Water-Soluble Vitamins: Definition, Function, Dietary Sources, and More

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The body needs 13 essential vitamins, and these can be divided into two categories: fat-soluble and water-soluble. 

In this article, we’ll talk about one category in particular – water-soluble vitamins. 

Discover what water-soluble vitamins are, its functions, dietary sources, and more. 

Water-Soluble Vitamins Definition

As opposed to fat-soluble vitamins, water-soluble vitamins are not stored in the body. Instead, the body absorbs what it needs and then it usually secretes the excess in your urine. Since they cannot be stored, the body needs a continuous supply through a steady daily intake. You can get water-soluble vitamins through the foods you eat, the supplements you take, or from a combination of both. 

Water-soluble vitamins include vitamin C and the B vitamins. 

Water-Soluble Vitamins List

NutrientWater-Soluble Vitamins FunctionsFood Sources of Water-Soluble Vitamins
Thiamine (Vitamin B1)Part of an enzyme needed for energy metabolism; important to nerve functionFound in all nutritious foods in moderate amounts: pork, whole-grain or enriched breads and cereals, legumes, nuts and seeds
Riboflavin (Vitamin B2)Part of an enzyme needed for energy metabolism; important for normal vision and skin healthMilk and milk products; leafy green vegetables; whole-grain, enriched breads and cereals
Niacin (Vitamin B3)Part of an enzyme needed for energy metabolism; important for nervous system, digestive system, and skin healthMeat, poultry, fish, whole-grain or enriched breads and cereals, vegetables (especially mushrooms, asparagus, and leafy green vegetables), peanut butter
Pantothenic Acid (Vitamin B5)Part of an enzyme needed for energy metabolismWidespread in foods
Pyridoxine (Vitamin B6)Part of an enzyme needed for protein metabolism; helps make red blood cellsMeat, fish, poultry, vegetables, fruits
Biotin (Vitamin B7)Part of an enzyme needed for energy metabolismWidespread in foods; also produced in intestinal tract by bacteria
Folic Acid (Vitamin B9)Part of an enzyme needed for making DNA and new cells, especially red blood cellsLeafy green vegetables and legumes, seeds, orange juice, and liver; now added to most refined grains
Cobalamin (Vitamin B12)Part of an enzyme needed for making new cells; important to nerve functionMeat, poultry, fish, seafood, eggs, milk and milk products; not found in plant foods
Ascorbic Acid (Vitamin C)Antioxidant; part of an enzyme needed for protein metabolism; important for immune system health; aids in iron absorptionFound only in fruits and vegetables, especially citrus fruits, vegetables in the cabbage family, cantaloupe, strawberries, peppers, tomatoes, potatoes, lettuce, papayas, mangoes, kiwifruit

(source: https://www.healthlinkbc.ca/health-topics/ta3868

Thiamin (Vitamin B1). Thiamine (Vitamin B1) is a coenzyme decarboxylase crucial for the metabolism of glucose and energy supply to muscle and nerve cells. 

  • Dietary Sources: Cereals, legumes, yeast, fish, meat
  • Daily Recommended Intake: 
Life StageRecommended Amount
Birth to 6 months0.2 mg
Infants 7–12 months0.3 mg
Children 1–3 years0.5 mg
Children 4–8 years0.6 mg
Children 9–13 years0.9 mg
Teen boys 14–18 years1.2 mg
Teen girls 14–18 years1.0 mg
Men1.2 mg
Women1.1 mg
Pregnant teens and women1.4 mg
Breastfeeding teens and women1.4 mg

(source: https://ods.od.nih.gov/factsheets/Thiamin-Consumer/

  • Deficiency: Thiamine deficiency (Vitamin B1 deficiency) is a medical condition characterized by low levels of thiamine (Vitamin B1). A chronic and severe form is known as beriberi. There are 2 main types in adults: dry beriberi and wet beriberi. Dry beriberi affects the nervous system, resulting in confusion, numbers of the hands and feet, and pain. On the other hand, wet beriberi affects the cardiovascular system, resulting in shortness of breath, fast heart rate, and leg swelling. 

Riboflavin (Vitamin B2). Riboflavin (Vitamin B2) is part of coenzymes flavin mononucleotide (FMN) and flavinadenine mononucleotide (FAD), and plays a crucial role in oxidative metabolism. 

