Navigating Nutrient Absorption: Functional Medicine for Optimal Digestion

Consuming a healthy diet is not just about what you eat but also about how well your body absorbs nutrients. You can consume the freshest whole foods and take powerful supplements, but with proper nutrient absorption, your body and health can optimally use that nutrition.

Your gastrointestinal tract plays a vital role in maintaining your health and well-being. One of its primary functions is carrying out the absorption of nutrients that you consume. You need to effectively absorb nutrients like fats, proteins, carbohydrates, and micronutrients to produce proper energy, growth, cellular maintenance, and repair. 

Functional medicine offers an effective understanding of gut health and optimizing digestion and nutrient absorption. Malabsorption and malnourishment can occur if you cannot correctly or fully assimilate nutrients due to health conditions, imbalances in your microbiome, stress, lifestyle, or other factors. Functional medicine for optimal nutrient absorption helps assess digestive health to uncover and target imbalances.

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Where Does Most Nutrient Absorption Occur?

Understanding the basics of nutrient absorption requires recognizing some anatomy of your digestive tract and how your body processes the food you consume. Your gastrointestinal tract is a highly specialized organ that stretches about 9 meters (30 feet) from your mouth to the anus. This important system helps you break down and absorb nutrients from the food you eat, excrete wastes and toxins out of your body, maintain crucial aspects of metabolism, hormone balance, and immunity, and influence your brain, skin, and other parts of your body. 

Nutrients such as carbohydrates, proteins, fats, vitamins, and minerals are broken down via chewing, enzymes, and muscular movements of your stomach into smaller substrates in order to be absorbed across the intestinal tract into your bloodstream. The digestion process occurs along the digestive tract from the mouth into the small intestine to break down food and other consumed substances into small absorbable units. These products of digestion can then cross the mucosa of the small intestine and enter the lymph or the blood in absorption. 

When you eat food, the digestive process begins with chewing and mixing that food with saliva in your mouth. Salivary amylase helps enzymatically break down carbohydrates at this stage so nutrients can later be adequately absorbed. 

Next, the food passes through your esophagus and into your stomach. Here, it mixes with stomach acid (hydrochloric acid) and enzymes that further break down your food and help to kill any harmful pathogens. You need adequate amounts of stomach acid to digest and absorb proteins, vitamin B12, and minerals like iron and calcium. 

This mixture (chyme) from the stomach passes into the small intestine. Your small intestine is the primary site for the absorption of carbohydrates, proteins, fats, vitamins, minerals, and other micronutrients. To carry out this vital job, mucosal cells in your small intestine called enterocytes are covered with small finger-like projections (microvilli) that increase the intestinal cells' surface area for absorption.

In the first portion of the small intestine or duodenum, the chyme mixes with digestive juices, enzymes, and bile from the pancreas, liver, and gallbladder to prepare it for further absorption. In this section of the intestines, most of the iron, calcium, phosphorus, magnesium, copper, selenium, thiamin, riboflavin, niacin, biotin, folate, and the fat-soluble vitamins A, D, E, and K are absorbed. 

In the next section of the small intestine (jejunum), broken-down fats are absorbed into the lymphatic system, and amino acids from digested proteins are absorbed into the bloodstream. Additionally, thiamine, riboflavin, niacin, pantothenate, biotin, folate, pyridoxine, ascorbic acid, calcium, phosphorus, magnesium iron, zinc, chromium, manganese, molybdenum, lipids, monosaccharides, small peptides, and the fat-soluble vitamins A, D, E, and K are absorbed in this area.

Finally, the remaining nutrients pass into the most distal segment of the small intestine (ileum). Bile salts and acids, ascorbic acid, folate, cobalamin, vitamin D, vitamin K, and magnesium are absorbed here. 

The remaining fibers and wastes pass into the large intestine, where water is absorbed, and feces are prepared for elimination. 

Common Digestive Disorders Affecting Absorption

A healthy and balanced digestive tract is required to properly absorb nutrients at these various locations along your small intestine. If your body cannot properly absorb the nutrients that you eat, malabsorption can occur and result in various types of malnutrition. Several common digestive disorders can impair nutrient absorption, such as low stomach acid, gallbladder issues, Crohn's disease, celiac disease, and irritable bowel syndrome (IBS).

