Title: Water-soluble vitamins

Key words: B-complex vitamins, water soluble, thiamin, riboflavin, niacin, pantothenic acid, pyridoxine, cyanocobalamin, folic acid, biotin, choline, inositol, vitamin C

Date: July 2000

Category: 3. Micronutrients

Type: Article

Author: DJE Candlish

 

Water-soluble vitamins

The B-complex vitamins

There are a number of different B vitamins which are often grouped together as ‘the B-complex’. This is because they have synergistic effects and are more effective in combination. All of the B-complex vitamins are water soluble and so a daily intake of each individual vitamin is needed.

Vitamin B1 (thiamin)

Sources

Vitamin B1 occurs in yeast extract, meat, wholegrain cereals, rice, beans, nuts and potatoes.

Main functions

  • needed for the efficient release of energy from carbohydrates and fats
  • supports heart, nervous system and muscle function
  • needed for correct foetal growth during pregnancy

Results of deficiency

Severe deficiency is rare in developed countries, but in poor countries it can cause beriberi, with symptoms including muscle weakness, nausea, loss of appetite and oedema. Less severe deficiency, common among alcoholics, can cause mental problems, including depression, memory loss and difficulties in concentrating.

Recommended intake

Age

0–9 months

10–12 months

1–3 years

4–10 years

11–14 years (f)

11–14 years (m)

15–18 years (m)

15+ years (f)

19–50 years (m)

50+ years (m)

Pregnancy

Lactation

intake (m g/day)

200

300

500

700

700

900

1,100

800

1,000

900

900

1,000

Who may benefit from supplements

  • anyone wanting to alleviate tiredness and improve appetite
  • the elderly and pregnant women, as their diet may not provide enough for their needs
  • alcoholics, as their problem very often leads to deficiency
  • people recovering from surgery or accidents

Precautions

There are virtually no side effects associated with thiamin supplements, even when taken for long periods of time at relatively high doses.

 

 

Vitamin B2 (riboflavin)

Sources

Good dietary sources of riboflavin include yeast extract, wholegrain cereals, liver and kidney, dairy products and eggs

Main functions

  • riboflavin is a component in two enzymes that play a key role in converting dietary fats, sugars and proteins into the building blocks used by the body
  • riboflavin is needed for healthy skin, eyes and hair

Results of deficiency

The symptoms of riboflavin deficiency include:

  • anaemia
  • over sensitivity to light
  • inflamed eyelids
  • dermatitis
  • dry lips, cracked tongue

Recommended intake

Age

0–12 months

1–3 years

4–6 years

7–10 years

11–14 years (m)

11+ years (f)

15+ years (m)

Pregnancy

Lactation

intake (m g/day)

400

600

800

1,000

1,200

1,100

1,300

1,400

1,600

Who may benefit from supplements

  • vegetarians and vegans, whose diet restricts their intake of riboflavine from food
  • people with anaemia, as riboflavin deficiency may be the cause
  • women taking the contraceptive pill, as this tends to deplete the body of riboflavine

Precautions

There are no recorded harmful effects of riboflavin supplements. The urine may sometimes become more intensely yellow in colour, but this effect is harmless.

 

 

Vitamin B3 (niacin)

Sources

Niacin occurs in meat, fish and some vegetables

Main functions

  • involved in many metabolic processes, including glycolysis (breakdown of glycogen for energy), fat synthesis and cell respiration
  • needed for healthy skin
  • involved in control of cholesterol levels

Results of deficiency

  • severe deficiency causes pellagra, with diarrhoea, dermatitis, inflamed mucous membranes and dementia
  • mild deficiency causes nervous tension and dermatitis

Recommended intake

Age

0–6 months

7–9 months

10–12 months

1–3 years

4–6 years

7–10 years

11–14 years (f)

11–14 years (m)

15–18 years (f)

15–18 years (m)

19–50 years (f)

19–50 years (m)

50+ years (f)

50+ years (m)

Lactation

intake (mg/day)

3

4

5

8

11

12

12

15

14

18

13

17

12

16

15

Who may benefit from supplements

  • people with nervous problems and/or dermatitis
  • Niacin supplementation is also used in the treatment of alcoholics and schizophrenics, and to lower cholesterol levels, but the very high doses used mean this should only be under medical supervision.

