Vitamins are essential nutrients for the proper functioning of the human body, but they can be divided into two main groups based on their solubility: water-soluble and fat-soluble. Water-soluble vitamins, such as B complex and vitamin C, are easily absorbed by the gastrointestinal tract and transported by the blood to the tissues where they are needed. However, they are not stored in large quantities in the body, being eliminated in the urine when consumed in excess. On the other hand, fat-soluble vitamins, such as vitamins A, D, E and K, are absorbed together with fats and transported by the lymphatic system, and can be stored in the liver and adipose tissues for prolonged periods.
This distinction between water-soluble and fat-soluble vitamins is crucial for understanding how they are absorbed, transported, and stored in the body, as well as for determining dietary needs and appropriate vitamin supplementation. While water-soluble vitamins need to be consumed regularly through the diet due to their rapid excretion, fat-soluble vitamins can be stored and used as needed, which impacts how they are recommended in diets and supplements.
Vitamin A (Retinol): dissolves in fat and is stored in body tissues. This feature allows retinol to be absorbed along with dietary fats and stored in the liver and fatty tissues for later use by the body.
Function: essential for vision health, as it is necessary for the formation of rhodopsin, a pigment present in retinal cells, hence the name "retinol". It is also known for stimulating cell renewal, promoting the production of collagen and elastin, and is often used in anti-aging products and acne treatments.
Retinol deficiency can lead to a condition known as hypovitaminosis A, which can cause symptoms such as night blindness, dry eyes (xerophthalmia), increased susceptibility to infections, stunted growth, skin problems and even irreversible blindness in severe cases. To combat vitamin A deficiency, many countries have implemented dairy product fortification programs.
Food sources: Liver, carrots, sweet potatoes, spinach, broccoli.
Vitamin B1 (Thiamine): water-soluble vitamin, which means it dissolves in water and is easily absorbed by the body through the gastrointestinal tract. This feature allows thiamine to be transported by the blood to the cells where it is needed and any excess is usually excreted in the urine.
Function: It is essential for the proper functioning of the nervous system, muscles and heart. Thiamine is also important for energy production as it acts as a coenzyme in several metabolic reactions that convert food into energy usable by the body. In many countries, fortified foods, such as breakfast cereals and baked goods, are fortified with thiamine to help prevent deficiencies of this vitamin, such as beriberi, which is characterized by symptoms such as muscle weakness, fatigue, loss of appetite, digestive problems, numbness and tingling in the extremities, and in severe cases, cardiac and neurological problems.
Chronic alcoholism is one of the main causes of thiamine deficiency in adults, due to the impact of alcohol on the absorption and metabolism of this vitamin. Wernicke's encephalopathy, is a serious neurological condition associated with alcoholism.
Food sources: Whole grains, beans, nuts, pork, fish.
Vitamin B2 (Riboflavin): like other B vitamins, it is water-soluble, which allows it to be transported by the blood and used by the body as needed. Any excess unused riboflavin is usually excreted in the urine.
Function: plays a crucial role in energy metabolism, cell growth, red blood cell production and maintaining the health of the skin and nervous system. Like other B vitamins, riboflavin acts as a coenzyme in several metabolic reactions in the body, helping to convert food into usable energy. Riboflavin also plays an important role in eye health, especially in preventing cataracts and age-related macular degeneration. Additionally, because riboflavin is sensitive to light, excessive exposure to sunlight or artificial light can degrade this vitamin in foods and supplements, decreasing its availability.
Riboflavin plays an indirect role in RNA synthesis, which is why it is named after "ribose", which is the five-carbon sugar present in RNA. Certain population groups, such as strict vegetarians, the elderly, and people with medical conditions that affect nutrient absorption, are most at risk for riboflavin deficiency.
Food sources: Milk, eggs, meat, green leafy vegetables, fortified cereals.
Vitamin B3 (Niacin): known as niconitic acid, is also soluble in water and is absorbed by the body through the gastrointestinal tract
Function: fundamental for energy metabolism, helping to convert carbohydrates, fats and proteins into energy usable by the body. Furthermore, niacin is essential for cellular metabolism and energy production, which indirectly influences hormonal regulation. Furthermore, niacin is a key component of the coenzymes NAD (nicotinamide adenine dinucleotide) and NADP (nicotinamide adenine dinucleotide phosphate), which play crucial roles in many metabolic reactions, including the synthesis of steroid hormones such as sex hormones (estrogen, progesterone and testosterone) and stress-related hormones (cortisol and aldosterone), through the regulation of fatty acid and cholesterol metabolism.
In addition to its importance in metabolic health, niacin has also been studied for its potential benefits for cardiovascular health. Niacin can help increase levels of HDL cholesterol (the "good" cholesterol) and reduce the levels of LDL cholesterol (the "bad" cholesterol) and triglycerides, which may help reduce the risk of heart disease. The name "niacin" is a combination of "niacotinamide" and "vitamin."
Food sources: Meat, poultry, fish, peanuts, eggs, whole grains.
Vitamin B5 (Pantothenic Acid): water-soluble vitamin, which means it dissolves in water and is easily absorbed by the body through the gastrointestinal tract.
