Vitamins are essential micronutrients that play a major role in the development and growth of our organism and the proper functioning of all its systems.

There are 13 essential vitamins that our body needs, though in very small amounts, to function properly. It includes 2 groups: fat-soluble (A, D, E, and K) and water-soluble (B Complex – Thiamine (B1), Riboflavin (B2), Niacin (B3), Pantothenic Acid (B5), Pyridoxine (B6), Biotin (B7), Folate (B9), Cobalamin (B12).

Our organism cannot synthesize vitamins (except vitamin D), and they must be obtained from a proper diet or taken through dietary supplementation (if prescribed by a doctor). It is well known, however, that natural vitamins are better recognized, absorbed, and used by our bodies than artificial ones. Some of these vitamins (B12, Biotin, Folic acid), from plant or animal food, are synthesized by certain bacteria of the upper gastrointestinal tract in our body.

Vitamins deficiency, i.e., a lack of vitamins in everyday nutrition can trigger various physiological and pathological changes that can affect the body’s organ systems, namely the immune system, nervous system, skeletal system, digestive system, and more.

The most important vitamins are:

Vitamin B Complex:

Vitamin B1 (Thiamine)

Vitamin B2 (Riboflavin)

Vitamin B3 (Niacin)

Vitamin B5 (Pantothenic Acid)

Vitamine B6 (Pyridoxine)

Vitamin B7 (Biotin)

Vitamin B (Folic Acid)

Vitamin B12 (Cobalamine)

Vitamin C (Ascorbic Acid)

Vitamin A

Vitamin D

Vitamin E

Vitamin K

Vitamin B Complex

All 8 B complex vitamins are essential for the optimal functioning of our bodies: they facilitate energy pathways (by helping carb conversion into glucose), maintain normal heart work and cell division, support the nervous system, regulate the metabolism of proteins and fats, and play other important roles. Like other water-soluble vitamins, they are eliminated through the urine within a short time. This means that our bodies do not create reserves of the vitamin B group and therefore must be consumed regularly. The exception is Vitamin B12, which is deposited in the liver. Vitamin deficiency is most common among the elderly, vegetarians, and people with chronic digestive problems.

Vitamin B1 (Thiamine)

The food rich in vitamin B1: Milk, eggs, pork meat (liver), brewer’s yeast, wheat cereals, bran, cereal grains (whole grain), cabbage, spinach, various fruits and nuts (especially walnuts), eggplant. Daily needs for adults are around mg, which is quite sufficient if we consume a variety of foods, especially fresh plants.

Physiological functions of B1: It helps convert carbohydrates into energy and tends to the proper functioning of the central nervous system.

Thermal treatment/heating: Very unstable at temperatures above 100 C°.

Vitamin B1 deficiency: It may develop due to an insufficient intake and/or decreased absorption of the vitamin, with certain conditions such as chronic alcoholism and in pregnancy (due to vomiting). Early symptoms of vitamin B1 deficiency include depression, fatigue, and various mental disorders.

Vitamin B1 drug interactions:

• Diuretics for lowering blood pressure may cause a deficit of vitamin B1;
• Oral contraceptives can also lead to vitamin B1 deficiency;
• Antidepressants increase the need for B1.

Vitamin B2 (Riboflavin)

The food high in vitamin B2: It can be found in foods of plant and animal origin like garlic, soy, germinating seeds, especially wheat germ, nuts, algae, and more. Rich sources of B2 are also green vegetables: lettuce, cabbage, green beans, potatoes, and dried apricots. Most of the B2 found in animal food is stored in the liver, kidneys, muscles, milk, and eggs.

Physiological functions of B2: It has an important role in the metabolism of carbohydrates, and is essential for maintaining important functions, such as good vision.

Thermal treatment: Stable when heated and resistant to acid and oxidation. Riboflavin is extremely sensitive to visible rays of the solar spectrum.