You need adequate stomach acid to break down your food for absorption in the small intestines and proper absorption of minerals like calcium, magnesium, and iron, and vitamin B12. Low stomach acid (hypochlorhydria) can occur due to conditions that damage the stomach and/or inactivate stomach acid, including atrophic gastritis that often results from long-term alcohol abuse, surgeries like gastric bypass, autoimmune thyroid conditions, pernicious anemia where an autoimmune attack occurs against parietal cells or intrinsic factors in the stomach, infections with helicobacter pylori or campylobacter pylori, aging cancers, and other health issues. 

Later on in the digestive process, you need bile to emulsify fats for absorption. Severe inflammation of the gallbladder or gallstones can prevent or reduce the release of bile, leading to inefficient absorption of fat and fat-soluble vitamins (A, D, E, and K). 

Celiac disease occurs when the immune system mounts an autoimmune attack in response to exposure to gluten, a protein found in grains like wheat, barley, rye, and spelt. This chronic inflammatory process damages the small intestinal villi that are crucial to nutrient absorption. In addition to diarrhea and other intestinal symptoms, the resulting nutrient malabsorption seen in celiac disease can cause fatigue, failure to thrive (in children), weight loss (in adults), recurrent canker sores, reduced bone density, and iron deficiency anemia.

In Crohn’s disease, an autoimmune process also occurs, creating inflammation and painful ulceration, swelling, and scarring of the intestines. This form of inflammatory bowel disease (IBD) causes deficiencies in iron, vitamin B12, folate, vitamin D, magnesium, and other nutrients since the damaged intestines cannot effectively absorb nutrients.

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder given when other causes of gastrointestinal discomfort and gastrointestinal dysfunction are excluded. Research suggests that IBS involves the interplay of genetics, lifestyle, stress, nervous system dysfunction, inflammation, and imbalances in the gut microbiome. IBS disrupts the absorption of various nutrients, with people with IBS having lower levels of vitamin B2, vitamin D, calcium, and iron.

Functional Medicine Lab Testing for Digestive Health

Functional medicine looks for underlying contributing factors that play a role in poor absorption, including assessing digestive health through lab tests. Evaluate the health of the gut and uncovering any conditions impacting the gastrointestinal tract and digestive process can help pinpoint specific issues affecting nutrient absorption to guide personalized treatment plans.

Lab testing in functional medicine for digestion includes stool analysis, micronutrient testing, and food sensitivity tests. For example, a comprehensive stool test like the GI-Effects by Genova Diagnostics provides a deep look at gut health and function by analyzing a stool sample. This test provides an extensive analysis of the byproducts of digestion to help pinpoint any maldigestion and malabsorption. It also looks at markers of intestinal inflammation and microbial balance to uncover underlying issues that can contribute to malabsorption, such as dysbiosis, infections, and immune dysregulation.

The Micronutrient Test by SpectraCell Laboratories assesses the levels of various nutrients in the body to diagnose deficiencies and help target areas of possible issues with absorption. For example, low zinc levels can contribute to poor production of stomach acid, resulting in poor absorption of proteins, vitamin B12, iron, and calcium. 

Food allergies, sensitivities, and intolerances can contribute to inflammation and damage to the absorptive surface of the small intestine. Functional medicine testing can uncover food allergies, sensitivities, and other issues with malabsorption. The 184-item Food Sensitivity test from Alletess Medical Laboratory evaluates IgG immune-mediated food sensitivities that can cause delayed reactions and digestive problems. Diagnostic Solutions can also test IgE-mediated Food Allergies with the IgE Allergy Explorer. 

Issues with malabsorption of various sugars can be tested with breath tests from Commonwealth Diagnostics looking at malabsorption of fructose, lactose, or sucrose malabsorption. 

Blood tests are also available to help diagnose wheat and gluten-related disorders that may contribute to absorption issues. Cyrex Laboratories' Array 3X (Wheat/Gluten Proteome Reactivity & Autoimmunity Profile) offers an in-depth analysis of the body's immune response to gluten to help identify wheat reactivity, non-celiac gluten sensitivity, celiac disease, food opioid reactivity, intestinal barrier issues, and wheat-related autoimmunity. 

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Functional Medicine Approach to Digestive Health

These laboratory tests are one part of a holistic approach to digestion optimization. Functional medicine identifies common root causes of digestive imbalances such as diet, lifestyle, stress, dysbiosis, and exposure to environmental toxins. These factors can then be addressed as part of an individualized plan to bring the body back into balance and optimize nutrient absorption.

