Why Quercetin's Bioavailability Matters
Quercetin is a powerful flavonoid with potential antioxidant, anti-inflammatory, and immune-supporting benefits. However, its inherent poor solubility in water and fat limits how much the body can absorb from both food and standard supplements. This low absorption rate, or bioavailability, means that much of the quercetin consumed may pass through the digestive system unused. To get the maximum health benefits, selecting a highly absorbable form is key to increasing its concentration in the bloodstream and tissues where it is needed.
Forms of Quercetin Compared
Standard Quercetin (Aglycone and Dihydrate)
Traditional quercetin supplements often contain the aglycone or dihydrate form. Quercetin aglycone is the plain, sugar-free form, while quercetin dihydrate contains two water molecules, which improves its stability and slight solubility over the anhydrous version. Despite being common and cost-effective, these basic forms have limited bioavailability. The body struggles to absorb the fat-soluble molecule effectively in its standard state, leading to low plasma concentrations.
Quercetin Phytosome
This is widely considered one of the most effective and absorbable forms available. Quercetin Phytosome utilizes phytosome technology, where quercetin is bound to a phospholipid, typically sunflower lecithin. This process creates a lipophilic (fat-loving) structure that mimics the body's own cell membranes. As a result, the quercetin is much more easily absorbed across the intestinal wall. Human clinical studies have demonstrated that quercetin phytosome can achieve plasma levels up to 20 times higher than unformulated quercetin.
Enzymatically Modified Isoquercetin (EMIQ)
EMIQ is a water-soluble form created by attaching glucose molecules to quercetin using enzymes. It is also known as isoquercitrin. By modifying the molecule this way, EMIQ becomes more readily absorbed in the small intestine via the same transporters that absorb glucose. Research has shown that EMIQ offers significantly better bioavailability than rutin and even standard quercetin. Its higher solubility makes it an excellent choice for those seeking a water-soluble option.
Quercetin Glucosides (from food sources)
Naturally occurring quercetin in foods like onions and capers is primarily in the glucoside form, attached to a sugar molecule. In the intestines, specific enzymes can cleave this sugar group, allowing for better absorption compared to the un-modified aglycone form. Studies have shown that quercetin glucosides from onions have higher bioavailability than those from other foods like apples. However, the bioavailability from these food sources is still less than that of advanced supplement delivery systems like phytosomes.
Comparison of Quercetin Bioavailability
| Quercetin Form | Key Characteristic | Bioavailability | Benefits |
|---|---|---|---|
| Quercetin Phytosome | Encapsulated in phospholipids for improved absorption across the intestinal wall. | Highest (Up to 20x higher than standard quercetin). | Significantly higher plasma levels, maximum efficacy, and optimal for targeted support. |
| EMIQ (Enzymatically Modified Isoquercitrin) | Water-soluble due to added glucose molecules, absorbed via glucose transporters. | High (Better than standard quercetin). | Excellent water solubility, better absorption than aglycone forms. |
| Quercetin Glucosides (from Onions) | Naturally occurring sugar-bound form found in certain foods. | Moderate (Superior to quercetin rutin or aglycone). | Natural source, absorption can be higher than aglycone forms. |
| Quercetin Dihydrate / Aglycone | Poorly water-soluble and lipid-soluble standard forms. | Low (Poorly absorbed, low plasma concentration). | Budget-friendly, but requires very high doses for minimal effect. |
| Quercetin Rutinoside (Rutin) | Quercetin bound to the sugar rutinose. | Very Low (Poorly absorbed in the small intestine). | Inexpensive but requires digestion by gut bacteria for partial absorption. |
Factors Influencing Quercetin Absorption
Beyond the specific form, several other factors can affect how well your body absorbs quercetin:
- Food Matrix: Consuming quercetin as part of a meal, especially one containing some dietary fat, can enhance absorption. A fatty meal helps with the solubilization and absorption of fat-soluble compounds.
- Companion Nutrients: Some evidence suggests that co-administering quercetin with other compounds like vitamin C or bromelain can improve its stability and potentially increase absorption. Bromelain, an enzyme from pineapple, is known to enhance the absorption of other compounds and may support quercetin uptake.
- Gut Microbiota: The bacteria in the large intestine play a crucial role in breaking down unabsorbed quercetin into smaller, more absorbable phenolic compounds. The state of your gut health can therefore influence overall utilization.
Conclusion
While standard quercetin supplements like dihydrate and aglycone forms are the most common, they are also the least absorbable. For superior efficacy and maximum benefit, quercetin phytosome and enzymatically modified isoquercetin (EMIQ) represent the most absorbable and efficient forms of quercetin. Quercetin phytosome is a clear winner for boosting systemic levels, with clinical evidence showing dramatically higher plasma concentrations. For those seeking an alternative, EMIQ offers high water-solubility and enhanced absorption. Selecting an advanced, patented formulation like Quercetin Phytosome is the best strategy to overcome the low bioavailability of traditional quercetin and unlock its full therapeutic potential. To make the most of your supplement, always follow the manufacturer's recommended dosage and consider taking it with a meal containing some healthy fats.
Authoritative Link
For further reading on how phytosome technology improves flavonoid absorption, see this detailed study: Improved Oral Absorption of Quercetin from Quercetin Phytosome®, a New Lecithin-Based Formulation
