Gut Health After 40: The Changes You Need to Know

31st July 2025

2 minutes read

Gut Health After 40: The Changes You Need to Know

After the age of 40, the human body begins to undergo a series of physiological changes, and the digestive system is no exception. The gut—often called the “second brain”—plays a crucial role not only in digestion but also in immunity, metabolism, and even mental health. With age, the functioning of the gastrointestinal tract can become less efficient, making it important to understand what changes occur and how to adapt.

Decline in gut microbiome diversity

One of the most significant changes is the decrease in the diversity of the gut microbiota. This rich ecosystem of beneficial bacteria, yeasts, and other microbes begins to lose its complexity after 40, potentially weakening the immune system and increasing the risk of chronic inflammation. A less diverse microbiome has been linked to metabolic disorders, digestive issues, and autoimmune conditions.

Slower intestinal transit

Aging slows down the motility of the intestines, meaning food moves more slowly through the digestive tract. This often results in bloating, constipation, and a general feeling of heaviness. The decline is associated with reduced smooth muscle function in the gut and hormonal changes that impact digestion.

Decreased digestive enzyme production

The body naturally produces fewer digestive enzymes with age, making it harder to break down and absorb nutrients—especially proteins, fats, and dairy. This can lead to deficiencies in essential nutrients like calcium, magnesium, iron, and vitamin B12.

Chronic low-grade inflammation

Aging is also associated with a persistent, low-grade inflammation known as “inflammaging.” In the gut, this state can damage the intestinal barrier, allowing toxins and pathogens to enter the bloodstream and trigger immune responses that may cause long-term harm.

Reduced gut sensitivity

Some people experience diminished nerve sensitivity in the intestines as they age. This can delay the diagnosis of gastrointestinal issues, including colorectal cancer—which becomes more common after the age of 50—because early symptoms may go unnoticed.

How to support your gut after 40

To maintain gut health as you age, consider the following:

Eat more fiber-rich foods (vegetables, fruits, legumes, whole grains);
Include fermented and probiotic-rich foods (yogurt, kefir, miso, sauerkraut);
Stay well hydrated;
Avoid excess sugar and ultra-processed fats;
Exercise regularly;
Manage stress, as it greatly affects digestion.

Caring for your gut after 40 isn’t just about avoiding discomfort—it’s a long-term investment in your overall health, resilience, and quality of life as you age.