By Michael Ormsbee, Ph.D., Florida State University

Edited by Kate Findley, The Great Courses Daily

If you find yourself on a constant quest to live a healthier lifestyle, then the most important area to focus on is your digestive health. It’s the first stop for all incoming nutrients that fuel the body. Michael Ormsbee, Ph.D., of Florida State University spoke to The Great Courses at length about how different nutrients can affect our digestive health.

Micronutrients in Digestive Health

First, it’s important to understand the role that micronutrients—vitamins and minerals—play in digestive health. While it’s their job to provide the body with energy, micronutrients do not provide direct energy. They are vital for making digestive processes occur and are the starting point for hundreds of other reactions and processes within the body. 

The water-soluble vitamins, the B-complex vitamins and vitamin C, are absorbed and transported throughout the bloodstream. They are not stored in your body for long periods of time, except for vitamin B₁₂, which can be stored for several years. They are either used very quickly in the body or excreted in the urine, so they need to be attained daily from the food we eat.

The fat-soluble vitamins, vitamins A, D, E, and K, are absorbed and transported very similarly to fats. Unlike water-soluble vitamins, excess fat-soluble vitamins can be stored in the body for a decent amount of time. For this reason, vitamin deficiencies are more common with water-soluble vitamins, than with fat-soluble vitamins.

Age-Related Digestive Issues

For the most part, the GI tract of a healthy individual works like a well-oiled machine. Along with the digestive system itself, the endocrine and the nervous systems play a major role in regulating digestion, absorption, and transportation of the nutrients. 

Unfortunately, as people start to age, some functions of these systems begin to slow down. The main cause is the degeneration of the enteric nervous system, which is the nervous system specifically tied to the GI tract.

The enteric nervous system controls muscle contractions in the esophagus, stomach, and colon. When it degenerates, the movements of food and food-like products through the GI tract usually slow down, potentially leading to serious GI complications, including dysphagia, which is a swallowing difficulty; GI reflux; and even constipation. Gastric acid secretions might also decrease with age, leading to bacterial overgrowth and inflammation.

Along with biological and nervous system complications, elderly individuals may experience what has come to be known as anorexia of aging. Not a psychological eating disorder, anorexia of aging refers to a physiological, age-related reduction in appetite and macronutrient energy intake, ultimately leading to significant weight loss and muscle wasting. 

With aging, there may come a time when elderly individuals just don’t feel hungry very often. While this change leads to weight loss, it significantly causes loss of muscle mass, which ultimately, prevents activity and mobility.

The best way for older individuals to avoid or slow this age-related reduction in appetite is to simply make sure they are leading a healthy lifestyle—keep regular doctor appointments, exercise, and eat foods that contribute to their macronutrient health.

Nutrient Partitioning

Perhaps you want to go the extra mile when it comes to optimizing your diet. You may be wondering, “Can I eat a particular way to digest and absorb foods for the specific purpose of improving body composition?”

You may have heard of nutrient partitioning, which describes how the food you eat is stored or partitioned into a specific area like muscle or fat. At the most basic level, the more of one type of food you eat—say, predominantly carbohydrates—the more of that fuel you will burn for energy. 

However, the bottom line is this: Exercise remains the most important and powerful tool for using the energy from foods that you eat while trying to improve your body composition. If you’re active, you will tend to use food to power your muscles as you exercise, but if you are sedentary, your body tends to partition the food to fat storage.

Dr. Edward Archer, of the Nutrition Obesity Research Center at the University of Alabama at Birmingham, produced a short video on this specific topic. He explained how exercise is what drives the nutrients we eat toward a useful end, rather than being stored simply as excess body fat. 

If you don’t exercise, you essentially always have a full gas tank—you never really tap into those fuels to create any sort of deficit. So when you eat, no matter if it’s a small meal or a large meal, there’s less of an opportunity for your body to actually use the incoming fuels, and as a result, you’ll probably store them as body fat. But when you exercise, your body has the best chance to use the food you eat in a positive way.

“Over time, your body will let you know what it needs,” said Dr. Michael Ormsbee, Associate Professor in the Department of Nutrition, Food, and Exercise Sciences at Florida State University. “If you listen to your body, it will respond in a positive way. You will feel healthy and ready to take on the day.” Pay attention to the foods you eat and how they actually make you feel and perform.

This article was edited by Kate Findley, Writer for The Great Courses Daily.

Dr. Michael Ormsbee is an Associate Professor in the Department of Nutrition, Food, and Exercise Sciences and Interim Director of the Institute of Sports Sciences and Medicine in the College of Human Sciences at Florida State University. He received his M.S. in Exercise Physiology from South Dakota State University and his Ph.D. in Bioenergetics from East Carolina University.