What is an antioxidant? An antioxidant is a molecule that inhibits oxidation, a chemical reaction that can produce free radicals.

– A free radical is an unstable and highly reactive molecule that can damage your body cells and DNA, accelerate aging and triggers some health conditions.

– The source and structure of antioxidants affect their composition.

🔅CLASSIFICATION OF ANTIOXIDANTS

– They are grouped into either synthetic or natural antioxidants.

1). Synthetic antioxidants: These are artificial compounds once added to products such as animal feeds and food for human consumption, cosmetics, pharmaceuticals, and other products prevent or delay oxidation and extend their shelf life . Examples include: butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate, tert-butylhydroquinone (TBHQ), and ethylenediaminetetraacetic acid (EDTA).

2). Natural antioxidants: These are naturally occurring compounds present in plants, animals, and microorganisms.

– Further divided into: endogenous and exogenous.

🔅 Endogenous antioxidants; are produced by the body as part of its defense system against oxidative stress. Most are enzymes like: Superoxide Dismutase (SOD), Catalase (CAT), Glutathione Peroxidase (GPx) & Glutathione Reductase (GR); and non-enzymatic molecules such as Glutathione (GSH), uric acid, bilirubin, melatonin, and coenzyme Q10

🔅 Exogenous antioxidants; are antioxidants utilized from the diet you eat or the supplements you take. I.e., vitamins such as Vitamin C, vitamin E, and beta-carotene, minerals such as selenium, zinc, copper, and manganese, phytochemicals such as flavonoids, phenolic acids, carotenoids, terpenoids, lignans, and glucosinolates, and other compounds such as lipoic acid, carnitine, taurine, and ubiquinol.

🔅THE STRUCTURE OF ANTIOXIDANTS:

– The solubility, stability, bioavailability, and activity of antioxidants are determined by their structural make-up.

– With a basis on their structure, antioxidants can be classified as: *lipophilic (fat-soluble), hydrophilic (water-soluble) and amphiphilic (both water- and fat-soluble).

1). Lipophilic antioxidants:

– These are mainly found in the lipid phase of cells and tissues. They include vitamin E, beta-carotene, coenzyme Q10, lipoic acid, carnitine, taurine, ubiquinol, carotenoids, terpenoids, lignans, and some enzymes.

2). Hydrophilic:

– These are mainly found in the aqueous phase of cells and tissues. They include vitamin C, glutathione, uric acid, bilirubin, melatonin, flavonoids, phenolic acids, glucosinolates, and some enzymes.

3). Amphiphilic antioxidants:

These have both hydrophilic and lipophilic properties. They can interact with both aqueous and lipid phases of cells and tissues. They include vitamin A (retinol), vitamin D (cholecalciferol), vitamin K (phylloquinone), selenium compounds (selenoproteins), zinc compounds (zinc proteins), copper compounds (copper proteins), manganese compounds (manganese proteins), and some phytochemicals.

🔅FUNCTIONS OF ANTIOXIDANTS

• They scavenge free radicals directly or indirectly by donating electrons or hydrogen atoms to them or by chelating metal ions that catalyze free radical formation.

• They regulate the expression or activity of antioxidant enzymes or other genes involved in oxidative stress response.

🔅 ANTIOXIDANT(S)' SOURCES

1). Plant-based foods. E.g., fruits and vegetables, grains and legumes, nuts and seeds, herbs and spices, and olive oil; & (Tea, coffee, cocoa)

2). Animal-based foods. E.g., honey , and bee products. (Meat, poultry , fish , eggs , dairy products).

3.) Some microorganisms E.g., bacteria , fungi , algae , and yeast

🔅Tips to choose foods rich in antioxidants:

• Eat a variety of fruits and vegetables of different colors. The colors of fruits and vegetables are often indicative of their antioxidant content. E.g.,

• Red, purple, and blue fruits and vegetables possess a high amount in anthocyanins;

• Orange and yellow fruits and vegetables have a high amount of carotenoids;

• Green fruits and vegetables, contain a high chlorophyll amount and polyphenols.

• Whole grains as preference to refined grains. Whole grains contain more antioxidants than refined grains because they retain the bran and germ, which are rich in phenolic acids, lignans, and phytic acid.

• Miss not nuts, seeds, and legumes in your diet since they are excellent sources of antioxidants such as vitamin E, selenium, zinc, copper, manganese, phenolic acids, flavonoids, and phytosterols.

• Flavor and season your food using herbs and spices. They contain concentrated phytochemicals such as terpenoids, phenolic acids, flavonoids, and curcuminoids that have potent antioxidant activity.

#NOTE:

– Considerably the quality and balance of your diet matters more than the individual foods or nutrients you consume.

– Don't you forget to thoroughly wash clean your fruits and vegetables before consumption lest you fall ill.

🔅The antioxidant (s)' capacity in food(s)

– This is a measure of their ability to scavenge free radicals and prevent oxidative damage to your body cells and vital genetic material.

• Though not universally acknowledged, some common methods used in measuring the antioxidant capacity of foods are:

1). The Ferric Reducing Ability of Plasma (FRAP). –This deducts the ability of food antioxidants to reduce a ferric (iron) salt to a ferrous (iron) salt The higher the FRAP value, the higher the antioxidant capacity.

2). The Trolox Equivalent Antioxidant Capacity (TEAC): – This method measures the ability of food antioxidants to scavenge an ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) radical cation. The results are expressed as equivalents of trolox, a synthetic water-soluble vitamin E.

3). The DPPH (2,2-diphenyl-1-picrylhydrazyl) assay: –This method measures the ability of food antioxidants to reduce a purple-colored DPPH radical to a yellow-colored DPPH-H molecule. The lower the DPPH value, the higher the antioxidant capacity.

4). The Oxygen Radical Absorbance Capacity (ORAC): – Here the ability of food antioxidants to inhibit the oxidation of a fluorescent molecule by a peroxyl radical is determined. The higher the ORAC value, the higher the antioxidant capacity.

#Important To Note:

– Caution is to be taken when comparing the results of the above methods since they have various advantages and limitations, which include: sensitivity, specificity, reproducibility, cost, and time*

–They also use different types of radicals and reactions, which may not reflect the complex and diverse nature of oxidative stress in the body.

– Also the antioxidant capacity of foods does not necessarily reflect their health effects or bioavailability in the body; hence a hygienic nutrition routine that ensures a balanced diet is highly recommended with an artistic marsh up of fruits and vegetables.

– Some examples of foods with high antioxidant capacity based on these methods are:

• Dark chocolate: 15 mmol FRAP, 28 mmol ORAC, 62 mmol TEAC, 0.5 mmol DPPH per 100 g4.

• Pecans: 10.6 mmol FRAP, 17.9 mmol ORAC, 31.5 mmol TEAC, 0.8 mmol DPPH per 100 g4.

• Blueberries: 9.2 mmol FRAP, 24.5 mmol ORAC, 15.8 mmol TEAC, 0.7 mmol DPPH per 100 g4.

• Strawberries: 5.4 mmol FRAP, 15.8 mmol ORAC, 11.7 mmol TEAC, 0.6 mmol DPPH per 100 g4.

• Kale: 4.7 mmol FRAP, 17.8 mmol ORAC, 7.6 mmol TEAC, 0.5 mmol DPPH per 100 g4.

_ Factors such as digestion, absorption, metabolism, distribution, and excretion Considerably affect how food antioxidants interact with free radicals and other molecules in different tissues and organs.

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