'Eat like a caveman for a healthy heart', is the headline in The Daily Telegraph today. It and several other newspapers report on a new study which claims that a 'paleolithic' or caveman diet of berries, nuts, lean meat and fish 'could help to reduce the risk of developing heart disease'.
The story is based on a small, short study of 20 young healthy volunteers which had a 30% drop out rate, with complete data for only six people available. However, these six people reduced their calorie intake by about 900 calories to about 1500 calories a day and the whole group of 14 who managed to stick with the study, lost on average 5lbs (2.3kg) in three weeks. There was no control group, so it is not possible to say whether there is anything about a caveman diet compared with any other low calorie diet that produces the weight loss or the other changes noted.
Where did the story come from?
Dr Magnus sterdahl and colleagues from the Karolinska Institute in Stockholm, Sweden carried out this research. The study was funded by grants from the Stockholm County Council and was published in the peer-reviewed: European Journal of Clinical Nutrition.
What kind of scientific study was this?
This was an uncontrolled observational study. The researchers say that they did not intend to copy stone-age eating habits but wanted to eliminate the harmful aspects of modern diets. They recruited 10 men and 10 women aged between 20 and 40 via a medical students association. They only included healthy people with a body mass index (BMI) of less than 30, who did not need hospital care, were not on prescription drugs, did not have an eating disorder or were already eating a special diet. Five of the 10 men and one of the 10 women did not complete the study either because of illness, an inability to complete the diet or they broke the study protocol for other reasons.
The average weight of the 14 volunteers who completed the study was 10stone 3lb (65.2kg) with a BMI of 22.2, so they were not overweight at the start of the study. The researchers measured a range of other factors, such as blood pressure and heart rate and took blood tests for haemoglobin, glucose, cholesterol and other markers of inflammation or clotting in the body such as plasminogen activator inhibitor-1 (PAI-1). PAI-1 protein is involved in the pathways that cause clotting within blood vessels. These tests were run on three occasions over 21 days.
There were strict instructions about what volunteers were allowed to eat freely, eat in restricted quantities and foods that were prohibited. They were allowed to eat fresh or frozen fruit, berries or vegetables, lean meat, unsalted fish, canned tomatoes, lemon or lime juice, spices and coffee or tea without milk or sugar, for three weeks. All dairy products were banned as well as beans, salt, peanuts, pasta or rice, sausages, alcohol, sugar and fruit juice. However, participants were allowed up to two potatoes a day and were also given some dried fruit, cured meats and a portion of fatty meat as a weekly treat.
