16 August 2013 | News | By Bureau Report
Antioxidant activity in food and nutraceuticals contribute to a reduction in the risk of free radical generation and subsequent damage to human cells and tissues, according to a research study "Measurement of Antioxidant Activity in Selected Food Products and Nutraceuticals” published in Journal of Nutrition & Food Science" on May 1, 2013.
The study was taken by up Dr Mohammed Amanullah, Associate Professor, Department of Clinical Biochemistry, College of Medicine, King Khalid University, Kingdom of Saudi Arabia along with Al-Shahrani M M, Zaman G S, to quantify the antioxidant activity of selected food products and nutraceuticals using a spectrophotometric assay.
The study observed that agave nectar syrup and xylitol sweetener (in descending order) had higher antioxidant properties than all the other common sweeteners tested. Among all the citrus fruits tested, grape fruit demonstrated the highest antioxidant activity per standard serving size; this may be due to the presence of high amounts of Vitamin C, lycopene and the soluble pectin in it.
Antioxidant activities of selected antioxidant beverages indicated that strawberry-kiwi blend demonstrates the highest antioxidant levels among selected antioxidant drinks. This high antioxidant activity is probably attributable to the high content of Vitamin C, carotenoids and d-alpha tocopheryl acetate (a form of Vitamin E) in strawberry and in kiwi. Because of the fairly high content of antioxidants and the frequent use, coffee and tea are important antioxidant sources in many diets.
Several different compounds contribute to coffee’s antioxidant content, e.g., caffeine, volatile aroma compounds and heterocyclic compounds. Many of these are efficiently absorbed and plasma antioxidants increase after coffee intake. In green tea, the major flavonoids present are monomer catechins, epigallocatechin gallate, epigallocatechin, epicatechin gallate and epicatechin. In black tea the polymerized catechins, the aflavin and the arubigen predominate in addition to quercetin and flavonols.
The study covered that many herbs and spices are subject of ongoing scientific investigations related to antioxidant properties and health. Epidemiological evidence exists indicating that there is a correlation between increased dietary intake of antioxidants and a lower incidence of morbidity and mortality. For instance, a population-based case-control study in approximately 500 newly diagnosed gastric adenocarcinoma patients and approximately 1,100 control subjects in Sweden found that the total antioxidant potential of several plant-based dietary components was inversely associated with gastric cancer risk
The largest published study to date which tested the antioxidant activity of food from a nationally representative food evaluated the antioxidant activity in both water-soluble and fat soluble fractions of 1,113 food samples from the USDA’s National Food and Nutrient Analysis Program (NFNAP) using the fluorescence recovery after photobleaching (FRAP) method. This study found that of the top 50 foods with antioxidants, the top five antioxidants were dried spices (ground cloves, dried oregano, ground ginger, ground cinnamon, turmeric powder); however, compared to other categories of food products within this study, herbs and spices displayed the largest range in antioxidant capacity, 0.803-125.549 mmol/100 g.
This study also evaluated the antioxidant activities of selected natural herbal products. Among the herbal products tested, spirulina demonstrated the highest level of antioxidant activity (2.970), followed by red yeast rice (1.067). Graviola (an herbal anti-cancer extract) was found to have no antioxidant activity. The constituents of Thieves’ oil blend, a combination of five essential oils that enhance the immune system, were also examined. Limonene, cinnamon, and clove oils were shown to possess high antioxidant activities, whereas rosemary and eucalyptus oil did not demonstrate any antioxidant activities by themselves. A prior study showed that limonene, cinnamon, and clove oils had all demonstrated high antioxidant effects on the oxygen radical absorbance capacity (ORAC) scale. Therefore, spectrophotometric assay-based examination of the antioxidant activities of these oils provided further evidence that these oil blends have high antioxidant properties.
Furthermore, a highly synergistic effect exists when all five essential oils are blended together into “Thieves” oil. Much remains to be done to understand the mechanisms of action for antioxidants, their impact on various types of tumors, the degree to which antioxidants are absorbed from food, and what effective concentrations are needed in humans to reduce oxidative stress at the tissue or cellular level and how the antioxidant capacity of foods and food components relates to physiologic events in humans.
To facilitate research in this area, there remains a need to collect additional data on the antioxidant capacity of herbs, spices, and their bioactive components from in vivo, in vitro, and clinical studies and establish more detailed research databases to serve as a repository for this data from a variety of disciplines to promote trans-disciplinary research and ultimately aid in fostering new discoveries.
Nutraceutical foods provide medical or health benefits, including prevention and treatment of diseases. Epidemiological studies have shown that consumption of a diet rich in fruit and vegetables is associated with decreased risk of developing certain chronic diseases, including heart disease, muscular degeneration and cancer. Vitamin C can reduce the risk for cardiovascular disease by protecting LDL-cholesterol from oxidation. Additionally, Vitamin C exhibits significant antioxidant function in the lungs, protecting the rest of the body from exogenous sources of free radicals. Furthermore, when Vitamin E is oxidized, Vitamin C regenerates Vitamin E back to its active form.
The richest source of Vitamin C is citrus fruit, such as lemons, limes, oranges and grapefruit. One study conducted on a small population of smokers suggested that Vitamin E may help in lowering the incidence of cardiovascular deaths in these individuals. Beta-carotene is a fat-soluble antioxidant, and a provitamin (precursor of Vitamin A). Dark-green leafy vegetables are a rich source of carotenes.
Over 600 phytochemicals, including flavonoids and phenols, identified to date, are unique to plants. Sources of these phytochemicals are: tea, garlic, oils, fruits, and vegetables. In general, the antioxidant activity of phytochemicals is 10-fold greater than the antioxidant activity of vitamins found in animal diets. The antioxidant activity of various foods and dietary supplements is an important subject for investigation.
Detailed information about the health promoting components of neutraceuticals could lead to a better understanding of the beneficial effects and an increased consumption of these fruits, including their utilization in functional foods and as ingredients in medicine and pharmaceuticals. The potential of antioxidants to lower the risk of chronic diseases by scavenging harmful free radicals in vivo, forces us to evaluate the antioxidant activity of food and nutraceuticals by using simple assays adaptable to the nutrition laboratory which are convenient, accurate, and rapid to perform.