Flavonoids In Foods Research Articles

Proanthocyanidins Should Be a Candidate in the Treatment of Cancer, Cardiovascular Diseases and Lipid Metabolic Disorder.

The conventional view of using medicines as routine treatment of an intractable disease is being challenged in the face of extensive and growing evidence that flavonoids in foods, especially proanthocyanidins (PAs), can participate in tackling fatal diseases like cancer, cardiovascular and lipid metabolic diseases, both as a precautionary measure or as a dietary treatment. Although medical treatment with medicines will remain necessary in some cases, at least in the short term, PAs’ function as antioxidant, anti-inflammatory drugs, signal pathway regulators remain critical in many diseases. This review article demonstrates the physical and biological properties of PAs, summarizes the health benefits of PAs found by researchers previously, and shows the possibility and importance of being a dietary treatment substance.

Application of Electrochemical Sensors Based on Carbon Nanomaterials for Detection of Flavonoids.

Flavonoids have a variety of physiological activities such as anti-free radicals, regulating hormone levels, antibacterial factors, and anti-cancer factors, which are widely present in edible and medicinal plants. Real-time detection of flavonoids is a key step in the quality control of diverse matrices closely related to social, economic, and health issues. Traditional detection methods are time-consuming and require expensive equipment and complicated working conditions. Therefore, electrochemical sensors with high sensitivity and fast detection speed have aroused extensive research interest. Carbon nanomaterials are preferred material in improving the performance of electrochemical sensing. In this paper, we review the progress of electrochemical sensors based on carbon nanomaterials including carbon nanotubes, graphene, carbon and graphene quantum dots, mesoporous carbon, and carbon black for detecting flavonoids in food and drug homologous substances in the last four years. In addition, we look forward to the prospects and challenges of this research field.

Sulfated Metabolites of Luteolin, Myricetin, and Ampelopsin: Chemoenzymatic Preparation and Biophysical Properties.

Authentic standards of food flavonoids are important for human metabolic studies. Their isolation from biological materials is impracticable; however, they can be prepared in vitro. Twelve sulfated metabolites of luteolin, myricetin, and ampelopsin were obtained with arylsulfotransferase from Desulfitobacterium hafniense and fully characterized by high-performance liquid chromatography, MS, and NMR. The compounds were tested for their ability to scavenge 1,1-diphenyl-2-picrylhydrazyl, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid), and N,N-dimethyl-p-phenylenediamine radicals, to reduce ferric ions and Folin-Ciocalteu reagent, and to inhibit tert-butyl hydroperoxide-induced lipid peroxidation of rat liver microsomes. The activity differed considerably even between monosulfate isomers. The parent compounds and myricetin-3'-O-sulfate were the most active while other compounds displayed significantly lower activity, particularly luteolin sulfates. No mutagenic activity of the parent compounds and their main metabolites was observed; only myricetin showed minor pro-mutagenicity. The prepared sulfated metabolites are now available as authentic standards for future in vitro and in vivo metabolic studies.

A-Type Cinnamon Procyanidin Oligomers Protect Against 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine-Induced Neurotoxicity in Mice Through Inhibiting the P38 Mitogen-Activated Protein Kinase/P53/BCL-2 Associated X Protein Signaling Pathway

Parkinson's disease (PD) is a common neurodegenerative disorder. Cinnamon procyanidin oligomers (CPOs) are flavonoids with many claimed health benefits. This study aimed to elucidate the neuroprotection of A-type CPOs (CPO-A) and the underlying mechanisms in cultured cell and animal models of PD. Thirty male mice (C57BL/6, 9-wk old) were assigned to 3 groups (n=10), and were given daily gavage of saline [control and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) groups] or CPO-A (150mg/kg, CPO-A group) during days 1-15 and daily intraperitoneal injections of saline (control group) or MPTP (20mg/kg; MPTP and MPTP+CPO-A groups) during days 11-15. After the motor behavior test, all mice were killed on day 16 to collect the substantia nigra (SN) for assaying the neuroprotective effects of CPO-A. SH-SY5Y cells were treated with 12.5 μM CPO-A for 2h or 3 activators of stress-related kinases (5-25 μM) for 12-48h followed by 1mM 1-methyl-4-phenylpyridinium (MPP+) for assays of viability, morphology, and stress status. Compared with the control, the MPTP treatment decreased (P < 0.05) locomotor activity by 21%, and tyrosine hydroxylase (TH) positive neurons by 55% and Th mRNA concentration by 51% in the SN. The CPO-A treatment attenuated or restored (P < 0.05) these changes and inhibited (P < 0.05) the MPTP-induced activation of P38 mitogen-activated protein kinase (P38MAPK) and P53, along with the downstream expression of BCL-2 associated X protein (BAX) in the SN. In SH-SY5Y cells, the CPO-A treatment blocked (P < 0.01) the MPP+-induced accumulation of intracellular reactive oxygen species and neurotoxicity. However, this protection was abolished (P < 0.05) by activators of the P38MAPK/P53/BAX pathway. CPO-A protected against MPP+-induced cytotoxicity in SH-SY5Y cells and MPTP-induced neurotoxicity in mice by regulating the P38MAPK/P53/BAX signaling. Our findings reveal a novel role and mechanism of a food flavonoid CPO-A in preventing neurodegeneration.

