Here is a list of nineteen main anti-oxidant foods.
1. Coffee and Tea:
Because of the fairly high content of anti-oxidants and the frequent use, coffee and tea are important anti-oxidant sources in many diets. Among beverages, coffee has the greatest total anti-oxidant capacity (TAC), regardless of the method of preparation or analysis, followed by citrus juices, which exhibit the highest value among soft beverages. Several compounds contribute to coffee’s anti-oxidant content, e.g., caffeine, polyphenols, volatile aroma compounds and heterocyclic compounds. Many of these are efficiently absorbed, and increase plasma anti-oxidant content after coffee intake.
Tea is particularly rich in polyphenols, including catechins, theaflavins and thearubigins, which are thought to contribute to the health benefits of tea. Tea polyphenols act as anti-oxidants in vitro by scavenging reactive oxygen and nitrogen species and chelating redox-active transition metal ions.
Clinical trials employing putative intermediary indicators of disease, particularly biomarkers of oxidative stress status, suggested that tea polyphenols could play a role in the pathogenesis of cancer and heart disease.
According to Frei and Higdon (2003) they may also function indirectly as anti-oxidants through:
(1) Inhibition of the redox- sensitive transcription factors, nuclear factor-kappaB and activator wprotein-1;
(2) Inhibition of “pro-oxidant” enzymes, such as inducible nitric oxide synthase, lipoxygenases, cyclooxygenases and xanthine oxidase; and
(3) Induction of phase II and anti-oxidant enzymes, such as glutathione S-transferases and superoxide dismutases.
Black tea consumed throughout the world is believed to be not only a popular beverage but also an anti-oxidative agent. In black tea the polymerized catechins theaflavin and thearubigen predominate in addition to quercetin and flavonols. Theaflavins have been also proved to inhibit the activity of pro- oxidative enzymes such as xanthine oxidase or nitric oxide synthase.
Black tea extract reversed the changes in the pro-oxidant and anti-oxidant status of the liver, and protected against apoptotic, cytogenetic and hepato-cellular damage. In green tea, the major flavonoids present are the monomer catechins, epigallocatechin gallate, epigallocatechin, epicatechin gallate and epicatechin.
The beneficial effects of green tea have been attributed to the presence of phenolic compounds that are powerful anti-oxidants and free iron scavengers. In green tea, the major flavonoids present are the monomer catechins. Of all the catechins found in green tea, namely (-)-epicatechin-3-gallate, (-)-epigallocatechin, (-)-epicatechin and (-)-epigallocatechin-3-gallate (EGCG), EGCG is the most abundant and powerful antioxidant.
2. Pomegranate (Punica Granatum):
Most parts of pomegranate (Punica granatum) are known to possess excellent anti-oxidant activity. The methanol extract of pomegranate (Punica granatum) peels showed the highest anti-oxidant activity among all other extracts. Its effect on lipid peroxidation, hydroxyl radical scavenging activity, and human low-density lipoprotein oxidation showed 56, 58 and 93.7 per cent inhibition using the thiobarbituric acid method at 100 ppm.
Alcoholic (ethanolic) extract of pomegranate flowers was found to contain a large amount of polyphenols and exhibit enormous reducing ability, both indicative of potent anti-oxidant ability. The extract showed 81.6 per cent anti-oxidant activity in DPPH model system. Therefore, Singh et al. (2002) recommended that pomegranate could be exploited for possible application for the preservation of food products as well as their use as health supplements and neutraceuticals.
Devatkal et al. (2010) confirmed the anti-oxidant effect of extracts of fruit by-products namely pomegranate rind powder and pomegranate seed powder in goat meat patties and their potential to be used as a natural anti- oxidant preservative in meat products.
Pre-treatment with pomegranate flower extract at a dose regimen of 50-150 mg/ kg body wt. for a week significantly and dose dependently protected against Fe-NTA induced oxidative stress as well as hepatic injury in mice. The extract showed 60 per cent protection against hepatic lipid peroxidation and preserved glutathione levels and activities of anti-oxidant enzymes viz., catalase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase by 36 per cent, 28.5 per cent, 28.7 per cent, 40.2 per cent and 42.5 per cent respectively.
Protection against liver injury resulted by inhibition in the modulation of liver markers viz., aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase bilirubin and albumin in serum. The histo-pathological changes produced by Fe-NTA, such as ballooning degeneration, fatty changes, necrosis were also alleviated by the extract.
