Flavonones
Also known as: Flavanones, citrus flavonoids, hesperetin, naringenin, eriodictyol, Flavonones
Overview
Flavonones are a subclass of flavonoids, which are naturally occurring polyphenolic compounds predominantly found in citrus fruits like oranges, lemons, and grapefruits. Chemically, they are characterized by a saturated 2,3-dihydro-2-phenylchromen-4-one backbone. As dietary supplements, flavanones are utilized for their antioxidant, anti-inflammatory, antiviral, and neuroprotective properties. They are commonly used for immune support, cognitive enhancement, ocular health, and potential metabolic benefits. While research is ongoing, multiple randomized controlled trials (RCTs) and meta-analyses support their health-promoting effects, though heterogeneity in study design and flavonoid composition can limit definitive conclusions. The evidence base is growing, with systematic reviews indicating their efficacy and generally good safety profile.
Benefits
Flavonones offer several evidence-based health benefits. A 2022 systematic review and meta-analysis of 20 RCTs demonstrated that flavonoid-containing supplements significantly reduced the incidence and duration of acute respiratory tract infections (ARTIs), indicating strong immune support. For cognitive function, a 2022 meta-analysis of dietary flavonoids showed positive effects across the lifespan, with benefits varying by source and duration of supplementation. In ocular health, a 2021 meta-analysis of 11 RCTs (n=724) reported significant improvements in clinical manifestations of disorders like diabetic macular edema and glaucoma (standardized mean difference = −0.39; 95% CI: −0.56, −0.21). These effects are clinically relevant, particularly for the elderly, cognitively impaired, and individuals with ocular conditions. Potential benefits in metabolic disorders like PCOS have been suggested but require further confirmation. Cognitive benefits can be observed with both acute and chronic supplementation, while immune benefits typically require regular intake over weeks to months.
How it works
Flavonones exert their beneficial effects primarily through their potent antioxidant activity, which helps reduce oxidative stress in the body. They also modulate inflammatory cytokines, such as TNF-alpha, thereby contributing to their anti-inflammatory properties. Furthermore, flavanones enhance endothelial function and activate neuroprotective signaling pathways, supporting nervous system health. Their interaction with body systems includes immune system modulation, neuroprotection in the brain, protection of ocular tissues, and regulation of metabolic processes. While flavanones have moderate bioavailability, their absorption is influenced by gut microbiota, which metabolize glycoside forms into absorbable aglycones.
Side effects
Flavonones are generally considered safe, with a low incidence of adverse effects reported in clinical trials. Common side effects are not consistently reported, and uncommon side effects (1-5% incidence) are typically limited to mild gastrointestinal discomfort in some individuals. Serious adverse events are rare, with no significant occurrences reported in studies. While potential interactions with drugs metabolized by cytochrome P450 enzymes exist, their clinical significance is currently unclear. There are no well-established contraindications, but caution is advised for patients on multiple medications due to the theoretical risk of drug interactions. Data on the safety of flavanones in pregnant or lactating women and children are limited, warranting caution in these special populations.
Dosage
The minimum effective dose of flavanones varies across studies, but many randomized controlled trials (RCTs) have utilized doses equivalent to 100–500 mg of total flavonoids daily. Optimal dosage ranges are not firmly established, but doses in meta-analyses typically ranged from 200–600 mg/day of total flavonoids. There is no established maximum safe dose, as high doses have generally been well tolerated in trials. For consistent benefits, daily supplementation is recommended. Acute cognitive effects may be observed within hours to days, while chronic effects, such as immune support, typically manifest over weeks. Supplements are often standardized extracts or purified flavanones, with citrus extracts being common. Co-ingestion with food may enhance absorption, and the status of an individual's gut microbiota can influence bioavailability.
FAQs
Are flavanones safe for long-term use?
Current evidence supports safety for short- to medium-term use. Long-term data is limited, but no major safety concerns have been reported.
How soon can benefits be expected?
Cognitive and immune benefits may appear within weeks. Ocular benefits might require longer supplementation for noticeable improvements.
Are natural sources as effective as supplements?
Natural dietary intake provides beneficial flavanones, but supplements offer controlled and often higher doses for specific therapeutic effects.
Can flavanones replace medications?
No, flavanones are dietary supplements intended to be adjunctive. They should not replace prescribed medications or medical treatments.
Research Sources
- https://pubmed.ncbi.nlm.nih.gov/35940344/ – This systematic review and meta-analysis of 20 RCTs found that flavonoid supplements significantly reduced the incidence and duration of acute respiratory tract infections (ARTIs) and were well-tolerated. The study highlights the immune-modulating potential of flavonoids, despite some heterogeneity in the included studies regarding flavonoid types and purity.
- https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2021.651441/full – This systematic review and meta-analysis of 11 RCTs (n=724) concluded that flavonoid supplementation significantly improved clinical manifestations of ocular disorders such as diabetic macular edema and glaucoma. The findings suggest a beneficial role for flavonoids in eye health, although the included studies had moderate heterogeneity and relatively small sample sizes.
- https://pmc.ncbi.nlm.nih.gov/articles/PMC9787524/ – This meta-analysis investigated the effects of dietary flavonoids on cognition across the lifespan, finding positive effects that varied by flavonoid source and duration of supplementation. The study provides robust evidence for the cognitive benefits of flavonoids, with a comprehensive analysis of moderating factors, despite variability in cognitive tests and flavonoid doses across studies.
