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Water-soluble vitamins: daily requirement

Water-soluble vitamins

Vitamins, or “vital amines” as they were named by their discoverer Dr. Casimir Funk (Vitamins are more Funky than Casimir thought), are the low molecular weight compounds that we receive from food or supplements. The most important function of vitamins is that they assist various biochemical reactions in the body.

All the vitamins can be divided into 2 groups – fat-soluble and water-soluble. Fat-soluble vitamins are stored in the tissues and the liver and require the assistance of fats to be used by the body. These are the vitamins D, A, E, and K. Water-soluble vitamins are the nutrients that we need in small amounts daily as they are not stored in our bodies. The water-soluble vitamins are the B vitamins and the vitamin C.

In this article, we will discuss the benefits of water-soluble vitamins.

Water-soluble vitamins

Water-soluble vitamins that include B vitamins and vitamin C are dissolved in water and can be immediately used by the tissues and the organs inside our bodies. Any excess of the water-soluble vitamins is excreted with the urine (Relationship Between Urinary Concentrations of Nine Water-soluble Vitamins and their Vitamin Intakes in Japanese Adult Males). This means that the water-soluble vitamins stay in our bodies for a relatively short time and need to be regularly replenished through food or supplements.

The following table provides a list of the water-soluble vitamins and information about the health issues associated with their deficiency.

Vitamin Its active form Health problems associated with its deficiency
B1 – thiamine or aneurin Thiamine pyrophosphate 

Thiamine triphosphate


Wet beriberi, dry beriberi, Wernicke’s disease, Korsakov’s syndrome
B2 – riboflavin Flavin mononucleotide (FMN) 

Flavin dinucleotide (FAD)

Dermatitis, problems with cellular respiration, cataract
B3 – vitamin PP or niacin Nicotinamide adenine dinucleotide (NAD+) 

Nicotinamide adenine dinucleotide phosphate (NADP+)

B5 – pantothenic acid Pantethine Insomnia, intestinal disorders
Vitamin B6 – pyridoxine Pyridoxal phosphate (PALP) 

Pyridoxamine Phosphate (PAMF)

Dermatitis, anemia, mental disorders
Vitamin B9 – folic acid Tetrahydrofolic acid Megaloblastic anemia, congenital malformations, cardiovascular diseases
B12 – cobalamin Adenosylcobalamin Methylcobalamin Hydroxocobalamin Megaloblastic anemia, dementia, cardiovascular diseases, subacute combined degeneration of the spinal cord
Vitamin C – ascorbic acid L-ascorbic acid Anemia, scurvy
Biotin – vitamin B7 or H D-biotin Dermatitis

Health benefits of B vitamins

B vitamins include: B1, B2, B3, B5, B6, B7, B9 and B12.

We will consider the key health benefits of these vitamins.

Vitamin B1 or thiamine

Vitamin B1 directly affects the course of biochemical reactions that provide the body with energy. It catalyzes the reactions of the Krebs cycle – the main energy furnace of our cells – and assists in glucose utilization, which gives us structural building blocks for DNA, RNA, and NADPH2 which prevents the destruction of red blood cells. It’s probably one of the reasons why the majority of vitamin B1 forms (about 80%) are located in the red blood cells.

Vitamin B1

Vitamin B1 is also an important player in the processes relating to the nervous system. It helps maintain the balance between sodium and potassium ions; affects the excitation and inhibition of neurons and the signalling between the neuron cells, muscles, and glands.

Vitamin B1 does not accumulate in the body. It doesn’t form complexes with proteins and occurs only in a free form, and therefore is easily excreted with urine.

Nata Gonchar

Holistic Nutritionist, founder
of the project WOW Bali

TOP-10 ingredients
for your health and
balanced meal plan
Nata Gonchar

Holistic Nutritionist, founder
of the project WOW Bali

As Hippocrates said, you are what you eat. The meaning of this phrase concerns every person, who takes care of his health. The food we eat has a big impact on our vital activity, state of health and quality of life.

Nowadays healthy diet is very popular and everyone knows that he should give up junk food. But not everyone knows what he must eat except for grain, vegetables and protein food.

It's essential to diversify your diet. Every bite of food should provide you with vitamins, minerals and phytonutrients that are necessary for good health.

So how can we have a proper nutrition plan?

We prepared a PDF-file to help you. It contains TOP-10 ingredients, which should be added to everyone's diet.

Thiamine is not produced in our body – we can get it from food and dietary supplements.

Vitamin B2 or riboflavin

Just like the B1 vitamin, B2 is also involved in energy production. In addition, it plays a key role in:

  • fatty acid oxidation;
  • restoration of glutathione which is the main antioxidant in the body, and in detoxification (Riboflavin (vitamin B2) and oxidative stress: a review);
  • assistance in red blood cells production;
  • formation of hydrochloric acid by parietal cells of the gastric mucosa;
  • vision, because vitamin B2 is part of rhodopsin – a protein of the retina – which provides adaptation in the dark.