Similarly Chidambara Murthy et al. (2002a) showed that pre-treatment of the rats with a methanolic extract of pomegranate peel at 50 mg/kg (in terms of catechin equivalents) followed by CCl4 treatment resulted in preservation of catalase, peroxidase, and SOD to values comparable with control values, whereas lipid peroxidation was brought back by 54 per cent as compared to control.
3. Drumstick (Moringa Oleifera):
Water, methanol, and ethanol extracts of freeze-dried leaves of Moringa oleifera from different agro climatic regions were found to be a potential source of natural anti-oxidants due to their marked anti-oxidant activity. All leaf extracts of each collection showed similar scavenging activities for the stable 1, 1-diphenyl 2- picrylhydrazyl (DPPH) radical. Both methanol and ethanol extracts of Indian origins showed the highest anti-oxidant activities, 65.1 and 66.8 per cent, respectively, in the beta-carotene-linoleic acid system.
According to Luqman et al. (2012) the successive aqueous extract of Moringa oleifera exhibited strong scavenging effect on 2,2-diphenyl-2-picryl hydrazyl (DPPH) free radical, superoxide, nitric oxide radical and inhibition of lipid per oxidation and the effect was comparable with that of the reference anti-oxidants.
The anti-oxidant capacity of ethanolic extract of both fruit and leaf was higher in the in vitro assay compared to aqueous extract which showed higher potential in vivo. They also found the aqueous extract of leaf was able to increase the glutathione and reduce malonaldehyde level in a concentration-dependent manner.
Sreelatha and Padma (2009) observed that both mature and tender leaves extracts of M. oleifera have potent anti-oxidant activity against free radicals, prevent oxidative damage to major biomolecules and afford significant protection against oxidative damage. Verma et al. (2009) concluded from their study that the different fractions of Moringa oleifera leaves possess high phenolic content and potent anti-oxidant properties, which may be mediated through direct trapping of the free radicals and also through metal chelation.
4. Betel Leaves (Piper Betel):
Ethanolic extract of Piper betel effectively prevented gamma-ray induced lipid peroxidation as assessed by thiobarbituric acid reactive substrates, lipid hydroperoxide and conjugated diene. Likewise, it prevented radiation-induced DNA strand breaks in a concentration dependent manner. The radio protective activity of the extract could be attributed to its hydroxyl and superoxide radicals scavenging property along with its lympho-proliferative activity.
The radical scavenging capacity of the extract was primarily due to its constituent phenolic, which were isolated and identified as chevibetol and allyl pyrocatechol. Betel leaf and its constituents-beta-carotene and alpha-tocopherol decreased the number of papillomas per animal exhibiting maximum protection. Except for beta-carotene, eugenol, hydroxyl-chavicol and alpha-tocopherol increased the levels of reduced glutathione in the liver while glutathione S-transferase activity was enhanced by all except eugenol. Of seven sources, Banarasi betel leaves showed the maximum amounts of beta-carotene and alpha-tocopherol.
5. Black Pepper (Piper Nigrum):
Simultaneous supplementation with black pepper or piperine to rats fed a high- fat diet significantly lowered thio-barbituric acid reactive substances and conjugated diene levels and maintained superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase and reduced glutathione levels in the liver, heart, kidney, intestine and aorta as compared to those of un-supplemented control rats. Similarly, piperine supplementation to high fat diet and anti-thyroid drug induced hyper-lipidemic rats markedly protected erythrocytes from oxidative stress by improving the anti-oxidant status.
6. Grapes and Grape Seed (Vitis Vinifera):
The ethyl acetate, methanol, and water extracts of grapes pomace showed 76, 87.1, and 21.7 per cent anti-oxidant activities at 100 ppm, respectively, using the 1, 1- diphenyl-2-picrylhydrazyl model system. Clinical studies revealed that lipid peroxidation could be restored to values comparable with the control.
Histopathological studies of the liver of different groups also support the protective effects exhibited by the methanol extract of grape pomace by restoring the normal hepatic architecture. In humans, Gollücke (2010) demonstrated effects of grape polyphenols as maintenance of endothelial function, increase in anti-oxidant capacity and protection against LDL oxidation.
Pretreatment of the rats with the methanolic extract of grape pomace at 50 mg/ kg (in terms of catechin equivalents) followed by CCl(4) treatment causes restoration of catalase, SOD, and peroxidase by 43.6, 73.2, and 54 per cent, respectively, as compared with control, whereas lipid peroxidation was restored to values comparable with the control. Histo-pathological studies of the liver of different groups also support the protective effects exhibited by the methanol extract of grape pomace by restoring the normal hepatic architecture.
