Vitamin Supplements Factsheet - Water Soluble Vitamins

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Water soluble vitamins are Vitamin C and B complex which includes B1 (thiamine), B2 (riboflavin), B6 (pyridoxine), niacin (nicotinic acid), B12, folic acid, pantothenic acid, and biotin. They are inactive in their free states, and become activated in their coenzyme form in the body. As the name suggests these are water soluble, thus not stored in our bodies and must be replaced on a day to day basis. These are abundantly available in fresh fruits and vegetables, thus optimum consumption of food sources can ensure to keep their deficiencies at bay.

However, certain water soluble vitamins are commonly consumed in the form of dietary supplements, these include Vitamin C, and B vitamins like folic acid, B12, and B6. Read more to find out about these vitamins.


Vitamin C

Vitamin C deficiency is very rare, but when present results in scurvy which causes  fatigue, inflammation of the gums, small red or purple spots on the skin, joint pain, poor wound healing, and corkscrew hairs. Depression, swollen, bleeding gums and loosening or loss of teeth are additional signs of vitamin requirement. If untreated it may even prove to be fatal.


Who Is At Risk of Vitamin C Deficiency

  • People consuming little or no (less than 10g) vitamin C per day

  • Smokers and passive smokers as they require more Vitamin C to repair damage caused by free radicals. People who smoke need 35 mg more vitamin C per day than nonsmokers

  • Infants fed with evaporated or condensed Cow’s milk.

  • People whose food choices are limited

  • People with severe malabsorption due to certain medical conditions like some types of cancer, and kidney disease requiring hemodialysis.


Toxicity of Vitamin C

Excess intake of Vitamin C results in diarrhea, nausea, stomach cramps, and sometimes in a condition termed hemocromotosis which causes excess iron storage in the body leading to iron overload and damage body tissues. The tabular given below would let you know about tolerable limits of intake.


Life Stage

Upper Safe Limit

Birth to 12 months

Not established

Children 1–3 years

400 mg

Children 4–8 years

650 mg

Children 9–13 years

1,200 mg

Teens 14–18 years

1,800 mg


2,000 mg


Pyridoxine (Vitamin B6)

Pyridoxine is vital as its deficiency can result in a range of symptoms, including anemia, itchy rashes, scaly skin on the lips, cracks at the corners of the mouth, and a swollen tongue. In severe cases ir may cause depression, confusion, and a weakened immune system. B6 deficient children are extremely sensitive to hearing or seizures, and also are very irritable.


Who Is At Risk of Vitamin B6 Deficiency

  • People poor kidney function, including those undergoing dialysis and transplant.

  • People with autoimmune disorders, like people with rheumatoid arthritis, celiac disease, Crohn's disease, ulcerative colitis, or inflammatory bowel disease sometimes have low vitamin B6 levels.

  • Alcoholics


Toxicity of Vitamin B6

Overdose of B6 can only occur due to supplement abuse for a year or longer, causing severe nerve damage (losing control over bodily movements), painful and unsightly skin patches, extreme sensitivity to sunlight, nausea, and heartburn. These symptoms disappear when intake of the supplement is curbed. Given below are the tolerable upper limits of B6 consumption, these do not apply to people who are taking extra B6 under physician supervision.


Life Stage

Upper Safe Limit

Birth to 12 months

Not established

Children 1–3 years

30 mg

Children 4–8 years

40 mg

Children 9–13 years

60 mg

Teens 14–18 years

80 mg


100 mg


Nutrient Drug Interactions

B6 interacts with the antibiotic prescribed for tuberculosis worsen any seizures and nerve cell damage that the drug might cause.

A few epilepsy drugs could decrease vitamin B6 levels and reduce the drugs' ability to control seizures


Folic Acid (Vitamin B9)

Folic acid dietary supplements are very important for pregnant women as its deficiency puts them  are at greater risk of giving birth to low birth weight, premature, and/or infants with neural tube defects. It can also result in a slower growth rate, anemia and weakness, sore tongue, headaches, heart palpitations, irritability, forgetfulness, and behavioral disorders.


Who Is At Risk of Vitamin B9 Deficiency

  • Pregnant and Lactating women

  • Alcoholics

  • People with malabsorption syndromes

  • People undergoing kidney dialysis

  • People with liver disease and certain types of anemia

  • People using medications that interfere with folate utilization like certain anticonvulsant drugs, metformin, barbiturates, certain medication used to control inflammation, and certain diuretics.


Toxicity of Vitamin B9

Folic acid supplementation can mask Vitamin B12 deficiency, but it only cures the associated anemia but has no effect on the changes in the nervous system due to B12 deficiency. Given below is the upper tolerance limits of folate, but these refer to the amount of synthetic form of the vitamin.



Males and Females



























Vitamin B12

Vitamin B12 deficiency affects between 1.5% and 15% of the public, who suffer from tiredness, weakness, constipation, loss of appetite, weight loss, and megaloblastic anemia. Other symptoms include  problems with balance, depression, confusion, dementia, poor memory, and soreness of the mouth or tongue. Severe deficiency can lead to nervous system damage. In infants it causes failure to thrive, problems with movement, delays in reaching the typical developmental milestones, and megaloblastic anemia.


Who Is At Risk of Vitamin B12 Deficiency

  • Elderly with insufficient hydrochloric acid in their stomach to absorb the vitamin B12 naturally present in food.

  • People with pernicious anemia whose bodies do not make the intrinsic factor needed to absorb vitamin B12.

  • People who have undergone gastrointestinal surgery (like weight loss surgery), and who have digestive disorders, such as celiac disease or Crohn's disease.

  • Vegetarians and vegans

  • Certain drugs interfere with certain antibiotics, proton inhibiter pumps, metformin, and histamine.


Toxicity of Vitamin B12

Excess B12 intake is known to cause no harm.


Water soluble vitamins

Vitamin Supplements – Facts you should know

  • Natural sources of vitamins are best absorbed in the body,  supplements not replacements!

  • Always consult your health care practitioner before consuming supplements.

  • Read nutrition labels carefully and get to know about foods fortified with water soluble vitamins, and do not forget to include these when you are calculating you daily vitamin intake.

  • Some supplements interact with medicines and over the counter drugs.

  • Some supplements can cause complications during surgery

  • Always ensure the supplements you are using are legitimate, do not fall for tall claims.

  • Ensure from authentic sources if the supplements are safe (eg. FDA)

  • In case of adverse reaction consult your physician immediately and also report the supplement directly to FDA


Learn more about fat soluble vitamins from our article.


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