Vitamin B3, also known as Vitamin PP or niacin

Vitamin B3’s active forms are involved in energy generation processes such as splitting of the glucose. Together with vitamin C, it plays a role in the formation of the bile acids and the steroid hormones produced by the gonads and the adrenal cortex. It also participates in the biotransformation of cholesterol. (Niacin to improve cholesterol numbers)

Our intestinal microbiota can produce small amounts of vitamin B3. For this to happen, we must have enough tryptophan and vitamin B6 in our system. A number of health issues and deficiencies can impede the production of vitamin B6. For example:

  • violation of protein breakdown, as in hypochlorhydria (when the parietal cells of the stomach do not produce enough acid);
  • problems with nutrient absorption, which can be a consequence of malabsorption syndrome or a serious disease like the genetically determined Hartnup’s disease;
  • vitamin B6 and B2 deficiency

Vitamin B5 or pantothenic acid

Vitamin B5 helps to break down the fatty acids from food (Pantothenic Acid – Vitamin B5). Just like with the vitamin B3, our gut microbiota produces small amounts of this vitamin, but not nearly enough of what we need. The remaining amount of this vitamin can be obtained from the foods and supplements.

Vitamin B6

Vitamin B6 acts as a coenzyme in the biochemical reactions in our bodies. It is active in the production of:

  • various neurotransmitters like dopamine, norepinephrine, adrenaline
  • thyroid hormones triiodothyronine (T3) and thyroxine (T4)
  • heme which is one of the key structures in the hemoglobin molecule that transfers carbon dioxide and oxygen from the tissues to the alveoli and back
  • vitamin B3
  • melatonin, known as the “sleep hormone”, and serotonin, known as the “happiness hormone”.

Vitamin B7 or biotin

Vitamin B7 helps to break down fats, carbohydrates, and proteins from food. It also helps to regulate the activity of the genes and is active in cell signalling. Biotin is known for helping to prevent hair loss and to keep skin, nails, and hair healthy.

Vitamins B9 and B12

Their most important functions include:

Health benefits of vitamin C

Vitamin C assists in converting cholesterol into sex hormones, the hormones of the adrenal cortex, and vitamin D, as well as bile acids. It plays a crucial role in the formation and maintenance of the normal structure of collagen which is a major protein of connective tissue (The Roles of Vitamin C in Skin Health).

It also supports the processes relating to the following amino acids:

  • proline and lysine – the most important amino acids that make collagen;
  • tyrosine – a precursor of thyroid hormones T3 (triiodothyronine) and T4 (thyroxine), adrenaline, melanin pigment, as well as a number of neurotransmitters such as dopamine and norepinephrine;
  • tryptophan – a raw material for the synthesis of serotonin and melatonin, as well as niacin (vitamin B3).

The active ingredient of vitamin C – the ascorbic acid – is involved in iron absorption in the intestines where it assists in the reduction of ferric iron to ferrous iron. It also ensures the release of iron molecules from the carrier proteins in the blood.

Vitamin C also stimulates the work of the immune cells (Vitamin C and Immune Function), and in particular, their migration from the bloodstream to the area of inflammation, and the secretion of the protective immune proteins.


The following symptoms are associates with the vitamin B1 deficiency:

  • acidic pH levels
  • water and sodium retention, which develops swelling
  • difficulties breathing

An insufficient intake of B1 vitamin or its excessive excretion or utilization in the body can lead to the development of the condition called beriberi (Vitamin B1 Thiamine Deficiency):

Development of the dry form of beriberi – a condition associated with disorders in the central and peripheral nervous systems. The symptoms are:

  • decreased sensitivity
  • burning sensations in the limbs, especially in the feet
  • convulsions
  • muscle weakness

A decrease in energy reserves in the cells of the heart muscle may lead to the development of the wet form of beriberi.

Development of the cerebral beriberi or Wernicke-Korsakoff syndrome. The most characteristic symptoms of this pathology include:

  • eye movement abnormalities
  • blurred consciousness and amnesia
  • walking abnormalities and posture instability

In general, moderate thiamine deficiency is usually accompanied by less severe, but clinically significant signs:

  • polyneuritis
  • anxiety, cognitive impairment
  • fatigue and lack of energy during the waking hours
  • numbness in hands and feet
  • deteriorating coordination

Vitamin B2 deficiency is accompanied by a set of distinct symptoms (Riboflavin. Fact Sheet for Health Professionals):

  • angular cheilitis or inflammation of one or both corners of the mouth – the main and common complaint
  • chapped sore lips
  • corneal neovascularization which leads to clouding of the eyeball
  • seborrheic dermatitis
  • hair loss (alopecia)
  • eye pain
  • fatigue and lack of energy

Vitamin B3 deficiency is associated with pellagra, a disease accompanied by the three Ds (Niacin Deficiency):

  • dermatitis
  • diarrhea
  • dementia

In some cases, the fourth D – death – is added, as pellagra can lead to serious complications if left untreated.

In addition, because vitamin B3 deficiency leads to a decrease in the amount of energy produced in the body, the common problems that can arise are apathy, fatigue, and depression.

Vitamin B5 deficiency symptoms include irritability, sleep disorders, nausea, vomiting, muscle cramps, fatigue, and headaches.