Vitamin B2 deficiency: Early symptoms are related to inflammation of the oral cavity (tongue) and eyes, including cheilosis (cracking of the corners of the mouth with the appearance of yellow scabs and painful inflammation of the lips) and glossitis (inflammatory changes of the tongue).

 Vitamin B2 drug interactions:

• Chemotherapeutic Doxorubicin can cause B2 deficiency;
• Oral contraceptives may cause vitamin B2 deficiency;
• Prolonged use of the antibiotic tetracycline may cause deficiency of B2;
• Probenecid, used in the treatment of gout, decreases absorption of vitamin B2 and increases the excretion of B2 by urine;
• Tricyclic antidepressants and vitamin B2 have a synergistic effect.

Vitamin B3 (Niacin)

The food high in vitamin B3: Yeast, tuna, chicken, turkey, pork, lamb (liver), rice, grains, green peas, peanuts, avocado.

Physiological functions of Niacin: It has an important role in the metabolism of fats, carbohydrates, and proteins; it participates in the processes of cellular respiration of the skin, mucous membranes, the formation of red blood cells, synthesis of hormones and normal functioning of the nervous system. Vitamin B3 is important for skin cancer prevention.

Thermal treatment: Stable when heated.

Vitamin B3 deficiency: Diarrhea, dermatitis, and dementia.

Vitamin B3 drug interactions:

• Niacin may raise levels of sugar in the blood.
• Parkinson’s disease medication acts synergistically with vitamin B3.
• Isoniazid for tuberculosis treatment may cause a deficiency of vitamin B3.
• Nicotine patches in conjunction with vitamin B3 can cause increased skin redness and pain.
• Oral contraceptives can lead to a slight deficit of vitamin B3.
• Vitamin B3 together with tetracycline may improve the efficacy of the treatment.
• Tricyclic antidepressants act synergistically with vitamin B3.

Vitamin B5 (Pantothenic Acid)

The food high in vitamin B5: Fresh vegetables, corn, tomato, broccoli, cauliflower, avocado, peas, peanuts, yeast, beef (liver, kidneys), turkey, chicken, milk, cereals, legumes, and more.

Physiological functions of vitamin B5: Essential for the metabolism of fats, carbohydrates, and proteins; it participates in the synthesis of fatty acids, cholesterol, and in the formation and activation of antibodies.

B5 deficiency: Unknown in those eating a variety of well-balanced food groups.  Symptoms of B5 malabsorption include nausea, intestinal problems, reduced immune function, dermatitis, convulsions, and other non-specific symptoms.

Supplement B5 toxicity: In some cases, a daily intake of 10 to 20 mg may cause diarrhea.

Vitamin B5 drug interactions:

• The vitamin may interfere with the absorption and effectiveness of some antibiotics.

Vitamin B6 (Pyridoxine)

The food high in vitamin B6: Brewer’s yeast is the best source of B6 and meat including beef (liver), tuna, salmon, chicken, egg, and more. Vegetables rich in B6 are potatoes, corn, spinach, rice (white), banana, watermelon, and more. The need for B6 increases with increased protein intake. For example, if we consume 100 grams of protein daily, the amount of vitamin B6 intake should be 2 mg.

Physiological functions of vitamin B6: It participates in the production of antibodies (a deficiency can cause skin problems) and in the synthesis of elastin and degradation of glycogen.

Vitamin B6 deficiency: No risk of B6 deficiency if consumed from a variety of food. Inadequate absorption of this vitamin may develop due to hyperthyroidism and alcoholism. Symptoms of B6 deficiency include changes to the skin around the eyes, nose, mouth, glossitis (inflammation of the tongue), and many other infections.

Supplement B6 toxicity: A very high dose of 2g (2000 mg) can cause nerve damage!

