In this winter period, coupled with an ongoing epidemic, it is as important as ever to take good care of your immune system, in order to avoid being contaminated or catching a cold. Read on to find out the ideal diet that will strengthen your immune system, and allow you to face this tricky period in the best possible way.What is the immune system?The immune system is important because it develops our immune defences, which can then resist against infections, and maintain one's health. In short, it is the body's ability to defend itself against threats to its survival. These threats can be of three different kinds:Microbes (viruses, bacteria, fungi) and therefore the coronavirusCancer cellsForeign bodies (a splinter, transplanted organ, piece of glass etc.)However, depending on the individual, the immune system is more or less resistant. It all depends on how healthy your lifestyle is. Diet, tobacco, alcohol, stress, sleep and physical activity are all factors that can impact your immune system, and make it more or less effective.Foods that are good for the immune systemSome foods boost the immune system and strengthen it. To know which ones to choose, you need to know about their properties and their benefits for the body. They should contain the following elements:Vitamin AVitamin A stimulates the production of antibodies and white blood cells. It is found in egg yolk, butter, and all dairy products.Vitamin CVitamin C fights against free radicals, absorbs iron, and stimulates the immune system. You can fill up on Vitamin C with lemons, red peppers and blackcurrants.ZincThe lack of zinc in sufficient quantities can cause immune system dysfunction. You can find it in (raw) oysters, shellfish such as crab or lobster, beef, or roasted sesame or squash seeds, and also in lentils.Probiotics or prebioticsThese are good bacteria that protect the intestines (the flora or microbiota). Intestinal flora is linked to the immune system since it represents 70% of it. It is therefore important to take good care of it by adopting a healthy diet. Go for yoghurt, miso, sauerkraut, garlic, chia seeds, onions, oats and citrus fruits.In short, eat a diet rich in fermented and dairy products. Stock up on fruits and vegetables, and don't forget to eat seafood and beef regularly. Add chia, squash or sesame seeds to your dishes. Your immune system will be stronger than ever!