Lactobacillus, bifidobacterium and bacillus...oh my! Some of these beneficial bacteria have become household names, and their role in a healthy microbiome is continually being explored by scientists and clinicians.

The microbiome is our body’s natural colony of bacteria. We have bacteria throughout our body. In fact, we are made up of more DNA from microorganisms than human DNA (cringeworthy, but amazing at the same time). The symbiotic relationship microorganisms have with their human hosts plays a critical role in immunity, digestion, lowering inflammation, nutrient production, electrolyte balance and much more. When the microbiome is thrown out of balance, all of these vital functions can become impaired.

All of the following cause imbalances in the microbiome. They are the top five I have observed in my clinic:

1. Antibiotics are designed to kill invading bacteria that do not belong in the body. However, most of these medications are broad-spectrum, meaning they do not differentiate between pathogens and our healthy bacteria. When someone takes a course of antibiotics, it is often recommended that they take a probiotic for a month afterward and increase their intake of certain probiotic foods (far right).
2. High sugar diets Since the bulk of our microbiome is located in the gut, eating high sugar diets can change the ratio of bacteria present. Typically, “good bacteria” feed off of fibers, while “bad bacteria” feed off of sugar and simple carbohydrates. Overfeeding the “bad bacteria” can lead to digestive complaints and other health issues.
3. Low stomach acid Our stomach acid is the first line of defense against bacteria on our food. As we age, the acid levels in our stomach tend to decrease, leaving us exposed to pathogens that can populate in our gut and damage beneficial bacteria.
4. Overuse of probiotics Probiotic supplements can be beneficial for a short period of time to restore levels of certain bacterial strains that may have become compromised from any of the above. However, taking these supplements long term can alter the body’s natural biodiversity and overpopulate certain strains, leading to an imbalance in the microbiome. Our body should have hundreds of strains, not just 12-16, so it’s important to rely more on diet than a supplement.
5. Stress Unfortunately, stress is a major factor in changes to the microbiome. When the body is under stress, biological functions not deemed necessary for survival in a fight-or-flight situation (like digestion) are turned down. Production of stomach acid, enzymes and other important digestive messengers decrease leaving opportunities for the “bad bacteria” and fungi like candida to overgrow. Stress also reduces our immune function, which is linked to a healthy microbiome. Everything is connected.

Common signs that the microbiome is out of balance are digestive symptoms like gas, bloating, diarrhea or constipation. Other signs may be poor immunity and susceptibility to illness.

While duration and severity of digestive imbalances may differ, dietary interventions can play an important role in building a healthy microbiome. Here are some to consider:

Increase intake of these foods:

• Dark leafy greens and non-starchy veggies
• Bitter foods like arugula, broccoli rabe, chicory, etc., which can improve production of stomach acid and digestive enzymes
• Naturally fermented foods like sauerkraut, yogurt, kimchi and miso
• Complex carbohydrates like beans and whole grains, which are also high in fiber
• Vegetarian proteins like tempeh, quinoa and tofu
• Low glycemic fruits like blueberries, apples, and citrus fruit

Decrease intake of these foods:

• Sugar and simple carbohydrates
• Alcohol
• Heavy meats, which can putrefy in the gut
• Deli meats
• Dried fruit
• Artificial sweeteners (small amounts of stevia are OK)

A healthy plant-based diet (with moderate intake of animal proteins) can go a long way toward restoring gut balance and bringing biodiversity back to the body.