  • Dietary Sources: A small amount of Vitamin B2 is found in many foods. Main sources are milk and milk products and meat. Other good sources are eggs, whole grain cereals, and fish. 
  • Daily Recommended Intake: 
Life StageRecommended Amount
Birth to 6 months0.3 mg
Infants 7–12 months0.4 mg
Children 1–3 years0.5 mg
Children 4–8 years0.6 mg
Children 9–13 years0.9 mg
Teen boys 14–18 years1.3 mg
Teen girls 14–18 years1.0 mg
Men1.3 mg
Women1.1 mg
Pregnant teens and women1.4 mg
Breastfeeding teens and women1.6 mg

(source: https://ods.od.nih.gov/factsheets/Riboflavin-Consumer/

  • Deficiency: There are two types of riboflavin deficiency (Vitamin B2 deficiency) – primary riboflavin deficiency occurs when the person’s diet is poor in Vitamin B2; and secondary riboflavin deficiency occurs when the body cannot absorb the vitamin properly or if it is being excreted too rapidly. Signs of riboflavin deficiency include mouth ulcers, tongue inflammation, cracked lips, dry skin, cracks at the corners of the mouth, sensitive eyes. 

Niacin (Vitamin B3). Niacin (Vitamin B3) is the name for nicotinic and nicotinamide acid. It is part of enzymes, oxido-reduction systems (nicotinamide adenine dinucleotide -NAD, nicotinamide adenine diphosphate -NADP).

  • Dietary Sources: Food sources of Vitamin B3 include whole grains, fortified cereals, fish, poultry, and meat. 
  • Daily Recommended Intake: 
Life StageRecommended Amount
Birth to 6 months2 mg
Infants 7–12 months4 mg NE
Children 1–3 years6 mg NE
Children 4–8 years8 mg NE
Children 9–13 years12 mg NE
Teen boys 14–18 years16 mg NE
Teen girls 14–18 years14 mg NE
Adult men 19+ years16 mg NE
Adult women 19+ years14 mg NE
Pregnant teens and women18 mg NE
Breastfeeding teens and women17 mg NE

(source: https://ods.od.nih.gov/factsheets/Niacin-Consumer/

  • Deficiency: Niacin deficiency (Vitamin B3 deficiency) may results from inadequate intake of Vitamin B3 and/or tryptophan – a dietary amino acid from which NAD can also be synthesized. Less severe cases of Vitamin B3 deficiency may cause less serious symptoms in the nervous system, digestive system, and skin, such as headaches, fatigue, irritated skin, unexplained digestive problems, and dizziness. Severe Vitamin B3 deficiency can cause a condition known as pellagra. Pellagra affects the digestive system, nervous system, skin, and mucous membranes. 

Pantothenic Acid (Vitamin B5). Pantothenic acid (Vitamin B5) is the combination of pantoic acid and β-alanine. 

  • Dietary Sources: Pantothenic Acid (Vitamin B5) is found in most foods, including whole grain cereals, sweet potatoes, broccoli, beans, lentils, meats, dairy products, and poultry. 
  • Daily Recommended Intake: 
Life StageRecommended Amount
Birth to 6 months1.7 mg
Infants 7–12 months1.8 mg
Children 1–3 years2 mg
Children 4–8 years3 mg
Children 9–13 years4 mg
Teens 14–18 years5 mg
Adults 19 years and older5 mg
Pregnant teens and women6 mg
Breastfeeding teens and women7 mg

(source: https://ods.od.nih.gov/factsheets/PantothenicAcid-Consumer/

  • Deficiency: Pantothenic acid deficiency (Vitamin B5 deficiency) is very rare in people as pantothenic acid is found in nearly all foods. However, clinical trials show that a deficiency may lead to tiredness, nausea, vomiting, sleep disorders, muscle cramps, irritability, hypoglycemia, and upper respiratory conditions. Vitamin B5 deficiency can cause an increased sensitivity to insulin. 

Pyridoxine (Vitamin B6). Pyridoxine (Vitamin B6) acts as a coenzyme, meaning it helps chemical reactions take place. It plays a crucial role in the creation of non-essential amino acids and helps your body break down glycogen. Vitamin B6 also helps your body metabolize fat, protein and carbohydrates and keeps your nervous and immune system healthy. 

