these are loaded with great fiber!). As for fresh vs. frozen, vs. canned, no need to get too obsessive. Just eat more of these foods overall. Me? I never peel apples, carrots or potatoes. I’m not tossing away good fiber!

While nothing is a guarantee of good mental health, optimizing our gut environment is likely to also optimize our gut’s ability to send good messages to the brain.  It may not cure depression but even if it doesn’t change our perceived quality of life, it’s very likely to lay down a good foundation for the gut to operate at its full potential. A higher fiber diet is good for our gut — and good for the rest of our body as well. #winwin

I’ll take that.     

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