Nutrition and Immunity: Fighting Colds and Flus with Food

Citrus_unshiu_20101127_c.jpg

It’s the middle of winter here in Australia and there are a lot of people coughing, sniffing and blowing their noses profusely right now. In fact, the number of flu cases in Adelaide has so far doubled that of this time last year.

Here’s something you should know: you don’t have to suffer through lengthy, debilitating bouts of sickness every winter or every time you come close to someone else with a bug or virus. The immune system can take a bit of a beating from our diet and lifestyle habits, so it’s important to keep these in check around wintertime to protect ourselves as best we can.

Here are the top nutrients shown to reduce both the likelihood of developing a cold or flu and severity and duration of them…

 

Vitamin D

Known as the sunshine vitamin, vitamin D plays a role in immunity by controlling the activity of the class of antibodies (proteins that fight foreign bacteria and viruses) known as T-cells. Considering that our best source of this vitamin comes from sun exposure, could it be more than a coincidence that winter time harbours both cloudy days and more cases of colds and flus? Perhaps!

Best sources: The sun! Osteoporosis Australia recommend that, depending on the latitude of your location, lighter-skinned people need about 7-30 minutes of head, neck and arm exposure to midday sun per day and darker-skinned people about 20 minutes-3 hours (darker skin contains more melanin, which prevents UV absorption). But, as we don’t see too much sun in winter, you may need a supplement (the recommended dose will depend on your vitamin D levels). The D3 form is preferable over D2, and vegan versions are available now that are made from lichen, a fungi/algae organism.

 

Probiotics & Prebiotics

The gut plays a major role in immune function. Probiotic supplements introduce more of the ‘good’ strains of bacteria into our gut, which is where most of our bacteria is found. Studies show that taking a probiotic everyday for three months prior to cold season can significantly reduce our risk of developing colds and flus. Also, make sure you’re consuming prebiotics, which feed the probiotics to keep them alive and happy (if you’re not providing them with a source of energy, they won’t survive). Good sources of prebiotics are wholegrains (particularly when cooked and eaten cold), allium vegetables (garlic, onion, leek) and legumes (peas, beans, lentils).

Best sources: Fermented foods are good, but supplements are the most reliable sources of probiotics when you need a good hit of them. Look for probiotic supplements with a live culture count of at least 10 billion per capsule, specifically containing Lactobacillus gasseri, Lactobacillus acidpholous, Lactobacillus casei, Bifidobacterium longum and Bifidobacterium bifidum.

 

Zinc

Zinc plays an important role in protecting our immune systems. Like vitamin D, it plays a role in the activity of cells that make up the immune system. Because it’s found in only a narrow range of foods in sufficient amounts, getting enough zinc in our diet can be a little difficult.

Best sources: Certain legumes (soybeans, lentils, adzuki beans), nuts (particularly cashew, pine, pecan), seeds (particularly pumpkin, sesame, poppy), wheat bran, dried shiitake mushrooms.

 

Vitamin C

This is a well-known one, but interestingly, rather than reducing our risk of getting a cold, vitamin C appears to be more effective at reducing the duration and severity of symptoms of a cold. 200mg is all we need to get the immune-boosting benefits, and always try to get it from food where possible. If you’re an athlete, vitamin C is highly important- studies show that getting 200mg per day can reduce your risk of a cold by as much as 50%!

Best sources: Kiwi fruit, capsicum, papaya, broccoli, berries, citrus fruit.

 

Beta Glucan

This is a type of soluble fibre that acts as an immunomodulator (immune system-regulators). It appears to reduce our risk of developing a cold quite effectively, and can reduce the severity of the symptoms of a cold. It can also significantly improve athletes’ recovery following strenuous exercise.

Best sources: Nutritional yeast (2 tsp/day has been shown to reduce cold risk, but choose Bragg’s brand due to possible lead toxicity concerns with other brands), mushrooms, oats, barley. Mushrooms are particularly powerful immune-boosters as they also stimulate the release of IgA antibodies.

 

Antioxidants

The hype around antioxidants is definitely warranted (however, not-so-warranted are the expensive and often useless supplements they’re concentrated in). Antioxidants include certain vitamins (A, C and E), minerals (selenium, copper, zinc) and phytonutrients (e.g. Lycopene, Lignans, Anthocyanins). The reason antioxidants are so great is because they prevent damage associated with development of serious diseases like cancer. To put it simply, antioxidants do this by neutralising or counteracting ‘free radicals’ in the body, which are the bad guys that cause ‘oxidative damage’ to our cells and put us at risk of disease.

Best sources: Fruits and vegetables (the darker or more vibrant coloured ones like berries and leafy greens are usually the more concentrated sources), spices (turmeric, clove, cinnamon).

 

Isolated Nutrients in Supplements

There is some evidence to show that ginseng and echinacea can help the immune system. A few studies indicate that taking around 2500mg echinacea and 200mg ginseng daily can both independently reduce the lifespan of a cold, however other studies have found no benefits, so the jury’s still out on these. It won’t hurt to take them, but don’t expect them to work wonders for your immune system.

 

Beyond Nutrition: Stress, Sleep and Activity

These aren’t nutrients, but all of these lifestyle factors effect our immune system. It’s important to ensure we’re getting enough sleep (that means at least 8 hours for most people) and keeping our stress levels low, both of which can be difficult can be difficult to achieve for many but are so important for many aspects of our health. Reducing screen time before bed and engaging in relaxation activities (meditation, reading, taking a bath, deep breathing) are great techniques to reduce these problems. A sedentary lifestyle can also weaken our immune system, so aim to get at least 30 minutes of moderate- or high-impact activity in everyday. It has been shown to reduce your risk of coming down with a cold by half!

 

The best sources of nutrients are whole foods (or in the case of vitamin D, UVB ray absorption). However, if it isn’t possible to get them from foods, supplements are a handy plan B. However, research shows that for some vitamin and mineral supplements, they’re not as effective at some of their roles in the body. When we eat whole foods, we’re getting a combination of many nutrients which work together to keep the body healthy. So, in order to ensure you’re consuming a wide range of nutrients and minimise your risk of developing a dreaded cold or flu, aim to eat a variety of healthy, whole plant foods everyday.

Stay Warm!

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s