why do we need vitamin a in our diet
Why do we need vitamin A? A main compound of vitamin A is retinol, which is primarily known for its role in promoting good eye health. This compound helps with low-light and with colour vision by protecting the retina and corneal surface. In a similar way to how vitamin A protects the eyes, it is also seen to promote healthy skin cells. It encourages immature skin cells to turn to mature cells. It also seems to reduce the size of sebaceous glands and release of sebum, a source of nutrients for bacteria. These actions combined seem to reduce tendency to develop acne, as well as help to develop effective treatments. Vitamin A is also thought to be important for immune function. It improves the bodys immune defences and helps the body to fight off infections more quickly. All the vitamin A that we need should be available through our diet. Typically, an adult man requires 900-3000mcg of vitamin A each day, and the average woman needs 700-3000mcg each day. There are two types of this vitamin: preformed vitamin A and provitamin A. Preformed vitamin A is one of the most active forms of the vitamin and is found in meat, poultry, fish and dairy products. Alpha-carotene, beta-carotene and beta-cryptoxanthin are plant pigments found in fruit and vegetables that the body converts into provitamin A. Diet is our only natural source of vitamin A, and certain foods are known to be particularly good sources of this vitamin. Preformed vitamins A is highest in liver and fish oils, and provitamin A is found in leafy green vegetables and yellow and orange vegetables. Typical values of vitamin A in food sources: Vitamin A deficiency most commonly affects children, particularly in developing countries. It is one of the most common vitamin deficiencies in the UK diet. Vitamin A deficiency can be primary of secondary. Primary vitamin A deficiency occurs when not enough vitamin A is being consumed in the diet. Secondary deficiency occurs when the vitamin A being consumed is not being properly absorbed.
This can be the result of impaired bile production, or long-term exposure to cigarette smoke or alcohol, for example. are usually the first indication of vitamin A deficiency. Impaired vision and reduced night vision can occur, though this can initially be reversed by restoring adequate levels of vitamin A into the diet. Prolonged deficiency can lead to permanent problems with vision and eventually total blindness. Other problems include reduced immunity, causing increased susceptibility to urinary tract infections, ear infections and weakening of tooth enamel. Just as too little vitamin A can cause problems, so can absorbing too much. Initially symptoms can include dizziness and nausea, although this can usually be reversed once the level of vitamin A returns to normal. The body stores any vitamin A that it does not use immediately. It is usually stored in the liver, and if the levels accumulate, can cause poisoning and damage to the liver. Prolonged toxic levels can cause irreversible damage. Too much vitamin A is found to be a risk for pregnant women, as it can damage the unborn foetus. Pregnant woman should seek advice before taking vitamin A supplements or consuming liver or liver products.
Dear Reader, Vitamin A is an essential, fat-soluble vitamin that has many diverse benefits for humans. It promotes eye health and helps you see in the dark; aids in the differentiation of cells of the skin (lining the outside of the body) and mucous membranes (linings inside of the body); helps the body fight off infection and support the immune system; and, supports growth and remodeling of bone. Sounds pretty vital, right? But before you stock up on supplements or make your way to the grocery to get your vitamin A fix, itБs also good to be aware of how best to get it and how much is safe to take to get the most out of this essential vitamin. Vitamin A can be found both in the flora and the fauna of the world Б and thatБs good, because itБs recommended that folks get their fill of it through their diet.
Because vitamin A is fat-soluble, cooking (but not overcooking) and making sure to get some fat within the same meal will allow your body to absorb the vitamin properly. Carotenoids, the plant-based form of vitamin A, are found in dark leafy greens and in yellow and orange fruits and veggies (e. g. , sweet potatoes, carrots, winter squash, mangos, and peaches). Carotenoids (including beta-carotene) are referred to as the БprecursorБ type of vitamin A, which means that once itБs in the body, it is then transformed into vitamin A. High intake of dietary beta-carotene has been linked to lower risk of age-related macular degeneration and lower risk of certain cancers, including cancers of the breast, colon, esophagus, and cervix. Retinol, on the other hand, is the active or БpreformedБ type of vitamin A, which comes from animal sources like beef and chicken liver, eggs, dairy products, and fish liver oil. Medications that are related to this type of vitamin A (called retinoids) are used to treat acne and other skin conditions such as psoriasis. Though everyone needs vitamin A, the specific need for each person may vary. The Recommended Dietary Allowance (RDA) for adult men (ages 19 and older) is 900 micrograms (mcg) per day and for adult women (ages 19 and older), it is 700 mcg per day. Pregnant and breastfeeding women 19 years old and older have different daily dietary intakes, which are 770 mcg and 1,200 mcg respectively. In either extreme of too little or too much vitamin A, there is potential for risks to your health. Vitamin A deficiency (when a person doesnБt have enough of the vitamin) is characterized by dry eyes, decreased night vision (which can eventually result in blindness), diarrhea, and skin issues. Those who are deficient are also more susceptible to infection. Folks with this deficiency are prime candidates for vitamin A supplements. On the flip side, excessive intake of vitamin A from food may result in a yellowing of the skin, but isn't usually harmful.
It is noted, however, that taking vitamin A supplements or medicines can contribute to taking too much. Symptoms of excess intake depend upon whether or not high vitamin A intake was over a long period of time (chronic) or a single excessive dose at one point in time (acute) and may include dry skin, rash, nausea, vomiting, fatigue, weakness, headaches, and hair loss. Large doses of preformed vitamin A (particularly in retinol supplements) can interfere with the function of vitamin D in the body, and increase the risk for bone fractures and birth defects. Beta-carotene supplements seem to carry less risk, but some studies have found that large doses as a supplement have been linked to higher risk of lung cancer among smokers. Both types of supplements have been found to increase triglycerides (fats in the blood) as well. Even when vitamin A supplements are taken within a safe, recommended dose, it still may not be appropriate for everyone. Diabetics and those with liver disease need to take vitamin A supplements under the supervision of a health care provider. Smokers and heavy drinkers are advised not to take beta-carotene supplements. Women who are pregnant or hope to be soon are advised not to have additional vitamin A (there is some in prenatal vitamins already) and to avoid synthetic forms of vitamin A. Children are at a greater risk for experiencing side effects from too much vitamin A at much lower levels, so itБs good to monitor their use as well. Additionally, there are a number of recognized drug interactions that may hinder or amplify the effects of the medication when used in conjunction with vitamin A. Other medications may block the absorption of vitamin A. In any case, itБs always a good idea to talk to a health care provider before taking vitamin A in supplement form. Hope this helps supplement your vitamin knowledge! Alice!
- Views: 135
why do we need minerals and vitamins
why do we need vitamins and minerals in our bodies
why is vitamin c good for your skin
why do you need regular sources of water soluble vitamins
why do we need food to live