How effective are flu shots, elderberries, echinacea, and cranberries?
The U.S. Centers for Disease Control and Prevention (CDC) recommends that everyone over the age of six months get a routine flu shot every year, unless you have some sort of contraindication, such as an allergy to any of the vaccine’s components. CDC recommends getting vaccinated by the end of October, but it may even be beneficial when received in December or later. How effective are flu vaccines? It depends on the year, but, as you can see below and at 0:33 in my video Friday Favorites: Elderberry Benefits and Side Effects: Does It Help with Colds and the Flu?, the flu vaccine typically reduces the risk of getting the flu by about 40 to 50 percent.
So, in healthy adults, we can say with moderate certainty that we can decrease our risk of influenza from about 2 percent each year down to just under 1 percent. Older adults may get a similar relative risk reduction, but the baseline risk is higher and the consequences greater, so the absolute benefits are greater, too. In kids, flu vaccines shine; there’s a high certainty of evidence of a substantial drop in risk. But even in this kind of best-case scenario, there’s still a risk with vaccination, so what else can we do?
In the United States alone, each year, Americans experience millions of cases of influenza and hundreds of millions of colds. What about elderberry supplements? In a test tube, elderberry extracts can inhibit pathogens, including the flu virus. In a petri dish, it can rev up the production of flu-fighting molecules from human immune system cells, like tumor necrosis factor, as much as nearly 45-fold. Elderberry juice can help mice fight off the flu. But what about actual people?
The first clinical trial was published back in the 1990s: a double-blind, randomized, placebo-controlled trial to treat flu-like symptoms. Researchers found that the odds for improvement before the fifth day in those in the treated group were more than 20 times the odds of the participants in the control group (p < 0.001). Two subsequent double-blind, randomized, placebo-controlled trials showed similar accelerated healing in the elderberry groups, as you can see here and at 1:54 in my video.
I was excited to see this study—“Elderberry Supplementation Reduces Cold Duration and Symptoms in Air-Travelers”—given a 200-city book tour I was embarking on. It was a randomized, double-blind, placebo-controlled clinical trial of 312 economy class passengers. While taking elderberry didn’t seem to prevent people from coming down with cold symptoms, the duration and severity of symptoms in those who did get a cold seemed to have been lessened, and they suffered an average of about five days instead of seven.
A similar study using the herb echinacea found a lessening of symptom scores, but it was of only borderline statistical significance. Nevertheless, even though most of the individual trials didn’t find statistically significant improvements, when all such studies were compiled, it seems there may be about a 20 percent decrease incidence of colds, as seen below and at 2:50 in my video.
Note, though, that there is a concern about publication bias and selective reporting. A number of findings and some entire studies seem to be MIA, suggesting that negative studies may have been quietly shelved. So, we aren’t really sure about echinacea, but all the elderberry studies seem to have positive results, suggesting elderberry supplementation “provides an effective treatment option when advanced or more invasive care [more serious treatment] is not warranted.” This conclusion came from someone with apparent conflicts of interest, though. In fact, each of the four elderberry studies was funded by the elderberry product companies themselves.
Any other berries that might be helpful? A randomized, placebo-controlled, interventional study—funded, predictably, by Ocean Spray—found that the gamma-delta-T-cells of those drinking a low-calorie cranberry juice beverage for ten weeks appeared to be proliferating at nearly fivefold the rate. These immune cells “serve as a first line of defense.” Though the study participants didn’t get fewer colds, they did seem to suffer less, but not enough to prevent days missed from work or an impairment of their activities, as shown here and at 3:56 in my video.
At least cranberries have never been reported to cause pancreatitis. A man taking an elderberry extract not only suffered an attack of acute pancreatitis, a sudden painful inflammation of the pancreas, but it went away when he stopped it, then reappeared again years later when he tried taking it again, which suggests cause-and-effect. Why take elderberry extracts when you can just eat the elderberries themselves? Well, cooked are fine, but “consuming uncooked blue or black elderberries can cause nausea and vomiting.”
I found out the hard way, as I explained in an answer to the question, “What was the worst day of your life?” in my London Real interview on my How Not to Die book tour. It turns out elderberry fruits form cyanide, such that eight people had to be medevacked out after someone brought freshly squeezed elderberry juice to a gathering.
Doctor’s Note:
Here’s the London Real interview I mentioned.
What else can we do for the common cold? See the related posts below.
And, speaking of cranberries, Can Cranberry Juice Treat Bladder Infections?. Watch the video to find out.
Michael Greger M.D. FACLM
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