Expression of a β-glucosidase in bacteria with biotechnological interest confers them the ability to deglycosylate lignans and flavonoids in vegetal foods.

Lignans and flavonoids are found in plants in their glycosylated forms and need to be hydrolyzed to aglycones to become bioavailable. Putative β-glucosidase genes from Lactobacillus mucosae INIA P508 were inserted into the plasmid pNZ:TuR. The strain Lactococcus lactis MG1363 harboring the plasmid pNZ:TuR.glu913 showed high β-glucosidase activity and was able to transform secoisolariciresinol diglucoside (SDG) into secoisolariciresinol (SECO). Lactic acid bacteria and Bifidobacterium strains harboring pNZ:TuR.glu913 were incubated with a soy beverage supplemented with flax seed extracts. SDG was almost completely consumed by the transformed strains, while concentration of SECO greatly increased. Moreover, these strains showed high deglycosylation of the isoflavone glycosides daidzin and genistin. In addition, other lignan and flavonoid aglycones were produced, i.e. matairesinol, pinoresinol, quercetin, and eriodyctiol. These deglycosylase activities were maintained when this glucosidase gene was cloned in a food grade vector, pLEB590, and transformed into L. lactis MG1363. This is the first report of the use of a food grade plasmid that confers the ability to efficiently catalyze the deglycosylation of lignans, isoflavonoids, flavones, and flavanones. The recombinant bacteria of this study would be of value for the development of fermented vegetal foods enriched in bioavailable forms of lignans and flavonoids.

An assessment of the interaction for three Chrysanthemum indicum flavonoids and α-amylase by surface plasmon resonance.

This study evaluated the interaction of Chrysanthemum indicum (CI) flavonoids (luteolin, acacetin, and buddleoside) with α‐amylase. Surface plasmon resonance (SPR) assay showed their equilibrium dissociation constants (KD) are 1.9695 ± 0.12, 2.9240 ± 0.20, and 3.2966 ± 0.08 mM at pH 6.0, respectively. Furthermore, their binding affinities were influenced by KCl, MgCl2, and CaCl2. Enzymatic kinetic studies revealed that three flavonoids exhibited noncompetitive α‐amylase inhibitory activity. The inhibitory sequence is luteolin > acacetin > buddleoside, which was in accordance with the results of binding affinity from SPR. 1,1‐diphenyl‐2‐picryl hydrazyl radical assay demonstrated that antioxidant activities of three flavonoids were inhibited significantly with α‐amylase. Meanwhile, the study reveals that hydroxyl on C′‐4, C′‐5, and C‐7 of flavonoids play an important role on the interaction of three flavonoids with α‐amylase. Also, SPR could be used as sensor for rapid screening inhibitors of α‐amylase and provide useful information for the application of C. indicum flavonoids in food and pharmaceutical area.

Effect of the Processing Temperature on the Degradation of Food Flavonoids: Kinetic and Calorimetric Studies on Model Solutions

Food flavonoids have a high antioxidant activity that make them bioactive to fight oxidation. However, when they are used in different formulations, these bioactive molecules are often the subject of at least one heat treatment step such as cooking, pasteurization. To establish the sensitivity of these molecules to heat treatment, the kinetics of degradation of 4 flavonoid extracts were evaluated under isothermal and non-isothermal conditions. The flavonoids tested belong to the aglycon (eriodictyol and mesquitol) and glycosylated (rutin, naringin) forms. The glycosylated flavonoids have a higher stability than the aglycons. Among the glycosylated flavonoids, rutin is more sensitive to heat than naringin because of the different degree of hydroxylation between these 2 compounds. For the aglycon form, the sensitivity to heat varies depending on the absence or presence of a carbonyl group at the 4-position and a hydroxyl at the 3-position. The addition of 10% of propylene glycol causes an effect protector delaying the thermal degradation of flavonoids. Activation energies are also affected by both the flavonoid structure and the heat treatment system. The differences observed between the isothermal and non-isothermal conditions can be attributed to the difference in heating intensity that can generate a difference in the composition of the solution. The evolution of antioxidant activity of flavonoid solutions after heat treatment is different depending on the structure of the flavonoid studied.