Pastrana-Bonilla et al (2003) found the anti-oxidant capacity/g of fresh weight for pulps, skins, seeds, and leaves to be 2.4, 12.8, 281.3, and 236.1 microM. Trolox equivalent respectively. Gallic acid, (+)-catechin, and epicatechin were the major phenolics in seeds and skin. Yilmaz and Toledo (2004) reported that dimeric, trimeric, oligomeric, or polymeric procyanidins accounted for most of the superior antioxidant capacity of grape seeds.
The antioxidant and hepato-protective roles of the grape seed supplementation on ethanol-induced oxidative stress have been indicated by Dogan and Celik (2012) and suggested that grape seed could be as important as diet-derived anti-oxidant in preventing oxidative damage in the tissues by reducing the lipid oxidation or inhibiting the production of ethanol-induced free radicals in rats.
Dulundu et al. (2007) found grape seed extract to protect the liver from oxidative damage following bile duct ligation in rats. This effect possibly involves the inhibition of neutrophil infiltration and lipid peroxidation, thus, restoring the oxidant and anti-oxidant status in the tissue.
On comparing the seeds, skin, and pulp of eight cultivars of Florida-grown muscadine grapes, Sandhu and Gu (2010) found the total phenolic content and antioxidant capacity, based on fresh weight, were highest in seeds followed by skin and pulp. On an average, 87.1, 11.3, and 1.6 per cent of phenolic compounds were present in seeds, skin, and pulp, respectively. A total of 88 phenolic compounds of diverse structures were tentatively identified in muscadines, which included 17 in the pulp, 28 in the skin, and 43 in the seeds.
Resveratrol (3, 4′, 5-trihydroxystilbene) is found in grapes, berries and peanuts. It is also present in wines, especially red wines. During the last years, it has been the focus of numerous in vitro and in vivo studies investigating its biological attributes, which include mainly anti-oxidant and anti-inflammatory activities, anti-platelet aggregation effect, anti-atherogenic property, oestrogen-like growth-promoting effect, growth-inhibiting activity, immuno-modulation and chemo-prevention. Resveratrol can exhibit pro-oxidant properties, leading to oxidative breakage of cellular DNA in the presence of transition metal ions such as copper.
7. Date Palm (Phoenix Dactylifera):
The anti-oxidant and anti-mutagenic activity in date fruit is quite potent and implicates the presence of compounds with potent free-radical-scavenging activity. Concentrations of 1.5 and 4.0 mg/mL of date fruit extract completely inhibited superoxide and hydroxyl radicals, respectively. Aqueous date extract was also found to inhibit significantly the lipid peroxidation and protein oxidation in a dose- dependent manner. Ethyl acetate extracts from two varieties of date palm flesh and pit Deglet nour and pit Alig showed an important free radical scavenging activity towards 1-1-diphenyl-2-picrylhydrazyl (DPPH) free radical.
Amira et al. (2012) analyzed four cultivars (Gondi, Gasbi, Khalt Dhahbi, and Rtob Ahmar) of Tunisian date palm (Phoenix dactylifera L.) fruits at 3 maturation stages or their antioxidant activities. All the samples showed the highest total phenolic, total flavonoid and condensed tannins. The major phenolic compounds were caffeic, ferulic, protocatechuic, and catechin for the majority of cultivars.
Thus, Amira et al. (2012) confirmed that common date fruits are rich in natural anti-oxidants as a source of bioactive health promoting phytochemicals. Pujari et al. (2011) found 15 days pre-treatment with methanolic extract of dates (100,300 mg/kg), significantly attenuated the depletion in superoxide dismutase, catalase, glutathione, glutathione reductase and the lipid peroxidation and the severe neuronal damage in the brain induced by the cerebral ischemia.
Hence, the authors suggested the possible use of dates against bilateral common carotid artery occlusion induced oxidative stress and neuronal damage. Saafi-Ben Salah et al. (2012) also from their study on rats indicated that dates may be useful in vivo in preventing oxidative stress induced nephro-toxicity.
8. Berries:
With their high content of phytochemicals such as flavonoids, tannins, stilbenoids, phenolic acids and lignans, berries and berry products are potentially excellent anti-oxidant sources. Among fruits, the highest anti-oxidant activities were found in berries (i.e., blackberry, redcurrant and raspberry) regardless of the assay used.
Phytochemicals have been demonstrated to be powerful inhibitors of lipid peroxidation when compared to other classic antioxidants. Berry extracts have proven to be effective in preventing the oxidative damage under different pathological conditions and the protective effect of polyphenols against oxidative damage seems to be via glutathione system.
