Consumer Reports has recently published “15 Supplement Ingredients to Always Avoid.” The list was put together by a panel of experts, but naturally opinions of experts don’t amount to a valid study. We don’t even know the authors or how they were selected for the panel, and yet the “report” is being generally treated as authoritative in the media.
There was a lot of material that raised eyebrows. Just one example – green tea extract – was on the “always avoid” list because of the following risks:
Dizziness, ringing in the ears, reduced absorption of iron; exacerbates anemia and glaucoma; elevates blood pressure and heart rate; liver damage; possibly death.
Their stated position: “Our experts agree that none of these supplement ingredients provide sufficient health benefits to justify the risk.”
These recommendations were not backed up by any references. It seems that the question of whether green tea provided benefits was answered with completely unrealistic criteria for research, but the question of whether there were risks was answered with the most lax and unscientific criteria. I can only conclude this panel had no problem using anecdotal case reports of adverse effects with mixed herbal combinations, and toxicology studies at dosages that far exceed what people consume.
I found a reference to a single case report of death, but this was a person who concomitantly abused drugs and alcohol. This was mentioned in a comprehensive review of green tea published last year (Braun, Lesley, and Marc Cohen. Herbs and Natural Supplements, Volume 2: An Evidence-Based Guide. Vol. 2. Elsevier Health Sciences, 2015. 510-532.) In contradiction of the Consumer Report claims, the long list of evidence-based benefits is remarkably impressive. The adverse effects are very infrequent and for there to be a risk there would generally need to be huge doses, unique conditions or drug interactions.
I was left wondering how this hepatoprotective supplement could cause liver damage, as this was the only risk on the list that I was unsure about. I found it interesting that a meta-analysis published three months ago counters the expert panel’s claims:
There remain liver-related safety concerns, regarding potential hepatotoxicity in humans, induced by green tea intake, despite being supposedly beneficial. Although many randomized controlled trials (RCTs) of green tea extracts have been reported in the literature, the systematic reviews published to date were only based on subjective assessment of case reports. To more objectively examine the liver-related safety of green tea intake, we conducted a systematic review of published RCTs. A systematic literature search was conducted using three databases (PubMed, EMBASE and Cochrane Central Register of Controlled Trials) in December 2013 to identify RCTs of green tea extracts. Data on liver-related adverse events, including laboratory test abnormalities, were abstracted from the identified articles. Methodological quality of RCTs was assessed. After excluding duplicates, 561 titles and abstracts and 119 full-text articles were screened, and finally 34 trials were identified. Of these, liver-related adverse events were reported in four trials; these adverse events involved seven subjects (eight events) in the green tea intervention group and one subject (one event) in the control group. The summary odds ratio, estimated using a meta-analysis method for spare event data, for intervention compared with placebo was 2.1 (95% confidence interval: 0.5–9.8). The few events reported in both groups were elevations of liver enzymes. Most were mild, and no serious liver-related adverse events were reported. Results of this review, although not conclusive, suggest that liver-related adverse events after intake of green tea extracts are expected to be rare.