Jan. 2 (UPI) -- While the vast majority of over-the-counter nutritional and herbal supplements are safe -- unless they are consumed in large quantities -- not all of them deliver on their promised benefits.
Researchers say that the $40 billion-a-year dietary supplement industry, which covers "tens of thousands" of products, exists on the offer of some health benefit.
While many people believe they work, there is little beyond anecdotal evidence for their efficacy, experts say.
"When it comes to their health, everybody is looking for a silver bullet," Martin J. Ronis, a professor of pharmacology at the Louisiana State University School of Medicine in New Orleans, told UPI. "And that silver bullet doesn't really exist."
Summary of supplements
The supplements label covers a broad range of products from vitamins -- like multivitamin, vitamin C and D tablets -- to herbal products like ginseng, touted for its energy-boosting benefits, and St. John's wort, billed as a natural anti-depressant. Melatonin is used as a sleep aid, and fish oil has been linked with improved heart health.
A wide array of herbal products with roots in Asian and Native American cultures, and supplements advertised on TV and sold online, also promise to help with weight loss and boost energy. An increasing number of CBD-based products have surged in use, particularly as states relax cannabis laws.
All of these products fall under the auspices of the Dietary Supplement Health and Education Act of 1994, which some experts believe provides inadequate oversight in terms of ingredients and safety and effectiveness.
The law effectively exempts many supplements from review by the U.S. Food and Drug Administration, and some accuse the federal agency of being lax in exercising the enforcement power it does have.
"Unfortunately, there are several weaknesses in the [DSHEA] that prevent consumers from being able to trust that a product sold as an over-the-counter supplement is safe," Pieter Cohen, an associate professor of medicine at Harvard's Cambridge Health Alliance and co-author of a recently published commentary in the New England Journal of Medicine, told UPI.
"And this problem is amplified by the FDA not enforcing the law -- the agency permits products they know to be adulterated to remain on store shelves. Furthermore, the few times that FDA does try to remove adulterated products, their enforcement is inadequate and adulterated supplements continue to be widely available."
The power of pills
Not all supplements are bad, unsafe or ineffective.
Cohen said he routinely recommends vitamins and minerals for specific conditions, such as iron supplements for those who are anemic.
But Ronis noted that, with few exceptions, vitamin and mineral supplementation is rarely necessary in places like the United States because "most people here get sufficient amounts of them in their diet," assuming they have healthy, well-balanced eating habits.
Though many of these vitamins and minerals are found in foods, consuming more of them may not be good, Ronis said. He cited the extreme example of an August 2017 study in the Journal of Clinical Oncology, which found that high doses of vitamin B6 and/or B12 actually increased the risk for lung cancer in men overall -- and even more in men who smoked.
Another example, said Peter Cogan, an associate professor of pharmaceutical sciences at Regis University in Denver, is prescription cannabidiol.
"Though not technically a dietary supplement according to federal definitions, yet treated like one by the states and possessed of all the attributes of any other herbal supplement, take a look at the side effects reported for prescription cannabidiol and compare them to those acknowledged by any vendor of CBD oil," Cogan said.
Cogan notes that CBD was marketed heavily before clinical trial results were known publicly, and the industry has continued to expand while acknowledging potential side effects, including sleep issues and increased risk for infection.
"What would we find if we subjected all dietary supplements to such assessments?" Cogan asked.
More scrutiny needed
Some supplement manufacturers have taken the step to bolster the credibility of their products by applying for, and receiving, USP certification of their composition.
USP, a non-profit that develops standards for drugs and other compounds, essentially certifies that these products contain the ingredients, and in the exact amounts, as noted on their labeling.
Ronis said this step is "better than nothing," but it doesn't provide the same assurances that large clinical trials testing the safety and effectiveness of these products in large populations of patients would.
"If a supplement is certified by a top-notch program it simply confirms that what is listed on the label is actually what is in the bottle," said Cohen, who added that he hopes Congress will address shortcomings in DSHEA when it returns from holiday recess. "No certification program, that I am aware of, provides consumers with assurance that the product works as advertised or that the product is safe."
So what should people looking into nutritional or herbal supplement do, particularly given that some of these products may provide health benefits?
"Talk to your doctor before taking anything," Ronis said. "Better yet, talk to a nutritionist who has expertise in supplements."