Five foods for an immune kick-start

Winter is upon us and, along with the sharp temperature drop and the preparations for Christmas, comes the expectation of a bout of cold or flu. But it is important to understand that suffering a drawn-out winter cold is not inevitable. It is possible to prepare by boosting the immune system to at least minimise, if not completely avoid, the risk. A good place to start is the diet: good diet is central to overall good health and research has found that many natural substances and nutrients within food can enhance a positive immune response. The following foods are good examples of those that can help fuel your immune system and aid your body in fighting infection.

Red peppers

Vitamin C is perhaps the most important and well documented vitamin for supporting a healthy immune system; oranges and other citrus fruits are usually first in line when we want increase our vitamin C intake.  However, did you know that one large red bell pepper contains over 200mg of vitamin C, almost three times the amount found in an average orange!  Red peppers are also rich in the compound lycopene, normally associate with tomatoes and one of the most potent antioxidants found in food.  As well as supporting immune function by scavenging free radicals, lycopene has  been linked to the prevention of diseases such as cancer.  Red peppers are also a rich source of the amino acid tryptophan, shown to be helpful for sleep, combating stress, weight loss and mood enhancement.  Adding some sliced red pepper to sandwiches and salads, or crudités with humus, may just help to keep you both happy and healthy!


Garlic contains thiosulfinates and sulfoxides, powerful compounds that help the body prevent and fight infections.  Importantly, consuming garlic doesn’t stop the inflammatory response altogether since it is an essential part of the immune system for certain infections, but rather it modulates it and helps to prevent it from going awry.   You can add garlic when cooking, eat it raw if you dare or, for those of you who wish to keep your friends close, purchasing garlic capsules is a less offensive alternative.


Broccoli is a very useful vegetable, packed with phytonutrients and phytochemicals, including sulforaphane – an organosulfur compound with a myriad of health benefits.  Sulforaphane is found in a number of cruciferous vegetables such as cauliflower, cabbage and kale; the richest source of sulforaphane is broccoli sprouts, which have concentrations approximately 10 times that of mature broccoli.   Sulforaphane not only boosts the immune system but is also a powerful antioxidant and stimulator of natural detoxifying enzymes. Broccoli is also a good source of vitamin C, as well as being particularly rich in vitamin K, involved in immune function and wound repair.  In fact, 100g cooked broccoli provides the RDA for vitamin C and twice the RDA for vitamin K.

Carrot juice

Carrots are a particularly rich source of beta-carotene, a powerful phytonutrient that boosts the immune system’s production of infection-fighting natural killer cells and T cells, which help to kill off undesirable microbes. Cooking carrots destroys many of the health benefits, but their raw juice retains all the nutrients. Carrot juice is not only a deliciously sweet alternative to eating cooked carrots but is also a rich source of other immune boosting nutrients, including vitamin C and many B vitamins.

Brazil nuts

Many studies suggest that the body needs selenium in order for the immune system to work properly. Selenium, along with other minerals such as zinc and magnesium, can influence how we respond to infection by increasing the number of white blood cells, which boosts the body’s ability to fight illness and infection. Nuts, especially Brazil nuts, are a great source of selenium, magnesium and zinc.  In fact, just a few Brazil nuts daily will provide the current RDA of 70μg.  For those who don’t like nuts, shellfish, fish, liver and sunflower seed are also rich sources of this important mineral.

Whether we are feeling mildly under the weather or have a full-blown cold, a fully functioning immune system is key to a swift recovery.  Incorporating a good variety of unprocessed, unrefined foods in your diet will help support a strong immune system.   Fruit and vegetables are particularly rich in immune supporting nutrients, many of which need to be consumed on a regular basis to avoid depletion of body stores.  Surprisingly, many of us still fall far short of the government recommendation of ‘5-a-day’.

Got a health-related question? Email Dr Nina Bailey, our in-house Nutrition Scientist.

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