There are quite a few reasons why people tend to get sick more easily during the “Cold & Flu” season. Understanding these reasons can help you avoid situations where your immune system will be compromised, causing you to be more prone to catching some bugs.

  • Most people spend a majority of their time indoors during the cold weather season. Enclosed environment and close proximity with others encourage the spread of germs.
  • High-sugar, high-fat “comfort foods” and holiday fares can weaken the immune system – sugar, in particular, can suppress immunity.
  • Stress caused by the holiday season induces the body to produce corticosteroids, which suppress the immune system.
  • Most people don’t get enough sleep during the holiday season, causing an increase in cortisol level and a decrease in immunity. Cortisol also makes us crave sugar, which suppresses immunity.
  • Shorter daylight hours can cause “winter blues” – low psychological states can suppress the immune system.
  • Dry weather reduces the moisture level of mucous membranes in the nasal passage, which are important in preventing unwanted bacteria and viruses from entering the respiratory system.


Nutrition for Strong Immune System

The best way to use nutrition to boost your immunity is to eat a balanced diet of fresh, whole foods. Sometimes it’s challenging to do so everyday, during the season when we are so busy with work, friends and family. The following are the nutrients that you should pay attention to (supplement when necessary) in order to help you keep your immune system healthy:

  • Vitamin A – helps maintain integrity of the cell membrane of the digestive tract and respiratory system, preventing the entry of bacteria into the body
  • Vitamin B6 – enhances T-cell function
  • Vitamin B12 and folic acid – promote proper T- and B-cell function
  • Vitamin B6, folic acid and zinc – promote rapid production of immune cells
  • Vitamin C – a natural antihistamine, it helps calm infection and control stress hormone cortisol, which weakens the immune system
  • Zinc – supports immune cell production and proper functioning of B- and T-cells. (Note: excess zinc can suppress the ability of macrophages to destroy bacteria. Zinc is therefore useful for viral infection, but may not be suitable for bacterial infection.)
  • Antioxidants (A, C, E, zinc, selenium) – help fight off infection


Holford, P. The New Optimum Nutrition Bible. Crossing Press, Berkley. 2004.


Immunity-Boosting Foods

These foods are great addition to your diet during the cold & flu season, because they contain high immunity-boosting nutrients, or anti-viral and anti-bacterial properties:

  • Probiotics (cultured and fermented foods such as yogurt, kefir, kimchi, sauerkraut and natto) – help boost immunity, and have been found to aid treatment of recurring bladder infection, sinusitis and tonsillitis
  • Sufficient protein, which is needed for growth and repair. However, excessive protein will use up vitamin B6, a nutrient needed for healthy immune system.
  • Essential fats – e.g. from cold-pressed seed oil and cold water fish
  • Fresh fruits and vegetables, especially carrots, beets, sweet potatoes, tomatoes – they are rich in beta-carotene, a precursor of vitamin A
  • Ground seeds, lentils, beans and whole grains – good source of B vitamins and protein
  • Fish – good source of protein and omega-3 fatty acids
  • Mushrooms (maitake, reishi, shiitake) – elevates flu-fighting agents


Holford, P. The New Optimum Nutrition Bible. Crossing Press, Berkley. 2004.


Using Herbs to Boost Immunity and Fight Infection

There are different ways that herbs can help boost the body’s immunity – by working directly with the immune system, by aiding the body to better deal with stress, and by helping the body fight infection.

You can boost your immunity with these herbs:

  • Astragalus
  • Bonset
  • Calendula
  • Echinacea
  • Lemon balm
  • Milk thistle
  • Pau-d’arco

You can help your body fight infection with:

  • Cat’s claw tea with ginger
  • Echinacea
  • Grapefruit seed extract
  • Oregano oil – potent anti-bacterial agent – use as short term remedy only

You can use adaptogens to help the body better deal with stress, which suppresses the immune system:

  • Ashwagandha
  • Tulsi (Holy Basil)
  • Shisandra Berry
  • Eleuthero/Siberian Ginseng
  • Rhodiola
  • Passionflower


Holford, P. The New Optimum Nutrition Bible. Crossing Press, Berkley. 2004.

Glastar, R., Herbal Recipes For Vibrant Health. Storey Publishing, 2008.


Gut Health and the Immune System

The gut houses 70% of the immune system. Keeping the digestive system healthy can boost your immunity.

These are a few things you can do to keep your digestive system healthy:

  • Support colon detoxification with carrot and apple juice
  • Start your day with a cup of warm water with juice of half a lemon first thing in the morning on an empty stomach to support liver and gall bladder (which feeds into the digestive tract)
  • Promote healthy gut flora by adding foods that are rich in probiotic – cultured and fermented foods such as yogurt and kefir, kimchi, sauerkrauts, natto (Japanese fermented beans) and kombucha
  • Alkalinize blood pH (particularly great for facilitating elimination):
    • “Green juice” made from algae, spirulina, leafy greens etc. (You can get them in powder form in canisters or packets)
    • Lemon juice in warm water, most effective when taken in the morning on an empty stomach
    • Fruits and vegetables – besides the alkalinizing properties, the fiber can aid elimination while the enzyme from raw fruits and vegetables can aid digestion and absorption of nutrients essential to building up immunity