The human body is home to trillions of microorganisms—bacteria, fungi, viruses, and more—collectively known as the human microbiota. The term “microbiome” refers to the genetic material of these microbes. Surprisingly, these tiny organisms:

• Can number around 100 trillion
• May weigh up to five pounds in total
• Outnumber our human cells many times over

Most reside in the gut, where they help break down food, support metabolism, aid nutrient absorption, and provide energy. The gut alone hosts thousands of different bacterial strains that influence digestion, immune function, and overall health.

The Size of Your Gut

The surface area of your gut is often compared to the size of a small studio apartment. It is a surprisingly large surface area due to its folds and villi.

Diet’s Influence on the Microbiome

Everything you eat passes through the gut, so diet heavily influences the balance between beneficial and harmful microbes. If the gut lining is repeatedly exposed to irritants—like certain processed foods, toxins, or pollutants—it may become “leaky” and inflamed, potentially leading to various health concerns. Recent research shows a strong link between gut health and overall well-being. A healthy, diverse microbiome:

• Produces essential vitamins
• Creates short-chain fatty acids (SCFAs) important for health
• Helps regulate the immune system

In contrast, an imbalanced microbiome—where harmful bacteria outnumber the good—can be associated with:

• Weight gain and metabolic issues
• Digestive disorders
• Cardiovascular disease
• Respiratory conditions like asthma

Factors That Affect the Human Microbiome

Several elements influence which microorganisms thrive in your gut:

• Early Life Factors:
  • Birth Delivery Method: Babies born vaginally encounter different microbes than those born by C-section.
  • Infant Feeding: Breastfeeding typically introduces more beneficial bacteria than formula.
• Diet:
  • Adult Eating Habits: Plant-based diets, rich in fiber, generally support more beneficial organisms. Even brief dietary changes can shift the microbiome.
• Antibiotic Use:
  • Antibiotics can wipe out both harmful and helpful bacteria. After a course of antibiotics, the gut may need time (and supportive foods) to regain balance.
• Lifestyle & Other Factors:
  • Stress can disrupt the microbiome.
  • Genetics may predispose some aspects of microbial composition.
  • Age can influence microbial diversity, which evolves from infancy to adulthood and may diminish in later years.

Supporting a Healthy Microbiome

While factors like genetics or birth conditions are beyond our control, dietary choices and lifestyle adjustments can help restore or maintain a balanced gut environment.

Probiotics

Probiotics are live, beneficial bacteria found in certain foods or supplements. They contribute to a healthy gut environment by adding “good” microbes directly to your system. Common probiotic strains include bifidobacteria and lactobacilli.

• Food Sources:
  • Kefir
  • Tempeh
  • Kimchi
  • Yogurt
• Potential Benefits:
  • May help reduce stress and anxiety
  • Can support mood and potentially lower cortisol (a stress hormone)
  • May assist with healthy aging by maintaining a robust, diverse microbiome

Prebiotics

Prebiotics are fibers that your body can’t digest directly. Instead, they serve as “food” for beneficial gut microbes, allowing them to grow, produce health-supporting compounds, and outcompete harmful bacteria.

• Food Sources:
  • Jerusalem artichokes
  • Leeks
  • Chicory root
  • Onions
  • uinoa, amaranth
• Potential Benefits:
  • May help with weight management by increasing feelings of fullness
  • Can boost immune function
  • upport the production of short-chain fatty acids, improving nutrient absorption and reducing oxidative stress

Achieving Balance

The Western diet—often high in processed foods and low in fiber—is associated with “dysbiosis,” or a disturbed gut ecosystem where harmful bacteria dominate. To help restore balance:

1. Combine Probiotics & Prebiotics:
   • Include fermented foods like yogurt, kefir, and kimchi for probiotics.
   • Add fiber-rich veggies, whole grains, and legumes for prebiotics.
2. Eat a Variety of Whole Foods:
   • Focus on fruits, vegetables, whole grains, beans, nuts, and seeds.
   • Limit highly processed foods and refined sugars.
3. Supportive Habits:
   • Manage stress through activities like yoga, meditation, or regular exercise.
   • Consider probiotic or prebiotic supplements
   • Add diversity to your diet, as varied foods encourage a range of beneficial microbial species.

The microbiome is a complex and ever-changing community of microorganisms that plays a critical role in human health. Diet, lifestyle, antibiotic use, and even how we enter the world affect the balance of our gut ecosystems. Fortunately, regardless of the past, we can support a healthy microbiome through mindful eating, focusing on probiotic and prebiotic-rich foods, and making simple lifestyle changes. Doing so can promote better digestion, stronger immunity, improved nutrient absorption, and a healthier, more resilient body over the long term.