Successfully rebalancing nutrient absorption requires a multimodal approach that is personalized for each individual’s needs, history, and preferences. Rather than solely focusing on symptoms, functional medicine for digestive health assesses your symptoms along with your medical and family history, lifestyle, environment, and testing to determine what nutrients are deficient and why you are having difficulty absorbing these nutrients. 

Based on the assessed information, functional medicine practitioners develop a tailored treatment plan that aims to address the specific underlying causes of poor nutrient absorption in an individual patient. Functional medicine management strategies for impaired digestive health and nutrient absorption issues commonly incorporate nutritional strategies, supplementation, and lifestyle modifications to support optimal digestion and absorption.

Nutritional Strategies for Enhanced Absorption

To optimize nutrient absorption, assessing and ensuring that each step of the digestive process is functioning adequately is essential. Nutritional strategies for digestion are a critical part of enhancing absorption and restoring nutrient levels in the body. For example, chewing thoroughly to liquid consistency before swallowing prepares your food for proper digestion and absorption. Similarly, taking bitters or apple cider vinegar can support stomach acid levels. 

A diet for better nutrient absorption should be individualized based on identifying specific nutrient deficiencies, gut health issues, and other health needs. This allows for implementing a diet rich in essential vitamins, minerals, and macronutrients that meet each person’s unique needs. 

In general, an anti-inflammatory diet tailored to each person’s unique food allergies and sensitivities can help to reduce inflammation and calm the immune system. It is also generally helpful for improving absorption and reducing inflammation for most people to eliminate gluten. This is crucial to improve intestinal permeability, inflammation, autoimmunity, and balance in the microbiome to optimize nutrient absorption. 

A plant-focused diet based around vegetables, fruits, whole grains, nuts, seeds, herbs, and spices provides plenty of fiber, polyphenols, and a variety of nutrients. These phytonutrients deliver bioactive compounds to the gut that help modulate immunomodulatory and inflammatory processes and heal intestinal permeability, inflammation, and/or dysbiosis to optimize nutrient absorption. 

Adding in fermented foods like kefir, sauerkraut, kimchi, and live-culture yogurt provides live probiotic cultures that support a diverse intestinal microbiome, providing anti-inflammatory, antioxidant, antimicrobial, and anti-allergenic properties that can improve digestion, lactose intolerance, and nutrient absorption.

Supporting bile flow from the liver and gallbladder can also help optimize nutrient absorption. Foods like artichokes and bitter greens like dandelion, arugula, and endives help to stimulate bile flow.

To help replete and optimize the absorption of particular nutrients, it is helpful to note that certain nutrients enhance each others’ absorption. For example, phytic and oxalic acids in plant foods can inhibit calcium absorption, but boiling green, leafy vegetables helps reduce oxalate content. To optimize the absorption of nonheme iron, consume foods rich in plant-based iron like whole grains, legumes, nuts, seeds, dried fruits, and green leafy vegetables with vitamin C. 

The Role of Gut Microbiota in Digestion

A key consideration of gut health for optimal digestion revolves around the interplay of gut microbiota and nutrient absorption. Your gut is home to trillions of microorganisms that make up your microbiome. A balanced microbiome plays many key roles in your health, including optimizing the production and absorption of nutrients. 

The balance of microbes at each section of your digestive tract significantly impacts your nutrient status by playing essential roles in the biosynthesis and bioavailability of several micronutrients. There is a bidirectional micronutrient–microbiome axis. The nutrients you consume help to shape the balance of microbes in your gut since they destroy many of these nutrients for growth and survival. In the other direction, your gut microbiota produces significant quantities of a wide range of nutrients. 

Your microbiome is especially important for the production of vitamin K and B group vitamins. The microbes in your gut also enhance the absorption of minerals such as iron and calcium. 

You need the right microbes in your microbiome to assist with the digestion of complex carbohydrates and fibers that you cannot digest on your own. This helps absorb essential nutrients and produces short-chain fatty acids (SCFAs) that help maintain a healthy gut, metabolism, and balanced inflammation. 

You can support a diverse microbiome by eating an anti-inflammatory diet rich in fiber, fermented foods, and prebiotics like asparagus, garlic, and dandelion greens while limiting processed foods, additives, and refined sugars. In some cases, probiotic supplementation can be added if needed based on stool testing.

