Eating 2 eggs for breakfast lowers SBP, does not negatively affect insulin sensitivity

Consumption of two eggs a day for breakfast for 6 days per week leads to less reduction in low-density lipoprotein cholesterol (LDL-C) and more lowering of systolic blood pressure (SBP) in adults compared to nonegg-based, energy-matched, control foods higher in carbohydrates (CHO), according to a study.

“Intake of egg-based breakfast meals (12 eggs/week), compared with consumption of nonegg, higher-CHO breakfast meals, did not adversely affect insulin sensitivity and other aspects of CHO homeostasis,” the researchers said.

This randomized, crossover study included two 4-week dietary intervention, separated by a ≥4-week washout, in which 30 men and women (mean age, 54.2±1.9 years; mean body mass index, 31.9±0.7 kg/m²) incorporated breakfast meals with either two eggs/day for 6 days/week (egg condition) or energy-matched, nonegg, higher CHO-based foods (nonegg condition) into their habitual diets.

The researchers measured that participants’ dietary intakes, insulin sensitivity and other CHO metabolism indices, lipid biomarkers, high-sensitivity C-reactive protein and BPs.

Insulin sensitivity indices were not significantly affected by neither diet, but the homeostasis model assessment for insulin resistance was significantly higher after the nonegg condition (p=0.028). [Eur J Clin Nutr 2020;74:784–795]

LDL-C decreased by 2.9 percent with the egg condition compared to 6.0 percent with the nonegg breakfast (p=0.023) from baseline (119 mg/dL). The egg condition also reduced SBP from baseline (127 mm Hg) by 2.7 percent (p=0.018). The nonegg breakfast did not reduce SBP (0.0 percent).

Of note, energy intake from nonstudy foods increased by 149 kcal/day (p=0.008) during the egg condition, as shown by diet records, but weight change from baseline showed no difference between the two conditions.

Earlier studies in which egg intake has been increased reported mixed results, with some indicating increases in LDL-C and others demonstrating neutral effects or a modest decline in LDL-C. [Nutrients 2018;10:E426]

“In our previous meta-regression analysis of studies that evaluated the effects of changes in dietary cholesterol on LDL-C level, we noted that the increase in LDL-C was [approximately] 50-percent lower when cholesterol was provided via egg yolks than with other forms (unpublished results, not tested statistically),” the researchers said. [Am J Clin Nutr 2018;109:7-16]

“Thus, it is possible that some component or components of egg yolks influence the LDL-C response, eg, by interfering with cholesterol absorption or altering hepatic cholesterol handling,” they added.

Egg yolks contain high levels of dietary phospholipids (about 1.75 g total phospholipids per yolk), which may partially explain the lower than expected circulating cholesterol response to higher dietary cholesterol intake during the egg condition. Changes in dietary intake at eating occasions other than breakfast could also potentially influence LDL-C levels. [Nutrients 2010;2:116-127; J Am Coll Nutr 2016;35:704-716]

“Additional research will be needed to confirm this finding and to evaluate potential mechanistic explanations,” the researchers said.