Of course we all know that carrots are one of the major source of vitamin A. Carrot’s main nutritive that, beta-carotene (responsible for this root vegetable’s characteristic orange colour) is a precursor to vitamin A and helps the eyes to adjust in dim conditions.
Vitamin A helps to support your dog’s vision. It can’t heal if the problem already exists, but it can support and not to worsen the condition.
Vitamin A also stimulates the production and activity of white blood cells, takes part in remodelling bone, helps maintain healthy endothelial cells (those lining the body’s inferior surface), and regulates cell growth and division such as needed for reproduction.
There are two main forms of vitamin A: Performed Vitamin A (retinol, retinol esters), and Provitamin A Carotenoids (such as: alpha-carotene and beta-carotene that are converted to retinol).
- Performed Vitamin A: comes from animal products, fortified foods, and vitamin supplements.
- Provitamin A Carotenoids: are found naturally in plant foods. There are other types of carotenoids found in food that are not converted to Vitamin A but have healthy-promoting properties (these include lycopene, lutein, and zeaxanthin).
Recommended Amounts
RDA (The Recommended Dietary Allowance): for adults 900 mcg for men (=3’000 IU) and 700 mcg for women (=2’333 IU).
UL (The Tolerable Upper Intake Level): in a maximum daily intake unlikely to cause harmful effects on health. The UL for vitamin A from retinol is 3’000 mcg of preformed vitamin A.
Vitamin A and Health
The evidence suggests that eating a variety of foods rich in vitamin A, especially fruits and vegetables, is protective from certain diseases, through the health benefits of vitamin A supplements is less clear.
Food Sources
Many fruits and vegetables and some supplements contain beta-carotene, lycopene, lutein, or zeaxanthin.
- Leafy green vegetables (kale, spinach, broccoli), orange and yellow vegetables (carrots, sweet potatoes, pumpkin and other winter squash, summer squash)
- Tomatoes
- Red bell pepper
- Cantaloupe, mango
- Beef liver
- Fish oils
- Milk
- Eggs
- Fortified foods
Signs of Deficiency and Toxicity
Deficiency
Vitamin A deficiency is rare but may occurs. Conditions that interfere with normal digestion can lead to vitamin A malabsorption such as celiac disease, Crohn’s disease, cirrhosis, alcoholism, and cystic fibrosis. Also at risk are adults and children who eat a very limited diet due to poverty or self-restriction. Mild vitamin A deficiency may cause fatigue, susceptibility to infections, and infertility. the following are signs of a more serious deficiency:
- Xerophthalmia, a severe dryness of the eye that if untreated can lead to blindness
- Nyctalopia or night blindness
- Irregular patches on the white of the eyes
- Dry skin or hair
Toxicity
Vitamin A is fat-soluble, meaning that any amount not immediately needed by the body is absorbed and stored in fat tissues or the liver. If too much is stored, it can become toxic. The tolerable upper intake of 3’000 mcg of Performed Vitamin A, more than three times the current recommended daily level, is thought to be safe. However, there is some evidence that this much preformed vitamin A might increase the risk of bone loss, hip fracture, or some birth defects. Another reason to avoid too much preformed vitamin A is that it may interfere with the beneficial actions of vitamin D. Signs of toxicity include the following:
- Vision changes such as blurry sight
- Bone pain
- Nausea and vomiting
- Dry skin
- Sensitivity to bright light like sunlight
In contrast to performed vitamin A, Beta-Carotene is not toxic even at high levels of intake. The body can form vitamin A from Beta-Carotene as needed, and there is no need to monitor intake levels as with Preformed Vitamin A. Therefore, it is preferable to choose a multivitamin supplement that has all or the vast majority of its vitamin A in a form of beta-carotene; many multivitamin manufacturers have already reduced their amount of preformed vitamin A in their products. However, there is no strong reason for most people to take individual high-dose beta-carotene supplements.
Smokers in particular should avoid these, since some randomised trails in smokers have linked high-dose supplements with increased lung cancer risk.
Did You Know?
- Passive smoking can cause a serious damage to your dog’s health. And to any living creature. It can cause cancer of the nose and progress heart problems.
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