When seasonal flu seems to be around every corner, indulging in carbohydrates and sugary stuff is one of the worst things we could possibly do. With winter now in full swing, people should, more than ever, make an effort to eat right, say nutrition experts.

"Garlic and its main component, allicin, represent an incomparable defence, especially in winter,” said Fawzi El-Shobaki, professor of nutrition at the National Research Institute. "Garlic, if eaten fresh, boosts the immunity system in several ways, mainly by increasing production of the white blood cells that combat infections and germs.”

Citrus fruits, meanwhile, represent a rich source of Vitamin P, or flavonoids, and Vitamin C, the recommended daily dose of which is 60 mg. Needles to say, fresh fruits and vegetables are far better than supplements in terms of their nutritional value and medical efficacy.

Various sources of Vitamin E, a potent antioxidant, are also highly recommended, such as pumpkins, potatoes, squash and parsnips. Seasonal nuts – such as chestnuts, almonds, hazelnuts and walnuts – are also an excellent source of Vitamin E.

According to El-Shobaki, it is also important to consume food containing omega-3 fatty acids – also known for combating infections – at least twice a week. Good sources of omega-3 include walnuts, salmon, tuna, mackerel and olive oil.

One should also pay special attention to food containing Zinc, which also combats infections and flu by increasing production of white blood cells. Zinc is found in pumpkins, dairy products, beef, sweet corn and turkey.

El-Shobaki also urges people to make an effort to eat more wholegrain wheat and brown rice. These complex carbohydrates contain selenium, which serves to bolster the immune system and raise the effectiveness of natural killer cells.

Abdel Hadi Mesbah, immunology professor and fellow at the American Academy of Immunology, for his part, emphasizes the supreme importance of antioxidants in combating the free radicals that swarm throughout our body and cause various health problems.

"Theses free radicals soar with increased consumption of fats and exposure to radiation or toxic chemicals,” he said. “Then they attack DNA in the cell, which causes various problems.”

“The key to combating this process is to consume food rich in antioxidants, which fight free radicals and markedly boost the immune system," Mesbah explained. “Immunity-boosting antioxidants include certain vitamins and minerals found everywhere around us – cheap and easily available types of food that help counter the germs that flourish in cold weather and poorly-ventilated areas.”

Mesbah calls good nutrition “the first line of defence” against cold and flu, but stresses that vitamin sources should be consumed on a regular basis before – not merely after – one is stricken with illness.