Vitamin B6 drug interactions:

• Some anticonvulsants may cause a deficiency of vitamin B6 since this vitamin increases the metabolism of anticonvulsant drugs;
• The antibiotic Erythromycin can interfere with the absorption of vitamin B6 if used long-term;
• Oral contraceptives may cause vitamin B6 deficiency;
• The topical treatment of Gentamicin may lead to a small deficit of vitamin B6;
• Hydralazine may lead to a mild B6 deficiency;
• Isoniazidand vitamin B6 interact as competitive antagonists;
• Tricyclic antidepressants with vitamin B6 show synergistic effects.

Vitamin B7 (Biotin)

The food high in Biotin: Yeast, egg (yolk), beef (liver, kidneys), mushrooms, cauliflower, apples, chocolate, etc.

Physiological functions: As a coenzyme, it participates in the oxidation of fatty acids and carbohydrates.

Biotin deficiency:  A condition known as a ‘disease of raw egg whites’ may develop after eating only raw egg whites over a prolonged period. Symptoms include dermatological (alopecia dermatitis, depigmentation of hair, eyebrow, and eyelash loss), as well as various neurological disorders.

Biotin drug interactions: 

• The use of anticonvulsants can cause biotin deficiency.

Vitamin B9 (Folic Acid)

The food high in Folic Acid: Green vegetables (spinach, broccoli, chickpeas), meat (liver), cereals, and more.

Physiological functions: An important cofactor in DNA synthesis, participates in the formation of red blood cells and supports other important biochemical processes.

Folic Acid deficiency may develop due to an insufficient intake of vitamin B complex or malabsorption. One of the causes of megaloblastic anemia may be a deficiency of the vitamin over a period of 3-5 months.

Folic acid drug interactions:

• Antacids can interfere with the absorption of folic acid;
• Aspirin leads to increased excretion of folic acid;
• Diuretics can cause increased excretion of folic acid;
• Erythromycin can interfere with the absorption of folic acid;
• Oral contraceptives can reduce the level of folic acid.

Vitamin B12 (Cobalamine)

The food high in vitamin B12: Dairy products such as cheese, milk and milk-based foods, shellfish, salmon, oysters, poultry, beef, soy, and more.

Physiological functions of vitamin B12: It participates in cell metabolism and tissue growth and is important for the maintenance of cognitive functions and the central nervous system. As a coenzyme, B12 is responsible for DNA synthesis and plays an important role in the formation of red blood cells.

The deficiency of vitamin B12 can lead to megaloblastic anemia, abnormal gastric mucosa, and neurological problems.

Overdose on B12 supplements: Before taking supplements, ask your doctor or pharmacist for information on a safe intake of B12 supplements.

Vitamin B12 drug interactions:

• Anticonvulsants can cause anemia by leading to a deficit of Folic Acid and B12;
• Colchicine (gout therapy) interferes with B12;
• Drugs for lowering blood pressure can also lower B12 levels;
• Oral contraceptives can cause B12 deficiency;
• Sulphonamide antibiotics can cause B12 deficiency.

Vitamin C

The food high in vitamin C: Fresh and raw fruits, vegetables (99%), and food of animal origin (1%). Most of the vitamin can be found in red, orange and yellow fruits, such as pomegranates, haw, oranges, mandarins, lemons, blackberries, red peppers, carrots, kale, tomato, cauliflower, radishes, irises and parsley leaves, pine needles, green walnuts with softcore, horseradish, cabbage, and more.

Thermal treatment: Vitamin C is the most sensitive of all the vitamins, and is destroyed at temperatures of 60 C° (dry heat); it is also unstable at low temperatures.

It is best to consume fresh, unprocessed fruit and vegetables because vitamin C dissolves in cellular juice that is acidic; and dried herbs lose the acidity through the drying process.

Oxidation (oxygen from the air) can also cause vitamin C depletion.

Sterilized, canned fruit and vegetables have 50% less of vitamin C than fresh ones.

The physiological role of vitamin C: It is necessary for collagen synthesis (a protein that participates in the composition of bones, skin, teeth, tendons, and more). The vitamin is said to be a constant ‘war’ with free radicals and plays an important role in a body’s immune system. It also participates in the production of thyroxin, a hormone essential for maintaining metabolic functions in our bodies.

