We are currently being advised that for a long and healthy life we need to eat 7 portions of fruit and vegetables a day, with the polite nudge that vegetables are better than fruit. Unless I have nodded off I’m not sure what actually constitutes a portion. At the moment I’m working on the basis that if it is large enough to see, identify and pick up with a fork then that’s a portion. This policy is flexible enough to include both a single pea and a beefsteak tomato.
In the eighteenth century the idea developed that the health of the body was governed by a balance between acidity and alkalinity, some foods being acid and some being alkaline. Meat, for example, was seen as having an ‘alkaline alkalescent tendency’ because if left to its own devices it would putrefy, producing alkaline substances like ammonia. Fruit and most vegetables on the other hand rot down to produce acidic substances and were therefore of ‘acidic acescent tendency’. (To break the rule cabbage was thought to have an alkaline tendency.) According to 18th century food science all you needed for health and happiness was to balance out the two tendencies. The idea sounded rather plausible. Scurvy, for example, thought to be caused by excessive consumption of salt meat, was seen as an alkalescent ‘putrid’ fever which could be cured by balancing it with an acescent diet of fresh fruit and vegetables – and lo and behold, to everyone’s delight – it actually worked!
Fans of “Treasure Island” by Robert Louis Stevenson will remember Jim Hawkins hiding in the barrel of apples left on the deck of the ‘Hispaniola’ for the general health of the crew and – “anyone to help himself that had a fancy.”
Albrecht von Haller outlined the principle in his book “First Lines of Physiology” translated into English in 1779…
…scurvy, ferocity, fœtor (an offensive stale or putrid odour), leprosy and every kind of alkaline corruptions, all of which evils are cured by change of diet, and the exclusive use of acid vegetables.
The interesting thing about this ‘alkaline v acid’ theory is that it ran counter to an earlier and centuries old notion that fruit and vegetables had evil, pernicious qualities, being bad for you and causing fevers. By the end of the eighteenth century this idea was firmly being shown the door….
“Ripe fruits, in moderate quantity, are wholesome: and, contrary to the vulgar prejudice, tend rather to prevent than to induce bowel complaints.”
W. BLAIR ‘The Soldier’s Friend’; or the means of Preserving the Health of Military Men. 1798
The ‘alkaline v acid’ concept was taken up with alacrity by the medical profession. Soon every disease, every symptom, every food was being discussed in terms of acescence or alkalescence. In “A Sure Guide in Sickness and Health” published in 1776, leading dietician William Smith wrote…
“When a person attempts to live upon flesh meat alone, though it be fresh, his appetite becomes keener, and even ravenous; and nature will crave for some acids and vegetables to correct the alkaline acrimony of the blood. And when he lives upon vegetables alone, whereby the stomach will contract an acid tendency, he will find a craving for animal food to temperate the acidities.”
William Smith was one of the first dieticians to promote the revolutionary idea that fruit was good for you…" the lightest, most wholesome food we can eat." He even advised a liberal diet of fruit as a preventative measure against certain diseases. Far from causing fever as was thought Smith pointed out that people living in Southern Europe where they consumed large quantities of fruit suffered no more fevers than people living in Great Britain who at the time steered well clear.
The idea of ‘neutralisation’ between ‘alkalescent’ and ‘acescent’ foods within a balanced diet enjoys support to this day although there has been some reversal in the ‘tendencies’ ascribed to food by eighteenth century scientists. Meat, for example, contains sulphur and phosphorus in different forms that can oxidise within the body to produce acids and therefore in the old parlance is ‘acescent’ not ‘alkalescent’- whereas the acids in fruit and vegetables can oxidise to form alkalis like soda, potash and limes making them ‘alkalescent’ not ‘acescent’.
These old definitions have largely disappeared now – replaced by more detailed classifications like vitamins, minerals, starches, fats, sugars, proteins, and carbohydrates. However we define our food the guidance remains just as granny gave it – a little of everything in moderation. Remember, a balanced diet does not mean a chocolate biscuit in each hand!
“I never worry about diets. The only carrots that interest me are the number you get in a diamond.”
In 1738 a food scientist William Forster decided that simply dividing foods into ‘acids’ and ‘alkalis’ did not sufficiently represent their various attributes. He proposed the following:
- The Saline
- The Acid and Ascescent
- The Alkalescent
- The Viscous and Glutinous
- The Oleaginous
- The Acrid Aromatick
- The Spirituous
- The Aqueous
Would you like chips with that?
— from Martyn Day
Credit: Some of the information in this article came from “The Englishman’s Food” by Drummond and Wilbraham published in 1939