Washing your hands and keeping away from people who are ill are always the most effective ways to stay well. But eating healthily so you avoid nutritional deficiencies is another vital weapon in your immune health armory. Tuck into these top foods, suggested by loveFOOD's nutritionist Angela Dowden, to help yourself stay well year-round.

Just one carrot supplies enough beta carotene for your body to convert into 1480mg of vitamin A (that’s plenty more than the daily recommendation of 800mg). Vitamin A is vital for your defenses as it keeps the mucous passages that act as a physical barrier to viruses and bacteria healthy. Eating carrots cooked is the best way as heat softens the cell walls, allowing more beta carotene to be absorbed.

Both red and green peppers have twice the vitamin C content of oranges. Vitamin C is important for maintaining a healthy immune system, particularly during and after intensive physical activity (marathon runners take note). Red peppers are also rich in vital vitamin A.

Another veg with more vitamin C than citrus fruit, kale is also a marvelous provider of vitamin A (from beta carotene) and provides antioxidant vitamin E too. For maximum flavor and health gains, stir-fry with garlic.

Garlic supposedly keeps away vampires but might also slightly up your odds against the common cold. Researchers assessed 146 participants who were given a garlic tablet or a placebo for three months. They found 24 occurrences of the common cold in the garlic group, compared to 65 in the placebo group. Supplements are obviously different from fresh garlic but the freshly crushed bulb is a good source of the active ingredient allicin and delicious too, so tuck in if you love it.

We need sufficient protein for the body's immune system, especially for healing and recovery according to the Academy of Nutrition and Dietetics. Its recommendation is to eat a variety of protein daily (some at each meal) including seafood, lean meat, poultry, eggs, beans and peas, and soya products like tofu, as well as nuts and seeds.

It's not just greens, reds and oranges that help your immune system – mushrooms are a decent source of selenium and B vitamins too. You can even find vitamin D-enriched mushrooms which have 2.5mg of vitamin D per 100g (3.5oz).

All nuts are nutritious but grab a mixture of cashews, brazils and peanuts, and you’ll get particularly good levels of zinc, selenium, iron and vitamin B6. They all play their part in keeping your immune system healthy.

The idea that sugar suppresses the immune system is based on a 1970s laboratory study looking at how white blood cells called neutrophils reacted after being dosed up with sugar. It’s not been replicated and a more recent study (in rats only, admittedly) suggests glucose may help viral infections get better but hamper recovery from bacterial ones. Either way there’s no evidence that a modest amount of sugar is going to make you more susceptible to illness.

With sweetness in mind, using honey to ease a cough makes some sense. In a review of children with a cough, honey relieved symptoms better than diphenhydramine (an antihistamine cough-suppressant), no treatment and placebo. For grown-ups, a honey-sweetened whisky-all-in (hot toddy) at bedtime is a top option if you're coughing at night.

Kefir provides a whole range of beneficial bacteria and yeasts which together may help to make your immune system work more efficiently. Some kefir-specific microbes have been shown to prime the immune system against bacterial infections. A product made the time-honored way with real kefir grains (cultures) is probably best.

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A little cold-pressed rapeseed oil has all the heart-healthy monounsaturated fats of extra virgin olive oil, with the added benefit of a high level of the antioxidant vitamin E. The Academy of Nutrition and Dietetics says it's another important nutrient for your immune system. Vitamin C regenerates vitamin E after it's done its job of protecting cells, so vitamin C-rich vegetables like peppers and leaves are the perfect foods to team it with.

In a Tufts University study, consumers of whole-grains were shown to have an increase of a type of bacteria called Lachnospira, which produces short-chain fatty acids needed for a healthy immune system. Those who consumed a whole-grain diet also showed an increase in T-cells – a type of white blood cells that ward off infection.

Oats supply beta-glucan which has been shown, given as a high dose supplement, to prevent and reduce the symptoms of a common cold. A bowl of porridge won't stop full-on sniffles but it does also provide fiber and B vitamins, and can contribute to lower cholesterol levels.

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Foods high in the specific prebiotic fibers that nourish good gut bacteria include asparagus, onions, garlic, leeks and Jerusalem artichokes. Prebiotics can help stimulate the immune system by improving the balance between anti-inflammatory and inflammatory chemicals called cytokines.

Berries contain a range of phytochemicals including anthocyanins which can boost the health of good bacteria in the gut, in turn benefiting the immune system. Most are also a top source of vitamin C.

Zinc helps the immune system work properly and aid in wound healing, while iron is also important for immune function. The best source of both? Lean red meat. However, follow World Cancer Research Fund guidelines for safe intake – have no more than 500g (about 18oz) cooked red meat a week. For non meat-eaters, nuts combine good amounts of these nutrients too.

Tuna is a protein rich in selenium, which many people have in short supply in their diet. A deficiency of this trace mineral was shown several years ago to increase the severity of a flu virus infection in mice. The same hasn’t been proven in people but it makes sense to have selenium on your radar when you’re trying to dodge a virus.

Another fishy wonder for your immune system, sardines also contain selenium, along with a smorgasbord of nutrients including vitamin B12, iron and vitamin D. They all contribute to building the body's resilience to infections.

If you don’t drink enough fluids, those all-important nasal passages can dry out and make infection more likely to take hold. Water doesn’t hold the monopoly in being able to hydrate – teas, coffee, soups and juices can all count.

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You'll get all the vitamin C you need from a healthy diet and extra in a supplement won’t stop you catching a cold. However if you're already infected, vitamin C might shorten symptoms – by about a day – if you have at least 200mg daily, according to a Cochrane Library review.

One of the simplest ways to keep your immune system fit is to get an early night. A study published in the journal Sleep, found that sleeping six hours a night or less correlated with people being four times more likely to catch a cold, compared to people sleeping more than seven hours in a night.

In a review in the Korean Journal of Family Medicine, people who did regular, moderate-intensity exercise such as brisk walking had a 27% lower risk of contracting a cold than those who didn't exercise. Regular exercise boosts circulation and leads to a higher number of infection-fighting white blood cells. But only venture outside if you're fit and well, with no symptoms such as a fever or cough.

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