Precautions

Niacin exists in two forms, nicotinic acid and nicotinamide. High doses of nicotinic acid can cause flushing, and the maximum recommended dose is 100mg/day. Daily doses of nicotinamide of up to 2000mg/day are considered to be safe. Nicotinic acid should not be taken by people with diabetes, gout, stomach ulcers or liver disorders.

 

 

Vitamin B5 (pantothenic acid)

Sources

Pantothenic acid occurs in virtually all foods. Good dietary sources of pantothenic acid include liver and other meat products, yeast, nuts and wholegrain cereals.

Main functions

  • plays a key role in the release of energy from food
  • the production and repair of body tissues and red blood cells
  • the production of antibodies and to help to increase disease resistance

Results of deficiency

  • tiredness and insomnia
  • depression
  • loss of appetite
  • skin disorders
  • indigestion

Recommended intake

The level of pantothenic acid in the body is affected by a wide range of variables, so there is no specific reference nutrient intake for the vitamin. However, a daily intake of 3–7mg is believed to meet the needs of most adults.

Who may benefit from supplements

  • alcoholics and smokers, as they are usually deficient
  • women taking contraceptive pills, as these deplete the body of Vitamin B5
  • pregnant women, who have an increased need

Precautions

No harmful effects have been reported in association with pantothenic acid supplements

 

 

Vitamin B6 (pyridoxine)

Sources

Pyridoxine is found in wholegrain cereals, meat, vegetables and soybeans

Main functions

  • the production of energy and metabolism of amino acids
  • helping to keep the skin, teeth, gums and nervous system healthy

Results of deficiency

  • premenstrual tension
  • seborrhoea (a skin problem)
  • depression or confusion
  • anaemia, diarrhoea and vomiting in infants

Recommended intake

Age

0–6 months

7–9 months

10–12 months

1–3 years

4–6 years

7–10 years

11–14 years (m)

11+ years (f)

15–18 years (m)

19+ years (m)

intake (m g/day)

200

300

400

700

900

1,000

1,200

1,000

1,500

1,400

These values are based on a diet in which protein provides 14.7% of the average energy intake. Pyridoxine requirements increase with increasing levels of protein in the diet

Who may benefit from supplements

  • supplements can be used to improve appetite as well as to help alleviate the symptoms of morning sickness, premenstrual tension and depression
  • women on the pill or undergoing hormone replacement therapy, as oestrogen can reduce absorption
  • alcoholics and smokers, as they are usually deficient

Precautions

Generally, there are no toxic effects due to pyridoxine supplements. However, high doses (greater than 100mg daily) should only be taken under medical supervision. Doses above 200mg may cause nerve damage, with symptoms including numbness and tingling.

 

Vitamin B12 (cyanocobalamin)

Sources

Good sources of cyanocobalamin include liver, fish and other meat products, and wholegrain cereals, eggs, yeast and milk

Main functions

  • development of healthy blood cells and nervous system
  • the metabolism of fatty acids
  • helps maintain the protective myelin sheath around nerves

Results of deficiency

  • anaemia
  • menstrual problems
  • severe deficiency may cause nerve damage and dementia

Recommended intake

Age

0–6 months

7–12 months

1–3 years

4–6 years

7–10 years

11–14 years

15+ years

Lactation

intake (m g/day)

0.3

0.4

0.5

0.8

1.0

1.2

1.5

2.0

Who may benefit from supplements

  • vegans and vegetarians, pregnant and lactating women, the elderly, as their diets may not meet their needs
  • alcoholics and smokers, as they are usually deficient
  • people taking medicine for gastrointestinal disorders, as these may affect absorption
  • anyone wishing to alleviate tiredness and improve appetite

