a bright sun, too little vitamin D, sunshine, summer sunshine

Is there a way to ward off colds & flu? For decades, mothers and grandmothers in northern climates dosed children with cod liver oil during the winter. They had no scientific studies to support their belief that there was something in that foul-tasting oil that was good for people. Nevertheless, they were convinced that when the weather turned nasty it was time for cod liver oil. Despite protests, children were dosed regularly.

Cod Liver Oil Against Colds & Flu:

Now it seems they may have been right. A study published in BMJ Open shows that an ingredient in the old-fashioned cod liver oil, vitamin D3, helps prevent sniffles and coughs.

Modern medicine has very little to offer when it comes to preventing what doctors call respiratory tract infections (RTIs). People are advised to wash their hands in a feeble effort to prevent viruses from invading nose and lungs. But ask most physicians how to boost your immune system and you will likely to be told to get plenty of sleep, eat a well balanced diet and good luck. Reasonable advice, of course, but it’s not well proven to prevent colds and probably not all that effective when everyone around you is sniffling and sneezing.

Vitamin D Against Colds & Flu:

The sunshine vitamin (Vitamin D) on the other hand, has now been demonstrated to be beneficial against RTIs in highly susceptible individuals. Swedish researchers recruited 140 patients who had immune deficiencies. All of the subjects experienced at least 42 days of respiratory tract infections during the previous year. They were given either 4,000 IUs of vitamin D3 (Vigantol made by Merck) daily or a look-alike placebo. They kept diaries of their symptoms and use of antibiotics was carefully charted. The study lasted for a full year.

The patients who were taking vitamin D3 daily were significantly lower on a respiratory tract infection score than those taking placebo. They were also much less likely to require antibiotics. The placebo group averaged 33 days on antibiotics compared to 16 days for the vitamin D3 group. They also had fewer ear infections, sinus infections and overall sick days. People on vitamin D were much less likely to develop infections due to Streptococcus aureus and the fungi Candida and Aspergillus.

The investigators summarized their findings this way:

“The main conclusion from this long-term RCT [randomized controlled trial] is that vitamin D3 supplementation reduces the total burden of respiratory tract infections… Thus, supplementation with vitamin D3 could provide a novel strategy to reduce antibiotic use among high consumers and indirectly prevent the emerging epidemic of bacterial resistance.”

This is not the first time that a study has shown fewer upper respiratory tract infections with regular vitamin D3 administration.

Japanese researchers

“conducted a randomized, double-blind, placebo-controlled trial comparing vitamin D(3) supplements (1200 IU/d) with placebo in schoolchildren. The primary outcome was the incidence of influenza A, diagnosed with influenza antigen testing with a nasopharyngeal swab specimen.”

They found that children getting vitamin D3 were about half as likely to come down with the flu compared to the kids taking placebos. Children susceptible to asthma were less likely to experience an attack if they were in the group getting vitamin D3 supplementation (American Journal of Clinical Nutrition, May, 2010).

Not All Studies Show Benefits from Vitamin D:

Not all studies have shown such benefit. New Zealand researchers recruited more than 300 healthy adults to get either vitamin D or placebo monthly. The first two doses were 200,000 international units each, and subsequent doses were 100,000 IU monthly for the rest of the 18-month study. This supplied more than five times the US RDA for vitamin D. There was no statistical difference in the number of colds & flu infections between the two groups. This study differs dramatically from the Swedish study, however. Instead of such huge doses on a monthly basis, the Swedes used a daily dose of 4,000 IU, which is more in line with the grandmothers of yore and their cod liver oil.

The nutrition establishment is still very cautious about vitamin D supplements. The current recommendation from the Institute of Medicine is 600 IU daily for everyone between the ages of 1 and 70 years old. We think that is woefully inadequate for the millions of people who are not able to expose wide areas of their skin to sunlight during the winter.

Do You Have Adequate Levels of Vitamin D?

