Absorption and Bioavailability: Understanding Nutrients from Microgreens and Supplements

Most people look at supplement labels and see numbers like 15% RDI, 100% RDI, or 300% RDI. But the body does not respond to numbers on the bottle. What matters is how the body handles nutrients during digestion. Two key concepts help explain this: absorption and bioavailability.

Absorption is the process where nutrients move from the digestive system into the bloodstream. Bioavailability describes how much of that absorbed nutrient becomes available for normal physiological functions. This means two products with similar nutrient values on a label may be processed differently depending on various factors.

Several elements may influence bioavailability, such as the chemical form of a nutrient, the food matrix it comes in, digestive health, and the presence of other dietary components. For example, vitamin C is known to interact with iron during digestion. This is one reason nutrients from whole foods and isolated synthetic nutrients may behave differently in the body.

This raises an important point regarding RDI numbers printed on packaging. A product may list 100% of the recommended daily intake of a nutrient, yet the amount available to the body depends on how it is digested and absorbed. Magnesium offers a clear example. Different forms of magnesium show different absorption characteristics in research. Magnesium oxide contains a high amount of magnesium per dose but has been shown to have low absorption in human studies, while organically bound forms such as magnesium citrate have demonstrated higher absorption rates.

Because of this, a supplement with a lower RDI percentage but different absorption characteristics cannot always be directly compared to one with a higher declared value. The RDI figure only reflects content, not how the body processes the nutrient.

Whole-food nutrients exist within a natural network of enzymes, fiber, antioxidants and plant compounds. Researchers refer to this as the food matrix. This matrix appears to influence how nutrients behave in the body. Studies note that naturally occurring vitamin E in food is handled differently compared to synthetic forms, even when intake levels are similar.

Microgreens provide a useful example of nutrients within a whole-food form. These young plants are harvested early and research suggests they can contain higher concentrations of certain vitamins and minerals compared to the fully grown plant. Radish microgreens contain naturally occurring vitamin E and antioxidants. Sunflower microgreens contain calcium along with other minerals. Mung bean microgreens contain vitamin C as part of the plant’s natural composition. This reflects how nutrients appear together in nature rather than in isolation.

When nutrients come from whole foods rather than isolated compounds, the interaction between components may influence how the body processes them. This may help explain why a whole-food source listing 15% of the RDI cannot always be compared directly to an isolated supplement listing 100%. The number represents content, not necessarily how the body handles it.

The key message is simple: the RDI number describes the amount present in a serving, not how it behaves during digestion. Whole-food nutrients, including those in microgreens, are present together with naturally occurring plant compounds rather than in isolated form, which may influence how they are processed in the body.

In everyday terms: it is not only about what is listed on the label — it is also about how the body handles it.

References

Ostrenga S. (2018). Are You Absorbing the Nutrients You Eat? Michigan State University Extension.

Barron K. (2024). The Power of Synergy and Bioavailability in the Whole Food Matrix. Wholistic Matters.

Magnesium King (2025). Magnesium Oxide in Supplements: Bioavailability and Safety.

NIH Office of Dietary Supplements. Vitamin E Fact Sheet.

Miller et al. (2023). Perspective: The Food Matrix and Human Nutrition. Advances in Nutrition 14(3):363.

Xiao et al. (2012). Microgreens as Nutrient Dense Foods. Journal of Agricultural and Food Chemistry.

USDA Agricultural Research Service (2014). Specialty Greens Pack a Nutritional Punch.

Malesu VK (2025). Microgreens Outshine Mature Vegetables. Scientific Reports Summary.

Jacobs DR et al. (2009). Food Synergy: The “More Than the Sum” Concept. American Journal of Clinical Nutrition.