Precautions

Cyanocobalamin supplements are virtually free of side effects, even at high doses

 

 

Folic acid

Sources

Folic acid is found in yeast, liver, wheatgerm and fresh green vegetables

Main functions

  • the regeneration and division of cells
  • the production of DNA and the formation of healthy cells
  • the normal development of the neural tube in the foetus

Results of deficiency

  • anaemia, with symptoms including weakness, insomnia, mental problems and breathlessness
  • gastric disturbances and sores in the mouth

Recommended intake

Age

0–12 months

1–3 years

4–6 years

7–10 years

11+ years

Pregnancy

Lactation

intake (m g/day)

50

70

100

150

200

300

260

Who may benefit from supplements

  • women planning pregnancy and pregnant women, to avoid developmental problems in their child
  • people intolerant to gluten (coeliac disease), as this affects absorption
  • the elderly, as their diet may be inadequate
  • alcoholics, as they are usually deficient

Precautions

There is very little risk of side effects with folic acid supplements, although very high doses (>15mg/day) should be avoided

 

 

Biotin

Sources

Good dietary sources of biotin include yeast, liver and other meats, wheatgerm and fatty fish

Main functions

  • needed for healthy skin, red blood cells and mucous membranes and the proper function of the circulation and nervous system
  • plays a role in the processing of carbohydrates, fats and proteins

Results of deficiency

Deficiency is more common in infants than adults. Symptoms can include:

  • scaly dermatitis
  • loss of appetite
  • diarrhoea, vomiting

Recommended intake

The daily recommended intake is 10–200m g.

Who may benefit from supplements

  • children with dermatitis, as deficiency is a common cause
  • pregnant women, as their need for biotin is increased
  • eczema and dermatitis sufferers may be helped

Precautions

Biotin supplements are not associated with adverse effects, even when given at doses of up to 40mg/day

 

 

Choline and inositol

Sources

The body can produce small amounts of these substances, so some authorities do not classify them as vitamins. The best dietary sources of choline and inositol include liver, heart and other meats, nuts, pulses and citrus fruits.

Main functions

  • involved in the breakdown of fats
  • help to control cholesterol levels, and may improve resistance to disease
  • involved in the transmission of signals in the nervous system

Results of deficiency

  • severe deficiency involved in kwashiorkor, a disease of malnutrition causing weakness and liver damage
  • eczema
  • hypertension
  • nervous tension

Recommended intake

The recommended intake of both inositol and choline is between 500–1000mg/day

Who may benefit from supplements

  • people with high cholesterol levels and/or coronary heart disease, may benefit from choline
  • people with eczema ,or suffering from stress, may benefit from inositol

Precautions

Both choline and inositol supplements are generally free of side effects, although high doses may cause depression

 

 

Vitamin C (ascorbic acid)

Sources

Good dietary sources of vitamin C include fresh fruit and vegetables, particularly blackcurrants, citrus fruits and potatoes. Humans are one of the few animal species unable to synthesise their own vitamin C

Main functions

  • involved in a wide range of processes in the body and also has antioxidant properties
  • the production of collagen requires vitamin C
    helps the immune system to work properly
  • helps the body to absorb and process iron
  • assists the healing process and promotes growth

Results of deficiency

  • scurvy, with symptoms including bleeding gums, joint and muscle pain, dry skin and bruising
  • chronic deficiency may contribute to the risk of cancer and heart disease

Recommended intake

Age

0–12 months

1–10 years

11–14 years

15+ years

Pregnancy

Lactation

intake (mg/day)

25

30

35

40

50

70

Who may benefit from supplements

  • the elderly, the ill, pregnant or lactating women, athletes, smokers, as their dietary intake may not meet their needs
  • alcoholics, as they are usually deficient
  • people taking antibiotics, steroids and/or the contraceptive pill, as these can affect absorption

Precautions

High doses of vitamin C should be avoided by people with kidney stones and may cause mild diarrhoea, but otherwise vitamin C is not associated with harmful side effects