Low-carb diets are all the rage right now, and with good reason. They have shown promising results in promoting
weight loss and encouraging people to eat less white flour, sugar, and other unhealthy foods. Hard to argue with that.
I’m on board.
Unfortunately, many get easily swept up into the low-carb diet craze without a full knowledge of how to construct a
healthy diet within those parameters. What do most then focus on? Protein and fats. Out the window go foods like
fruits, starchy vegetables, whole grains, and sometimes dairy.
What’s the big deal? Well, research is now indicating that diets such as these, which are very low in fiber, might be a
problem when it comes to the health of our gut. While we know fiber is important for regularity, supporting healthy
blood sugar, and increasing satiety, did you also know that fiber feeds your healthy gut bacteria, or the microbiome as
it is commonly known?
The problem is, as seen via research, that this decline in fiber corresponds with a decline in microbiome diversity. In
simple terms, over time we starve out many beneficial strains of healthy glut flora residing in our digestive tract.
Additionally at the same time we promote more of the unhealthy and less desirable strains.
For example, a recent study looked at microbiome diversity among rural Africans and the average US population.
They found much greater diversity and more beneficial strains of bacteria in the guts of Africans. Not exactly
surprising. What is interesting is that when they switched their diets and fed this group of Africans the Standard
American Diet for two weeks, stool analysis showed a significant decrease in the “good” bugs.1 This was after only
two weeks! What does this say for those of us consuming low fiber diets for weeks or years on end?
This creates some cause for concern because research has shown that the health of our microbiome influences the
health of the host.2 In other words, our personal health is influenced by the bugs living in our digestive tract. For
example, Crohn’s Disease and other inflammatory bowel diseases seem to be linked with alterations in the
microbiome. 3 Also more and more studies are linking obesity and increases of certain types of bacteria in the guts of
Americans. In rats, we can directly influence their weight by the type of bacteria we put in their system!4 Fascinating
stuff, and yet scary at the same time.
If you are one of those embarking on a low carb diet, don’t fret! It can be done in a healthy way to support your health
goals, while at the same time supporting your microbiome. Clearly the main goal is to keep up the fiber in whatever
way possible. Let’s talk about some ways to do that.
Main key when going low carb: Include as many fiber sources as you can!
• Fruit: Choose the lower carb ones like berries, avocado, tomatoes. For higher carb fruits, keep the portions smaller.
• Vegetables: Make sure to get as much vegetable intake as you can every day! Many veg options are low carb and
can be included in abundance. Add lots of low carb leafy greens and cruciferous (broccoli, cauliflower), or consider
green beans, zucchini, peppers, etc. Consume starchier choices like squash, carrots, peas and potatoes in smaller
• Eat nuts and seeds! These are a great low carb option with protein and fat but which also have an appreciable
amount of fiber. Think almonds, walnuts, cashews, flax seed, chia seed, hemp seed, pumpkin seeds…. you get the
• Eat beans! Yes they do have carbs, but again, watch the portions. Generally about ½ cup of beans equals 15g of
carb, so you can have beans and still keep the carbs in check.
• Don’t forget about fermented foods! These can help replenish and support a healthy microbiome. Try adding a daily
dash of sauerkraut, kefir, cultured yogurt, kombucha, pickled veggies, or tempeh.
What about the Ketogenic Diet?
Yes, I realize there is a big push towards the “keto” diet as of late. If you are not aware of this trend, it’s a diet that
decreases carbs to the extent that it puts the body in ketosis. This encourages the body to burn fat as fuel, producing
ketones, which the body can use in a similar way to carbs. It is extremely low carb, obviously, and followers often test
their urine to measure ketones and thereby ensure they are in the state of ketosis. Many health benefits, including
weight loss, improved cardiovascular health and neuro-protective benefits have been purported by this plan, and there
are many functional and integrative health professionals who are choosing this as a way of life for health and
The problem is that, if not followed correctly, one can easily over-consume on foods like animal proteins, dairy (like
cheese and butter), eggs, artificial sweeteners, and low-carb processed concoctions. Very quickly the diet becomes
reduced and limited to a set of foods which are low in carb yet also low in fiber, thus potentially eradicating many
healthy bacteria strains from one’s digestive tract.
The keto diet can be done successfully, however, and without drastic harm to the microbiome, if done appropriately,
utilizing some of the tips provided above. Also some supplementation with probiotics or increased servings of
fermented foods is a good idea.
Hopefully for you low-carb lovers, your fears have been allayed. Look for ways to get in that fiber, enrich your diet with
fermented foods, and consider supplementation when needed.