Vitamin A: What is it good for and which are the sources?

Today we start the series of ABCs, in which we will take each vitamin separately and discuss it function by function. But first of all, I want to talk a little bit about vitamins, in general. Let's get on the road…

What are vitamins?

I think we've all heard about "macros", the well-known macronutrients - carbohydrates, proteins and fats . However, vitamins and minerals are micronutrients , essential factors in the harmonious development of any organism, regardless of species. If these factors are missing, or in excess, certain imbalances, developmental deficiencies are formed and the disease sets in.

Before the term vitamin was known, it was observed that certain foods were needed to maintain health, or to treat certain diseases : the Egyptians noticed that nictalopia ("night blindness" caused by a lack of vitamin A ) can be treated by eating liver, and scurvy (caused by vitamin C deficiencies), which appeared in navigators in the Middle Ages, could be cured by consuming citrus.

Vitamins are in turn divided into water-soluble (B, C, P) and fat-soluble (A, D, E, K, F) , depending on their solubility in water or lipids. In fat-soluble ones, there is a higher risk of toxicity, because they are not eliminated as easily from the body as soluble ones, which dissolve in water and are eliminated in the urine. Therefore, my advice is to do your tests before taking vitamins in the form of supplements.

Deficiencies in people may be primary , caused by bad nutrition, poor in vitamins, or secondary , caused by smoking, excessive alcohol consumption or drugs that interfere with the absorption of vitamins in the body. But, as mentioned above, there are cases at the opposite pole, of hypervitaminosis , which can upset the body. For example, an excessive amount of vitamin C can influence the formation of kidney stones… but we will talk about this when we get to C.

Let's talk first about A…

Vitamin A is a fat-soluble vitamin, available in nature in two forms: vitamin A and vitamin A precursors, carotenoids . Main ideas:

• Active form of vitamin A is found only in animal tissues. The richest animal sources of vitamin A are: eggs, liver, butter and fish such as tuna, sardines or herring. So that means I can only take vitamin A from animal products? No, in plants we find the precursors of vitamin A, which are transformed by the body into vitamin A, as much as it needs. Plant sources : green leaves (spinach, lettuce, parsley, etc.), anything orange, yellow, or red (carrots, pumpkin, sweet potatoes, peppers, tomatoes, apricots, peaches, etc.) . See here the richest foods in beta-carotene ;
• It plays an important role in various body functions: sight (do you know the carrot story?), immunity (directly involved in immune function, and beta -carotenes have a strong antioxidant effect), skin and hair health , bone development (yes, including teeth and nails), genetic transcription and embryonic development (attention to pregnant women or those who want to have a child). Rapid signs of vitamin A deficiency: blurred and poor eyesight at night, dry skin and cracks, hair loss, broken nails and slow wound healing.
• Vitamin A, like glucose, is stored in the liver and therefore there is a risk of overdose (too bad it is not deposited as fat, right?). It has been observed that in developed countries about 75% of the population consumes more vitamin A than necessary, but you can rarely develop symptoms of toxicity in the body (nausea, dizziness, vomiting, irritability, drowsiness, or even worse, risk of stroke). It is important to remember that plant precursors, or carotenoids (you've probably heard of beta-carotene) can be consumed without limit , because the body creates from them as much vitamin A as it needs and risk of toxicity disappears!
• Is it sensitive to cooking? Yes, partially, but it degrades if exposed to air and light over time;

Recommendations

- I advise you to snack on more fresh carrots and include greens in your daily diet! Eat vegetables and fruits as fresh as possible, to get a good dose of carotenoids;

- Try to reduce the consumption of animal protein (meat, milk, or eggs) to a maximum of one meal a day. The risk of reaching an overdose of vitamin A is low, because we tend to cook most foods of animal origin and lose more of vitamin A, but the excess is not good for the body;

- Do a set of blood tests before taking supplements with vitamin A, or any other fat-soluble vitamins, so as not to reach a hypervitaminosis;

Sources:

• How Dietary Deficiency Studies Have Illuminated the Many Roles of Vitamin A During Development and Postnatal Life: https://www.ncbi.nlm.nih.gov/pubmed/32297294
• Vitamin A: Introduction – Biochemistry | Lecturio: https://www.youtube.com/watch?v=XPjq2uxZWnM
• Hipervitaminoza (toxicitatea vitaminelor): https://www.romedic.ro/hipervitaminoza-toxicitatea-vitaminelor
• Vitamin C Supplementation and Urinary Oxalate Excretion: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1472830/
• Foods highest in Beta Carotene: https://nutritiondata.self.com/foods-000135000000000000000-w.html

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