Whether or not consuming eggs or dietary cholesterol has an association with cardiovascular disease or death has been a debate for years. The 2015 updated dietary guidelines removed a previously-recommended limit of 300 mg of dietary cholesterol due to a lack of strong evidence. A study published in the Journal of the American Medical Association on March 19 rekindled discussion of this highly controversial topic (abstract below). Dietary cholesterol is only found in foods of animal origin, and is absent in plant based foods such as fruits, vegetables, whole grains, legumes, nuts, and seeds.
Essentially, the study analyzed data from 6 population studies using a technique called “meta-analysis”. While the information gathered from these studies has shortcomings, and needs to be interpreted with some caution, the results suggest that increased egg and cholesterol consumption is associated with a higher risk of cardiovascular disease and all-cause death.
The trial reviewed 6 studies that included nearly 30,000 people who were followed on average for 17.5 years (and up to 31 years). It concluded that for each additional 300 mg of cholesterol consumed daily (an egg has about 200 mg), there was a relative 17% increase in cardiovascular disease and an 18% increase in death. In looking at the absolute increase in these same endpoints, there was a 3.2% increase in cardiovascular disease and 4.4% increase in all-cause death. Using real numbers, this could be interpreted as and additional 32 cases of cardiovascular disease or 44 cases of death for for every 1000 people that consumed an additional 300 mg of cholesterol daily.
The study also demonstrated that for each 1/2 egg consumed, there was a relative 6% increase in cardiovascular disease and an 8% increase in death. This correlates with an absolute increase of 1.1% and 1.9% respectively (translating into an additional 11 cases of cardiovascular disease and 19 cases of death per 1000 people that consume 1/2 egg daily). Keep in mind, that very few people eat only 1/2 egg, so theoretically these numbers could be doubled.
It is felt that previous studies failed to show a similar association due to shorter term follow up, inclusion of a less diverse population, and an inability to accurately adjust for other high-cholesterol foods being consumed in the diet (this is usually accomplished by using statistical methods).
In conclusion, publication of this study doesn’t provide a definitive answer on the safety of consumption of eggs and dietary cholesterol as they relate to cardiovascular disease and mortality (only a randomized control trial could do that), but it certainly provides evidence that supports a higher risk of these endpoints. Ultimately, it seems to be best for our health to avoid dietary cholesterol (our bodies can produce what they need) and stick with healthy plant-based sources of food!
More Egg-citing Studies
The Nurses Health Study showed that eating more than 5 eggs weekly increases the risk of diabetes, and that in diabetics that consume more than 1 egg daily compared to fewer than 1 weekly doubled their risk of cardiovascular disease.
A 2010 Harvard study in men with early stage prostate cancer showed twice the rate of progression in those eating 1 egg daily versus rare consumption. In men that consumed 2.5 eggs weekly, there was an 81% risk of dying from prostate cancer. This effect was felt to be primarily due to the choline in egg yolks.
An analysis of 44 studies involving over 400,000 subjects published in the European Journal of Nutrition showed eating more than 5 eggs weekly increased colon cancer risk by 42%. Felt to be due to cholesterol and choline.
The 2008 Physicians Health Study showed eating more than 1 egg daily increased mortality by 23%. The Nurses Health Study showed eating more than 7 eggs weekly doubled mortality in males.