Chapter 8. Introduction to Micronutrients
Nutrient Bioavailability
Micronutrients found in food and supplements are not always found in a form that can be used by our cells. Therefore, our body modifies such micronutrients to maximize absorption and utilization.
Bioavailability
Nutrient bioavailability refers to the amount of nutrients that are absorbed and utilized. Macronutrients are absorbed efficiently (85-99% of what we eat enters the bloodstream), whereas micronutrients may not be as efficiently absorbed, with some absorptions being as low as 3-10%.
Minerals are not as efficiently absorbed as most vitamins, so the bioavailability of minerals can be very low. Plant-based foods often contain factors, such as oxalate and phytate, that bind to minerals and inhibit their absorption. In general, minerals are better absorbed from animal-based foods. For example, the absorption of calcium from vegetables and nuts is lower than that from milk because the oxalate in plant-based foods binds to the calcium and affects absorption.
The chemical form of nutrients can also impact absorption. Heme iron, found in meats, fish, and poultry, is better absorbed than non-heme iron from plant and animal sources, iron-fortified foods, and supplements. Additionally, the presence of other minerals (e.g., calcium) or dietary factors like caffeine can impair non-heme iron absorption, while the presence of vitamin C can enhance absorption.
Some minerals influence the absorption of others and some foods can also impact absorption. For instance, excess zinc in the diet can impair iron and copper absorption. Conversely, certain vitamins enhance mineral absorption. For example, vitamin D boosts calcium and magnesium absorption. High-fibre foods can decrease zinc and iron absorption and fat-soluble vitamins are better absorbed with meals containing fat. Additionally, different ethnic cuisines and cultural practices can influence mineral bioavailability. For example, traditional Indian cooking often incorporates spices such as turmeric, which contains compounds that enhance the absorption of certain minerals. Similarly, fermented foods, commonly consumed in Korean cuisine, can improve mineral bioavailability.
Certain gastrointestinal disorders and diseases, such as Crohn’s disease and kidney disease, as well as the aging process, can impair mineral absorption. This puts individuals with malabsorption conditions and the elderly at a higher risk for mineral deficiencies.
Did You Know?
When compared to the typical American diet, traditional Indigenous diets provide a minimum of four times the water-soluble vitamins, calcium and other minerals, and ten times the fat-soluble vitamins, which come from animal foods such as butter, fish eggs, shellfish, organ meats, eggs and animal fats.[1] Due to the effects of colonization and the modernization of food, it is impractical to completely revert to primitive Indigenous harvesting and food-sourcing practices. However, components of traditional Indigenous diets continue to exist in many cultures around the world today. For example, Asian and European traditional cuisines consist of a wide range of organ meats and fish.[2] Therefore, incorporating culturally diverse foods into our diets may be beneficial in meeting the recommended intakes of essential vitamins and minerals.
- Timeless Principles of Healthy Traditional Diets. The Weston A. Price Foundation. https://www.westonaprice.org/wp-content/uploads/MainBrochure.pdf ↵
- Audette AJ, Anello F & Johnson RR (2021) Comparison of traditional indigenous diet and modern industrial diets and their link to ascorbate requirement and status. J Orthomol Med. 36(1) ↵
