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The Truth About Supplement Studies

Why negative supplement research may not be so gloomy after all.

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Q: There seems to be a lot of controversy lately about what I thought were foundational supplements such as fish oil, vitamin D, and probiotics. What’s up with that? 

—Stephon W., San Jose, Calif.

A: The more “we the people” take responsibility for our health, the more likely we are to live healthy, vibrant lives. It may sound cynical, but pharmaceutical companies, with their profit motives and lobbyists, need us to be chronically unwell. I believe they go to disturbing lengths to discredit so-called “alternative” medicine. The level of misrepresentation in the headlines is shocking sometimes. It’s crucial to look at the actual studies before making any judgements

Life on planet Earth is not what it used to be. Less than 100 years ago, there were no prescription antibiotics. Potent, natural antimicrobials (which still work today) came from minerals (especially sulfur) and plant medicines, including goldenseal, osha, and thyme. While antibiotics have prevented many fatalities—from septic war wounds to ulcers to myriad bacterial infections—there are inherent problems with them. First, within 10 years of the production of any antibiotic (penicillin was the first), resistant strains of bacteria emerge. Second, taking a broad-spectrum antibiotic (which indiscriminately kills all microbes) wrecks the body’s gut flora.

Did You Know?

It’s important to look at the actual studies, rather than just the headlines. To find full studies, try PubMed:

Are probiotics helpful or harmful?

It’s unnecessarily premature to take one negative study on probiotics and make it the new norm, especially given that there are hundreds of positive studies on probiotics.

Let’s look at two recent studies that cast doubt on probiotics. One study (not in people, but on a gut “chip,” which is lined with living human cells) showed that inflammation in the gut causes intestinal permeability (leaky gut). The researchers, whose findings were published in the journal PNAS, theorized that leaky gut could allow probiotics into the bloodstream, causing more harm than good. I disagree. For example, in cases of C. difficile (a hard-to-treat, hospital-acquired infection in the colon caused by antibiotics), pouring billions of good bacteria into a damaged gut often resolves the infection. Also, research has shown that taking probiotic sachets (with 450 billion CFUs) three times daily for 6–18 weeks significantly helps people with inflammatory bowel disease (IBD).

A study published in Cell tracked around 20 people on antibiotics. Researchers divided participants into three groups: one took nothing after their course of antibiotics; the second group got a fecal transplant with their own stool, which was collected prior to antibiotic treatment; and the third group was given a commercial probiotic strain that had never been scientifically studied. The folks who got their own fecal transplant had the quickest return to a “normal” microbiome; those who took only antibiotics returned to normal next; and the probiotic group had the slowest recovery.

We have abundant proof that probiotics can reduce and cure post-antibiotic diarrhea; therefore, this one study does not invalidate using probiotics after antibiotics. Further, folks who need antibiotics are probably not particularly healthy, so returning their guts to their pre-antibiotic state may not be a good thing. It’s unnecessarily premature to take one negative probiotic study and make it the new norm, especially given that there are hundreds of positive studies on probiotics, not to mention entire conferences dedicated to studying different strains of beneficial bacteria.

It’s unnecessarily premature to take one negative study on probiotics and make it the new norm, especially given that there are hundreds of positive studies on probiotics.

The bottom line: Trust your own experience. My favorite way to help improve your gut flora is to eat fermented foods and a high-fiber diet. Fiber is the main “prebiotic” that good bugs need to flourish.

Do you need to take a vitamin D supplement?

Next, let’s look at the vitamin D kerfuffle set off by the VITAL study at Brigham and Women’s Hospital that involved nearly 26,000 patients. One of the emerging “issues” with vitamin D supplementation concerns Michael Holick, PhD, MD, of Boston University, an ardent proponent of vitamin D supplements. He’s recently been accused of profit-mongering. He helped Quest Labs develop a test for serum vitamin D (which many other labs have since started using), and he receives a consulting fee of $1,000 per month from Quest.

That’s nice, but it’s hardly extravagant. Being a consultant for a large, nationwide lab using a test that you developed doesn’t invalidate the test—or vitamin D supplementation. It is intuitively obvious in our sun-averse culture that we would be deficient in a vitamin that requires exposure to sunlight for the body to produce.

In the VITAL study, the so-called “high-dose” vitamin D amount was 2,000 IUs daily. I generally recommend my patients take 5,000 IUs, and if their serum levels are below 40, I’ll have them take 10,000 IUs daily (in 2 divided doses for better absorption, and always with food) to approach the optimal serum levels of 60–90 ng/mL.

Even with a relatively low dose, the rate of death was significantly lower with vitamin D supplementation than with a placebo (if you exclude the first two years after the trial). If someone has an aggressive form of cancer, then starting a vitamin D regimen wouldn’t save them. But it can help prolong the lives of otherwise healthy folks. In this study, the vitamin D group had 25–37 percent lower death rates. That’s impressive.

The fact is, we have become an indoor-living species. Most of us are deficient in vitamin D (and melatonin, thanks to artificial lighting). And studies show that adequate vitamin D supplementation reduces influenza A (over 60 percent better than the flu shot). It also reduces asthma incidence and MS flare-ups, and, along with weight-bearing exercise, helps maintain bone density.

Do fish oils protect your heart?

As for fish oil, the recent VITAL study also assessed the impact of Omacor (840 mg of marine omega-3 fatty acids) on cardiovascular disease. “Fish Oil Has No Impact on Strokes” and similar headlines spread over the Internet after the study results were released. But, according to the study’s website (, “The omega-3 fatty acid intervention lowered the risk of heart attack by 28 percent and the risk of fatal heart attack by 50 percent, but had no benefit on stroke or cardiovascular deaths not related to heart disease. Additionally, omega-3 fatty acids reduced the rate of angioplasty procedures by 22 percent.” So, “Fish Oil Has No Impact”? Lowering rates of fatal heart attacks and angioplasty certainly qualifies as a significant impact in my book. also notes, “In participants with low fish consumption (less than 1.5 servings, 3–4 ounces, per week), omega-3 supplementation led to a 19 percent reduction in major cardiovascular events, including a 40 percent reduction in heart attack, as well as a trend toward a reduction in death from any cause. Among African-Americans, omega-3 supplementation led to a 77 percent reduction in heart attacks, and a benefit was observed regardless of fish intake.” African-Americans, a high-risk group for premature death from heart disease, take note! No drug—ever—has given this kind of hope. Please, take your fish oil. Or at least eat wild salmon and small tinned fatty fish regularly.