Want to see a good example of disagreement within the scientific community? Not only disagreement, but a disagreement that is based soley on the interpretation and use of scientific evidence.
Here in the United States, one of the leading medical organizations, the American Heart Association (AHA), continues to recommend that everyone to limit their consumption of eggs due to the cholesterol contained within the yolk. In fact, the upper limit per day is maybe one egg and that's IF total dietary cholesterol intake from all sources is within the AHA recommended upper limit of 300mg per day.
A large egg contains about 213mg of cholesterol, so one egg per day is probably unrealistic due to cholesterol in other foods that are part of the diet. The AHA even clarified this restriction on their website to ensure anyone thinking that an egg a day is okay would understand that is not the AHA position!
The recommendation remains even though various large, long-term population studies have resulted in mixed findings about egg consumption and health outcomes. Some studies do show an increased risk of heart disease while others clearly show no additional risk. None of these large studies look at a fundamental that really is key to understanding the role of eggs in the diet, and certainly necessary in making a general population recommendation - the overall nutrient-density in the diet of those eating or limiting eggs. Add to this the fact that many population studies start from a point of disadvantage for reliability - many are based on self-reported recall data. But I digress...
In other countries, the medical organizations that are comparable to our American Heart Association take a different view. Take the National Heart Foundation (NHF) in Australia. Not only do they make no recommendation to limit egg consumption in healthy individuals, they have given eggs the "National Heart Foundation Tick" (the equivalent of the AHA 'heart-check' logo in the United States).
In fact, the NHF website states the reason for the endorsement of eggs:
The Tick is all about quickly highlighting healthier choices for the general population. Sometimes Tick also needs to help dispel myths and remind people that nutritious foods like eggs, lean meat and poultry, plain unsalted nuts and avocadoes are an important part of healthy eating.
So, the NHF in Australia considers the AHA position to be one built on myths, not scientific evidence! They do make it clear that those with heart disease will need to work with their healthcare professional to assess whether including foods higher in cholesterol is appropriate, but for healthy individuals there is no restriction.
The Heart Foundation does not restrict consumption of eggs for the general population. For healthy people, the best guide is to include a wide variety of nutritious foods, including eggs. People at risk of or living with heart disease may still be able to eat eggs but they should discuss their intake of egg yolks with their doctor or Accredited Practising Dietitian.
Here is where the Australian NHF is doing a much better job in communicating with their population than the AHA is doing here in the United States. The NHF is using the evidence while the AHA continues with the "conventional wisdom" that holds that the recommendations developed for those with disease or at high risk for disease should be streamlined to the general population to reduce risk.
It isn't that the scientists and researchers in the US don't know that the evidence shows that there is a segment of the population that should limit cholesterol - this is well known within scientific circles, and is a segment of the population known as "responders" to cholesterol in the diet. From my understanding, those who are "responders" represent about 10% of the general population. Which leaves 90% of the population unaffected by dietary cholesterol intake.
Yet, the recommendations in the US are based on that small population of people instead of recommending testing to determine if one is a responder or not. In a recent Lean Plate Club column, Alice Lichtenstein, a professor of nutrition at Tuft's University was quoted as saying, "Some people are responders, some people are not. If you're not, then there's no reason to be concerned, but the only way you can tell is by getting a blood cholesterol test."
So you know, it isn't a single test either, but atleast two tests done months apart, to measure the effect of including dietary cholesterol foods on your cholesterol levels.
But, rather than make recommendations toward healthy individuals and separate recommendations for those with disease or high risk, the current recommendations ignore the healthy and continue to recommend for the general population what is more appropriate for the sick in an effort to try to reduce the risk of those who are healthy.
The real question we need to ask and seek an answer to is this - have the recommendations, when actually followed by healthy individuals over a long-term period, worked to improve their long-term health AND reduced their risk of disease? To date there is no convincing evidence that a healthy individual, specifically one who is not a "responder," should limit their intake of eggs or dietary cholesterol below 300mg per day.
What is much more important to the overall achievement of good health and well-being is the quality of the foods you eat and their nutrient-density and eggs meet that standard for healthy people!