Among the countless supplements being advertised on TV, radio, and print media as anti
oxidants, only vitamins have been classified as potent or strong antioxidants with an established
dose-strength basis. This refers to their corresponding minimum daily requirement (MDR) and recommended dietary allowance (RDA).
The minimum daily requirement of a nutrient is enough to prevent the appearance of signs and symptoms of a deficiency, while RDA refers to the amount of a nutrient needed for maximum or optimum metabolism, for the entire body to function at its best.
The enemy of antioxidants are the ROS or reactive oxygen species and the so-called free radicals—species of oxygen with an odd number of electrons, so they are always looking for “victims” that can combine with their unpaired electrons, which the human body has a lot of.
Vitamin E is first in the list of antioxidants. Known as a fat-soluble vitamin—vitamins that require bile for maximum absorption—it belongs to the tocopherol family, the most potent and useful of which for humans is the alpha tocopherol. Vitamin E comprises hydrogens and oxygens which can act as scavenger-attackers of free radicals, eventually neutralizing and converting them into less toxic or non-toxic substances. They also act as willing victims that combine with free radicals, if necessary, to save bodily organs and spare them from the destructive effects of the oxidizing agents.
Vitamin E, however, has been in the forefront of debate among nutritionists and doctors, particularly cardiologists. Time was when the daily dose for vitamin E was a whopping 1000 I.U. or international units. The last 10 years, however, saw the American Heart Association (AHA) coming up with disturbing data, based on the meta-analysis of various research studies and clinical trials, that showed a positive correlation between vitamin E doses and an increase in heart problems—meaning very high doses of vitamin E resulted in an increased incidence of heart ailments, not to mention heart attacks.
Nowadays, daily vitamin E doses range from 160-400 I.U. This dose, according to experts, is the optimum dose that provides all the beneficial effects of vitamin E, including its antioxidant capabilities, especially if selenium is added to it.
Vitamin A is also recognized and accepted as an antioxidant. Known chemically as retinol, vitamin A is consumed two ways: as preformed vitamin A that we get when we eat chicken liver, pork liver, or cod liver oil, or taken in as provitamin A or carotenoids, substances which require further degradation and conversion inside the human body into active, ready-to-function vitamin A.
We all know about beta carotene sourced from yellow vegetables and fruits. It provides us with the color pigments that make us appreciate the greens and reds of Christmas or the heavenly blues of the sky or to distinguish the body from its shadow at night.
The structure of vitamin A, likewise, offers a lot of “docking sites”of hydrogen and oxygen, with which free radicals or ROS can combine. The daily recommended dose for vitamin A could range from 1500-4500 I.U., depending on the special needs of the person. For example, pregnant women need more vitamin A than single ladies.
To complete the triumvirate of vitamin antioxidants is vitamin C. Also known as ascorbic acid, vitamin C, strictly speaking, is not an antioxidant. However, since it’s a very strong reducing agent, vitamin C defends and protects both E and A vitamins from the destructive effects of ROS or free radicals.
Vitamin C’s MDR is a mere 75 mg but its RDA is 500 mg per day to prevent the development of its deficiency called scurvy. In terms of source, on a weight-per-weight basis, guava is the richest
source, with one medium-sized (about the size of a golf ball) guava having the same amount of vitamin C as 20 pieces of kalamansi. Bell pepper and tomatoes are also abundant providers of vitamin C.
Hopefully, our readers will not be easily swayed by the fantastic claims made by advertisers and (paid) endorsers about the purported health benefits—including anti-ageing, antioxidant, anti-cancer effects—of the herbal concoctions or fruit juices or vegetable shakes they are promoting.
Admittedly, some naturally occurring nutrients from fruits, vegetables, and herbs have medicinal value, but their actual dose vis-a-vis their claimed therapeutic effects may not have been accurately established, much less proven in scientifically controlled clinical studies. So, it’s best to keep a “buyer beware” attitude, conduct research on trusted or reputable sites, and always consult your doctor before buying or taking any type of health supplement.