9. Blue Berries:
Among the different species, there is a group classified as blueberries that have a dark color due to anthocyanins and polyphenols as principal pigments with antioxidant activities.
Previously, it has been demonstrated that blueberry enriched diet reduced the adverse effects of oxidative stress in rat neuron cell lines and brain tissues. Fuentealba et al (2011) reported that blueberry extract protects neuronal tissue from amyloid-β peptide toxicity mainly through its anti-aggregation property, and its antioxidant properties while mitochondrial membrane potential capacities are secondary mechanisms important in chronic stages.
Such extract has shown to cross the blood-brain barrier thus influencing brain homeostasis. Zepeda etal (2012) demonstrated that blueberry extract significantly reduced the harmful effects of oxidative stress caused by hypobaric hypoxia in rat testis by affecting glutathione reductase and superoxide dismutase activities.
10. Blackberry (Rubus spp.):
Some bioactive compounds present in blackberry have the ability to act as natural anti-oxidants and minimize effects of reactive oxygen species. The blackberry nectar was found to reduce the serum triglyceride levels, total cholesterol and LDL- cholesterol in hyper-cholesterolemic hamsters, without influencing the HDL and blood glucose concentrations. A decrease in the initiation of lipid peroxidation reactions in the blood, brain and small intestine was also observed.
Aqueous methanol extract of Brassica vegetables, including York cabbage, broccoli, Brussels sprouts and white cabbage showed high flavonoid contents in the order of 21.7, 17.5, 15.4 and 8.75 mg QE/g of extract. With regard to total phenolic content, York cabbage extract had the highest total phenolic content, (33.5), followed by 23.6, 20.4 and 18.4 mg GAE/g of dried weight (dw) of the extracts for broccoli, Brussels sprouts and white cabbage, respectively. All the extracts studied showed a rapid and concentration dependent anti-oxidant capacity in diverse anti-oxidant systems.
Among vegetables, spinach had the highest anti-oxidant capacity in the Trolox equivalence anti-oxidant capacity (TEAC) and ferric ion reducing anti-oxidant power (FRAP) assays followed by peppers, whereas asparagus had the greatest anti-oxidant capacity in the total radical trapping anti-oxidant parameter (TRAP) assay. The antioxidant activity of the methanol extracts of carrot (Daucus carota) and beetroot (Beta vulgaris) pulp waste determined by the DPPH method exhibited 40 per cent and 78 per cent activity respectively.
11. Swallow Root (Decalepis Hamiltonii):
One of the major constituents of the root vegetable Decalepis hamiltonii which is responsible for its anti-oxidant activity, is 2-hydroxy-4-methoxy benzaldehyde (2H4MB). Hence Murthy et al. (2006) suggested that the extract of D. hamiltonii can be utilized for the production of anti-oxidant rich fractions required for various health benefits.
Later Srikanta et al. (2011) reported that insignificant anti-oxidant attribute of HMBA revealed the anti-H.pylori activity via mechanisms other than anti-oxidative routes.
12. Vanilla Beans (V. Planifolia):
The word vanilla (a flavoring agent) derived from the diminutive of the Spanish word vaina (vaina itself meaning sheath or pod), simply translates as little pod. The major compounds, viz, vanillic acid, 4-hydroxybenzyl alcohol, 4-hydroxy-3- methoxybenzyl alcohol, 4-hydroxybenzaldehyde and vanillin, in vanilla extract at a concentration of 200 ppm, showed 26 per cent and 43 per cent of anti-oxidant activity by beta-carotene-linoleate and DPPH methods, respectively.
Interestingly, 4-hydroxy- 3-methoxybenzyl alcohol and 4-hydroxybenzyl alcohol exhibited anti-oxidant activity of 65 per cent and 45 per cent by beta-carotene-linoleate method and 90 per cent and 50 per cent by DPPH methods, respectively. In contrast, pure vanillin exhibited much lower anti-oxidant activity. Thus the authors revealed the potential use of vanilla extract components as anti-oxidants for food preservation and in health supplements as nutraceuticals.
13. Wine:
Caffeic acid (3, 4-dihydroxycinnamic acid) is among the major hydroxy 1-cinnamic acids present in wine. At the concentrations of 10 and 30 µg/ ml, caffeic acid showed 68.2 and 75.8 per cent inhibition on lipid peroxidation of linoleic acid emulsion, respectively. In addition, caffeic acid is an effective ABTS (+) scavenging, DPPH scavenging, superoxide anion radical scavenging, total reducing power and metal chelating on ferrous ions activities.
