New research shows that earlier tolerance of chemical supplements because they are poorly absorbed when compared to naturally occurring minerals, vitamins and antioxidants may need further study. Laura Pitel in The Times reports, - Calcium pills "double risk of heart attacks"(24/05/12)". In the case of calcium, a warning has been published that previous therapeutic effects of higher calcium intake, such as a reduction in factors that cause heart disease - e.g. high blood pressure, in the case of calcium supplements may cause hard deposits on artery walls. In a study of 30,000 German men and women on the European Prospective Investigation into cancer and Nutrition, those on calcium supplements were found to be 86% more likely to have a heart attack than those not taking the supplement. At this website the lack of scientific evidence to support supplementation has meant that natural sources have been preferred. So this experiment is noted and will be monitored.
The flavanoid antioxidants are largely secondary metabolites synthesised by plants to deter herbivorous predators, repel competitors and attract pollinators. Humans have “managed” secondary metabolites such as nicotine, have succumbed to others, such as atropine (in deadly nightshade), exploited many, as medicines e.g. digoxin, and enjoyed the colours and perfumes, flavours and aromas, of the large number of them present in foods, flowers and medicines. The better known antioxidants are some of the mineral elements e.g. selenium and vitamins A, C and E which play important cooperative roles, and polyphenols and carotenoids. Grouped together as antioxidants (which in in vitro experiments they are) these compounds are thought to be therapeutic to humans ingesting them in diets rich in fruits and vegetables. Read more ....
Why the interest in them?
It has been observed in in vitro experiments that they can neutralise damaging free radicals, the by-products of necessary energy generating processes that, if left in body cells in excess, cause oxidative stress, a precursor of ill-health. They operate at three levels: 1. Preventing the formation of reactive oxygen species (ROS) by chelation with e.g. metal-binding proteins such as metallothionein. 2. Diverting those ROS that survive away from vulnerable centres in the cell, a possible role for phenolic flavonoids. 3. Repairing the damage caused by surviving ROS, e.g. multiple enzyme systems. (H. Sies, Exp. Physiol. 82, 291-295, 1997) in vivo studies are slowly building a picture of the efficacy of food-based natural antioxidants (FBNA) in support of epidemiological surveys that for many years have linked diets rich in antioxidants (e.g. the mediterranean diet) with good health and lower levels of degenerative diseases and longer life. Scientists are curious about the mechanisms involved in this process. Read more ...
The bioavailability of food-based antioxidants
For food-based compounds to be therapeutic antioxidants they have to:-
1. Exhibit in vitro antioxidant activity (capacity).
2. Be absorbed from the gut into the blood stream.
3. Be able to accumulate at the target (tissue or organ) site, or to trigger the production of secondary endogenous antioxidants, e.g. enzymes, etc. that can.
4. Reduce oxidative stress.
5. Be efficacious. "Stars" (1-5 based on the above requirements) have been awarded to scientific studies evaluated here, depending upon the depth of the enquiry. 1 star has been awarded to a great many studies of FBNA isolated and tested in the lab, 2 stars can be awarded to many trials reporting the absorption of single compounds raising the antioxidant capacity of blood plasma. 3 stars have been awarded to relatively few experiments demonstrating the antioxidant present in increased amounts at the target site soon after administration. 4 and 5 star demonstrations await further research. Read more ....
Welcome to "The availability of food-based natural antioxidants" website.
So far there is little evidence that antioxidant supplements have any effect. Browse among the links to explore some examples of the current experiments and hypotheses to determine the possible roles of food-based natural antioxidants in human nutrition, health and well-being. Because there is only epidemiological evidence that antioxidants are the active agents in the process of oxidative stress reduction, a page on alternative theories has been included. Although at this time (April 2009) there is a lack of analytical methodology to support the hypothesis of hormesis, the idea is most appealing in the search for mechanisms to explain the experimental evidence being gathered on how food-based antioxidants work.Read more ...
The scientific literature on antioxidants is growing rapidly and only a few examples from the various subject areas are given here. Strenuous efforts are made to report the literature results accurately and to make factual deductions from these data. To discuss alternatives Always consult medical and/or nutritional practitioners about uncertainties relating to diet and health issues.
Antioxidants and specific health issues
In a survey of 100 randomly-selected atrial fibrillation patients, 34 reported that an arrhythmia triggering factor was alcohol, 26 in the form of red wine, 26 as spirits, and 16 as white wine. Could it be antioxidants rather than alcohol that are the antagonists? Going one step further; could it be the proanthocyanins which are present in higher concentration in red wine and spirits than in white wine? Reference: A. Hansson et al., Cardiovascular disorders, 4 (13), 2004. doi:10.1186/1471-2261-4-13
Fact: epidemiological studies correlate diets rich in fruits, nuts, grains and vegetables (e.g. the Mediterranean diet) with improved health by reducing the incidence of degenerative diseases and increasing the lifespan. However, a recent study (EPIC) did not find a correlation between such diets and prevention of cancer.
Assumption: that the trace amounts of antioxidants in these foods are the active ingredients. If they are, several uncertainties about their mode of action are listed below. If they are not, then other factors, for example, longer exposure to sunlight, or a less stressful lifestyle have to be invoked. Interestingly, new work published in PNAS suggests that UV radiation is more therapeutic than vitamin D in treating multiple sclerosis - sun not supplements (and perhaps not natural antioxidants either).
Hypotheses: (at Spring 2009) 1. that a combination of antioxidants works better than individuals - eat a mixture of the above foods.
2. that small amounts at regular intervals [2-3 hours (approx. post-prandial residence time)] are better than less frequent larger meals - eat small amounts of mixtures regularly.
3. supplements are less effective because, even taken as multivitamins, they do not contain the mixture of traces of natural antioxidant compounds present in foods, and may be administered in too high concentrations. (see 4).
4. hormesis predicts that only small amounts of natural food-based antioxidants will be therapeutic, while large amounts will be inhibitory and may even be toxic [it has been alleged that too high a dose of beta carotene can actually reduce life expectancy, especially for smokers - details atInactivity page].