Vitamin C deficiency: Lack of ascorbic acid in foods leads to scurvy, joint pain, gum swelling, tooth loss, etc. Humans can’t synthesize vitamin C but are able to store it (between 2-4g), which is the amount sufficient for up to 3 months before the first symptoms of deficiency become visible.

Overdose and toxicity on vitamin C supplements: Excessive vitamin intake (exceeding 1g/day) may cause diarrhea, the formation of oxalate in kidneys in people with kidney problems, and increased oxidative stress in individuals who have increased levels of Fe (hemochromatosis).

Vitamin C drug interactions:

• The antibiotic Ampicillin lowers vitamin C in the body;
• Epinephrine, adrenaline, a natural hormone available as over-the-counter (OTC) product to relieve asthma symptoms, reduces levels of vitamin C in plasma;
• Oral contraceptives can cause a vitamin C deficiency;
• Aspirin increases the elimination of vitamin C;
• Long-term use of the antibiotic Tetracycline may lead to a potential vitamin C deficiency;
• Phenothiazine, used to treat various psychoses, has synergistic effects with vitamin C.

Vitamin A

The food high in vitamin A: Good sources of vitamin A are meat, dairy products, fish, and fish oil which is highly recommended for better calcium transport, growth and development of bones, and as the first line of defense against various diseases in children. Biologically active forms of vitamin A can be found in animal food (retinol, retinal, retinoic acid), and are stored to be readily available for a range of physiological processes in the body.

On the other hand, plants cannot synthesize retinol, and instead, contain carotenes (an inactive form of vitamin A). After absorption in the animal or human organism, some carotenes are converted to an active form of vitamin A.

Carotenoids are responsible for the coloring of orange, red, and yellow fruit and vegetables such as red peppers, pomegranate, pumpkin, carrots, cranberries, wild pumpkin, and more.

Good sources also include cabbage, pine needles, haw, cranberries, peaches, apricots, plums, and other fruits.

Milk products or milk obtained from grazing animals have more vitamin A and D than butter and milk from cows fed with dry hay.

Thermal treatment: Vitamin A is resistant to elevated temperatures, but it is very sensitive to oxidizing agents and light, which underlines the importance to consume fruit and vegetables while they are fresh.

Low temperatures do not influence vitamin depletion, but a significant amount of vitamin A can be lost by leaching into hot water during cooking.

The physiological function of vitamin A: It has an important role in a variety of biochemical and physiological processes including the normal functioning of the immune system and vision. Retinol (a form of vitamin A) has a synergistic, antioxidative effect with vitamin E.

Vitamin A deficiency can cause a variety of symptoms from night blindness to serious eye damage, skin changes, stunted growth, and increased susceptibility to infections.

Vitamin A supplement toxicity:

Vitamin A overdose (consumption above the recommended daily intake) might be dangerous for pregnant women because of potential embryotoxicity. Pregnant women should seek the advice of a healthcare professional regarding the safe dosage of carotene supplements.

The symptoms of acute and chronic vitamin toxicity include liver damage, dermatitis, scabs, sweating, fatigue, and even death in amounts exceeding 300 mg.

Vitamin A drug interactions:

• Vitamin A in ointments and creams helps repair wounds;
• Oral contraceptives interfere with the absorption of vitamin A;
• Vitamin E is necessary for the absorption and storage of vitamin A and prevents potential toxic effects in the organism;
• Zinc increases the absorption of vitamin A.

Vitamin D

The food high in vitamin D: Cod liver oil, salmon, tuna, sardines, butter, cheese, milk, meat (liver), mushrooms, and other food.

Because breast milk contains a low vitamin D content, speak to your doctor about considering an additional amount of vitamin D (via drops) when breastfeeding.

Physiological functions of vitamin D: It has an essential role in the construction and regeneration of bones, the absorption, and metabolism of calcium and phosphorus, phospholipids, muscle activity, and many more.

