Winter Diet: The Key Ingredients You Need to Boost Your Immunity

Boost your immunity this winter with nutrient-rich foods and supplements. Photo: skynesher/GettyImages

Some older Canadians may remember when a spoonful of cod liver oil was as much a part of winter as warm mittens and frosted windshields.

There was wisdom in that choice of supplement we were made to swallow every cold morning even though we thought it was disgusting.

Cod liver oil, unlike other fish oils,  is very high in vitamin D. 

And vitamin D is crucial for immunity, which diminishes in winter.

Our immune systems vary with the seasons, according to a study led by the University of Cambridge that helps explain why certain conditions, including heart disease and rheumatoid arthritis, are aggravated in winter while people tend to be healthier in the summer.

Also, notes consulting dietitan Sue Mah, “As the weather gets colder, we tend to spend more time indoors — and this means that we’re probably in closer contact with other people who could pass on their germs.”

Fortunately, there are ways to boost immunity and top up vitamin D in winter that don’t involve cod liver oil. One small change Mah suggests that can be a big help: “Incorporate dairy products into your daily routine.

“Vitamin D in dairy products helps fight infection, helps with calcium, keeps bone and muscles healthy. It’s just essential for the immune system.” 

It’s hard in winter to get enough vitamin D because the body can’t make it without sunlight, Mah explains. But even with sun, people over age 50 are less efficient at converting sunlight into vitamin D and, as people age, their need for vitamin D increases.

“Adults over the age of 50 should focus on getting enough vitamin D by eating/drinking foods which contain vitamin D (e.g. milk, fatty fish, eggs, mushrooms) as well as taking a vitamin D supplement of 400 IU a day from October to March.“

(Health Canada recommends 600 IU of vitamin D for adults up to the age of 69 and 800 IU for people age 70 and older, with an upper limit of 4,000 IU for both.)

In general, Mah recommends getting nutrients from foods rather than from supplements. “Food tastes so much better,” she says, “and if you eat well and enjoy a variety of foods, you can keep your immune system healthy and well supported.”

However, she suggests that probiotics may be useful at times because “healthy bacteria sometimes get wiped out if the body is under stress or if you’re taking antibiotics.”


Waging War Against Colds & Flu


When colds and viruses strike, Mah says it’s important to get enough vitamin C, preferably from food such as oranges, peppers and strawberries.

“When a person starts to feel body aches and a scratchy throat,” she says, “that’s a sign that the immune system is responding.”

While vitamin C supplements are relatively safe even if you take higher doses when you have a cold, she says, if you take take too much you’re just wasting your money because it comes out in urine and you’re just flushing it down the toilet.

However, it’s good to fill up on fluids, especially warm fluids like chicken soup, when you’re under the weather.

No matter how you’re feeling, even if your appetite isn’t great, it’s important to get enough protein, says Mah. “Seniors should try to have protein at every single meal. Space it out throughout the day instead of overdoing it at dinner.”

Mah suggests thinking of healthy eating and immunity boosters as “a team of different nutrients that work together to keep the immune system strong.” 

Some of the key nutrients on Team Immunity that Mah identifies: 

  • Vitamin A — found in carrots, red peppers, butternut squash, sweet potatoes
  • Vitamin C — found in oranges, kiwi red peppers, strawberries
  • Vitamin D — helps our bodies fight infection; not many foods sources
  • Milk is a source of vitamin D which helps to support a healthy immune system.
  • Fatty fish such as salmon, egg yolks and mushrooms also contain vitamin D.
  • Protein — helps to build antibodies which protect your body from harmful bacteria and viruses; found in meat, poultry, fish, beans, tofu, nuts, milk, cheese and yogurt
  • Selenium — found in nuts, whole wheat pasta, canned tuna, ricotta cheese
  • Zinc — found in oysters, nut, barley, quinoa.

Meals that include a variety of these nutrients are ideal for keeping the immune system strong. Some ideas:

  • Breakfast: Hot oatmeal (selenium) made with milk (protein, vitamin D), strawberries (vitamin C) and nuts (zinc, selenium).
  • Lunch: Butternut Squash & Quinoa Salad made with butternut squash and tomatoes (vitamin A), quinoa (zinc), cheese (protein).
  • Snack: Nuts (zinc, selenium, protein) with an orange (vitamin C).
  • Dinner: Easy Cheesy Tuna Casserole made with canned tuna (selenium, protein), whole wheat pasta (selenium), carrots (vitamin A), peas (vitamin C), milk (vitamin D, protein), cheese (protein)