  • Dietary Sources: Pyridoxine (Vitamin B6) is found in a wide variety of foods, including peanuts, pork, poultry, soya beans, bananas, fish, milk, and fortified breakfast cereals. 
  • Daily Recommended Intake: 
Life StageRecommended Amount
Birth to 6 months0.1 mg
Infants 7–12 months0.3 mg
Children 1–3 years0.5 mg
Children 4–8 years0.6 mg
Children 9–13 years1.0 mg
Teens 14–18 years (boys)1.3 mg
Teens 14–18 years (girls)1.2 mg
Adults 19–50 years1.3 mg
Adults 51+ years (men)1.7 mg
Adults 51+ years (women)1.5 mg
Pregnant teens and women1.9 mg
Breastfeeding teens and women2.0 mg

(source: https://ods.od.nih.gov/factsheets/VitaminB6-Consumer/)  

  • Deficiency: Isolated pyridoxine deficiency (Vitamin B6 deficiency) is uncommon. Inadequate Vitamin B6 status is typically associated with low concentrations of other B-complex vitamins, such as folic acid and Vitamin B12. Signs of Vitamin B6 deficiency include confusion, depression, swollen tongue, scaling on the lips and cracks at the corners of the mouth, electroencephalographic abnormalities, and weakened immune function. 

Biotin (Vitamin B7). Biotin (Vitamin B7) is involved in a wide range of metabolic processes primarily related to the utilization of amino acids, carbohydrates, and fats. 

  • Dietary Sources: Biotin (Vitamin B7) is found in a number of foods, though in small amounts. This includes egg yolks, milk, cereals, peanuts, and walnuts. Other foods that contain biotin are salmon, pork, whole breads, cauliflowers, bananas, avocados, sardines, and raspberries. 
  • Daily Recommended Intake: 
Life StageRecommended Amount
Birth to 6 months5 mcg
Infants 7–12 months6 mcg
Children 1–3 years8 mcg
Children 4–8 years12 mcg
Children 9–13 years20 mcg
Teens 14–18 years25 mcg
Adults 19+ years30 mcg
Pregnant teens and women30 mcg
Breastfeeding teens and women35 mcg

(source: https://ods.od.nih.gov/factsheets/Biotin-Consumer/

  • Deficiency: A biotin deficiency (Vitamin B7) deficiency isn’t as common as other deficiencies. People who eat a healthy and well-balanced diet can get this vitamin naturally. Still, a biotin deficiency may occur. Symptoms of Vitamin B7 deficiency include red rashes on the skin, dry eyes, hair loss, fatigue, insomnia, loss of appetite, nausea, muscle pain, prickling or burning sensation in the hands and feet, and cracking in the corners of the mouth.

Folic Acid (Vitamin B9). Folate is the natural form of folic acid (Vitamin B9). Folate helps to form RNA and DNA and is involved in protein metabolism. It also plays a key role in breaking down homocysteine – an amino acid that can exert harmful effects in the body if it is present in high amounts. Folate is also crucial in the production of healthy red blood cells and is crucial during periods of rapid growth, such as during pregnancy and fetal development. 

  • Dietary Sources: A wide range of foods naturally contain folate, but folic acid – the form that is added to foods and supplements – is better absorbed. Good sources of folate include fresh fruits, dark green leafy vegetables (i.e. spinach, asparagus, Brussels sprouts), seafood, eggs, and fortified foods and supplements. 
  • Daily Recommended Intake: 
Life StageRecommended Amount
Birth to 6 months65 mcg DFE
Infants 7–12 months80 mcg DFE
Children 1–3 years150 mcg DFE
Children 4–8 years200 mcg DFE
Children 9–13 years300 mcg DFE
Teens 14–18 years400 mcg DFE
Adults 19+ years400 mcg DFE
Pregnant teens and women600 mcg DFE
Breastfeeding teens and women500 mcg DFE

(source: https://ods.od.nih.gov/factsheets/Folate-Consumer/

  • Deficiency: Folic acid deficiency (Vitamin B9 deficiency) is rare because it is found in a broad range of foods. However, certain factors, such as pregnancy, genetics, and digestive disorders may cause a deficiency. Signs of deficiency can include fatigue, weakness, shortness of breath, difficulty concentrating, pale skin, mouth sores, hair loss, and irregular heartbeat. 

