Why are antioxidants important?
The job of antioxidants are to combat the effects of oxidative stress â something that we are all exposed to in varying degrees (if you live in the city or are exposed to a large dose of stress this would make you a prime target for the oxidant nasties). Oxidative stress is basically when your body is exposed to environmental stress, which can be natural (i.e. aging) or unnatural (i.e. pollution). As you are exposed to more and more environmental stress, your body cannot perform the repair work needed at a fast enough pace. Your cells cannot grow and reproduce at the same rate as the environmental stress is dealing its damage, and this imbalance is referred to as oxidative stress. Oxidative stress is a serious issue, and can lead to arthritis, cancer, cardiovascular disease, cataracts, diabetes and infection.
Why vitamin A?
Vitamin A, known as the anti-infection vitamin, helps to restore this imbalance and is active in ensuring healthy teeth, skeletal and soft tissue, mucous membranes and skin â both inside and out. Vitamin A is essential for the maintenance of epithelial tissue, which is tissue that lines the skin walls of your outer skin as well as "internal skin" covering your lungs, intestines, uterus, stomach, etc. Vitamin A also boosts your immune system and protects against infections â and is essential for eye health. Every time you look at something, a chemical process begins that enables your brain to process the light gathered by the retina and turn it into a picture, which you "see". A vitamin A compound is required for this process to start. This is why a deficiency in vitamin A can cause problems with vision, predominantly at night.
Are you lacking in vitamin A?
The main symptoms of vitamin A deficiency are mouth ulcers, poor night vision, acne, frequent colds and infections, dry, flaky skin, dandruff, thrush, cystitis and diarrhea. If you find that you are experiencing any of these symptoms, it may be time to check your vitamin A intake.
Sources of vitamin A
Vitamin A is found in two main forms â retinol and natural betacarotene.
Betacarotene, which is obtained from plants, can be seen as a natural resource that is used in the liver to "manufacture" vitamin A. This is the safest form as your body will manufacture what it needs. It is only dangerous if taken on its own by smokers, as it may increase the risk of cancer for this group â but the worst that could happen to a non-smoker is a reversible yellowing of the skin (which would require very high doses). The best sources of this type of vitamin A are carrots, watercress, cabbage, squash, sweet potato, melon, pumpkin, mango, tomatoes and broccoli.
Retinol is the pre-manufactured form that is obtained from plant eating animals and is not as safe as it can lead to overdoses, resulting in adverse side effects and toxicity (also, these sources contain fat and cholesterol â which is not present in plant derived sources). Side effects depend on the dosage taken and can include nausea, headaches, and blurred vision at lower doses (over 20 000IU) and liver damage, menstrual problems, itchiness, skin dryness, vomiting, hair loss, bone and muscle pain and anaemia at higher doses (roughly 100 000IU and more). These dosage quantities are explained in the next section. Retinol can be found in beef, calf, chicken liver, eggs and fish liver oils.
Dosage and Supplementation
In order to get your daily dose of vitamin A, it is best to consume a healthy diet that includes foods high in betacarotene. If you feel that you may be deficient in vitamin A, it is best to consult a doctor before consuming any vitamin A supplements â if you are indeed in need of such supplements, knowing how vitamin A quantities are measured will help you to choose the best supplement for your individual needs.
Vitamin A is measured in Retinol Equivalents (RE), which can be converted to micrograms (mcg) and International Units (IU). These measurements relate to each other in the following way:
Plant sourced products: 1RE is equal to 6mcg of betacarotenec, or 10IU.
Animal sourced products: 1RE is equal to 1mcg of retinol, or 3,33IU.
Up to 2500mcg (8250IU) retinol or 15000mcg (25000IU) betacarotene is a good amount of vitamin A to aim for on a daily basis for most healthy adults. Women who are trying to conceive or are pregnant should ensure that they do not take more than this amount (from dietary sources) and should avoid extra supplementation unless under the supervision of a medical practitioner, as this has been associated with foetal malformations.
As with any healthy diet, rather than trying to micro manage your daily intake of foods (and vitamins and minerals), it is best to include a variety of healthy foods that include the nutrients that you require, and to eat these as you feel your body needs them. As an example, incorporating a cup of carrots and a cup of sweet potato into your day should be sufficient for you vitamin A needs. Consuming daily smoothies containing carrots, broccoli and various fruit (to improve the taste) is a great and easy way to give yourself a vitamin A (along other vitamins and minerals) boost.
If you do choose to take a Vitamin A supplement -these are best taken with food as well as with other antioxidants (Vitamin C and vitamin E) and Zinc. Therefore, it is best to do so with a good multivitamin or antioxidant formula. Whole food supplements (such as barley grass and spirulina) are highly recommended as they contain the perfect balance of natural vitamins and minerals (including high amounts of betacarotene) which your body will be able to use as intended.