Life in a glass
How long can a human being live for if their sole source of food or drink is beer? And do different beers 鈥� ale, lager, stout, mild 鈥� confer a better chance of survival?
鈥� Beer has had a reputation since antiquity as being a staple in the diet, often called 鈥渓iquid bread鈥�. In ancient Egypt, workers received beer as part of their salary, as did the ladies-in-waiting of Queen Elizabeth I of England. In 1492, one gallon of beer per day was the standard allocation for sailors in the navy of Henry VII.
This high reputation for beer came about because it was made from malted barley, which is rich in vitamins. This is still true today. A quick check using nutritional tables shows that a pint can provide more than 5 per cent of the daily recommended intake of several vitamins, such as B9, B6 and B2, although other vitamins such as A, C and D are lacking.
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It is of course unethical to conduct an experiment to see whether one can live on beer alone. However, during the Seven Years War of 1756-63, John Clephane, physician to the English fleet, conducted a clinical trial. Three ships were sent from England to America. One 鈥� the Grampus 鈥� was supplied with plenty of beer, while the two control ships 鈥� the Daedalus and the Tortoise 鈥� had only the common allowance of spirits. After an unusually long voyage due to bad weather, Clephane reported that the Daedalus and Tortoise had 112 and 62 men respectively requiring hospitalisation. The Grampus, on the other hand, had only 13, arguably a clear-cut result.
Needless to say, the sailors鈥� allowance of eight pints of beer per day is no longer within the accepted confines of current moderate alcohol consumption. One can only speculate on the state of their livers. Living on beer alone may be a fantasy for some, but it is not a good health strategy.
C. Walker
Brewing Research International
Nutfield, Surrey, UK
鈥� I do not know how long a human could survive on beer alone, although I suspect the critical factors would be cirrhosis of the liver and vitamin deficiencies. Nonetheless, monks would be the ones to ask. Bavarian-style bock beers (or dark lagers) have been closely associated with monasteries for centuries, where they were brewed for times of fast and lent. They are commonly known as liquid breads. Possibly the most famous beer of this style is Paulaner Salvator, and at 7.5 per cent alcohol by volume it should keep your mind from food.
Neil Watt
Knighton, Powys, UK
鈥� I offer the following answer: I鈥檓 39 and still alive.
Chris Jack
St Albans, Hertfordshire, UK
鈥� I once put myself on a beer and cabbage diet. I can vouch that I lost weight, friends and control of my lower bowel, often simultaneously.
Bill Coppock
Edinburgh, UK
Take a lettuce break
I have heard that lettuce contains large quantities of caffeine, which it uses to poison predators in an attempt to avoid being eaten. Is this true and if it is, how much does it contain?
鈥� Cultivated lettuces, such as romaine, iceberg and butterhead, do not contain any detectable amount of caffeine. As a matter of fact, lettuce has a long-standing reputation for promoting sleep, while it is well known that caffeine in all forms should be avoided when treating sleep disorders.
Lettuce eaten raw or juiced (mixed with a little lemon juice for flavour) is often recommended as an effective sleep-time snack, as are all leafy green vegetables. This is because very minute amounts of lactucarium 鈥� an alkaloid with similar physical properties to opium 鈥� is present, as is the anti-cramping agent hyoscyamine.
The confusion might stem from a report in Nature in 2002 by the US Department of Agriculture in Hawaii, which stated that solutions of caffeine are effective in killing or repelling slugs and snails when applied to the foliage or the growing medium of plants (vol 417, p 915). The researchers noticed the caffeine solution did not damage the foliage on some of the plants used in the experiments, but it did yellow the leaves of others, including lettuce.
I. Rosenthal
Department of Food Science
Volcani Center, Agricultural Research Organization
Bet-Dagan, Israel
鈥� My mother used to warn me when I was young never to eat too much lettuce, especially from the garden, and certainly never to eat the old leaves or flowering stalks. While this may have been to save the salad garden from ravaging hordes of children, she also frequently told the story of her grandfather who was once unable to sell all of his lettuces at the market, despite staying all day.
After a very early start and nothing to eat all day, coming home hungry and tired in his cart, he munched his way through four whole lettuces. When his horse dutifully arrived home pulling the cart, my great-grandfather was sound asleep in the back. They carried him inside and he slept for all the next day and the next night, waking during the following day. While I accept that some of this may be apocryphal I wonder if it is at all likely?
Jan Horton
West Launceston, Tasmania, Australia
鈥� Lettuce is well known for its sleep-inducing properties. Fans of author Beatrix Potter will recall that after stuffing themselves on Mr McGregor鈥檚 bolted lettuces, the Flopsy Bunnies were overcome by slumber 鈥渂ecause the lettuces had been so soporific鈥�. This enabled Mr McGregor to put them into a sack without waking them!
Amanda Randall
Leamington Spa, Warwickshire, UK
This week鈥檚 questions
Siren screams
When emergency sirens pass by, all the dogs in my neighbourhood yowl. The reason, I鈥檝e read, is the sound of the siren hurts their sensitive ears. Yet my cat, whose hearing seems to be more sensitive than that of my dog, pays no attention. Why would the sound hurt a dog鈥檚 ears and not those of a cat?
Michael Ham
Monterey, California, US
Food chains
Broadly speaking, plants obtain energy through photosynthesis of sunlight and animals by eating those plants or each other. Surely evolution will have experimented with other means. Is there any fossil evidence to suggest what this might have been?