Based on our review of the literature, we believe that many people have inadequate levels of this essential nutrient. A recent study revealed that older people with low vitamin D levels in their bloodstream [under 30 nanograms/ml] were 50 percent more likely to die from any cause. [Journal of Clinical Endocrinology and Metabolism, Nov, 2012]. For those confused about nanograms/ml, this is a measure of the active form of vitamin D (25-hydroxyvitamin D) circulating in their blood. When your doctor draws blood and sends it to a lab for analysis, she can tell you what your levels are. This will guide you and your doctor on how much vitamin D supplementation you will need.

Learn More:

To better understand this complicated topic and estimate how much vitamin D3 you may need, you may wish to consult our Guide to Vitamin D Deficiency. It will provide details about other conditions for which this nutrient can be helpful, beyond colds & flu. You can also read more about respiratory infections in our Guide to Colds, Coughs & the Flu.

If you would like to listen to our one-hour interview with two of the country’s leading nutrition authorities debating the benefits and risks of vitamin D, you will want to download our one-hour mp3 or CD of show # 846. If you want a more enthusiastic review of vitamin D research, we recommend show # 749 with Dr. Bruce Hollis. And if you want the big picture on vitamins in general, we offer Show 876, “The Great Vitamin Debate.”

We would also love to hear from you about your experiences with cod liver oil or vitamin D. Please comment below.

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  1. hoofen
    S/E Alabama

    Took the senior citizens, extra strength shot and pneumonia shot in nov.014.Jan.27/015 Started with cough& sore throat, cough got severe, could only inhale about 15/20 percent of air in short gasps. Constantly had choking sensation, especially during violent coughing spasms. 4 days later right tonsil became sensitive, still couldn’t cough down into lungs to work up mucous. 6 days into it, left tonsil became sensitive and left ear. Sleep nearly impossible, due to constant coughing all night long. Thought I had pneumonia, scared me half to death. I’m 71. Now, 7 days into it, first flu symptoms showed. Still no sleep. Coughing wheezing, sinuses draining constantly but the cough seems to dissipate. After 8/9 days of pure hell. Actually got some sleep last night “hallelujah”, today cough almost gone, only mild cold symptoms left. Hope this little time line helps some of you. Above all “I am still alive” really had me worried there for awhile. Best way to fight this IMO (Which sadly I don’t have anymore ;-((.Have a loving partner, so you can care for each other. Best of luck. WB

  2. Jake's Mom

    I have a three year old little boy who has had 3 sets of tubes and his adenoids removed at two. My son would get ear infection right from a cold every two weeks. We tried everything to help him. Once we added 400iu D to his 600 in his Flintstone vitamin he has not had a ear infection or cold. Amazing our ENT was blown away and I am a happy mom.

  3. P. G.

    I have had this flu for almost two months. And yes, I DID GET A FLU SHOT. I finally got into the doctor last week. She told me that the flu vaccine this did not cover the current year’s flu. She gave me antibiotics, which of course doesn’t work for a virus. However, I have a bronchial infection. I’ve been taking them for about a week and feel no better. I am praying for a better life soon. At this point I am fearful that I will never be well. Thanks for listening.

  4. RLB

    Toxicity from VitamnD is another of the urban legend tales. I searched in vain to to find any documented eveidence of said toxicity.I ain’t there folks.
    PEOPLE’S PHARMACY RESPONSE: Toxicity from vitamin D is possible but very uncommon. Mostly it has been reported as a result of supplement manufacturing accidents. Taking massive doses of vitamin D can definitely cause toxicity. It’s been reported more often in children.
    Single large doses can be a problem:
    This review indicates just how difficult it is to get into toxicity trouble

  5. cpmt

    WHAT ABOUT toxicity from vit. D3? What should be the maximum levels to be taken? I read someone got kidney damage from too much vit. D.

  6. RLB

    Congratulations to those of you who have discovered the connection between vitamin D3 and not having colds. My doctor (who I please by seeing every six months) is a very nice, well-intentioned practitioner who cannot understand why I never get sick. Those of you who have been taking 5000iu of D3 may have discovered that, in addition to not having colds, also, just feel better overall.The RDA is ridiculously inadequate.

  7. KAC

    Before I started taking 1000 iu/day of D3 several years ago, I routinely got 2-4 bad colds a year. I haven’t had a single one in several years, despite my husband getting a couple a year. I was recently tested though and am still deficient (19 ng/ml) (I live in Seattle, but spend a LOT of time outdoors) so have upped my intake to a 5000 iu/day supplement. So don’t assume 1000/day is enough, if you live in the north!

