With kids back in school, flu season is top of mind for many parents. Resurgent H1N1 virus, seasonal influenza and the common cold are expected to bring sneezing, coughing, aches and chills.
While you can't prevent these viruses from making their fall appearance, a healthy diet can bolster your immune system making it better prepared to respond. The right nutrients and certain supplements may also help ease cold and flu symptoms.
Flu season starts in October and lasts until April and colds typically occur between September and May. It's no coincidence we get sick more often during the fall and winter. Cooler temperatures keep us indoors where we're more likely to come into prolonged contact with others who are infected.
Vitamin D is thought to play a role in seasonal flu. The nutrient increases the body's production of proteins that destroy viruses, including influenza. Given that vitamin D is synthesized in our skin on exposure to sunlight, low blood levels of the vitamin in the winter months may make us more susceptible to getting the flu. Canadian researchers are currently investigating vitamin D for swine flu protection.
Your first defence against colds and flu is good personal hygiene. Frequent and thorough hand washing, covering your mouth when coughing or sneezing, and cleaning surfaces that you touch with germ-killing disinfectant will help protect you, your family and your co-workers from infection-causing germs.
Adequate sleep also helps guard against infection. Sleep deprivation disrupts immune function and increases levels of proteins in the body associated with inflammation. Aim for seven to eight hours of sleep each night; children and teenagers need nine to 10 hours.
A healthy immune system also needs regular exercise. Studies show that physically active people get fewer colds each year than do their sedentary peers. But don't overdo it. Intense workouts or prolonged endurance exercise steps up the production of stress hormones, which can hinder the body's ability to fight infection. Aim to get 30 to 60 minutes of light to moderate activity most days of the week.
When it comes to nutrition, a healthy diet that includes protein and plenty of fruit and vegetables will help build a strong immune system. While no single food or supplement is guaranteed to keep winter viruses away, studies suggest the following strategies may help.
Vitamin C
Although this nutrient promotes the body's production of immune compounds, there's little evidence that taking vitamin C can prevent colds and flu in average folks. However, in individuals under physical stress (such as marathon runners), supplementing with vitamin C cuts the risk of developing a cold in half.
Vitamin C does seem to lessen cold symptoms in adults and kids. A review of 30 studies involving 11,350 participants concluded that vitamin C reduced the duration of colds.
To reduce cold symptoms, 2,000 milligrams of vitamin C a day, taken in divided doses, appears to be most effective. Children, people under physical stress and those with low dietary intakes of vitamin C tend to respond best to this vitamin.
High doses of vitamin C may increase the risk of oxalate kidney stones. People with a history of kidney stones should restrict their intake to 100 milligrams a day.
Vitamin D
The advice for Canadian adults to take a vitamin D supplement in fall and winter to help reduce cancer risk may also protect from the flu by enhancing the body's immune system.
Take 1,000 IU (international units) of vitamin D each day throughout the fall and winter. Older adults, people with dark skin, those who don't go outdoors often and those who wear clothing that covers most of their skin should take the supplement year-round.
Children should supplement with 400 IU a day.
Zinc
