The concept of ‘clean eating’ is nothing new, but ideas about what constitutes ‘clean’ or ‘dirty’ food have varied within and across cultures. In the later seventeenth century, the popular health writer Thomas Tryon promoted a “radically clean” vegetarian diet as a route to longevity and clarity of mind. However, Tryon’s meat-free menu was rather different from the quinoa bowls and kale smoothies of modern-day clean-eaters. His 1694 Pocket-companion contains the following recipe (easy to follow, but emphatically not to be tried at home):
Boniclabber is made by letting your Milk stand till it sowers, which will be in Twenty-fours hours, if the weather be very hot. 
Tryon’s ‘bonny clabber’ – an Irish country dish that was later enjoyed by immigrants to the USA – would have great difficulty in meeting twenty-first century Western standards of food hygiene. Writing well before the advent of pasteurization, Tryon would likely have used raw milk straight from the cow, which would have been rich in bacteria that could be both beneficial and harmful to the human body. If it was left at just the right temperature and for the appropriate length of time, the finished product would be a thick, fermented milk, similar to yoghurt or kefir.
Perhaps unsurprisingly, not all of Tryon’s contemporaries shared his enthusiasm. Gideon Harvey wrote that “Bonny-Clabber Physicians” routinely endangered their patients by their over-use of milk products, which he viewed as highly corruptible and prone to curdling in the belly.  Harvey had the weight of medical tradition on his side. Humoural physicians since Hippocrates frequently expressed mistrust or even fear over the coagulability of milk, with Galen writing that it “turns to wind in the stomachs of most people, and there are very few who avoid this.” 
Tryon attempted to forestall this sort of criticism in his own writing. Since he believed that digestion operated by a process of fermentation, it logically followed that fermented foods should be easier on the stomach, having already undergone the initial stages of this process. While he was prepared to admit that it “may not be so agreeable to the Pallat at first”, Tryon assured his readers that “a little Custom will make it familiar and pleasant.” 
Attitudes towards the healthiness of clabber were also closely tied up with racial stereotypes about the Irish, whose perceived gluttony and barbarism were ridiculed by many English Protestants. In 1652 the parliamentarian Samuel Sheppard wrote of an anonymous royalist that “his Intellect is as foule, as an Irish Firkin of Bonny Clabber”, suggesting that many viewed it as a disgusting or dangerous substance.  By contrast, in a 1635 letter from Dublin, the English royalist and Lord Deputy of Ireland Thomas Wentworth described clabber as “the bravest freshest Drink you ever tasted.” 
The example of bonny clabber raises some interesting questions about the relationship between ideology and diet. As Carla Cevasco has flagged up elsewhere on this blog, the categories that shape affective responses to food can be highly variable, ranging from the genetic makeup of a population to its social norms. Disgust that feels instinctive or biologically hard-wired might just as easily be the product of a specific cultural moment. As the debate over clean eating continues to rage, we need to pay closer attention to the ideological fault-lines upon which we construct our ideas about food and hygiene.
 Thomas Tryon, A pocket-companion, containing things necessary to be known by all that values their health and happiness (London: Printed for George Conyers, 1693), 6.
 Gideon Harvey, The art of curing diseases by expectation (London: Printed for James Partridge, 1689), 38.
 Galen, Galen on Food and Diet, ed. Mark Grant (London and New York: Routledge, 2000), 165. See also Ken Albala, “Milk: Nutritious and Dangerous,” in Milk: Beyond the Dairy: Proceedings of the Oxford Symposium on Food and Cookery, 1999, (Devon, UK: Prospect Books, 2000), 19-30.
 Tryon, Pocket-companion, 7.
 Samuel Sheppard, The vveepers: or, the bed of snakes broken (London: Printed for Thomas Bucknell, 1652), 6.
 Thomas Wentworth, The Earl of Strafforde’s Letters and Dispatches, Volume 1, ed. William Knowler (London: Printed for the editor, by William Bowyer, 1739), 441.
Michael Walkden is currently completing his doctoral thesis in History at the University of York, UK. His research explores understandings of the relationship between emotions and digestion in early modern English medicine. He is particularly interested in the intersection of diet, health and spirituality in the seventeenth century.