A streamlined stack of supplements designed to meet your most critical needs - Adapt Naturals is now live. Learn more

5 Steps to Staying Healthy during Cold & Flu Season


Published on

prevent cold and flu

We’re in the thick of cold & flu season now, so perhaps this is a little tardy. But better late than never. I thought I’d share a few ways to boost your immune system and protect yourself from infections, and lessen their intensity if you do get them.

#1: Avoid common food toxins

The worst offenders are:

  • Gluten
  • Sugar
  • Industrial seed oils
  • Soy

Food toxins provoke an immune reaction that can make us more vulnerable to foreign invaders like bacteria and viruses. Many people, myself included, find their immune system works best if they avoid all grains – not just those that contain gluten – and legumes as well as the toxins listed above.

#2: Take your cod liver oil

Vitamins A & D both play significant roles in immune health. Cod liver oil is rich in both, and also contains vitamins K2, E and various quinones which are also essential to health. All of my patients who take it regularly report fewer colds and milder and shorter colds if they do get them. This has been true for me as well. I suggest 1 tsp/day as a preventative, and then 2-3 tsp/day if you feel a cold coming on.

#3 Eat fermented foods

Probiotics found in fermented foods like yogurt, kefir, sauerkraut and kimchi strengthen and maintain the mucosal barrier system (in our respiratory and intestinal tract), which is our first line of defense against pathogens. What’s more, 75% of our immune system is found in the gut.

#4: Wash your hands frequently

Maybe you already know this, but studies have shown that frequent hand-washing is one of the most important things we can do to protect ourselves during cold & flu season. Consider washing your hands every time you arrive at a destination while out and about, and first thing when you get home.

#5: Supplement when necessary

In addition to all of the steps above, there are certain supplements that can be helpful in fighting off a cold or lessening its duration. Many people have reported that high doses of vitamin D (i.e. 20,000 IU/day) at the first signs of a cold keep it away. There isn’t any research to support this, and I’m not sure what the mechanism is, but I’ve tried it myself and it does appear to be effective. If it’s placebo, I’m happy to get the effect because high doses of vitamin D over the short term (1-3 days) are not harmful.

Iodine is another important nutrient for boosting immune health. It’s best to start this early in the flu season, and gradually build up to a dose of 50 mg/d. (Do not take iodine if you have Hashimoto’s disease. It can cause an immune flare up.)

Vitamin C is also useful for fighting off colds. Take 1g every 3-4 hours.

Finally, there are a number of botanicals that have a potent immune-boosting effect. These include echinacea, astragalus, codonopsis, Siberian ginseng, catnip, ginger root, garlic and Elder flower (Sambucus).

ADAPT Naturals logo

Better supplementation. Fewer supplements.

Close the nutrient gap to feel and perform your best. 

A daily stack of supplements designed to meet your most critical needs.

Chris Kresser in kitchen
Affiliate Disclosure
This website contains affiliate links, which means Chris may receive a percentage of any product or service you purchase using the links in the articles or advertisements. You will pay the same price for all products and services, and your purchase helps support Chris‘s ongoing research and work. Thanks for your support!


Join the conversation

  1. What do you think about cod liver oil on a low histamine diet? I know FCLO is out because anything fermented has much higher levels of histamine.

  2. Jesse,
    When I take cod liver oil I get the burps. Not so with capsules. My friends and family company of the same thing. Have you heard this complaint and do you suggest just sticking with capsules?

  3. Hi Chris, I wonder how you feel about beginning a Potassium Iodine supplement. I just bought “Eidon” Ionic Minerals, which provides 225mcgs, per 2 drops. To begin slowly, should I dilute this and build up? Would be greatful for your thoughts. Thanks Susan

  4. Chris, re: iodine up to 50 mg per day. My MD says that high dose iodine, such as Iodoral, will increase progesterone. He monitors thyroid function and sex hormones (by saliva!) in all patients taking high dose iodine, and will not pursue an iodine dose that pushes progesterone too high.

  5. “Vaccinations are good for everyone else.” That is probably the best line I have heard. So either they work and there are less infected folks or they don’t work and you don’t get exposed to the toxins.

  6. The capsules are just as effective. However, they are more expensive. For example, to take 2 tsp/day, which is the dose I recommend when fighting a cold/flu, you’d have to take 32 capsules! That’s almost half a bottle.

    I’ve found that the new Arctic Mint flavored FCLO is completely tolerable in liquid form. I really had a hard time with the other flavors, so this is saying something.

  7. Chris, do you think the capsules are just as effective as taking the oil straight up? (I’m hoping, of course, that you’ll say yes 😉

  8. I like Green Pastures. Either the FCLO/Butter Oil blend, or just the straight FCLO. Best to think of it as a nutrient-dense, superfood rather than a supplement.

    I have no affiliation with Green Pastures. I just think they have the best product on the market by far.

  9. Let’s just say vaccination is one of the most controversial and heated topics of debate in the health care world. I’ve said my piece, and you all know where I stand on this issue. Ultimately it’s a personal decision and everyone has to do what they’re comfortable with.

  10. I don’t agree with Jesse with regard to flu shots boosting immune system, but will defer and eagerly await Chris’s reply.

  11. Jesse:

    For every study you show me suggesting it works, I can show you one suggesting it doesn’t. It’s a simple risk/benefit analysis. Do I want to simply eat well and take care of myself, which has no risk or side effect other than feeling better, or take a vaccine that can potentially cause harm?