Function: is part of the B vitamin complex and is essential for the metabolism of carbohydrates, proteins and fats, being necessary for energy production. In addition to its role in energy metabolism, pantothenic acid plays a crucial role in the synthesis of essential coenzymes, such as coenzyme A (CoA) and phosphopantothenylpyruvate, which are required for a variety of metabolic processes, including the synthesis of fatty acids, the cholesterol synthesis, the synthesis of steroid hormones and the production of neurotransmitters. The pantothenic acid is found in a variety of common foods, so the deficiency of this vitamin is rare in individuals who have a balanced diet.
Pantothenic acid is also often used in skin and hair care products, however the effectiveness of these products when applied topically is still subject to debate and research. The name "pantothenic" derives from the Greek words "pantos", meaning "everywhere", and "then", meaning "free". Vitamin B5 is called pantothenic acid because it is widely distributed in nature, found in a wide variety of foods
Food sources: Meat, poultry, fish, eggs, vegetables, whole grains.
Vitamin B6 (Pyridoxine): water-soluble vitamin, which means it dissolves in water and is easily absorbed by the body through the gastrointestinal tract.
Function: essential for the metabolism of amino acids, carbohydrates and lipids, in addition to playing an important role in the synthesis of neurotransmitters, such as serotonin, dopamine and norepinephrine, which are essential for brain function and mood. In addition to its role in metabolism, vitamin B6 is crucial for immune system health, red blood cell formation, blood sugar regulation, and maintaining skin, eye, and nervous system health. It also plays a role in the production of hemoglobin, the protein in red blood cells that carries oxygen around the body.
The pyridoxine is found in a variety of common foods, so the deficiency of this vitamin is rare in individuals who have a balanced diet.
Food sources: Meat, fish, chicken, bananas, potatoes, green leafy vegetables.
Vitamin B7 (Biotin):
Function: essential for several biochemical reactions in the body, including the synthesis of fatty acids, the formation of glucose, and the conversion of amino acids into proteins.
In addition to its role in metabolism, biotin plays an important role in skin, nail, and hair health. It is often used in personal care products because of its ability to promote hair growth and strength, prevent hair loss, and improve nail and skin health. Biotin is produced by bacteria in the human gastrointestinal tract, but the amount produced is not enough to meet the body's daily needs.
Its name reflects its importance for health and its classification as an organic substance vital to life. This vitamin has been studied for its potential benefits in regulating blood sugar in people with type 2 diabetes, brain health, and preventing certain health conditions such as multiple sclerosis.
Food sources: Eggs, almonds, walnuts, spinach, sweet potatoes.
Vitamin B9 (Folic Acid):
Function: one of the main functions of folic acid is its participation in DNA synthesis and cell division, which is especially crucial during periods of growth and development, such as pregnancy and childhood. One of the reasons folic acid is often associated with pregnancy is its importance in preventing neural tube defects, such as spina bifida and anencephaly, which occur in the early stages of fetal development. For this reason, women of childbearing age are often advised to consume folic acid before and during pregnancy to reduce the risk of these birth defects.
In addition to its role in pregnancy, folic acid is necessary for the production of healthy red blood cells, the synthesis of amino acids, and the metabolism of several other B vitamins. It also plays an important role in cardiovascular health, helping to reduce blood homocysteine levels, which are associated with a higher risk of heart disease.
Folic acid deficiency can lead to a condition known as megaloblastic anemia, characterized by symptoms such as fatigue, weakness, shortness of breath, paleness and irritability. Folic acid deficiency may also increase the risk of neurological and cardiovascular problems. To prevent this, wheat-based products are normally enriched with this vitamin.
Food sources: Green leafy vegetables, beans, lentils, avocado, oranges.
Vitamin B12 (Cobalamin):
Function: a unique vitamin among the B complex because it contains cobalt in its chemical structure, hence the name "cobalamin". Vitamin B12 plays an essential role in the formation of red blood cells, maintenance of the central nervous system and DNA synthesis. It is necessary for the proper metabolism of fatty acids and amino acids, as well as for the production of myelin, the protective layer that surrounds the nerves and helps in the transmission of nerve impulses.
Vitamin B12 deficiency is relatively common in certain population groups, such as the elderly, vegans, and people with gastrointestinal disorders that affect nutrient absorption. B12 deficiency can lead to a condition known as megaloblastic anemia, characterized by symptoms such as fatigue, weakness, shortness of breath, paleness and neurological problems such as numbness and tingling in the extremities and difficulty with balance. Vitamin B12 supplementation is often recommended for people who are deficient in this vitamin, especially those who follow vegetarian or vegan diets. Vitamin B12 is also often given by injection to people with absorption problems due to gastrointestinal disorders, such as Crohn's disease or celiac disease.
Food sources: Meat, fish, eggs, dairy products, fortified products.
