Let me tell you about Tribulus terrestris — and about one of the more extraordinary pieces of regulatory reasoning I have encountered in my career as a herbalist.
Tribulus terrestris has been used in traditional medicine across the Indian subcontinent, the Mediterranean, and China for centuries. It is widely used as a supplement for men's health — sexual function, testosterone support, athletic performance. Clinical trials in humans show it to be well tolerated at standard doses, with adverse effects limited to mild gastrointestinal symptoms.
And it is on a European restriction list. The primary concern cited? Sheep.
I am not making this up. ** The concern — stated fairly.**
The regulatory concern centres on a veterinary toxicological phenomenon called "staggers syndrome." In sheep grazing extensively on Tribulus terrestris pasture in Australia and South Africa, researchers observed a locomotory disorder — stumbling, neurological impairment, liver-related photosensitisation. This syndrome has been documented in the scientific literature since the 1980s. The cause was traced to beta-carboline alkaloids in the plant material consumed by the sheep, and to steroidal saponins causing hepatogenous photosensitisation.
Now. I am going to give you the data that contextualises this concern, because I want you to understand why applying a sheep grazing phenomenon to human supplement use is a species-pharmacology error of the first order.
Why the staggers model does not translate.
The sheep in these studies were grazing ad libitum — continuously, freely, over extended periods — on large quantities of fresh Tribulus terrestris plant material under field conditions. The experimental hepatogenous photosensitisation was induced using crude steroidal saponin extract at approximately 54 milligrams per kilogram of bodyweight. That is a dose of crude saponin extract, not whole plant.
A standard human supplement dose of Tribulus terrestris extract is 250 to 750 milligrams per day total — equivalent to approximately 3.5 to 11 milligrams per kilogram for a 70-kilogram person. This is not a marginal difference. It is a dose difference of approximately 5 to 15 times, applied to a different species, by a different route, in a different biological context.
Sheep are ruminants. Their gastrointestinal pharmacology, their gut flora, their alkaloid metabolism are fundamentally different from human physiology. The beta-carboline alkaloids responsible for neurological staggers in sheep have not been implicated in any human supplementation toxicity report. The hepatogenous photosensitisation mechanism — phylloerythrin accumulation due to liver dysfunction — has not been observed in human users of Tribulus supplements.
This is a category error. Taking a veterinary toxicology finding from sheep grazing on fresh plant material and applying it to encapsulated standardised extract consumed by humans at clinical doses is not evidence-based risk assessment. It is regulatory post hoc rationalisation.
What the human data actually show.
A 2017 randomised controlled trial by Kamenov and colleagues, published in Acta Facultatis Medicae Naissensis, evaluated Tribulus in men with mild to moderate erectile dysfunction over twelve weeks. Significant improvement in sexual function versus placebo. No significant adverse events reported. A 2022 systematic review in the International Journal of Environmental Research and Public Health, covering multiple studies, concluded that Tribulus supplementation is safe, with adverse effects in human studies limited to mild gastrointestinal complaints such as stomach cramps and nausea.
The US Department of Defense Operation Supplement Safety database confirms: short-term studies up to three months have reported few adverse effects.
Now, I will be honest with you about the limitation here: controlled trial data for Tribulus beyond three months in humans is genuinely limited. The absence of long-term RCT data is a real evidence gap. That is a legitimate observation. It is not the same as a demonstrated long-term safety risk. ** The proportionality argument.**
The pharmaceutical comparator for erectile dysfunction is sildenafil and tadalafil — Viagra and Cialis. These carry genuine cardiovascular risks, documented drug interaction profiles, and specific contraindications including patients on nitrate therapy, where combination can cause life-threatening blood pressure collapse. They are available — in some cases over the counter, in others by prescription — without anyone suggesting they should be banned from European markets.
Tribulus, with its twelve-week RCT showing safety and efficacy, and its well-documented mild GI side effect profile, is being treated as a public health threat on the basis of sheep grazing data.
Sign the petition. https://www.change.org/p/demand-uk-regain-control-over-food-supplements-regulation?recruiter=1403120945&recruited_by_id=ca366360-0a66-11f1-a119-071922cd5010&share_id=Qv72WrhZDN
Respond to the EU consultation. Write to your MP at writetothem.com.
The UK Government has committed to align food supplement law with EU restrictions under the SPS Agreement — without Parliament voting on it. That commitment is published at www.gov.uk/government/news/uk-eu-sps-agreement-legislation-in-scope .
Parliament should vote before any EU restriction on Tribulus or any other supplement becomes British law. That is not a partisan position. It is a constitutional one.
#RightToHeal #HerbalAccessNI #SaveOurSupplements