Structure-Antioxidant-Antiproliferative Activity Relationships of Natural C7 and C7-C8 Hydroxylated Flavones and Flavanones.

Common food flavonoids: chrysin, apigenin, luteolin, diosmetin, pinocembrin, naringenin, eriodictyol, hesperetin, and their analogues with an additional hydroxyl group at the C-8 position obtained via biotransformation were tested for antioxidant activity using the ABTS, DPPH, and ferric ion reducing antioxidant power (FRAP) methods. They were also tested for antiproliferative activity against selected human cancer cell lines—MV-4-11 (biphenotypic B myelomonocytic leukemia), MCF7 (breast carcinoma), LoVo (colon cancer), LoVo/DX (colon cancer doxorubicin resistant), and DU 145 (prostate cancer)—and two normal human cell lines—MCF 10A (breast cells) and HLMEC (lung microvascular endothelial cells). Flavonoids with a C7–C8 catechol moiety indicated much higher antioxidant activity compared with the C7 hydroxy analogues. However, because they were unstable under the assay conditions, they did not show antiproliferative activity or it was very low.

Food flavonoid ligand structure/estrogen receptor-α affinity relationships – toxicity or food functionality?

In silico molecular modelling is used to study interactions between flavonoid phytoestrogens and estrogen receptor (ER)α. Twenty flavonoids from foods were studied; e.g., genistein from soy, naringenin from grapefruit, phloretin from pears, chrysin from oyster mushrooms. These potential ligands' molecular attributes and their spatial arrangements that favour binding to the ligand binding cleft (LBC) of ERα are identified, and Docking Scores calculated. The Docking Score order is the same as the estrogenicity order for 8 of the flavonoids studied in detail. The number and position of flavonoid ring hydroxyls influence the Docking Scores which might relate to ERα′s bio-activity. Hydrophobic interactions between ligands and ERα are also important; the number of rotatable CC bonds in ligands likely affects the magnitude of hydrophobic interactions and ligand fit. Our findings suggest that flavonoids with diverse structural features could have different binding energies and binding affinities with ERα, which might confer different functionalities and toxicities.

The activity of transient receptor potential channel C-6 modulates the differentiation of fat cells.

Previously, the V1-3 isoforms of the transient receptor potential channel (TRP) have been shown to promote or prevent adipocyte differentiation. In the current study, the C isoforms were screened for blocking adipogenesis. The hypothesis that the TRP classic or canonical (TRPC) deters adipocyte differentiation was investigated in 3T3-L1 cells employing the channel-specific activator and antagonist, silencing, and overexpression techniques. Fat accumulation in cells was visualized by Oil Red O staining. Intracellular calcium inflow was estimated by confocal microscopy. A high-fat (HF) feeding study was also performed on C57BL/6J mice to verify the findings in the cell model. Among the 6 C isoforms tested, only TRPC-6 inhibited the differentiation of fat cells. The phytochemical quercetin induced the channel protein expression. Calcium-imaging results also revealed that the flavonoid could trigger calcium inflow. Coadministration of quercetin (1 or 20 mg/kg body weight) in an HF diet prevented TRPC-6 from declining and attenuated phosphorylated (p)-PKB and PI3k, as well as the proliferation of visceral fat cells. The present study illustrated that TRPC-6 activation could perturb adipocyte differentiation. The food flavonoid quercetin was a TRPC-6 inducer and activator and it could prevent adipogenesis in mice.-Tan, Y. Q., Kwan, H. Y., Yao, X., Leung, L. K. The activity of transient receptor potential channel C-6 modulates the differentiation of fat cells.

