Green tea,sage,water and wine: Thomas Short's comparative experiment on speed of digestion (1730)

Dear Editor,

The origins of the controlled trial go back to the book of Daniel ¹ in the Sixth century BCE. This compared two groups of people following different diets and is chronicled in the King James Version as follows:

Modern enquiries into digestion have their roots in Sanctorius (Santorio Santorio, 1561–1636). ² Basic observations on the effect of eating upon pulse rate were recorded by Sir John Floyer (1702) including some data presented within simple tables. ² One overlooked author on digestion was physician Thomas Short (1690–1772). Short was born in southern Scotland and practised in Sheffield, England. ³ He is remembered for his works on human populations and on mineral waters. In 1730, Short published a ‘dissertation’ on the health benefits of drinking tea and eating the herb sage (Salvia officinalis). Herein, Short praised the ‘celebrated [Robert] Boyle’ ⁴ but his ‘chymical’ experiments bear the hallmark of Lord Bacon by dint of choosing raw ‘flesh’ as a substrate. ⁵ For example, he compared the astringent (contractile) effects of each of four types of tea upon meat. In Short's day, astringency was believed to be beneficial for strengthening/healing and, thus, a sign of the superiority of green tea in patients:

It is of note that Short offers little evidence of the same strict comparison of such teas in humans. The closest he comes to this was (like Sir John Floyer) tasting plants himself. ^{3 p 27} Short does, however, include a notable description of a simple controlled trial to test his belief that alcohol impaired digestion:

Let any two Persons of equal Health, Appetite and Digestion, dine upon Goose, Duck, Venison or Salmon, and each eat equal Quantities; let one drink clear, fine Table Beer, Water, or a little Wine in his Water, and the other drink Claret, or Strong Beer, or Ale; the first shall digest his Dinner much sooner, easier [sic], and have finer Chyle from it, than the latter. ^{3 p 89}

Rather than an experiment which he undertook himself, this account comes across as a rhetorical device to support Short's own ideas about digestion. Despite describing clear steps towards a fair comparison of two individuals, Short's proposed trial may have fallen foul of his premise that ‘Diet affords us the pathognomick [sic] Signs of each Constitution’. ^{3 p 104} That is because the ancient and very subjective notion of ‘constitution’ could always be invoked to account for the different effects of interventions (such as alcohol) observed in individuals.

Short's writing is also of wider historical note for favouring experiments rooted in Hippocrates’ principle of ‘first do not harm’. This is hinted at in Short's praise for experiments ‘without.. Danger to any Animal’. ^{3 p 17} Such a notion is ahead of his time and a departure from the ideas of Bacon. ⁶ Short would be pleased to know that 250 years after his death, experiments on living animals are declining in Britain. ⁷

Short's dissertation is topical, given recent media publicity about the health benefits of tea, especially its green varieties. Without access to modern technology (imaging, smart pills or computers), it is unsurprising that he should refocus his efforts upon ‘chymical’ experiments and descriptive self-reported evidence. Short's account reflects the obstacles facing eighteenth-century physicians in the transition from ‘chymical’ experiments or astute study proposals to meaningful comparisons of treatments in people ⁶ : overcoming entrenched ideas of ‘constitution’, defining measurable outcomes and devising controlled trials that were safe and acceptable to participants.