There’s no one-size-fits-all answer—each nutrient has its own half-life and dynamics and may be further impacted by intra-individual variability.
In general, water-soluble vitamins (e.g. B-vitamins, vitamin C) circulate for hours to days, they are not stored extensively, and are cleared quickly via urine if in excess. Fat-soluble vitamins (e.g., A, D, E, K) can remain in circulation longer—days to weeks, especially when bound to carrier proteins. Minerals and trace elements (e.g. iron, zinc, selenium) vary widely- from hours to days, depending on form and whether they are bound to proteins.
Several factors influence how long and how much of a nutrient stays in circulation, including:
- Form of the Micronutrient: Free vs. protein-bound (e.g., free vitamin D vs. vitamin D bound to vitamin D binding protein) or ionized vs. stored in cells (e.g., calcium or magnesium).
- Binding Proteins: Albumin, transferrin, ceruloplasmin, vitamin D binding protein, retinol binding protein, and calcium binding protein, among others, control how nutrients circulate.
- Tissue Demand & Storage: Active transport into tissues can pull nutrients out of circulation quickly. Stored nutrients in the liver (e.g., A, D, E, K, B12, iron, and copper) help regulate blood levels when there is increased tissue demand.
- Inflammatory Responses & Illness: During periods of illness or inflammation, the body's demand for certain micronutrients may increase, leading to decreased circulating levels. Inflammation can also cause redistribution of nutrients, affecting their measurable concentrations in blood compartments.
- Organ Function: Kidney function plays a critical role in water-soluble vitamin clearance, and liver function plays a key role in processing and transporting fat-soluble vitamins and trace elements.
- Metabolic & Physiological Changes: Circadian rhythms, hormonal fluctuations, and metabolic processes can alter micronutrient levels in whole blood. For example, iron levels might vary throughout the day due to its role in various metabolic functions.
- Nutritional Status: Deficiency may increase uptake from blood into tissues, whereas excess may increase clearance or storage.
- Dietary Intake: The consumption of foods rich in specific micronutrients can cause transient spikes in their blood levels. For instance, ingesting vitamin C-rich fruits may temporarily elevate plasma vitamin C concentrations.
- Hydration Status: Dehydration or overhydration can concentrate or dilute blood components, respectively, impacting the measured levels of micronutrients.
- Physical Activity: Exercise can influence the metabolism and utilization of micronutrients, potentially altering their circulating levels (e.g., intense physical activity may increase the turnover of antioxidants such as vitamin E, C, zinc, glutathione among others).
There is extensive scientific literature supporting the validity of micronutrient testing in different biological samples, including whole blood, plasma, serum, intracellular, and urine samples. As with all laboratory testing, results should be clinically correlated, with micronutrient results evaluated and monitored in conjunction with clinical and dietary history.
The Whole Blood Nutrient Profile assesses nutrient status in the blood by measuring nutrients in a mix of capillary blood, arterial blood, interstitial fluid, and extracellular fluid. This provides micronutrient data similar to a serum nutrient assessment, but with the convenience of an at-home sample collection.