A Vitamin is a micronutrient element that is needed in an adequate quantity by the body for it to function normally.
Vitamins is are usually obtained through the consumption of a variety of food such as meat, liver, fish, grains, nuts, vegetables and fruits. Besides food resources, vitamins may also be consumed in pharmaceutical dosage forms to fulfill individual daily needs.
Vitamin products in the market are available in various forms, such as capsules and tablets. There are also preparations in the form of chewable tablets or effervescent tablet for those who have difficulties in swallowing capsules or tablets. Multivitamin preparations are also available in the market for easier consumption of vitamins and minerals as according to individual requirement.
Function of vitamins
Generally, vitamins act as catalysts to help enzymes in certain chemical reactions in the body. Consumption of different kinds of vitamins may help in the development of body tissues control of metabolism as well as maintaining the health of skin, eyes, teeth and bone.
Vitamin must be consumed in sufficient quantity to prevent certain illness. Lack of vitamins may cause illnesses such as scurvy (due to vitamin C insufficiency), rickets (due to vitamin D insufficiency), pellagra (due to vitamin B3 insufficiency) or beri-beri (due to vitamin B1 insufficiency).
Types of vitamins
Vitamins can be categorized into two types, which are water-soluble vitamins and fat-soluble vitamins. Examples for each type of vitamins are shown below:
The dose of vitamin that should be taken are different for each individual depending on the gender and age. It must also be taken into consideration if the individual is having certain illness, pregnant or breastfeeding.
For example, for an individual with bone problems such as osteoporosis, would have a higher requirement of vitamin D than the recommended dose to help calcium absorption into the bone, and strengthening the bone. For a pregnant woman, the require dose of folic acid is higher to prevent neural tube defect, which is the defect of the central nervous system (spinal cord and brain in the unborn baby).
The table below shows the recommended doses as well as the maximum doses allowed in a day for an adult according to the types of vitamin :
Recommended dose per day
Maximum dose allowed per day
|A||3000 IU||5000 IU|
|B1||1.2 mg||100 mg|
|B2||1.3 mg||40 mg|
|B3||14 mg||15 mg|
|B5||5 mg||200 mg|
|B6||1.3 mg||100 mg|
|B7||0.03 mg||0.9 mg|
|B9||0.4 mg||0.9 mg|
|B12||0.024 mg||0.6 mg|
|C||90 mg||1000 mg|
|D||600 IU||1000 IU|
|E||22.4 IU||800 IU|
|K||0.09 mg||0.12 mg|
Vitamins should not be consumed beyond the maximum dose to avoid any side effects. Generally, fat-soluble vitamins may have the higher risk of side effects as compared to water-soluble vitamins because fat-soluble vitamins can be stored in body tissues and liver. This may lead to toxicity after a certain period of time.
Depending on the types of vitamin, consumption of vitamins that exceed the maximum limit may cause side effects such as nausea, constipation, headache, abdominal pain, tiredness, confusion or blurred vision.
- Ensure that you read the label on vitamin supplement products to avoid accidentally taking two or more products with the same vitamins.
- Do not take the vitamin more than the dose stated on the label of the product.
- If you are having any health conditions or are taking certain medicines, do inform and discuss with your doctor before taking any vitamin supplement products or other health supplement products to prevent drug interactions.
- Seek medical attention immediately if you suspect having symptoms of toxicity due to excessive consumption of vitamins.
- MIMS Gateway Service Portal
- Institute of Medicine : Recommended Dietary Allowances and Adequate Intakes, Vitamins (2011)
- Biro Pengawalan Farmaseutikal Kebangsaan : Drug Registration Guidance Document (First Edition, Jan 2013)
- WebMD : Vitamins and Supplements Lifestyle Guide (www.webmd.com, 2013)
|Last Reviewed||:||17 July 2014|
|Writer||:||Hazlin bt. Othman|