You can’t make a myth about cholesterol without breaking eggs
Do you think eating eggs gives you high cholesterol? Do you follow the maxim: feed a cold, starve a fever? And does an apple a day really keep the doctor away?
Health myths abound and can be incredibly resilient. Some have emerged unchallenged through generations, while others are more recent. Perhaps the most destructive in recent times was the research allegedly showing a link between childhood vaccination and autism. It was the result of poorly conducted scientific research given a deliberate spin for media consumption. Children are still suffering from the fallout.
A number of health myths centre on food, as I discovered from a book I picked up on holiday. Don’t Cross your Eyes . . . They’ll Get Stuck that Way is written by American paediatricians Aaron Carroll and Rachel Vreeman. A collection of myth-busting and quirky facts about our health that we take for granted, it’s a nice balance of authoritative research and humour.
Although the book isn’t just about food myths, it does contain some interesting health and food conundrums. Starting with eggs and cholesterol it is true that one egg contains about two-thirds of the recommended daily intake of cholesterol. However, the assumption that if you eat food high in cholesterol you will automatically develop a high cholesterol level in your blood is not as strong as people think.
In fact about 70 per cent of people who were asked to eat three eggs a day for a month showed no increase in their blood cholesterol levels. And even in those who “hyper-respond” to dietary cholesterol, it seems that for every additional 100mg of cholesterol in their diet, their blood cholesterol rises by about 2mg per decilitre.
The final nail in the coffin of this so-called link comes when you look at research into heart disease. One study of 120,000 men and women showed no difference in the risk of heart attack or stroke, over a 14-year period, in participants who ate one or more eggs a day compared with those who consumed one egg a week. In the authors’ words: “Eggs just don’t seem to lead to heart disease in otherwise healthy people.”
Starve a fever?
Feed a cold, starve a fever may have its origins in the 1500s. John Withals, who made a living compiling dictionaries, announced that “fasting is a great remedie of feuer [fever]”. It was then hypothesised that eating generates heat, which would not be a good idea if you already had a temperature, but made sense when you had a cold. Except, of course, that having a cold and having a low temperature are not the same thing.
But when a thorough literature search was carried out, not a single scientific study has looked at whether people get better by following this advice. Yet the authors found a number of articles that continued to hypothesise why this maxim makes sense.
“These aren’t studies proving this myth is true. These are attempts to imagine scenarios as to why it might be true,” they point out rather sagely.
An apple a day
Which brings us to the question of whether an apple a day does actually keep the doctor away. Some large studies do indeed suggest that eating apples is associated with fewer cases of some cancers.
But so is eating pears, onions and grapefruit. When it comes to heart disease, we know the “five a day” fruit and vegetable association is especially strong. Again the specific evidence for eating apples alone is weak. And the confounding factor overshadowing all studies about whether eating apples helps reduce heart disease and cancer is the fact that people who eat healthily tend to make other healthy choices such as exercising regularly and not smoking.
However, if you really want to keep the doctor away my personal recommendation is a diet of garlic and onions.
Nothing quite compares to examining someone who has garlic fumes coming out their pores.
mhouston@ irishtimes.com muirishouston.com