Vitamin B6 deficiency is accompanied by mouth ulcers, seborrheic and atopic dermatitis, and high levels of homocysteine in the blood (hyperhomocysteinemia).

Vitamin B7 deficiency symptoms are hair loss; scaly skin rashes around eyes, nose, or mouth; fatigue; depressions; thyroid disorders; brittle nails; numbness and tingling in the hands and feet; and hallucinations.

A deficiency of vitamins B9 and B12 is associated with increased homocysteine levels. This in turn causes damage to the endothelium – the inner lining of blood vessels – and is a leading marker of cardiovascular pathologies.

The lack of vitamin C – affects the structure of the connective tissues and the vascular walls. Further symptoms include:

  • nose and gums bleeding
  • slow wound healing
  • small red or purple spots caused by hemorrhage of capillaries (petechiae)

The lack of vitamin C

Vitamin C deficiency can also lead to a decrease in bile levels which may lead to stone formation in the bile ducts.

Foods rich in water-soluble vitamins

Vitamin B1 Vitamin B2 Vitamin B3 Vitamin B5 Vitamin B6
Wheat Beef liver Tuna Liver Potatoes with skin
Oats Kidneys Peanuts Kidneys Bananas
Lentils Eggs Turkey Beef Beans and soy
Soy Almonds Chicken Avocado Pink salmon
Pistachios Red caviar Mackerel Mushrooms Chum salmon
Pork Sesame seeds Honey Dairy products Wheat
Vitamin B7 Vitamin B9 Vitamin B12 Vitamin C
Beef liver Spinach Shellfish Rosehip
Eggs Lentils Mussels Sea buckthorn
Salmon Avocado Lamb Bell peppers
Avocado Watercress Mackerel Kiwi
Pork Walnuts Dairy products Citrus fruits
Sweet potatoes Hazelnuts Beef Strawberries
Walnuts Parsley Eggs Spinach
Peanuts Almonds Turkey Blackcurrants
Yeast Millet Nori German turnip


The following tables provide daily vitamin requirements for B vitamins.14

Age Vitamin B1 Vitamin B2 Vitamin B3 Vitamin B5
0-6 months old 0,2 mg 0,3 mg 2 mg 1,7 mg
7-12 months old 0,3 mg 0,4 mg 4 mg 1,8 mg
1-3 years old 0,5 mg 0,5 mg 6 mg 2 mg
4-8 years old 0,6 mg 0,6 mg 8 mg 3 mg
9-13 years old 0,9 mg 0,9 mg 12 mg 4 mg
Over 14 years old 1 – 1,2 mg 1 – 1,3 mg 16 mg 5 mg
Pregnancy 1,4 mg 1,4 mg 18 mg 6 mg
Breastfeeding 1,4 mg 1,6 mg 17 mg 7 mg
Age Vitamin B6 Vitamin B7 Vitamin B9 Vitamin B12
0-6 months old 0,1 mg 5 mcg 65 mcg 0,4 mcg
7-12 months old 0,3 mg 6 mcg 80 mcg 0,5 mcg
1-3 years old 0,5 mg 8 mcg 150 mcg 0,9 mcg
4-8 years old 0,6 mg 12 mcg 200 mcg 1,2 mcg
9-13 years old 1 mg 20 mcg 300 mcg 1,8 mcg
Over 14 years old 1,2 mg (for women) 

1,3 mg (for men)

25 mcg 400 mcg 2,4 mcg
Pregnancy 1,9 mg 30 mcg 600 mcg 2,6 mcg
Breastfeeding 2 mg 35 mcg 500 mcg 2,8 mcg

If you are treating a vitamin deficiency, and changing dietary habits doesn’t help, consult your healthcare provider who will be able to prescribe the correct supplementation. Self-prescription may lead to excess vitamin consumption and there is a risk of overdosing on some active ingredients. It is important to remember that, when consumed in excess, even the water-soluble vitamins can have harmful effects on your body, for example:

B vitamins and folic acid

  • excess intake of B6 vitamin can lead to loss of feeling in limbs
  • excess intake of vitamin B9 can cause irreversible nervous system damage
  • excess intake of vitamin B3 can result in skin flush and contribute to liver damage

Note that some over-the-counter and prescribed medications can inhibit the absorption of water-soluble vitamins, and lead to vitamin deficiencies. Here we list some of them.

The absorption of vitamin B12 is suppressed by:

  • proton-pump inhibitors (for example, Omeprazole) – reduce the secretion of the hydrochloric acid;
  • histamine antagonists (H2-) which also cause hypochlorhydria;
  • Colchicine – is used in the treatment of gout;
  • Some antibiotics, for example, chloramphenicol.

The absorption of vitamin B9 is suppressed by:

  • long-term use of non-steroidal anti-inflammatory drugs (like Ibuprofen);
  • drugs used to lower cholesterol levels (cholestyramine);
  • some antibiotics and chemotherapy drugs.

The following substances increase the excretion of the vitamin B1 (thiamine) from the body:

  • alcohol;
  • tea;
  • coffee.

The material is based on research: