A newly released study in The Journal of Nutrition shows that consuming 7 commercially available eggs per week for 12 weeks effectively offsets wintertime decline in circulating vitamin D concentrations, with 12 eggs per week not providing any additional benefits.
Vitamin D is important to bone health and has also been shown to lower risk to several other chronic diseases. The main source of vitamin D is sun exposure, as few foods naturally contain vitamin D. Of the limited dietary sources, eggs have significant quantities of vitamin D-3. There has been interest in whether eggs can play a key role in maintaining vitamin D concentrations, particularly during winter when blood levels decrease due to changes in sun exposure, but the optimal dose required is not known.
To bridge this knowledge gap, Professor Robin Daly (Deakin University) and colleagues conducted a 12-week randomized controlled trial, which included 51 adults 25 – 40 years old residing in southern Australia. Subjects were randomly assigned to consume 2 eggs per week (control), 7 eggs per week, or 12 eggs per week. The intervention was conducted from May (late autumn) to August (winter) when sunlight exposure is low. In addition to measuring vitamin D status at baseline and post-intervention, blood lipid levels were also assessed. The vitamin D-3 content of the eggs was assessed at baseline and week 6. Nutrient intakes were assessed using 24-hour food records. A questionnaire was used to estimate sun exposure throughout the study.
The main finding from this 12-week randomized controlled trial was that consumption of 7 commercially available eggs per week, in line with most dietary guidelines, represents a safe and effective dietary approach to attenuate the wintertime decrease in Vitamin D concentrations. In contrast, those in the control group had a significant reduction in vitamin D concentrations. Consuming 12 eggs per week did not result in any added benefits to vitamin D concentrations over 7 eggs per week, and there were no adverse effects on blood lipid levels. The results of this study indicate that weekly consumption of 7 eggs should be included as an important dietary approach to help optimize vitamin D status during winter months when sunshine exposure is limited.
References
Robin M Daly, Belinda De Ross, Jenny Gianoudis, Sze-Yen Tan, Dose–Response Effect of Consuming Commercially Available Eggs on Wintertime Serum 25-Hydroxyvitamin D Concentrations in Young Australian Adults: a 12-Week Randomized Controlled Trial, The Journal of Nutrition, Volume 152, Issue 7, July 2022, Pages 1702–1710, https://doi.org/10.1093/jn/nxac044.
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