Flavonoids consumption

A significant protective effect of flavonoid consumption was observed on men, in the Finnish Mobile Clinic Health Examination Survey (Knekt and others 1996). In contrast, in a group of 35,000 men from the USA, coronary death was associated with high intakes of flavonoids in men with a previous history of coronary disease (Rimm and others 1996). 

Estimation of the daily intake of flavonoids is not a straightforward matter because of the mentioned variation in the content and composition of flavonoids in foods. Moreover, the variability and the lack of standardized analytical methods for their estimation further hinder the creation of compositional databases necessary to calculate flavonoids consumption. Intakes wUl also be affected by seasonal and regional availability of plant foods, as weU as by dietary habits dependant of cultural traditions and individual preferences. 

The Zutphen Elderly study thus suggests that regular flavonoid consumption, as part of the food matrix, may reduce the risk of death from CHD in elderly men. This study also provides evidence for flavonoid-mediated protection against stroke. Dietary flavonoids (particularly quercetin) were inversely associated with stroke incidence. The relative risk of the highest versus the lowest quartile of flavonoid was 0.27 (95% confidence interval, 0.11-0.70). Black tea contributed approximately 70% to flavonoid intake and the relative risk for a daily consumption of 4.7cups or more of tea versus less than 2.6 cups of tea was 0.31 (95% confidence interval, 0.12-0.84). This study also found that intake of catechins, whether from tea or other sources (e.g., chocolate), may reduce the risk of ischemic... 

It is important to note that diet is a complex mixture that contain compounds with varying activity. Chemical stimulators of colon cancer growth include bile acids, 1,2-diglycerides and prostaglandins which stem from consumption of fat. In contrast, fruits and vegetables contain substances such as carotenoids, flavonoids and fibre, which may inhibit cancer cell growth, and the risk of colon cancer appears to be mirrored by the ratio of plant sterols to cholesterol in the... 

It is important to quantify the content of tea infusions when evaluating the intake of flavoiioids from consuming tea. However, the daily consumption of flavonoids from tea is difficult to estimate because values depend on accurate assessment of drinking habits and flavonoid content in teas. 

Tea flavonoids, or tea extracts, have been linked to benefits in reducing the risk of certain cancers and cardiovascular diseases in experimental animals. However, epidemiological studies have produced inconsistent evidence in the relationship between tea drinking and cancer (Blot et a/., 1997 Goldbohm etal, 1996 Hertog eta/., 1997 Yang eta/., 1996). Therefore, further research is needed before definitive conclusions on the impact of tea consumption upon the cancer risk in humans can be reached. The metabolites of catechins and flavonols after consumption of tea infusions have scarcely been investigated, and thus more research is needed as to the role of those compounds in the reported health benefits of tea consumption. 

Cyanidin is the most common anthocyanin in foods. In addition, anthocyanins are stabilized by the formation of complexes with other flavonoids (co-pigmentation). In the United States, the daily anthocyanin consumption is estimated at about 200 mg. Several promising studies have reported that consumption of anthocyanin-rich foods is associated with reductions of the risks of cancers - and atherosclerosis and with preventive effects against age-related neuronal and behavioral declines. These beneficial effects of anthocyanins might be related to their reported biological actions such as modulators of immune response and as antioxidants. Knowledge of anthocyanin bioavailability and metabolism is thus essential to better understand their positive health effects. 

The consumption of flavonoids in different populations is variable, and in many cases the amount is underestimated because calculations are derived from the analysis of few foods or because of the lack of proper food composition tables in the countries (Sarria, 2004 Nijvelt and others 2001). Chun and others (2007) estimated the consumption of flavonoids by adults in the US as 189.7 mg/day. This value was much higher than those reported by other authors for the same population as well as for other countries such as Denmark (23 16 mg/day), Finland (3.4-24 mg/day), Netherlands (23 mg/day), and Japan (63 mg/day)(Chun and others 2007). Johannot and Somerset (2006) estimated the ingestion of flavonoids for an Australian population (n = 13,858) at around 351 mg/day. They found that tea was typically the main source of flavonoids. Although it was observed that the types of flavonoids and their sources varied according to age, these authors noted that it is necessary to carry out more research with more consistent methodologies to validate the ingestion of specific flavonoids and to facilitate the international comparison. 

