How Tos,  Nutrition

Cracking the problem of eggs

During my time at university I lived in halls with several international students. One of them was a student from China called Zhang. Instead of indulging in the traditional student diet of beer and kebabs, Zhang preferred to maintain the culinary traditions of his homeland. He would often disappear to the local Chinese market and return with an array of unidentifiable produce – none of which would be found in the aisles of your local supermarket. 

The meat was, generally, processed, dried and full of streaky bits of fat and gristle. Trying desperately not to sound xenophobic or patronising, I once asked him: “Why don’t you buy nicer meat, like a nice fillet of chicken or fish?” Zhang wasn’t offended, however, and with a shrug and look of ‘why did you ask me that’ he simply said: “Because that is not what we eat in China”.

The reason I tell this story is that we are all socially conditioned to accept some foods as being unacceptable. This is evident in both my friend’s inability to understand why I would challenge his food choice and also in my decision to question it in the first place. However, what if we were to step out of our normal mind-set and challenge our version of what we should and should not be eating? As swimmers, interested in both health and performance, and based on research, there may be some ‘normal’ food choices that we should be questioning. First under the microscope are eggs.

Whether eggs – a staple of the western diet – are good for us is a major debate within the nutrition community. This is largely because of their high levels of cholesterol, a fatty substance made in the liver which is vital for the normal functioning of the human body. Cholesterol bonds to proteins to form lipoproteins and is then able to be transported round the body in the blood. However, there are both good and bad forms. The two types of lipoproteins are described by nhs.co.uk as follows:

“There are harmful and protective lipoproteins known as LDL and HDL, or ‘bad’ and ‘good’ cholesterol.
 

Low-density lipoprotein (LDL)

LDL carries cholesterol from your liver to the cells that need it. If there is too much cholesterol for the cells to use, it can build up in the artery walls, leading to disease of the arteries. For this reason, LDL cholesterol is known as ‘bad cholesterol’.
 

High-density lipoprotein (HDL)

HDL carries cholesterol away from the cells and back to the liver, where it is either broken down or passed out of the body as a waste product. For this reason, it is referred to as ‘good cholesterol’ and higher levels are better.
The issue of whether high levels of LDL cholesterol negatively affects artery heath increasing the risk of cardiovascular disease (CVD) is not open to debate. What is, is whether eating animal-derived foods (like eggs) that contain high levels of cholesterol impacts arterial health directly.
The UK based website egginfo.co.uk gives industry guidelines on egg consumption and states: “All major UK heart and health advisory bodies have removed the previous limits on egg consumption due to their cholesterol content”. Indeed, NHS online summarises: “Although eggs contain cholesterol, the amount of saturated fat we eat has more effect on the amount of cholesterol in our blood than the cholesterol we get from eating eggs”.
Whether it is saturated fat or cholesterol from eggs that is likely to harm us is contentious. However, the findings of a 2013 meta-analysis (in which the results of several studies are taken into account) published in the British Medical Journal reported that out of 5,847 cases of CVD there was little or no association between egg consumption and risk. This was backed up by another larger 2013 review, which again found that there was a minimal association between egg consumption and disease risk in healthy individuals. However, there was a reported increased risk for those with type 2 diabetes.

Of course, as with any complicated topic, there are always two sides to the debate. Other research provides different results: in 2011 the Harvard Nurses study, which had followed more than 50,000 nurses over an 18-year period, reported that daily consumption of the amount of cholesterol contained in a single egg held the same CVD risk factor as smoking five cigarettes a day. Furthermore, in 2012 another article observing 1,262 people (average age >60yrs) found eating more than two eggs per week had significant increases in arterial plaque build-up, increasing the risk of CVD – again at similar rates to smokers. The most up-to-date (2013) and in-depth study currently available took into account all relevant studies back to 1930 and reported that those with the highest egg intake had a 19% increase in cardiovascular disease, a 68% increased risk of developing type 2 diabetes (T2D) and then, if you do develop T2D, an 85% increased risk of CVD. Even four eggs per week was found to increase risk by 6%. In it’s conclusion the study suggests that there is a “dose–response positive association between egg consumption and the risk of CVD and diabetes” and that egg consumption should be limited.

The difference of opinion is nothing new, but in the case of eggs the mixture has been beaten into frothy peaks by the egg industry. Back in the 1970s when Mark Spitz was blazing a trail in the swimming world, early research suggesting a link between cardiovascular health and egg consumption started to damage egg sales. In response, the National Commission on Egg Nutrition was set up in the US to counter this research and the American Egg Board (AEB) has battled ever since to convince the public that the research is wrong and that eggs are indeed healthy. The issue is that the AEB has been convicted by the supreme court of misquoting the American Heart Association’s (AHA) egg consumption guidelines and are on record as stating that the link between egg consumption and T2D might be a “show stopper” in convincing people eggs are healthy. The US Department of Agriculture have told them they can’t describe eggs as “healthy”, “healthful” or “nutritious”, but only “nutrient dense” – interestingly the same description you’ll find on the UK based egginfo.co.uk. Eggs can’t be described as “good for you”, “low in calories”, “low in saturated fat” or a “rich source of protein” (to help you recover after a hard swim session) because these things aren’t considered to be based on research.  There is evidence that the depiction of birds in cages has been minimised and, perhaps most shockingly, eggs can’t even be described as “safe” because of the high rates of salmonella cases each year (at least 50,000 in the US. No UK data is available). NHS online also backs up US guidelines which suggest “cooking till firm” is the only acceptable way to eat eggs. You won’t find a recommendation to soft-boil anywhere.

As if this wasn’t enough to have us question our culturally acceptable high level of egg consumption, there’s also the issue of choline. In short, a study published in 2012 observing more than 47,000 men described how egg consumption is a determinant of blood choline levels and in turn blood choline levels are a determinate of prostate cancer risk. In fact, men in the study with the highest levels of choline intake were 70% more likely to develop prostate cancer. Another meta-analysis study last year found egg intake was linked to breast cancer risk in women. 

Given all of this, you might be surprised that my recommendation would not be to cancel your weekend cooked breakfast and throw away Mary Berry’s latest bakery book! But why? Firstly, it’s not as simple as just eggs. As swimmers we are active and this exercise is protective against many risk factors and may balance out moderate egg consumption. It’s also key to assess your own situation. If you are healthy, active and under 60 years of age, while I think the research suggests limited egg consumption, some should be fine – especially when coupled to a largely plant-based whole food diet. However, eggs are worse for us if we are over 60 and if we have T2D. In an aging population, which through diet and inactivity is increasingly at risk of T2D, lowering egg intake should be a focus.  It has been contended that dietary cholesterol does not affect blood cholesterol; however, research shows this is wrong and so attention must be paid to how much we put in our mouths.

So why are eggs still certified as ‘ok’ on health websites? Well, it may come down to maths. Nutritional guidelines suggest a daily cholesterol intake of less than 300mg for healthy adults or less than 200mg for those with high cholesterol readings. A medium egg contains around 215mg of cholesterol so while one a day might be ok, if you have an egg for breakfast, animal foods for the rest of the day are out: no milk in your tea or hidden eggs in baked goods.

And what about my Chinese friend? Well, he adjusted some of his cultural norms by fully embracing cereal; however, he still insisted on eating it with chopsticks. We must do the same – not eating with chopsticks, but rather embracing new and better thinking, while not entirely writing off our old ways…sometimes!