OK, here's yet another food dilemma: should you eat plenty of eggs, because they contain various healthy vitamins and minerals? Or should you not eat many eggs, because of the cholesterol they contain? As usual I'm determined to find an evidence-based answer.
The first things I find in a web search come from the egg marketing boards. So, bearing in mind that they're obviously quite biased, I check out "Healthy eggs" from britegg.co.uk and "Eggs and cholesterol" from nutritionandeggs.co.uk. So, as expected, they confirm that eggs are full of lots and lots of nutritious things, but they also argue that recent evidence shows that eggs aren't bad for health. They have two scientific studies to support this argument: one which looked at a large number of people in the USA and found eggs didn't increase the risk of heart disease; and one which reviewed the current state of scientific knowledge and found that saturated fat (rather than dietary cholesterol) was the main cause of people having high blood cholesterol levels.
So far, so good, although the source is not what you'd call 100% neutral. And even if saturated fat is the main cause of high blood cholesterol, could dietary cholesterol be a lesser but still important cause?
So, I found the cholesterol review article and had a look. It's a very tricky subject to unpick, actually. For example, the study finds that people who eat more dietary fat tend to eat more dietary cholesterol too. So it could be tricky to separate out the effect of these two. There are methods for doing this, of course, and in the multiple regression analysis used by the researchers, it seems that there were three significant influences on a person's blood cholesterol levels: their intakes of saturated fat, polyunsaturated fat (the more people eat, the lower their cholesterol, for polyunsaturates), and cholesterol. However, although these influences all took part, the cholesterol influence is strongly outweighed by the influence of saturated fat vs unsaturated fat - if I gloss over some of the details to come up with a very approximate rule of thumb, the study finds that reducing saturated fat is someting on the scale of ten times more influential than reducing cholesterol.
OK, so what about some other sources of information? The BBC often has a lot of health information, but searching their site didn't actually find very much. The story Eggs 'protect against breast cancer' reports on a USA study of women, finding that eating eggs in teenage years seems to help lessen the likelihood of breast cancer; the study involved a large number of people and was published in a reputable journal so it seems trustworthy. The only other article I found was An egg a day 'is good for you' which seems to be based on the same studies as the ones I mentioned above. They did however confirm with a British Nutrition Foundation scientist, who agreed that there was unlikely to be a health risk from eating an egg a day (they recommend 2 or 3 a week apparently). There is opposition from the Vegan Society, but once again, they're hardly an unbiased source of information about whether people should eat eggs or not!
What about UK government advice? The UK government seems to be quite keen on inventing websites for public information these days, and one of their sites I searched is eatwell.gov.uk. They have two useful pages here: a page about eggs (including the section: "How many eggs?" - aha!) and a Q&A about eggs and cholesterol. The message from them is: eggs are good for you, and you don't need to cut down on them (unless your doctor tells you to for a specific reason). Just eat a balanced diet, as they always say.
And that's pretty much my conclusion. It seems that people used to (reasonably) assume that eating food with cholesterol in, would raise your blood cholesterol, and that was a reason not to eat too many eggs. But that assumption is too simple, and dietary cholesterol isn't that worrying after all. As long as you eat a balanced diet you can enjoy your eggs.