Vitamin C (Ascorbic Acid): the word "ascorbic" derives from "anti-scorbutus"
Function: is a water-soluble vitamin with a wide range of functions and health benefits. It is known for its crucial role in strengthening the immune system, wound healing, iron absorption, skin health and antioxidant function. As an antioxidant, vitamin C protects the body's cells against damage caused by free radicals, unstable substances that can cause damage to cells and contribute to premature aging and the development of chronic diseases, such as cancer and cardiovascular disease. Furthermore, vitamin C regenerates other antioxidants in the body, such as vitamin E, further increasing its effectiveness in cellular protection. One of the best-known functions of vitamin C is its ability to strengthen the immune system, helping the body fight viral and bacterial infections. It stimulates the production and activity of white blood cells, which are immune system cells responsible for fighting invading pathogens, and also increases the production of antibodies.
Ascorbic Acid is sensitive to light, so the excessive exposure to sunlight or artificial light can degrade this vitamin in foods and supplements, decreasing its availability.
Additionally, vitamin C plays an essential role in the synthesis of collagen, an important structural protein found in skin, bones, cartilage, tendons and blood vessels. Collagen is essential for the health of skin and connective tissue, helping to maintain skin elasticity, prevent wrinkles and promote wound healing. Despite its importance for health, the human body does not produce vitamin C on its own, so it is essential to obtain this vitamin through diet or supplementation. Vitamin C deficiency can lead to a condition known as scurvy or scorbutus, characterized by symptoms such as fatigue, weakness, bleeding gums, joint inflammation and wounds that are slow to heal.
Food sources: Citrus fruits, kiwi, strawberries, peppers, broccoli.
Vitamin D:
Function: Vitamin D is a fat-soluble vitamin essential for bone health, immune function, cardiovascular health and many other aspects of human health. It plays a crucial role in the absorption of calcium and phosphorus in the intestine, promoting bone mineralization and proper growth of bones and teeth. One of the main sources of vitamin D is exposure to sunlight. When the skin is exposed to UVB sunlight, it produces vitamin D from the cholesterol present in the skin.
Vitamin D plays a key role in regulating the immune system, helping to reduce the risk of infections and inflammation. It has also been linked to reducing the risk of autoimmune diseases such as multiple sclerosis and Crohn's disease. Additionally, vitamin D is important for cardiovascular health, helping to regulate blood pressure, reduce inflammation, and improve blood vessel function. Vitamin D deficiency has been linked to an increased risk of cardiovascular diseases such as coronary artery disease, stroke and hypertension. Vitamin D deficiency is common in many parts of the world, especially in regions where there is little sun exposure or during the winter months when sunlight is less intense.
Food sources: Sunlight, fatty fish, egg yolk, fortified foods.
Vitamin E (Tocopherol):
Function: is a fat-soluble antioxidant essential for cellular health and protection against oxidative damage. There are several types of tocopherols, with alpha-tocopherol being the most common and biologically active. As an antioxidant, tocopherol protects the body's cells against damage caused by free radicals, unstable substances that can damage cells and contribute to premature aging and the development of chronic diseases such as cancer and cardiovascular disease. It neutralizes free radicals, preventing them from causing damage to cells and DNA.
In addition to its antioxidant function, vitamin E plays an important role in cardiovascular health, helping to prevent the oxidation of LDL cholesterol ("bad cholesterol") and the formation of plaque in the arteries, which can lead to heart disease. It also plays a role in regulating immune function, skin health, and wound healing. Vitamin E is also present in fortified foods such as breakfast cereals and soy products.
Vitamin E deficiency is rare, but can occur in people with fat absorption problems, such as celiac disease, cystic fibrosis, or liver and gallbladder disorders. Symptoms of vitamin E deficiency can include muscle weakness, vision problems, difficulty with coordination and compromised immune function.
Food sources: Oilseeds, seeds, vegetable oils, green leafy vegetables.
Vitamin K:
Function: there are two main forms of vitamin K: vitamin K1 (phylloquinone) and vitamin K2 (menaquinone). Vitamin K1 is found in green leafy vegetables such as spinach, kale and broccoli, while vitamin K2 is found in fermented foods such as cheese, natto and fermented soy products. The main function of vitamin K is its contribution to the blood clotting process. It plays a crucial role in activating proteins involved in the formation of blood clots, helping to prevent excessive bleeding in response to injuries or cuts. Additionally, vitamin K also plays a role in regulating bone metabolism, helping to maintain bone mineral density and prevent osteoporosis.
In addition to its importance in blood clotting and bone health, vitamin K has also been linked to other health benefits, such as preventing heart disease, regulating blood glucose, and improving brain health. Vitamin K deficiency is relatively rare in healthy adults, but can occur in newborns, especially premature babies, due to the lack of vitamin K reserves in the fetus and lower bacterial production in the intestine. Vitamin K deficiency can lead to blood clotting problems and increase the risk of bleeding. Most people get enough vitamin K through a balanced diet, but supplementation may be recommended in certain cases, such as newborns or people with fat absorption problems. However, it is important to avoid excess vitamin K supplementation, as very high doses can interfere with blood clotting and cause complications.
Food sources: Green leafy vegetables, broccoli, cauliflower, vegetable oils.
These are the main vitamins needed for optimal health, and a balanced diet generally provides them all in adequate amounts.
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