Vitamins are micronutrients, which means that we only need them in small amounts. They are important for maintaining health, especially in cell growth and metabolism. Vitamins can be divided into 2 main groups, fat-soluble and water-soluble vitamins. Water-soluble vitamins (vitamin B & C) can dissolve in water and the excess from intake will be excreted through urine. Fat-soluble vitamins (vitamin A, D, E, & K), on the other hand, can only be dissolved in fat and have to rely on fat for digestion and absorption. Prolonged excessive consumption can lead to toxic effects.
Vitamins are found in various food groups. It is easy to achieve adequate intake by following a balanced diet according to the “Healthy Eating Food Pyramid” recommendations.
Water-soluble vitamins (vitamin B & C) are labile micronutrients. They can be destroyed easily during food storage, processing, and cooking. Here are some ways to minimize nutrient loss when preparing the food.
Fruits and vegetables are rich in vitamins. A daily intake of 3-4 servings (6-8 taels) of vegetables and 2-3 servings of fruits daily can provide most of the recommended vitamins. For elderly with impaired chewing ability, they can choose fruits with softer texture, such as papaya, watermelon, banana, kiwifruit, dragon-fruit, etc. and cut fruits into small pieces before eating. Although the levels of water-soluble vitamins in vegetables after prolonged cooking decrease substantially, they still contain fat-soluble vitamins, minerals and dietary fibre, which are all beneficial to health. For those who have chewing problems, proper cooking and texture modification methods can help them to have adequate fruits and vegetables intake and avoid the unnecessary use of vitamin supplements.
The best way to get vitamins is through a nutritionally balanced diet as nutrients can be better absorbed and utilized. Supplements are not substitutes for healthy eating. They do not provide minerals, fibre, antioxidants and phyto-chemicals that we get from foods. When nutrient intakes are insufficient, such as in people with health problems that prevent them from eating properly, vitamin supplementation may complement their diets in achieving the nutrition recommendations. Until now, there is little evidence to show that vitamin intakes higher than the suggested level can further promote health in healthy individuals.
There are many formulations of vitamin supplements available in the market with different dosages which may not be suitable for everyone. The levels of vitamins contained in the supplement are usually much higher than the recommended level. Side effects may occur with prolonged intake of certain vitamins. For example, liver toxicity may occur with excessive intake of vitamin A. Adverse effects from vitamin C supplement can include stomach discomfort and risk of developing kidney and urinary stones. Before considering taking a supplement, consult your doctor or dietitian.