Estimation of dietary flavonoid intake of the Brazilian population: A comparison between the USDA and Phenol-Explorer databases

A lack of data regarding flavonoid food composition and flavonoid intake has limited the ability to evaluate proposed health benefits effects in populations. We estimated the dietary flavonoids intake of the Brazilian population based on the diet composition obtained through two dietary surveys, which were available from a Food Service and Brazilian Household Budget Survey, using the USDA and Phenol-Explorer databases. The mean daily estimated flavonoid intake was similar when calculated using the USDA and Phenol-Explorer databases in the Household Budget Survey (56.32 mg/day and 64.22 mg/day, respectively). Similar results were observed when calculated using both databases in a Food Service (86.66 mg/meal and 106.33 mg/meal, respectively). The major class contributor was flavanones mainly from oranges, followed by flavonols mainly from onions and apples. The main difference was found in the third flavonoid class, anthocyanidins and flavan-3-ol using the USDA and Phenol-Explorer databases, respectively. In conclusion, there was a balance of intake between the five flavonoid subclasses, which is determined to be important to diversity in a diet. Despite some technical features, both databases are a useful source of food flavonoid contents, but the method of data collection used to estimate the intake impairs great differences in the results.

Antiplatelet activity of flavonoids

The review is devoted to the influence of the main subclasses of food flavonoids on the organism. The role of these polyphenolic compounds and containing them foods in reducing the risk of cardiovascular diseases is discussed. Particular attention is paid to the influence of flavonoids on the functional activity of platelets. The possible mechanisms of the effect of flavonoids on various links and stages of activation, adherence and aggregation of platelets are analyzed in detail. Most of the available data indicate the ability of these plant polyphenols to correct platelet abnormalities by affecting various receptors, mechanisms of intracellular mobilization of Ca2+, and multiple pathways of intra-platelet signaling. Problems that arise when transferring information obtained in in vitro experiments to the conditions of the whole organism are noted, which indicate the urgent need for further in-depth study of the effects of flavonoids. The data presented allow us to consider flavonoids as a basis for the creation of potentially effective and safe antiplatelet agents that can make a significant contribution to the treatment and prevention of a number of cardiovascular diseases.

Apigenin attenuates patulin-induced apoptosis in HEK293 cells by modulating ROS-mediated mitochondrial dysfunction and caspase signal pathway

Mycotoxins like patulin (PAT) are among the most significant food contaminant with regard to public health. This study aimed to evaluate the protective effect of apigenin (API), one of the most bioactive flavonoids in plant-derived food, on PAT-induced apoptosis in HEK293 cells. Cells were treated under basic conditions, 8 μM PAT without or with API (2.5, 5 and 10 μM) concomitantly for 10 h. API exerted renoprotective effect by inhibiting intracellular reactive oxygen species (ROS) accumulation, modulating oxidative phosphorylation especially elevating the expression of ATP synthase, re-establishing mitochondrial membrane potential (MMP) and maintaining higher intracellular ATP level, accompanied by p53, Bax downregulation and Bcl-2 upregulation. Thereby, cytochrome c release from mitochondria to cytoplasm was reduced, causing inhibition of initiator caspases-9 and executioner caspases (3, 6 and 7) expression and enzyme activities. Results revealed dietary apigenin attenuates patulin-induced apoptosis in HEK293 cells by modulating ROS-mediated mitochondrial dysfunction and caspase signal pathway.

Development of a Comprehensive Flavonoid Analysis Computational Tool for Ultrahigh-Performance Liquid Chromatography-Diode Array Detection-High-Resolution Accurate Mass-Mass Spectrometry Data.

Liquid chromatography and mass spectrometry methods, especially ultrahigh-performance liquid chromatography coupled with diode array detection and high-resolution accurate-mass multistage mass spectrometry (UHPLC-DAD-HRAM/MSn), have become the tool-of-the-trade for profiling flavonoids in foods. However, manually processing acquired UHPLC-DAD-HRAM/MSn data for flavonoid analysis is very challenging and highly expertise-dependent due to the complexities of the chemical structures of the flavonoids and the food matrixes. A computational expert data analysis program, FlavonQ-2.0v, has been developed to facilitate this process. The program first uses UV-vis spectra for an initial stepwise classification of flavonoids into classes and then identifies individual flavonoids in each class based on their mass spectra. Step-wise identification of flavonoid classes is based on a UV-vis spectral library compiled from 146 flavonoid reference standards and a novel chemometric model that uses stepwise strategy and projected distance resolution (PDR) method. Further identification of the flavonoids in each class is based on an in-house database that contains 5686 flavonoids analyzed in-house or previously reported in the literature. Quantitation is based on the UV-vis spectra. The stepwise classification strategy to identify classes significantly improved the performance of the program and resulted in more accurate and reliable classification results. The program was validated by analyzing data from a variety of samples, including mixed flavonoid standards, blueberry, mizuna, purple mustard, red cabbage, and red mustard green. Accuracies of identification for all samples were above 88%. FlavonQ-2.0v greatly facilitates the identification and quantitation of flavonoids from UHPLC-HRAM-MSn data. It saves time and resources and allows less experienced people to analyze the data.