Vitamin D deficiency: In children, various deformities may develop such as scoliosis (spine curvature) bowed legs or delay teeth growth.

In adults, deficiency may cause osteomalacia, brittle and fragile bones, some neurological disorders, and other conditions. This is particularly the case in the northern hemisphere where many people don’t get enough sunlight over the winter, which is necessary for our body to synthesize enough vitamin D. Therefore, supplements should be taken regularly.

Vitamin D supplement toxicity warning:

It is necessary to seek medical advice on the safe dosage of vitamin D supplements, especially during pregnancy and breastfeeding. Supplement overdose symptoms include nausea, vomiting, increased blood pressure, and kidney damage, growth retardation in children, and other serious conditions.

Vitamin D drug interactions:

• Antiepileptic drugs can accelerate the metabolism of vitamin D;
• Mineral oils reduce the absorption of vitamin D;
• Verapamil can raise levels of calcium in the blood;
• Digitalis can increase levels of calcium in the blood;
• Barbiturates reduce the activity of vitamin D.

Vitamin E

The food high in vitamin E: Plants are good reservoirs of this vitamin, primarily the germ of cereals, such as wheat. Other rich sources of vitamin E include walnuts, peanuts, almonds, chestnuts, soybeans, the young green leaves, lettuce, clover, peas and cottonseed, banana, apples, and more. Vitamin E is most resistant to heat, oxygen and oxidation, and ultraviolet rays.

The physiological function of vitamin E: The protection of cell membranes and plasma lipoproteins from free radicals. This vitamin has an important role in the development of sex cells. Furthermore, vitamin C “backs up” (regenerates) vitamin E.

Toxicity is unknown even in larger doses.

Vitamin E deficiency: Many serious conditions may develop due to malabsorption or an insufficient intake such as muscle weakness, visual field limitations (even complete blindness), and heart disease and brain changes.

Vitamin E drug interactions:

• Mineral oils interfere with the absorption of vitamin E;
• Orlistat, cholestyramine, isoniazid reduces the absorption of vitamin E;
• Iron can oxidize the non-esterified vitamin E;
• Vitamin E affects (potentiate) the antiplatelet activity of aspirin;
• Hypolipemics, orlistat, reduces the absorption of vitamin E;
• Vitamin E interferes, at the level of absorption, with tricyclic antidepressants (desipramine), chlorpromazine, beta-blockers (propranolol, atenolol, metoprolol).

Vitamin K

Food rich in vitamin K: Leafy greens are rich in chlorophyll, which is a form of vitamin K. The underground organs of plants contain much less of the vitamin than the aboveground green parts. Good sources of vitamin K are Indian alfalfa, leaves of sweet and horse chestnut, spinach, nettle, cabbage, cauliflower, seaweed, tomatoes, peas, grains, soybeans, carrots, potatoes and more. Foods of animal origin are also rich in vitamin K – pork liver, milk, eggs, spinach, cauliflower, and leafy vegetables. This vitamin can be synthesized in the organism by the gut bacteria, but quantities may vary because each individual has its different intestinal flora.

Physiological functions in the body: The vitamin is very important for all coagulation proteins (clotting factors) and skeletal system.

Vitamin K deficiency: Malabsorption of vitamin K may develop due to prolonged use of antibiotics, obstructive jaundice, and other conditions. Individuals with osteoporosis have lower levels of vitamin K. Monitoring is necessary for stented patients and those on anticoagulant therapy because of the potential deficiency/surplus of this vitamin.

Overdose of vitamin K supplements: Can be severe and symptoms may include jaundice due to liver damage, red blood cell destruction, coma, and even death.  It is necessary to seek medical advice on a safe dosage of vitamin K supplements.

Vitamin K drug interactions:

• Oral anticoagulants interfere with the absorption of vitamin K.
• Antibiotics (cephalosporin) extended application inhibits the synthesis of vitamin K by intestinal microflora.
• Mineral oils, orlistat, cholestyramine, colestipol, interfere with the absorption of vitamin K.