  8. B.C.

    We spent 6 mos. yearly for 22 years in sunny Florida playing golf, going to the beach etc. We are in a northern climate now and take Vitamin D3 but have never had the flu, bad colds etc. and are in our mid-eighties.
    Lucky —or —lots of Vitamin D ?

  9. JFR

    I am in my eighties and have been taking 5,000 IU of Vitamin D3 for about four years. I have not had a cold, during those four years, that lasted more than 2 days if I began zinc lozenges and other supplements–natural throat spray, vitamin ginger tea–upon noticing the first symptoms. I do not take flu shots.

  10. HY

    Cod liver oil: Of course our mothers were right!
    I was spoon-fed the stuff summer and winter.
    Why else am I now 87?

  11. PS

    I was given cod liver oil via a medicine dropper every day during the winter while I was growing up. It was always followed by a small glass of orange juice.
    Is cod liver oil still available to take? Or must we take Vitamin D3 only? I certainly could resume the old tradition. I never minded the taste. There was no way to get out of the daily dose in my house.
    It was a rule of my parents that my siblings and I had to follow.
    And luckily for us, it worked.

  12. BA

    In the above studies there’s no mention if the people in them had their Vitamin D levels checked prior to receiving either either Vitamin D3 or a placebo. I would think that would be important to know in order to fully assess the outcomes of the studies.

  13. JR

    I remember Cod Liver Oil. I loved it. I think mom used a small spoon or eyedropper, but I couldn’t get enough. She never had to explain the medicinal value. We also didn’t go out after a bath because our pores were open and when we did get a URI mom put Vicks in the steam humidifier. I kinda liked that too. I also like sardines, anchovies, capers, squid, and a lot of other stuff that I can get plenty of because nobody else eats it. I’m 69 and take no meds.

  14. Paul

    > Please speak with your health care provider to determine if these additions might help you …
    This is the standard CYA statement that accompanies every drug ad, exercise program, home remedy suggestion, and even poor Peoples’ Pharmacy must use to keep themselves out of court or on the FDA’s ‘hit list.’
    People, stop and think!
    It’s the doctors, brainwashed by the AMA and the Drug Cos. that are pushing the so-called silver bullet pills on us. Its the same doctors who cringe at or pooh-pooh our suggestion that we use some alternate form of treatment or medication. When there is sufficient evidence (e.g., the studies that caused PP to send out this Alert) to indicate a non-FDA approach is viable and reasonable, it is up to we thinking people to stand up to the Drs. and make the informed decision for ourselves.
    Remember, Drs. are not always right. Give them a vote, but not complete authority.

  15. RLB

    I have read the results of innumerable “analyses” conducted by the medical/pharmaceutical establishment(s) regarding the use of nutrients. The majority were grossly flawed, ie. synthetic rather than natural vitamin E, under dosing in all trials (everyone who knows anything about nutrition raeises the RDI’s are grossly inadequate), D2 rather than D3 in the vitamin D studies, time spans of too short a duration to be effective. If you construct a study that is designed to fail, it is going to fail!!
    The FDA maintains that only drugs can cure. Every “trial” which could contradict this concept is going to fail.
    Please tell me, by the way, how taking a drug every day for the rest of your life can be considered a cure.

  16. JAS

    QUESTION: Have there been thorough studies that compare the effectiveness of a “processed” Vitamin D pill to the “unprocessed” element of sunlight with good controls (like a person living in lab conditions)? What about other vitamins that are from a processed pill as opposed to “living food” that gives the same vitamins? Have thorough studies been done comparing the “dead” vitamin pills to “living” unprocessed food vitamins?

  17. Clm

    I grew up in northern Wisconsin and my mother gave us the cod liver treatment every year to prevent rickets. We all have strong and straight legs. Some of my classmates had the bowed legs, parents did not give them cod liver oil during the long sunless months.

  18. pwj

    I was given cod liver oil as a child. I am 88 years old.