Usual Intakes of Flavonoids: Estimates from What We Eat in America, NHANES 2007–2010

Usual intakes are estimates of the long‐term average daily consumption of foods, food components, or nutrients. Despite a vast number of studies suggesting favorable effects of dietary flavonoids on human health, usual intakes of flavonoids have never before (to our knowledge) been determined. Recent release of a comprehensive database of the flavonoid content of foods has made possible the calculation of usual flavonoid intakes. The purpose of this study was to ascertain and describe distributions of usual intakes of flavonoids (total and 6 classes) in the U.S. population. Intake data collected in What We Eat in America, NHANES 2007–2010 from 17,892 individuals were analyzed. Day 1 and day 2 flavonoid intakes were estimated using Flavonoid Values for USDA Survey Foods and Beverages 2007–2010. For anthocyanidins, flavan‐3‐ols, flavanones, flavones, and isoflavones, the two‐part National Cancer Institute approach for estimating the probability of consumption on a day and the amount consumed (which assumes a correlation between the two) was used. For total flavonoids and flavonols, it was assumed that at least a minimal amount is consumed every day by everyone (i.e., probability of consumption = 1). For individuals age ≥1 year, median usual intake of total flavonoids was 117.18 mg/day. Estimates at the 5th, 25th, 75th, and 95th percentiles were 17.01 mg, 55.37 mg, 236.09 mg, and 595.26 mg, respectively, indicating a positively skewed distribution. Due to high concentrations of flavonoids in certain foods, positively skewed distributions were also observed for all flavonoid classes. In descending order by weight, usual median intake of flavan‐3‐ols was 57.76 mg; flavonols, 14.38 mg; flavanones, 7.02 mg; anthocyanidins, 6.70 mg; flavones, 0.62 mg; and isoflavones, 0.17 mg. On an average day in 2007–2010, the likelihood of consuming the episodically consumed flavonoid classes (i.e., anthocyanidins, flavan‐3‐ols, flavanones, flavones, and isoflavones) ranged from 94% for flavan‐3‐ols to 39% for isoflavones. Tables describing usual intakes of flavonoids (total, class, and 29 individual flavonoids) by selected sociodemographic variables will become available in 2017 on the Food Surveys Research Group web site (www.usda.gov/nea/bhnrc/fsrg). This novel information will add to the body of knowledge concerning flavonoid intake and thus facilitate the eventual establishment of recommendations regarding safe and adequate dietary intakes of these beneficial compounds.Support or Funding InformationARS, USDA

Metabolism of Quercetin and Naringenin by Food-Grade Fungal Inoculum, Rhizopus azygosporus Yuan et Jong (ATCC 48108).

Rhizopus azygosporus Yuan et Jong (ATCC 48108), a starter culture for fermented soybean tempeh, produces β-glucosidases that cleave flavonoid glycosides into aglycones during fermentation. However, recent data suggest that fermentation of a flavonoid glycoside-rich extract with this strain did not result in the production of aglycones. Thus, in this paper, flavonoid metabolism of this strain was investigated. Incubation of flavonoid aglycones, naringenin and quercetin, with R.azygosporus resulted in the production of flavonoid glucosyl-, hydroxyl-, and sulfo-conjugated derivatives. Naringenin was completely metabolized within 96 h into eriodictyol sulfate and eriodictyol glucoside, whereas quercetin was partially metabolized into quercetin glucoside, diglucoside, sulfate, and glucosyl-sulfate. Most of these metabolites were found to be excreted by the fungi into the culture medium. Toxicity analysis revealed that incubation with both quercetin and naringenin did not exert inhibitory effects on fungal growth. This study presents an interesting mechanism of fungal detoxification of flavonoids in foods.

Synthesis of Effective Food Constituents toward the Development of Chemical Biology Investigations.

