Why "Used for Thousands of Years" Is Not Proof: What History Can and Cannot Tell Us

The claim

"Used for thousands of years" is one of the most common lines in marketing for herbs and other remedies. It sounds like a test that has already been passed. It is not. A remedy can be used for a very long time because it helps, because it comforts, because people recover on their own, or because no one ever checked. History tells us which of these is true only if someone also looks closely.

This is not a judgment on traditions. Traditional knowledge carries cultural, social and practical value, and some of it has led to important medicines. The point is narrower: long use is a reason to study a remedy, not a result.

Why a remedy can seem to work when it does not

• Many illnesses get better on their own. The NHS says you should begin to feel better from a cold in about 1 to 2 weeks. [1] A remedy taken at the start of a cold is likely to be followed by recovery whether or not it did anything.
• Expectation can change how people feel. A large Cochrane review of placebo trials found no important clinical effects of placebo in general, but said that in some settings placebo can influence patient-reported outcomes, especially pain and nausea, and that this is hard to tell apart from biased reporting. [2] Feeling better is real; it does not show that an ingredient worked.
• People remember successes. Stories of recovery are passed on, and the many cases where nothing happened are not. This is a general feature of word-of-mouth knowledge, which is why trials with comparison groups exist.

When long use did not mean safe

Historical use is not evidence of safety. Documented examples:

• Aristolochic acid. Aristolochic acid nephropathy, a progressive kidney disease often linked with urinary tract cancers, was first reported in a Belgian group of more than 100 patients after slimming pills containing a Chinese herb, Aristolochia fangchi. [3] The review also warned that in Asian countries where traditional medicines are popular, substitution of botanical products by herbs containing aristolochic acid is a risk. [3]
• Metals in traditional preparations. A study of Ayurvedic medicines sold online found 20.7 percent of the products tested contained detectable lead, mercury or arsenic. [4] The authors note that metals may be present because of the practice of rasa shastra, which combines herbs with metals, minerals and gems. [4] See heavy metals in traditional medicines.
• Ephedra. A systematic review of herbal weight-loss supplements reported an increased risk of psychiatric, autonomic or gastrointestinal adverse events and heart palpitations with herbal ephedra and ephedrine-containing products. [5]

More examples are in traditional remedies with documented harm.

When history pointed to something real

The 2015 Nobel Prize in Physiology or Medicine recognized Tu Youyou, who turned to traditional herbal medicine in the search for new malaria treatments. A large-scale screen of herbal remedies in malaria-infected animals pointed to an extract of Artemisia annua, but the results were inconsistent, so Tu revisited the older literature, found clues for extracting the active component, and showed that it, artemisinin, was highly effective against the malaria parasite in infected animals and in humans. [6]

Notice what made this a discovery. The herb was tested in animals, the active compound was isolated, and then it was tested in people. Later trials compared artesunate with quinine in severe malaria: a Cochrane review of eight trials with 1,664 adults and 5,765 children found that artesunate significantly reduced the risk of death in both adults and children. [7] The proof came from testing, not from the age of the tradition. See ethnopharmacology: from folk use to drug discovery.

Testing sorts traditional remedies both ways

When researchers test herbs that have long been used, some show benefit and some do not. A Cochrane review of herbal medicine for low-back pain included 14 trials with 2,050 participants. It found moderate-quality evidence that capsicum (cayenne) cream or plaster probably produces better results than placebo for chronic low-back pain, and evidence of lower quality for other herbs, with poor reporting of the trials. [8] That is the right standard: look at each remedy, for each use, one trial at a time.

What history can fairly tell us

• It can point researchers to plants and practices worth testing.
• It can document how people use a remedy, in what form and for what purpose.
• It can carry meaning for people and communities, which matters in its own right.

What it cannot do alone is show benefit, rule out harm, or establish that a modern product matches the traditional preparation. For more, read historical use vs clinical evidence, the doctrine of signatures and understanding evidence in complementary health.

Questions to ask when you see "ancient" or "time-tested"

• What exactly is claimed, and for which condition?
• Has the product, or the herb in a similar form, been tested in people with a comparison group?
• Is there any known harm or interaction? Herbal medicines are not tested in the same way as standard medicines. [9]
• Does the label wording rest only on history? See reading "traditionally used for" claims on labels.

Do not stop or delay prescribed treatment for a remedy because it has a long history. Talk to a clinician or pharmacist about anything you take.