Fitness bunnies, bodybuilders and dieters often put blind faith in supplements to burn fat quicker, build muscle, feel more energetic, enhance performance or simply augment their workout. But there’s little evidence that these supplements actually work, as most are never independently tested – despite being readily available online and in retail pharmacies. 

In the latest warning against sport supplements, Dr Pieter Cohen, a researcher at Cambridge Health Alliance and Harvard Medical School in Cambridge, Massachusetts, and colleagues tested 57 sport supplements to analyse their contents and found that a third didn’t contain key ingredients that appeared on the labels.

Cohen, who leads the Supplement Research Programme, is a leading voice on supplement safety in the United States.

Since the US Food and Drug Administration (FDA) banned ephedrine and related ephedra alkaloids in dietary and sports supplements due to their serious safety risks in 2004, supplement manufacturers have promoted an increasingly complex variety of alternative botanical compounds for sports enhancement.

Some of the substances included in supplements since the ban include plant extracts of Rauwolfia vomitoria (linked to blood pressure, irregular heartbeat, heart attack and seizures), the caffeine-like compound methylliberine, halostachine (deemed to be unsafe by the FDA), the plant steroid turkesterone (often marketed as a natural alternative to anabolic steroids), and octopamine (a central nervous system stimulant), with purported performance-enhancing properties. 

“The FDA does not pre-approve these ingredients, or any supplement ingredient, for either efficacy or safety before their introduction,” Cohen and colleagues write in their paper published in JAMA Network Open.

“But FDA inspections have found that supplement manufacturers often fail to comply with basic manufacturing standards, such as establishing the identity, purity, or composition of the final product.”

This study shows that only 11% of products were accurately labelled and five FDA-prohibited ingredients were found, including an unapproved drug available in Russia (omniracetam), three drugs formerly available in Europe (octodrine, oxilofrine and deterenol), and one drug that has never been approved in any country (1,4-dimethylamylamine).

Around 40% of the supplements bought online did not contain a detectable amount of the ingredient listed. Half displayed the wrong amount and 12% were found to contain illegal additives.

Of the 63 products purchased, six did not list one of the five ingredients on the label; 23 of 57 products (40%) did not contain a detectable amount of the labelled ingredient; and of the products that contained detectable amounts of the listed ingredient, the actual quantity ranged from 0.02% to 334% of the labelled quantity.

Six of 57 products (11%) contained a quantity of the ingredient within 10% of the labelled quantity.

Seven of the products (12%) contained at least one FDA-prohibited ingredient. Five FDA-prohibited compounds were found in these products, including four synthetic stimulants. Six products contained one of these prohibited ingredients, and one product had four prohibited ingredients.

The researchers said 89% of dietary supplement labels did not accurately declare the ingredients found in the products, and 12% of products contained FDA-prohibited ingredients.

Supplements do not fall into a subcategory of medication; the FDA regulates them as a subcategory of food, Cohen told the American Medical Association in 2021.

“This has huge consequences for the whole category of dietary supplements, from vitamins, minerals, probiotics and all sorts of new ingredients, because what it means is that the manufacturer can introduce anything into the [US] market that they believe is safe.”

In April this year, experts on natural products and toxicology highlighted the problem of liver damage due to herbal dietary supplement (HDS) use in the United States. They said the Dietary Supplement Health and Education Act of 1994 provides an insufficient framework for regulating HDS products, which are consumed regularly by up to 20% of adults in that country.

Twenty percent of all drug-induced liver injuries – many of which required hospitalisation and liver transplantation or resulted in death, were due to HDS in 2013, said the Drug-Induced Liver Injury Network.

Most of these HDS-induced liver injuries were attributable to unusual and untested combinations of exotic botanical extracts and/or purified phytochemicals, poorly researched new dietary ingredients, products intentionally adulterated with approved or unapproved drugs, or combinations of these.

Multi-ingredient products linked to these liver injury cases have included several formulations marketed by Herbalife.

Since 1994, the market has been flooded with HDS products such as green tea extract, Hoodia gordonii, Garcinia cambogia, or Scutellaria – all said to be responsible for a significant proportion of liver damage cases.

In South Africa, the Supreme Court dismissed an appeal by the South African Health Products Regulatory Authority (Sahpra) and the Health Department on 11 April 2022 of an earlier ruling finding for the Alliance of Natural Health Products, which had sought declaratory orders and a review of the General Regulations, published in terms of the Medicines Act. 

These regulations had introduced a new category of medicines – “complementary medicines” – setting out a number of obligations with regard to the labelling and advertising of such medicines, which include “discipline-specific traditional claims” and “health supplements”.

The General Regulations therefore only apply to substances that make therapeutic claims.

Sahpra is expected to head to the Constitutional Court to apply for leave to appeal against the SCA judgment. DM