If you are feeling tired most of the time, you must listen to your body as it is showing signs of low immunity. Deficiency in vitamin D, vitamin C, and iron can lead to low immunity and increase the risk of infection. There is a large population that is at risk of vitamin deficiency and the right vitamin and dietary supplement should be used to overcome it. Even though you intake a well-balanced diet, you may need a supplement. Note 'small amount' of vitamin deficiency isn't good for you, but vitamin overdose is also not healthy! Instead, these supplements should only be taken after careful analysis by your health advisor.