This article describes the development of various probes and immunogens for chemical-biological investigations of food flavonoids. We accomplished a large (gram)-scale asymmetric synthesis of a key intermediate, 5-aminopentyl deoxy epigallocatechin-3-gallate (APDOEGCg; 3), an analogue of green tea polyphenol EGCg, in which the key step was cationic cyclization utilizing neighboring group participation of the gallate carbonyl group. The synthetic APDOEGCg (3) was efficiently converted to a fluorescent probe 18 and an immunogen 19 by utilizing the high reactivity of the amine functional group. We confirmed the usefulness of these probes for imaging studies and the generation of antibodies, respectively. We also describe the efficient synthesis of a positron emission tomography (PET) probe [11C]20 by incorporation of 11C into EGCg (1), for which synthetic 4″-Me-EGCg (20) was utilized as an authentic sample. Our synthetic strategy was also applied for the practical synthesis of nobiletin (21), a polymethoxylated flavone from citrus. Synthetic nobiletin was readily converted to various probes by selective demethylation and incorporation of fluorescein, biotin or 11C. These probes should be useful for a range of biological applications. Detailed examination of the mechanisms and further applications are in progress.

Tuning the inflammatory response to silver nanoparticles via quercetin in Caco-2 (co-)cultures as model of the human intestinal mucosa.

Interaction of nanoparticles with food matrix components may cause unpredictable health complications. Using an improved Caco-2 cell-based in vitro (co-)culture model the potential of quercetin as one of the major food flavonoids to alter the effect of silver nanoparticles (Ag-NPs) <20 nm in the human intestinal mucosa at real life concentrations was investigated. Ag-NPs (15-90 μg/ml) decreased cell viability and reduced thiol groups, induced oxidative/nitrosative stress and lipid peroxidation and led to activity changes of various antioxidant enzymes after 3h exposure. The contribution of Ag(+) ions within the concentrations released from nanoparticles was shown to be less important, compared to Ag-NPs. While leading to inflammatory response in the intestines, Ag-NPs, paradoxically, also showed a potential anti-infammatory effect manifested in down-regulated IL-8 levels. Quercetin, co-administered with Ag-NPs, led to a reduction of cytotoxicity, oxidative stress, and recovered metabolic activity of Caco-2 cells, suggesting the protective effects of this flavonoid against the harmful effect of Ag-NPs. Quercetin not only alleviated the effect of Ag-NPs on the gastrointestinal cells, but also demonstrated a potential to serve as a tool for reversible modulation of intestinal permeability.

Calculation of Retention Factors for Flavonoids in Cooked Broccoli

Thermal processes such as cooking have a large influence on flavonoids in foods, which further impact the accuracy of developing food flavonoid database and the estimation of their dietary intake. The objective of this study was to determine how common cooking methods alter complex flavonoids in broccoli, and to compare the effects of different cooking and calculating methods for estimating retention factors. Fresh broccoli samples were purchased from local grocery chains and were cooked by three common ways (boiling, steaming and microwaving). Flavonoids were analyzed by HPLC‐MS/MS. Eight major kaempferol (Km) tri‐ or tetra‐glycosides and one quercetin tri‐glycoside were identified and quantified in raw and cooked broccoli. Retention factors were calculated on individual flavonoids based on the dry weight; they ranged widely from 33.9% to 237.2%, depending on the chemical structure and cooking method. Contents of certain Km glycosides elevated after cooking, probably due to the increased release from cells or from binding with other components. In addition, different calculation methods to generate an overall retention factor for multiple flavonoids with the same aglycone were compared. Among the three methods, namely “retention factor by aglycone”, “retention factor by weight” and “retention factor by average”, the “retention factor by aglycone” was shown to be an appropriate method. The retention factors by aglycone for Km glycosides in broccoli was calculated as 83.9% for boiling, 131.6% for steaming and 136.1% for microwaving.Support or Funding InformationNIH Agreement 58‐1235‐3‐126 and USDA

Improving the estimation of flavonoid intake for study of health outcomes

Imprecision in estimating intakes of non-nutrient bioactive compounds such as flavonoids is a challenge in epidemiologic studies of health outcomes. The sources of this imprecision, using flavonoids as an example, include the variability of bioactive compounds in foods due to differences in growing conditions and processing, the challenges in laboratory quantification of flavonoids in foods, the incompleteness of flavonoid food composition tables, and the lack of adequate dietary assessment instruments. Steps to improve databases of bioactive compounds and to increase the accuracy and precision of the estimation of bioactive compound intakes in studies of health benefits and outcomes are suggested.