Cracking on with the debate: Whole eggs deemed healthy for the young
Researchers have tackled the ‘are eggs good for us?’ debate in a new way. Instead of looking at how egg consumption affects specific body systems and diseases, they adopted a broader approach and found that, overall, eating whole eggs improved the health of young adults.
The health benefits of eggs have been studied for decades, often with conflicting results. Some research has found that eggs increase LDL ,or ‘bad’ cholesterol, and inflammatory markers associated with heart disease and diabetes, while other research has commended eggs’ nutrient density.
Most previous research has looked at the effect of eggs on specific biomarkers for heart disease, diabetes, body composition, inflammation, immune health and anemia in isolation rather than as a complete body picture. A new study by researchers at the University of Connecticut (UConn) has provided a broader perspective.
“It helps to provide a comprehensive picture of the effects of egg intake in a young, healthy population utilizing standard, routine clinical biomarkers,” said Catherine Andersen, lead and co-corresponding author of the study. “We believe that allows for greater translation to the general public.”
The researchers recruited 28 healthy participants aged 18 to 35 and fed them one of three diets for four weeks: egg-free, three egg whites a day, or three whole eggs daily. After a four-week egg-free washout, egg-eating participants switched to the alternative diet. The eggs could be prepared however the participants preferred. Researchers then examined the effect of the different egg diets on the participants’ metabolic, immune and hematological profiles.
They found that blood samples from participants eating whole eggs showed a significant increase in choline, an essential nutrient found in yolks. The brain and nervous system use choline to regulate memory, mood, muscle control, and other bodily functions. The metabolism of choline produces trimethylamine N-oxide (TMAO), and studies have linked TMAO to heart disease. However, the researchers observed that TMAO was unaltered in whole-egg-eating participants.
“That’s kind of the best-case scenario,” said Andersen. “We want to have rich amounts of this important nutrient, but not increase this metabolite that could potentially promote cardiovascular disease.”
Nor did the researchers observe any adverse changes in inflammation or blood cholesterol levels. Egg white consumption increased serum isoleucine, a marker of increased risk of insulin resistance, whereas eating whole eggs reduced serum glycine, a marker of decreased risk of insulin resistance. Whole egg intake increased hematocrit – a measure of the proportion of red blood cells in the blood, which can be lowered in anemia – whereas egg whites and whole eggs reduced blood platelet counts. Platelets are the blood cells that form clots.
“The fact that we were looking at the comprehensive range of measurement allows for a better assessment of the overall effects of egg intake that one might expect,” Andersen said. “I think that’s important because if you see one marker change that is less positive, you can see, perhaps in context, beneficial shifts in others.”
The researchers did find that female participants who were taking a combination oral contraceptive pill produced some different results. Blood samples from females who were not taking the pill had greater increases in the ratio of total cholesterol to HDL (‘good’) cholesterol, considered a risk factor for heart disease.
“That was the opposite of what we could expect,” said Andersen. “Because hormonal birth control medications are often associated with adverse metabolic changes. But, in this case, it seemed to have more of a protective effect in response to eggs.”
Females not taking the pill also had greater levels of monocytes in the blood compared to those taking the pill. Monocytes are part of the body’s first-line immune response.
“Overall, the intake of whole eggs led to greater overall improvements in micronutrient diet quality, choline status, and HDL and hematological profile while minimally – yet potentially less adversely – affecting markers of insulin resistance as compared to egg whites,” the researchers said.
The researchers will continue to study the effect of egg intake on HDL-immune system relationships and plan to study the effects of egg eating on older participants.
The study was published in the journal Nutrients.