In Greece, a case-control study was conducted to investigate the incidence of liver cancer by estimating the consumption of six types of flavonoids with a semiquantitative questionnaire on the frequency of foods. The intake of flavones was inversely associated with hepatocellular carcinoma, irrespective of its etiology (viral or nonviral). With respect to cholangiocarcinoma, an inverse association with the consumption of flavan-3-ols, anthocyanidins, and total flavonoids studied was found. However, this last result should be viewed with caution because of the small sample size, due to the fact that this is a rare type of cancer (Lagiou and others 2008). 

Other studies have estimated the consumption of fruits or vegetables (rich in flavonoids) and have reported an inverse relationship with some types of cancer but in different extent among men and women (Park and others 2007 McCullough and others 2003 Voorrips and others 2000). 

Lotito SB and Frei B. 2006. Consumption of flavonoid-rich foods and increased plasma antioxidant capacity in humans cause, consequence, or epiphenomenon Free Radic Biol Med 41(12) 1727—1746. 

Cytotox/c/ty There has been some concern raised over cytotoxic and mutagenic in-vitro effects of hypericum, which have been ascribed to the constituent quercetin (Tyler 1994). However, quercetin is a flavonoid that is present in many plants and vegetables, and it is estimated that the average person consumes 50 mg per day. Consumption of hypericum would not significantly add to this (1 mg in commonly used amounts). The German Commission E has concluded that this is not of great concern. 

Because of human consumption of plant and plant products, there has been much interest on the impact of flavonoids on human health and this has been recently reviewed [149, 150 and ref therein]. Additionally, Passamonti et al. [151] have recently reviewed the issue of bioavailability of dietary flavonoids. Citrus flavonoids have been shown to have many beneficial effects on human health including anti-inflammatory activity, anticancer activity, antioxidant activity, and protection against coronary heart disease [reviewed in 152-154]. This has led to... 

As its name suggests, supercritical fluid extraction (SEE) relies on the solubilizing properties of supercritical fluids. The lower viscosities and higher diffusion rates of supercritical fluids, when compared with those of liquids, make them ideal for the extraction of diffusion-controlled matrices, such as plant tissues. Advantages of the method are lower solvent consumption, controllable selectivity, and less thermal or chemical degradation than methods such as Soxhlet extraction. Numerous applications in the extraction of natural products have been reported, with supercritical carbon dioxide being the most widely used extraction solvent. However, to allow for the extraction of polar compounds such as flavonoids, polar solvents (like methanol) have to be added as modifiers. There is consequently a substantial reduction in selectivity. This explains why there are relatively few applications to polyphenols in the literature. Even with pressures of up to 689 bar and 20% modifier (usually methanol) in the extraction fluid, yields of polyphenolic compounds remain low, as shown for marigold Calendula officinalis, Asteraceae) and chamomile Matricaria recutita, Asteraceae). " ... 

While typical flow rates for the HPLC analyses of flavonoids lie in the 1.0 to 1.5 ml/min range, the introduction of short columns containing stationary phases with smaller pore sizes (allowing narrower peaks to be obtained in shorter separation times) means that considerably lower flow rates are the trend. Not only is there a decrease in solvent consumption but coupling to mass spectrometers or NMR instruments is facilitated. 

Zhang, K. and Zuo, Y., GC-MS determination of flavonoids and phenolic and benzoic acids in human plasma after consumption of cranberry juice, J. Agric. Food Chem., 52, 222, 2004. 

Flavones and flavanones were less frequently consumed during the 4-day collection period. Flavones were not consumed at all by 38 participants, while 29 people did not consume any citrus flavonoids — flavanones. The interquartile range of intake of flavones was relatively limited, ranging from 0.0 to 2.0 mg/day. Flavone consumption was not normally distributed and was negatively skewed toward a lack of consumption of foods rich in flavones such as olives and lettuce. Likewise, flavanone intake was also not normally distributed with a mean flavanone intake of 1 mg/day compared to the median intake of 1.2 mg/day. This is accounted for by the fact that the range of flavanone intakes was very wide (0 to 239 mg/day), 36%i of participants not consuming any flavanone-rich foods. The main dietary... 

Linseisen, J., Radtke, J., and Wolfram, G., Flavonoid intake of adults in a Bavarian subgroup of the national food consumption survey, Z. Ernahrungswiss., 36, 403, 1997. 

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