    You say the flu “kills thousands” each year. Actually, the CDC grossly overestimates the number of deaths caused each year by the flu by including deaths from pneumonia in that count, which is disingenuous and inaccurate. The actual number of deaths caused by flu in 2005 was 1,806. That’s a far cry to the 30,000 statistic the CDC throws around.

    It’s very likely those that died were either very young or very old, and/or had compromised immune systems. And there’s no proof that a flu vaccine, which may or may not contain the appropriate strain, would have protected these people from dying.

    For example, this study shows that there has been no decrease in flu deaths in the elderly, despite a dramatic increase in vaccination coverage in that population from 15 percent in 1980 to 65 percent now.

    And a Cochrane review in 2006 found that flu vaccines aren’t any more effective than placebo in children. Yes, it’s a meta-analyses and all caveats apply, but the 51 studies covered 260,000 children aged 6 to 23 months.

    So much for the flu vaccine helping the most vulnerable sections of the population.

    Anecdotally, it’s interesting to note that 70 percent of doctors and nurses don’t get a flu shot. The reasons they gave for abstaining included:

    • They didn’t believe the vaccine would work
    • They believed their immune systems were strong enough to withstand exposure to the flu
    • They were concerned about side effects

    Of course then there’s the issue of mercury and other toxins present in vaccines. According to the CDC, the majority of flu vaccines contain thimerosal. Some contain as much as 25 mcg of mercury per dose. This means that it may contain more than 250 times the Environmental Protection Agency’s safety limit for mercury.

    Flu vaccines also contain:

    • Aluminum — a neurotoxin that has been linked to Alzheimer’s disease
    • Triton X-100 — a detergent
    • Phenol (carbolic acid)
    • Ethylene glycol (antifreeze)
    • Betapropiolactone – a disinfectant
    • Nonoxynol – used to kill or stop growth of STDs
    • Octoxinol 9 – a vaginal spermicide
    • Sodium phosphate

    Yeah, I think I’ll stick with a paleo diet, cod liver oil, fermented foods, supplements and washing hands for prevention, and bone broths, botanicals, and other natural remedies for treatment.

    • “Do I want to simply eat well and take care of myself, which has no risk or side effect other than feeling better, or take a vaccine that can potentially cause harm?”

      Considering how low risk of harm from the vaccine is (one in a million chance of potential harm), I’d rather do both.

      “Actually, the CDC grossly overestimates the number of deaths caused each year by the flu by including deaths from pneumonia in that count, which is disingenuous and inaccurate.”

      You do know that pneumonia is a complication caused by the flu, right? So prevent the flu, and you prevent pneumonia.

      “Anecdotally, it’s interesting to note that 70 percent of doctors and nurses don’t get a flu shot.”

      The survey you cited didn’t say that. It was looking at health care workers as a group, of whom almost 40% get vaccinated. Doctors and nurses were more likely to be vaccinated than health aides or technicians, up to 70%.

      Some flu vaccines have thimerosal, if they come in multi-dose containers. FluMist and single doses do not. This form of mercury (ethylmercury) seems to be less harmful than other forms, though (methylmercury), and hasn’t been associated with negative effects in such small doses.

      As for phenol, antifreeze, and aluminum, not sure where you got that information, since the lists at cdc.gov don’t include those.
      And haven’t you heard that aluminum and Alzheimer’s probably aren’t linked anymore?

      Anyway, I probably won’t be able to say “I told you so” even if you get the flu, since a sample size of one isn’t good data for anything, but hopefully science will clear up the issue to our satisfaction soon.

    • “For every study you show me suggesting it works, I can show you one suggesting it doesn’t.” – Seems like you should do that. He posted a lot of studies, you posted a couple.

  12. Two other fantastic helpers are olive leaf extract and quercetin
    When I start to get a cold – I take this – oliviral http://health.nutralife.co.nz/Product.aspx?id=84
    and quercetin http://psa-rising.com/foodnews/2007/02/quercetin-protects-immune-system-from-stress-study-says/

    Quercetin is also great as it reduces histamine type inflammation.

    Both these together with a ginger / garlic / curcumin combo supplement just knocks a cold dead in its tracks.

  13. Yes sir.

    Immunization of children helped prevent disease in elderly:

    Direct tests of vaccine efficacy:

    Effectiveness in the elderly:

    Effectiveness in healthy adults:

    Effectiveness in sick people:
    COPD: http://www.ncbi.nlm.nih.gov/pubmed/17035445?dopt=Abstract
    HIV: http://www.ncbi.nlm.nih.gov/pubmed/16965629?dopt=Abstract

    Vaccine reduces antibiotic prescriptions:

    Effectiveness of infant illness prevention by vaccinating mothers:

    These are somewhat hesitantly positive, with reserve. Meta-analyses are somewhat uncertain evidence though, since the bias of the reviewer can affect the results. It is interesting to note that all the meta-analyses seem to have been done by the same person.

    Here’s a good summary:

    Studying effectiveness of the flu vaccine is complicated by a number of things: whether the vaccine is a good match for the circulating strain, what to count as prevention (such as, if someone gets the vaccine and then gets the flu but the flu is not as bad because of the vaccine), and stuff like declining immunity and herd immunity. But the evidence that the vaccine is generally safe is much more certain, and considering the risk of getting the flu, which kills thousands, I’d say the vaccine is worthwhile.