Supplements and Digestive Enzymes

In some cases, supplements for digestion, like digestive enzymes or bitters, may be necessary to support nutrient absorption and healing. 

As discussed above, your body needs enzymes from your gastrointestinal tract and its accessory organs to fully break down and absorb nutrients. Certain health conditions result in insufficiency of some of these digestive enzymes. In these cases, taking exogenous replacement enzymes may be necessary to help your GI tract break down and absorb nutrients. 

For example, exocrine pancreatic insufficiency (EPI) can develop due to cystic fibrosis, autoimmune diseases like Sjogren's syndrome, and pancreatitis, causing the pancreas to produce too few digestive enzymes. In other cases, a person may have insufficient enzymes needed to digest specific sugars. This can be genetic in conditions like congenital sucrase-isomaltase deficiency or acquired in lactose intolerance caused by acute gastrointestinal infections, small intestinal bacterial overgrowth (SIBO), celiac disease, and Crohn's disease. 

Environmental and lifestyle factors can also impact digestive enzyme production. Excessive alcohol intake, smoking, and chronic stress can all decrease the production of digestive enzymes. 

Depending on your individual needs, digestive enzymes are available in various forms. Individual specific enzymes like lactase can be taken to target a specific deficiency, or multi-enzyme supplementation containing a variety of enzymes such as amylase, lipase, and protease enzymes can work synergistically. These can be derived from animal sources or come from plants like bromelain from pineapple. Microbe-derived enzymes synthesized from yeasts or fungi are another alternative and generally require lower dosing. 

Herbs with bitter flavor are also used to support and improve digestion and nutrient absorption. Digestive bitters like ginger, wormwood, gentian, burdock root, dandelion root, and artichoke leaf are taken in your mouth before eating to stimulate the bitter taste buds. This signals your digestive system to start the process of digestion by producing more saliva, gastric juices, and enzymes to optimize digestion and absorption of your food. 

Managing Stress and Lifestyle Factors

‍Stress profoundly affects digestion, largely through the bidirectional gut-brain axis. Studies show that stress has many impacts on digestion and nutrient absorption, is related to functional gastrointestinal disorders such as irritable bowel syndrome (IBS), and creates imbalances in the gut microbiome. 

The activation of the sympathetic nervous system during stress contributes to changes in motility or movement in the gastrointestinal tract. If motility slows, you can have an increased risk of dysbiosis like SIBO. On the other hand, stress can also contribute to increased motility, which impairs nutrient absorption. 

Stress also increases inflammatory cytokines that damage the intestinal lining and cause impaired nutrient absorption. In this way, stress contributes to leaky gut or intestinal permeability that can impair the intestine’s ability to absorb nutrients. Studies also show stress-induced changes in the microbiome that lead to dysbiosis and significantly affect the microbiome's functioning. 

You can adapt your lifestyle for better nutrient absorption in several powerful ways. Mindful eating involves your food and mind-body present moment state with a non-judgmental awareness. This approach has been shown to counter digestive disturbances attributed to stress.

Getting adequate restorative sleep is also crucial for digestion and the health of your microbiome. To get at least 7-9 hours each night, establish a regular sleep routine to go to sleep and wake up at the same time each day and set up your sleep environment to be dark, quiet, and cool.

Exercising regularly but not too intensely is also beneficial for digestion and the microbiome. Incorporating mind-body practices like yoga and tai chi can be especially beneficial for calming the mind and nervous system while getting in movement. 

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Nutrient Absorption for Optimal Digestion: Final Thoughts

You need the proper balance of nutrients to maintain optimal health and functioning. Your digestive tract allows you to digest and absorb nutrients you consume in food and supplements when it works properly. 

The small intestine is the primary source of nutrient absorption and depends on help from the mouth, stomach, liver, gallbladder, and pancreas to adequately digest and absorb nutrients. Health issues that impact these organs, the intestinal surface, the balance of microbes in your gut (microbiome), inflammation levels, and more can influence how well you absorb various nutrients.

Functional medicine offers a comprehensive multimodal approach to understanding and addressing the underlying factors contributing to poor absorption of nutrients. This allows for a personalized approach incorporating diet, lifestyle, supplementation, and stress management to optimize nutrient absorption and restore balance.