  19. Newly inspired... by this and happen-stance.

    Delighted in reading this news item and these comments and remembered, as I’m trying to un-clutter, I noticed two unopened fish oil containers in my cabinet. Omega-3, not vitamin D, but ingredients are Anchovy and Sardines. Is cod-liver oil derived from fish, too?
    The Fish Oil bottles expire February 2013. If taken diligently, will be used up by the end of February. We try to get a lot of sunshine and exercise, although we could always do more. Thank you all for inspiring me to actually take the vitamins we bought and put this freebee to good use.
    Cod liver oil comes from fish…cod to be precise.

  20. ebw

    Since using 4000-6000 IU of Vitamin D3 daily plus a product called Mushroom Immune Defense, I’ve had no respiratory problems. Before,I had at least 2 colds and year and a cough that lasted 6 weeks. I also believe that my memory is improving. When I was first tested for D3, I was surprised that my level was only 30. Most recent test shows 75. This may also contribute to my record recovery from shoulder surgery (took 2 weeks and I was well.)

  21. BL

    I take 1,400 IU of vitamin D3 daily and get a flu shot. All of this can not prevent you from getting the flu or a cold when you are around people who have it but when I come down with this, it is not as bad as the others seem to be and I get better faster.

  22. Lisa T

    So much of our modern lives are spent inside that we don’t benefit, even when we have access to the sun like here in the South. So much emphasis has been placed on the dangers of over-exposure that we’ve forgotten about the benefits that a little outside work (or play) provides.

  23. HN

    Karen, thanks for your interpretation. The study’s translation to the English language must have created that uncommon terminology. :-)

  24. Karen

    HN, I read “high” to mean “people who use a lot of antibiotics.” I guess we all bring our own perspectives to our interpretation of a word…

  25. HN

    Very good information, if it could only be shared with many more people than just the readers here. The majority of our doctors are too slow to recommend natural alternatives to their patients when they can profit more from many sick patients on antibiotics.
    By the way, I wonder what the Swedish study meant by “reduce antibiotic use among high consumers”–I doubt that consumers need to be “high” to experience the benefit of vitamin D3. ;-) Maybe they meant “reduce antibiotic use among high-risk consumers”, which would reflect what the study was about.

  26. Noah T.

    I was. I dreaded that bottle of sitting in the back of the frig.. I whined so that I usually got a piece o chocolate afterward… I am 68 still active now. Take no meds (minimal dose aspirin when I remember, that’s all) and avoid docs. They unintentionally near killed me several times. We need to remember they are peeps too with problems. Difference is they have the presc. pad. (:

  27. SL

    After working recently with small children, many of whom were suffering from flu and bronchitis, I caught their ailments. My sickness was short-lived and not nearly as severe as these children. The only difference in my lifestyle is that I have been taking 6000 mg of Vit D3 daily and I have eliminated refined sugars and foods as much as possible.
    Last year at this time I would have been much sicker. Vit D3 has also reduced much of my arthritis pain. I have added 500 mg of Magnesium as well. Please speak with your health care provider to determine if these additions might help you as well. Thank you to the People’s Pharmacy for the information you provide. You are a trusted source of information for my family.

  28. Karen

    “Getting lots of sun” only only counts if you live south of Washington DC (in the US). For the northern parts of the country, you don’t get enough sun to make enough Vit D.

  29. Lisa T

    Half of my thyroid gland was removed some 15 years ago which requires an annual exam with my endocrinologist. Every year he checks my blood levels and, in the last few years, orders a bone scan. He asks if I’ve been taking calcium (“uh…not really”) and Vitamin D (“I get lots of sun…does that count?”).
    I tried to slip something I’d heard on The People’s Pharmacy into some of those conversations but didn’t receive much of a response.
    After several years of these exchanges, my doctor let out a small gasp as he reviewed my bone scan (which had been described as pre-osteo at an earlier time). “What’s wrong?”, I asked. “Your bone mass has increased!, says he ,What have you been doing?”. “Manual work and sunshine, says I, and The People’s Pharmacy”. :o)
    PEOPLE’S PHARMACY RESPONSE: Thank you so much for this heartwarming success story! Health to you in 2013!

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