Consuming a balanced, nutrient dense diet is one of the best ways to support your overall health, but the habit alone is not always enough. While nutrient deficiencies can certainly arise from inadequate intake, they can also point to a deeper issue concerning absorption and utilization. This is why it’s important to look at more than just the food on our plate — we are only able to reap the benefits of nutrient dense foods when our digestive system is able to absorb and turn our food into fuel effectively.
How The Gut Functions
Digestion begins in the mouth, where food is mechanically broken down via chewing and salivary enzymes begin to break down carbohydrates.
As food enters the stomach, parietal cells produce stomach acid and intrinsic factors. Stomach acid serves to break down proteins, activate enzymes, and release nutrients, like vitamin B12 from the food for absorption. Stomach acid also supports the absorption of plant based iron. Intrinsic factor is a glycoprotein which allows B12 to be absorbed later on in the digestive process.
The resulting mixture of food, acid, and enzymes is referred to as chyme. Chyme moves on to the small intestine, which is where the majority of nutrients are absorbed. The small intestine has three primary regions, all of which absorb different nutrients: the duodenum, jejunum, and ileum. This is where bile and pancreatic enzymes are added to the mix and aid in absorption of different nutrients.
Once absorption is complete, the remaining contents move into the large intestine. This where water and electrolytes are reabsorbed. Some fibers are fermented into short chain fatty acids (substances that support the gut lining and may lower inflammation), and waste becomes stool that eventually gets eliminated.
Common Nutrient Deficiencies & How Digestion Factors In
Ferritin
What Is Ferritin?
- Ferritin is a protein that is responsible for storing iron in the body. A low ferritin level can be reflective of low iron stores.
What May Contribute to Low Levels?
- Iron deficiency, increased iron needs, or blood loss.
GI Considerations
- People with celiac and Crohn’s disease are prone to iron deficiency due to high levels of intestinal inflammation and impaired absorption associated with these conditions. GI bleeding related to IBD, hemorrhoids, or fissures can also contribute to iron losses.
Foods that Support Healthy Levels
- Iron rich foods can improve ferritin levels. Animal-based sources of iron like red meat, poultry, and seafood are the most readily absorbed. Plant based sources of iron include beans/legumes, leafy greens, nuts and seeds. These are best absorbed when paired with a source of Vitamin C. For example, a leafy green salad with lemon juice drizzled on top or lentil soup with cherry tomatoes in it.
Vitamin B12
How It’s Absorbed
- The intrinsic factor produced in the stomach acts as a vehicle for the absorption of vitamin B12 in the terminal ileum.
What May Contribute to Low Levels?
- Inadequate intake, long-term use of certain medications, like metformin or PPIs, vegan/vegetarian diet, etc.
GI Considerations
- Autoimmune gastritis impacts the parietal cells, thereby reducing intrinsic factor which can result in vitamin B12 deficiency and/or pernicious anemia. Other factors include celiac disease, Crohn’s disease, and surgical resections or ileostomies that bypass parts of the terminal ileum.
Foods that Support Healthy Levels
- Meat, poultry, eggs, seafood, nutritional yeast, and fortified plant milks.
Folate
How It’s Absorbed
- Folate is a water soluble vitamin that is primarily absorbed in the jejunum. There are two forms of this nutrient: dietary folate that is found in whole foods and folic acid found in fortified foods.
What May Contribute to Low Levels?
- Inadequate intake, frequent alcohol use, and increased needs during certain periods of life such as pregnancy. Since the body’s storage capacity for folate is limited, deficiency can develop relatively quickly.
GI Considerations
- Similar to other nutrient deficiencies, celiac and Crohn’s disease are a consideration, as they can result in malabsorption and damage to the intestinal lining. Certain medications, such as methotrexate, can be used to treat Crohn’s disease and is known to interfere with folate metabolism.
Foods that Support Healthy Levels
- Leafy greens, broccoli, beans/legumes, avocado, etc.
Vitamin D
How It’s Absorbed
- Vitamin D is a bit different from the other nutrients discussed in that it is fat soluble, meaning it requires dietary fats in order to be absorbed. Bile and pancreatic enzymes play a large role in the absorption and utilization of Vitamin D.
What May Contribute to Low Levels?
- Low intake, limited sunlight exposure, impaired fat digestion, autoimmune conditions, etc.
GI Considerations
- Conditions that directly impact the digestion and absorption of fats like cystic fibrosis and pancreatitis/pancreatic insufficiency will impact vitamin D status since it is fat soluble. If not treated appropriately, these conditions can lead to deficiencies in not only vitamin D, but also vitamins A, E, and K.
Foods that Support Healthy Levels
- Fatty fish (salmon, sardines, etc.), egg yolks, fortified dairy, cereals, etc.
FAQ
1. Can you have nutrient deficiencies even if you eat healthy?
Yes! If you have any underlying or undiagnosed condition that affects how your gut functions, your ability to absorb and use the nutrients in your diet may be compromised. Our Salvo Health registered dietitians can guide you through changes to your diet or supplements to help you get the nutrients you need.
2. Can blood tests diagnose digestive disorders?
Blood tests can be a helpful piece of data, however, they are typically not the only factor in making a diagnosis. Your medical team can use your lab data alongside your symptoms, health history, and imaging or biopsies that are available to get a more complete picture of your health.
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