Flavonoids beneficial health effects

As flavonoids are ubiquitous components of fruits and vegetables, they are part of almost any human diet. The identification of potential targets for the beneficial health effects of flavonoids exponentially increased over the years. The physiological relevance of the interactions of flavonoids with cell... 

Despite the apparently beneficial health effects of flavonoids, several studies indicate their mutagenicity and genotoxicity in mammalian systems. This may be due to their activity as pro-... 

Flavonoids as antioxidants have been reviewed several times 45s including an outline of many claims to their beneficial health effects . Due to their complex structures and different classes (eight thousand different compounds are known ), researchers often resorted to qualitative screening methods to evaluate their antioxidant potentials in mixed aqueous/lipid phases. For example, the so-called Trolox equivalent antioxidant capacity (TEAC), the concentration of Trolox with equivalent antioxidant activity of a 1 mM concentration of the substrate, is frequently used in heterogeneous systems. Unfortunately, this can be an unreliable measure of the activity of the substance, especially if initiation is also carried out in the aqueous phase. Nevertheless, there have been some efforts made to evaluate antioxidant activities of specific flavonoids using more quantitative methods in heterogeneous systems in order to mimic natural environments. A few examples are cited below to illustrate some approaches to determine flavonoid activities in micelles or lipid membranes. 

The average consumption of polyphenols in the diet is 1 g/d and PAs account for a large fraction of the total flavonoid intake in Western populations. PAs are considered responsible for a number of beneficial health effects and are deemed to prevent the onset of various chronic (cardiovascular, cancer, neurodegenerative) diseases, but a... 

Phenolic compounds from fruits contribute to their quality, nutritional value, color, taste, aroma and flavor. They are also known to provide the beneficial health effects of many fruits. Phytophenols comprise a wide variety of compoimds, divided into several classes hydroxy-acids, anthocyanins, flavonoids, lignans, and taimins. 

Flavonoids are part of the hiunan diet, and high levels occm in fruits, vegetables, wine, tea, and cocoa. It is suggested that dietary intake of flavonoids has beneficial health effects due to their antioxidant and radical-scavenging properties... 

In conclusion, berries and herbs contain large numbers of flavonoids and phenolics with antioxidant properties. Different flavonoids and phenolics contribute to antioxidant activity depending on their chemical structure and concentration. This study revealed that berries and herbs are effective potential sources of natural antioxidants. Consumption of berry crops and herbs indeed is beneficial to our health. The relevance of this information to the human diet is summarized by Rice-Evans and Miller (i) who state that total antioxidant potential of fruits and vegetables is more important than levels of any individual specific antioxidant constituent. Therefore, supplementing fhiits, vegetables and herbs with a balanced diet should have beneficial health effects. 

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 above evidence shows that flavonoids can interact and modulate the activity of several membrane proteins. These effects can in part explain the beneficial health properties of flavonoids and could also help develop new therapeutic approaches for major human diseases. 

Numerous health benefits have been reported or claimed for flavonoids and isoflavones, such as in cancer prevention, cardiovascular effects, and relief of menopausal syndromes. However, concerns have been raised about potential adverse effects, such as enhancement of reproductive organs and anti-thyroid effects. In order to evaluate potential beneficial or hazardous health effects from flavonoids. 

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... 

The observation of a lower incidence of coronary heart disease (CHD) and certain types of cancers in the Mediterranean area led to the hypothesis that a diet rich in grain, legumes, fresh fruits and vegetables, wine in moderate amounts, and olive oil was beneficial to human health. To date, this effect has been mainly attributed to the low saturated fat intake of the Mediterranean diet and its high proportion of monounsaturates, which indeed may favorably affect the plasma lipid and lipoprotein profiles. Nevertheless, other components of the diet, such as fiber, vitamins, flavonoids, and phenols, may play an important role in disease prevention, acting on different cardiovascular variables. 

As previously mentioned, flaxseed is a rich source of dietary fiber (28%). Dietary fiber has been widely viewed as a component essential to lowering the risk of colon cancer. The flaxseed protein is similar to soy thus may be beneficial to health. Bhathena et al. (2002) first reported that flaxseed protein was effective in lowering plasma cholesterol and triacylglycerides (TAG) compared to soy and casein protein in male F344 and obese SHR/N-cp rats. The role of protein in disease prevention warrants further investigation. Components, such as PAs and flavonoids, may also contribute to the health benefits of flaxseed. 

Compared with phenothiazines, much less is known about the effects exerted by different types of flavonoids on the properties of ionic channels. These compounds exert mostly beneficial effects on human health, acting mainly as nonspecific antioxidants that cause almost no side effects. Therefore, there was only a limited need to study specific interactions of flavonoids with different types of ionic channels. 

Epidemiological studies in the Mediterranean region evidenced that a diet rich in grain, legumes, fruits and vegetables, wine and olive oil has beneficial effects on human health. In fact, these foods are rich in antioxidant vitamins, flavonoids and polyphenols that play an important role in prevention against cancer and coronary heart disease. 

There is also a need to assess the role of the colonic microflora in the overall bioavailability and potential bioactivity of dietary flavonoids. The amoxmt of absorption of colonic metabolites is unclear at this time, and there is growing interest in the potential effects of the phenolic acids and their derivatives as potentially beneficial agents. For example, thehumanintestinalbacteriametabolites of rutin and quercetin, 3,4-dihydroxyphenylacetic acid, and 4-hydroxyl-phenyl-acetic acid have been shown to possess more effective antiplatelet aggregation activity than ratin and quercetin [107]. Furthermore, 2,4,6-trihydroxybenzaldehyde and quercetin were more effective than rutin in their cytotoxicity against tumor cell lines. The effects the phenolics themselves have on the microflora are an emerging field, and it is possible that a flavonoid-induced change in the rich colonic bacterial population may have an influence on the overall health of the individual. 

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