- June 12, 2017
- Breda Gavin Smith
- Nourish Notes
‘’Mommy, Mommy’’, the little girl screams in the middle of the night. A bad dream and afraid of the dark she calls to her mommy who switches on a light. Calm is restored. But what if the girl wakes and cannot see? For many children in the developing word this is a reality. Vitamin A deficiency (VAD) is the leading cause of preventable blindness in children and increases the risk of disease and death from severe infections. Today Vitamin A deficiency remains a public health problem in more than half of all countries, especially in Africa and South-East Asia, with young children and pregnant women in low-income countries at greatest risk.
What Vitamin A does
Vitamin A plays a central role in our vision, skin, genes, growth, and immune system. It is especially important during the early stages of pregnancy in supporting the developing embryo. Infections and fevers increase the requirement for vitamin A.
Three different forms of vitamin A are active in the body: retinol, retinal, and retinoic acid. These are known as retinoids. The cells of the body can convert retinol and retinal to the other active forms of vitamin A as needed.
Each form of vitamin A performs specific tasks. Retinol supports reproduction and is the major transport form of the vitamin. Retinal is active in vision and is an intermediate in the conversion of retinol to retinoic acid. Retinoic acid acts like a hormone, regulating cell differentiation, growth, and embryonic development. Foods derived from animals provide retinol in a form that is easily digested and absorbed.
Foods derived from plants provide carotenoids, some of which have vitamin A activity. The body can convert carotenoids like β-carotene, α-carotene and β-cryptoxanthin into vitamin A. The conversion rates from dietary carotene sources to vitamin A are 12:1 for β-carotene and 24: 1 for β-cryptoxanthin.
Sources of Vitamin A
Retinol: Liver, Egg Yolk, Butter, Whole Milk, and Cheese
Carotenoids: Orange flesh fruits (i.e. Sweet Potatoes, Melon, Mangos), Green leafy vegetables (spinach, broccoli), Carrots, Pumpkins, Red pam oil
Bioavailability of vitamin A
The degree to which it is absorbed in our bodies, bioavailability, of vitamin A derived from animal sources is high – about 70–90% of the vitamin A ingested is absorbed by the body. Carotenoids from plant sources are absorbed at much lower rates – between 9% and 22% – and the proportion absorbed decreases as more carotenoids are consumed.
Dietary fat enhances the absorption of vitamin A. Absorption of β-carotene is influenced by the food matrix. β-carotene from supplements is more readily absorbed than β-carotene from foods, while cooking carrots and spinach enhances the absorption of β-carotene. Diarrhea or parasite infections of the gut are associated with vitamin A malabsorption.
Risks related to inadequate or excess intake of vitamin A
About 90% of vitamin A is stored in the liver. Vegetarians can meet their vitamin A requirements with sufficient intakes of deeply colored fruits and vegetables, with fortified foods, or both. Vitamin A deficiency is a major problem when diets consist of starchy staples, which are not good sources of retinol or β-carotene, and when the consumption of deeply colored fruits and vegetables, animal-source foods, or fortified foods is low. Vitamin A plays a role in mobilizing iron from liver stores, so vitamin A deficiency may also compromise iron status.
Excessive intakes of pre-formed vitamin A can result in high levels of the vitamin in the liver – a condition known as hypervitaminosis A. No such risk has been observed with high β-carotene intakes.
Additional information on vitamins and micronutrient deficiencies is available though our partner, Vitamin Angels.
Here are some recipes to easily incorporate Vitamin-A rich foods in your diet!
Sweet Potato Fries
95g of sweet potato
¼ tsp cayenne pepper (substitute with whatever spices you have available locally such as chill flakes or chill powder)
½ tsp rapeseed oil
Heat oven to 200C/180C fan/ gas 6. Put the sweet potato fries on a baking tray and mix with the rapeseed oil and cayenne pepper. Bake in the oven for 20 mins
Put the spinach in a large colander and pour over a kettleful of boiling water. Drain well and, when cooled a little, squeeze dry, trying not to mush up the spinach too much.
1. Put a large non-stick frying pan on a low heat. Cook the onion slowly in the oil and butter until soft but not brown – this should take about 15 mins. Add the potatoes, cover the pan, and cook for a further 15-20 mins, stirring occasionally to make sure they fry evenly
2. When the potatoes are soft and the onion is shiny, crush 2 garlic cloves and stir together with the spinach followed by the beaten eggs
3. Put the lid back on the pan and leave the tortilla to cook gently. After 20 mins, the edges and base should be golden, the top set but the middle still a little wobbly. To turn it over, slide it onto a plate and put another plate on top, turn the whole thing over and slide it back into the pan to finish cooking. Once cooked, transfer to a plate and serve the tortilla warm or cold.