14. Green Ginger (Artemisia Absinthium):
Bora and Sharma (2011) found in their in vivo studies, oral administration of methanol extract of Artemisia absinthium (100 or 200mg/kg) inhibited cerebral I/R- induced oxidative stress by decreasing the thiobarbituric acid reactive substances (TBARS) and restoring levels of superoxide dismutase (SOD) activity and glutathione (GSH).
15. Jamun (Eugenia Jambolana):
Eugenia jambolana seed kernel decreased oxidative stress in diabetic rats, which in turn may be due to its hypoglyceamic property. The anti-oxidant effect of Eugenia jambolana seed kernel wag also compared with glibenclamide, a standard hypoglycemic drug. Diabetic rats treated with seed kernel extract restored almost normal architecture of liver and kidney and were confirmed by histopathological examination.
16. Honey Mushroom (Basidiomycete Armillaria Mellea):
Fermented polysaccharides of edible honey mushrooms in submerged cultures are potential antioxidant source. Lung and Chang (2011) confirmed that the extracts with good anti-oxidant properties from fermenting products by A. melleaare are potential good substitutes for synthetic antioxidants and can be applied to anti-oxidant-related functional food and pharmaceutical industries.
17. Watercress (Nasturtium Officinale):
Watercress is a fast-growing, aquatic or semi-aquatic, perennial plant native to Europe and Asia, and one of the oldest known leaf vegetables consumed by humans. It has been used as a home remedy by the people of south eastern region of Iran as a medicinal plant. This therapeutic application has been attributed to its anti-oxidant capacity as the extract has notable scavenging activity against DPPH radicals as well as potent reducing power in FRAP assay.
Treatment of hyper-cholesterolaemic rats with N. officinale extract significantly increased the GSH level along with enhanced catalase and superoxide dismutase activities in liver tissues. Furthermore, N. officinale extract significantly decreased hepatic malondialdehyde level as well as glutathione peroxidase and glutathione reductase activities in plant-treated rats. Based on the data, Yazdanparast et al. (2008) confirmed that N. officinale has a high hypo-lipidaemic activity and this may be attributed to its anti-oxidative potential.
Administration of the ethanol extract to rats decreased lipid peroxidation in liver, brain and kidney. Thus Ozen (2009) concluded that N. officinale extracts show relevant anti-oxidant activity by means of reducing cellular lipid peroxidation and increasing anti-oxidant activity, reducing power, free radical and superoxide anion radical scavenging activities.
18. Brahmi (Bacopa Monnieri):
In rats, bacosides A from Bacopa monniera enhanced anti-oxidant defenses, increasing superoxide dismutase, catalase and glutathione peroxidase activity. The sulfhydryl and polyphenol components of Bacopa monnieri extract have also been shown to impact the oxidative stress cascade by scavenging reactive oxygen species, inhibiting lipoxygenase activity and reducing divalent metals. This mechanism of action may explain the effect of Bacopa monniera extract in reducing beta amyloid deposits in a mouse model of Alzheimer’s disease.
19. Amrita Bindu (A Salt-Spice-Herbal Mixture):
Amrita Bindu is a salt-spice-herbal mixture containing pepper and ginger along with natural or artificial salt substitute. Shanmugasundaram et al (1994) observed that Amrita Bindu supplementation prevented N-methyl-N’-nitro-N- nitrosoguanidine- induced depletion of the anti-oxidant enzymes and the scavenger anti-oxidants glutathione and vitamins A, C and E. Amrita Bindu provides protection against free radical and reactive oxygen species induced tissue lipid peroxidation and the resultant tissue degeneration.
Similarly, Amrita Bindu supplementation for 3 months to asthmatic children resulted in stoppage of all anti-asthmatic medications and the children were free from attacks of asthma. Co-administration of Amrita Bindu along with 100µg of aflatoxin B1 (AFB1) was found to protect lipids and protein against the AFB1 induced oxidative damage in kidney, liver and brain tissues.
The anti-oxidant supplement, Amrita Bindu, has a potential role also in ameliorating the aflatoxin B- induced DNA damage thus suggesting its applicability in preventing the vital macromolecule DNA. Rats fed diets with Amrita Bindu pretreatment showed significantly lower levels of free radicals, lipid peroxidation and protein carbonyls along with significantly higher levels of anti-oxidants on phenyl hydrazine administration as compared to rats without Amrita Bindu pre-treatment.