You don't literally have to eat an apple a day to keep the doctor away, but a healthy diet and lifestyle habits can improve your chances of staying free from illness.
Here's some easy and natural ways to strengthen your immune system and prevent colds and the flu all year long.
80 per cent of our immune system is located in our gut, so it's really important to keep our intestines healthy.
One way is to eat probiotic foods like yoghurt, sauerkraut and kimchi. Another is to start using Thieves Oil, which is a blend of cloves, lemon, cinnamon, rosemary and eucalyptus oils. It's been proven to be more than 99 per cent effective against air-borne bacteria.
Get enough vitamin D. Either get in the sun for 20 minutes a day or start eating more eggs, cheese, milk and oily fish like mackerel.
Zinc, which most people don't get enough of, is essential for immune cell function. Foods high in zinc include oysters, lean beef and pumpkin seeds.
Eliminating sugar is a great way to prevent illness. Refined sugar drastically decreases your immune function. If you're starting to feel like you're coming down with something, avoid sugar because it could be the breaking point.
The NHS says that if you find yourself craving a sugary treat, try a juicy clementine or satsuma instead, or sweet dried fruits such as dates or raisins.
Finally, don't forget to get enough sleep because an insufficient amount weakens the immune system.