Cobalamin (Vitamin B12). Cobalamin (Vitamin B12) is a nutrient that helps keep the body’s nerve and blood cells healthy and helps make DNA. Moreover, Vitamin B12 helps prevent a type of anemia known as megaloblastic anemia. 

  • Dietary Sources: Cobalamin (Vitamin B12) is naturally found in a wide variety of animal foods and is added to some fortified foods. Plant foods doesn’t contain any Vitamin B12 unless they are fortified. Some rich sources of Vitamin B12 include clams, beef liver, poultry, eggs, fish, fortified breakfast cereals, milk, and other dairy products. 
  • Daily Recommended Intake: 
Life StageRecommended Amount
Birth to 6 months0.4 mcg
Infants 7–12 months0.5 mcg
Children 1–3 years0.9 mcg
Children 4–8 years1.2 mcg
Children 9–13 years1.8 mcg
Teens 14–18 years2.4 mcg
Adults2.4 mcg
Pregnant teens and women2.6 mcg
Breastfeeding teens and women2.8 mcg

  (source: https://ods.od.nih.gov/factsheets/VitaminB12-Consumer/

  • Deficiency: Most people get enough Vitamin B12 from the foods they eat. However, some people have trouble absorbing Vitamin B12 from food. Cobalamin deficiency (Vitamin B12 deficiency) causes weakness, fatigue, loss of appetite, weight loss, constipation, and megaloblastic anemia. Nerve problems, such as tingling and numbness in the hands and feet, may also occur. Other symptoms of Vitamin B12 deficiency include confusion, poor memory, balance problems, and soreness of the tongue or mouth. 

Vitamin C. Ascorbic acid (Vitamin C) is an antioxidant that helps protect cells and keeps them healthy. It is needed by the body to produce collagen, the most abundant protein in the body which helps keep blood vessels, bones, teeth, and skin healthy.

  • Dietary Sources: Citrus fruits such as oranges, guava, grapefruit, kiwi, and lemon are the most popular sources of Vitamin C. However, other fruits and vegetables such as broccoli, cauliflower, cantaloupe, strawberries, papaya, and Brussels sprouts are rich sources of Vitamin C as well. 
  • Daily Recommended Intake: 
Life StageRecommended Amount
Birth to 6 months40 mg
Infants 7–12 months50 mg
Children 1–3 years15 mg
Children 4–8 years25 mg
Children 9–13 years45 mg
Teens 14–18 years (boys)75 mg
Teens 14–18 years (girls)65 mg
Adults (men)90 mg
Adults (women)75 mg
Pregnant teens80 mg
Pregnant women85 mg
Breastfeeding teens115 mg
Breastfeeding women120 mg

 (source: https://ods.od.nih.gov/factsheets/VitaminC-Consumer/

  • Deficiency: Ascorbic acid deficiency (Vitamin C deficiency) can occur as a part of general undernutrition; however, severe Vitamin C deficiency causing scurvy is uncommon. Symptoms of scurvy include fatigue, irritability, lethargy, anemia, gum disease, hair loss, poor wound healing, shortness of breath, and joint pain.   

Treatment for Deficiencies 

Deficiency of water-soluble vitamins can be treated by administration of the deficient vitamin. 

The Bottom Line

Water-soluble vitamins include vitamin C and the B vitamins – Thiamine (Vitamin B1), Riboflavin (Vitamin B2), Niacin (Vitamin B3), Pantothenic Acid (Vitamin B5), Pyridoxine (Vitamin B6), Biotin (Vitamin B7), Folic Acid (Vitamin B9), and Cobalamin (Vitamin B12).

Deficiency of water-soluble vitamins can occur if you don’t eat enough foods containing these vitamins, or if your body has trouble processing or absorbing these vitamins. Deficiencies can be treated by administration of the deficient vitamin. 

Disclaimer: The information on this site is not intended to be a substitute for professional medical advice, diagnosis, or treatment. All information contained on this web site is for general information purposes only.

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