Citrus Bioflavonoids (from Citrus sinensis Fruit Extract)


Bioflavonoids | Flavonoids | Vitamin P | Citrin


Supports brain function *

Supports healthy gut microbiota *  

Supports health of blood vessels *


Bioflavonoids were discovered in 1936 by Nobel-prize winning scientist Albert Szent-Gyorgi. He originally named the group of compounds "vitamin P," because his experiments revealed that they positively influenced the permeability of capillaries (i.e, strengthened blood vessels). Szent-Gyorgi was also a pioneer in early vitamin C research: He discovered that vitamin C alone was not always as effective as a crude bioflavonoid and vitamin C-containing extract from oranges, lemons, or paprika. This and other research is why citrus bioflavonoids are often combined with vitamin C—think of bioflavonoids as being a complement to vitamin C for supporting some of its functions.* Citrus bioflavonoids are found in citrus fruits (oranges, tangerines, grapefruit, etc.), where they concentrate in areas like the skin, white material, and pulp. Citrus × sinensis, which includes sweet oranges and blood oranges,  is the source for the citrus bioflavonoids. Citrus sinensis contains a variety of bioflavonoids, including hesperidin, diosmin, narirutin, naringin, nobiletin, rutin, and quercetin. 


Citrus sinensis Fruit Extract is standardized to supply not less than 90% bioflavonoids, as a wide range of citrus bioflavonoids. The product is made from 100% whole citrus fruit from sweet orange.

This standardized extract is supplied by Brewster Nutrition, a leader in citrus bioflavonoids since 1950. 

Citrus sinensis Fruit Extract is a gluten-free, non-GMO, and vegan ingredient.


Citrus bioflavonoids have been used in a wide range of doses in human studies, depending on the intended use and whether they have been used alone or combined with other ingredients. Cognitive studies, as an example, where citrus flavonoids have been used alone, have used doses ranging from about 70 to 380 mg [1–3]. A single medium-sized orange has about 20 mg of flavanones (the most predominant type of citrus bioflavonoids) [4]. Since we are using citrus bioflavonoids to complement vitamin C, our 50 mg recommended serving was selected to provide approximately an amount that would be consumed by eating a couple of oranges.* 


Supports healthy brain function*

Supports neuroprotective functions [5–11]

Supports cognitive function [12–14]

Supports emotional memory [15]

Supports neural immune signaling [16,17]

Supports hippocampal mitochondrial bioenergetics [18]

Supports BDNF signaling [8,19]

Supports healthy stress hormone levels [20–27]

Supports a healthy gut microbiota*

Supports healthy gut microbiota composition [28–31]

Supports healthy gut microbial metabolism [30]

Supports gut barrier function [28]

Supports mitochondrial function*

Supports healthy mitochondrial function [9,10]

Supports complex I-V activity [13,32]

Supports ATP production [18]

Supports mitochondrial membrane potential [9]

Supports peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) signaling (mitochondrial biogenesis) [32–35]

Supports the activity of nuclear transcription factors of mitochondrial biogenesis [6,34,36,37]

Promotes healthy metabolism*

Supports maintenance of healthy blood glucose levels [33,35,38–41]

Supports glucose transporter activity (GLUT1 and GLUT4) [39,40]

Helps balance the respiratory quotient [38]

Supports a healthy urea cycle [42]

Promotes a healthy body weight* 

Supports healthy body weight [33,35,38,39,41]

Supports maintenance of healthy blood and liver fat levels [33,35,38,41,43,44]

Supports maintenance of healthy blood triglyceride and cholesterol levels [35,43–45]

Supports adiponectin levels [39,40]

Supports the differentiation of brown adipose tissue [34,41]

Supports UCP-1 and UCP-2 activity [34,35,39,41]

Supports thermogenesis [41]

Supports circadian rhythms*

Supports the activity of the circadian system [12,38,46]

Supports metabolic function through a circadian-dependent mechanism [32,38]

Enhances antioxidant defenses*

Supports antioxidant defenses [6,10,36,47]

Counties ROS production and oxidative stress [9,10,32,36,47]

Supports heme oxygenase-1 (HO-1) activity [37,48]

Supports signaling pathways*

Supports AMP-activated protein kinase (AMPK) signaling [32,36,49,50]

Supports peroxisome proliferator-activated receptor alpha (PPARα) and delta PPARδ [34,36,39,40,43]

Influences PPARγ signaling [34,39,40,43,48,49]

Influences glycogen synthase kinase 3 beta (GSK-3β) activity [5,13,32]

Influences mTOR signaling [5]

Supports SIRT1 signaling [32,34]

Promotes general health*

Supports healthy cardiovascular structure and function [33,35,51–53]

Supports healthy liver structure and function [36]

Supports healthy gastrointestinal structure and function [47]

Supports healthy immune cell activity [35,54]

Influences immune signaling [5,6,16,17,35–37,39,40,43,47,48]

Complementary ingredients*

Citrus bioflavonoids support bioavailability and the accumulation of vitamin C in some tissues [55–59]

Citrus bioflavonoids may be needed to support some of Vitamin C’s functional benefits [60–62]

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.


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