Nutrients In Eggs

For years, research questioned the role of dietary protein in bone health. Metabolic balance studies in the 1970s and early 1980s showed higher protein intakes increased urinary calcium but did not enhance intestinal calcium absorption, leading to the conclusion that the source of the additional urinary calcium must be from bone breakdown (1-8). However, recent short-term dietary intervention studies using more sophisticated methodologies have refuted this conclusion, demonstrating that protein increases intestinal calcium absorption more than urinary calcium excretion, therefore not leading to bone breakdown as originally hypothesized (9-11).

One of the top questions we receive here at the Egg Nutrition Center is whether the nutritional profile of an egg is influenced by the housing conditions of the hen, particularly free-range versus caged.  It’s a reasonable question to ask.  Free-range hens may forage for bugs and plants, which could conceivably alter the nutritional intake of the hen and hence affect the nutritional content of the egg.  It has also been questioned whether certain housing systems affect stress levels of the hens that may in turn, lead to changes in the nutrient content of an egg.

Tomorrow marks the start of the Chinese New Year. 新年快乐 – Xin nian kuai le! Eggs are significant in Chinese culture, as a symbol for fertility and a big healthy family. Additionally, the egg white and yolk symbolize silver and gold, respectively, and can be gifts for friends during the new year’s festival.

Choline is hot! In 2016, the Food and Drug Administration established a Reference Daily Intake value for choline of 550 mg. Then in June of 2017, the American Medical Association (AMA) House of Delegates recommended the addition of choline to prenatal vitamins because of its essentiality in promoting cognitive development of the offspring. This was followed in August by a study that showed that more than 90% of pregnant women (as well as adults in general) do not consume recommended intakes of choline.

Now the story continues. This month, Dr. Marie Caudill and colleagues at Cornell University published evidence that infants exposed to higher levels of maternal choline (930 mg/day) during the third trimester have improved information processing speed during the first year of life, an indicator of cognition and intelligence. Similar studies have been conducted in rodents and shown that the cognitive effects of maternal exposure to choline last beyond infancy. Whether the same will be observed in humans remains to be determined. But one thing is clear: there’s much to learn about the role of choline in brain development. Hopefully this study will be a catalyst for other scientists to start unraveling the unknowns about this previously underappreciated nutrient.

Reference: Caudill MA, et al. Maternal choline supplementation during the third trimester of pregnancy improves infant information processing speed: a randomized, double-blind, controlled feeding study. FASEB J. 2018;32:2172-2180.

In nutrition science, individual nutrients are often recognized for their specific roles in physiology. We know that calcium is critical for bone health, choline is important for brain development and a lack of vitamin C will result in scurvy. However, whole foods are complex and contain numerous compounds, often leading to effects that extend beyond the sum of their parts.