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Featured article in the Spring 2019 Issue of Nutrition Close-Up; written by Maggie Moon, MS, RD

Health is not just the absence of disease, but the presence of optimal wellness. Though nutritional guidance historically focused on preventing deficiency and toxicity from nutrients, today there is a growing interest in leveraging nutrients to improve the “healthspan,” or years of life in good health.

Time is of the essence to apply this to neuronutrition. According to the Alzheimer’s Association, the number of Americans living with Alzheimer’s dementia is expected to more than double by 2050 from today’s 5.7 million to nearly 14 million.¹ Worldwide, today’s 50 million people with dementia will more than triple by 2050, according to the World Health Organization.²
Lutein and choline are among the most underconsumed and underappreciated nutrients emerging into the spotlight for brain health and cognition. Recent research highlights their potential
for preventing and improving cognitive decline. Continue reading “Research News: Choline, Lutein, and Cognition” →

As mandated by the Agricultural Act of 2014, the 2020-2025 Dietary Guidelines for Americans (DGA) will include dietary guidance for infants and toddlers from birth to 24 months of age, as well as pregnant women.  Scientific questions being examined by the current DGA Advisory Committee include recommendations for complementary foods and beverages, dietary patterns, as well as the mother’s diet during pregnancy.  Evaluation of how specific foods help to build healthy dietary patterns is a component of these reviews.  Recent evidence supports that eggs are a nutrient-dense component of early eating patterns, and introducing eggs in the first year of life (>4 months) may reduce the risk of developing a food allergy to eggs.

Previous recommendations from health organizations¹ included guidance to avoid early introduction of eggs.  However, more recent data show that introduction of eggs after four to six months does not increase the risk of allergy.  A recent USDA/Department of Health and Human Services literature review evaluated complementary foods in relation to food allergy.  Twenty-eight studies that examined consumption of eggs as a complementary food in relation to development of any atopic disease was one component of this extensive review.²  The conclusion statement summarized, “Moderate evidence suggests that introducing egg in the first year of life (>4 months of age) may reduce risk of food allergy to egg.”  Although more research is needed to fill gaps related to complementary foods and beverages and allergy, these most recent data support that eggs should not be avoided once a child is developmentally ready to eat them.

Another recent analysis found that consumption of eggs in infants 6-24 months of age is associated with intake of several nutrients.³  Based on National Health and Nutrition Examination Survey 2001-2012 data, egg consumption in infants 6-24 months of age was linked with higher energy, protein, choline, lutein + zeaxanthin, α-linolenic acid, docosahexaenoic acid (DHA), vitamin B12, phosphorus, and selenium.  Infants who ate eggs also consumed higher levels of total fat, monounsaturated fat, saturated fat, and sodium, and lower amounts of total sugar compared to infants who did not eat eggs.  Further, egg consumption in infants was linked to longer recumbent length compared to non-consumers and not associated with body weight.

These observations build on the evidence that the nutrients in eggs are important for growing children.  Emerging evidence shows that both choline and lutein are critical for brain and neurological development during the first 1000 days post-conception,⁴ and a recent paper found it is difficult to achieve the Adequate Intake for choline without eating eggs or taking a dietary supplement.⁵   These nutrient intake observations in infants also demonstrate that a total-diet approach is important.  Eggs are one food within healthy dietary patterns and there is opportunity to offer children other nutrient-dense foods in combination with eggs to meet all nutrient needs.  Please see our First 1000 Days toolkit for more information.

1. Zeiger, R.S., Food allergen avoidance in the prevention of food allergy in infants and children. Pediatrics, 2003. 111(6 Pt 3): p. 1662-71.
2. Obbagy, J.E., et al., Complementary feeding and food allergy, atopic dermatitis/eczema, asthma, and allergic rhinitis: a systematic review. Am J Clin Nutr, 2019. 109(Supplement_7): p. 890s-934s.
3. Papanikolaou, Y. and V.L. Fulgoni, 3rd, Egg Consumption in Infants is Associated with Longer Recumbent Length and Greater Intake of Several Nutrients Essential in Growth and Development. Nutrients, 2018. 10(6).
4. Wallace, T.C., A Comprehensive Review of Eggs, Choline, and Lutein on Cognition Across the Life-span. J Am Coll Nutr, 2018. 37(4): p. 269-285.
5. Wallace, T.C. and V.L. Fulgoni, Usual Choline Intakes Are Associated with Egg and Protein Food Consumption in the United States. Nutrients, 2017. 9(8).

By Natalie Rizzo, MS, RD

The Egg Nutrition Center partnered with Natalie Rizzo, MS, RD to write this blog post.

May is National Egg Month, which makes it the perfect time to brush up on your egg knowledge. Sure, you likely know that eggs are an affordable high-quality protein and a nutritious addition to your breakfast routine. But there are a few other little-known facts about eggs that may surprise you. In honor of National Egg Month, test your egg-spertise and see how many of these unexpected facts are news to you.

1. The eggshell color doesn’t affect quality.

The only difference between eggs with white and brown shells is the hen. Those with red feathers and red ear lobes lay eggs with brown shells, while eggs with white shells come from white feathered and white lobed hens. Hens that lay brown eggs tend to be larger and require more feed than hens that lay white eggs, so brown eggs are often more expensive to cover the cost of the extra feed. The quality, flavor, nutrition or cooking uses are the exact same, regardless of the shell color.

2. Eggs are one of the most concentrated food sources of choline in the U.S. diet.

Choline is a nutrient necessary for gene expression, the formation of cell membranes, lipid transport, metabolism and early brain development (1). Because choline is considered so critical to neurocognitive development, a 2018 position paper from the American Academy of Pediatrics (AAP) states that although all nutrients are necessary for brain growth, key nutrients that support neurodevelopment include protein, zinc, choline, iron, folate, iodine, vitamins A, D, B6 and B12 and long-chain polyunsaturated fatty acids (2). Eggs are an excellent source of choline and provide varying amounts of all of the nutrients recommended by AAP.

3. They are one of the few food sources of Vitamin D.

Vitamin D plays an important role in the absorption of calcium and the immune system’s defense against diseases (3). Recent data from NHANES 2001-2010 examined Vitamin D status of adults over the age of 18 and found that 28.9% of people were deficient in this crucial vitamin (4). Vitamin D is in relatively few foods, such as fatty fish, eggs, dairy products, and mushrooms. One large egg has about 41 IU of Vitamin D (6% daily value).

4. Eggs contain carotenoids.

Lutein and zeaxanthin are carotenoids present in eggs, both of which are important for brain and eye health. Specifically, lutein and zeaxanthin help protect the eye from harmful blue light and macular degeneration (5).

5. Older hard boiled eggs make them easier to peel.

It’s been speculated that older eggs are easier to peel because the air cell that forms between the shell membranes as the egg ages, and this helps separate the shell from the egg. In fresher eggs, the air cell is small, making it more difficult to remove the shell. If it sounds like an old wives’ tale, try hard boiling and peeling a week old egg versus a brand new one and see for yourself!

References:

1. Office of Dietary Supplements – Choline. (2019). Retrieved from https://ods.od.nih.gov/factsheets/Choline-HealthProfessional/
2. Schwarzenberg SJ and Georgieff MK, AAP COMMITTEE ON NUTRITION. Advocacy for Improving Nutrition in the First 1000 Days to Support Childhood Development and Adult Health. Pediatrics.  2018;141(2)e20173716
3. Office of Dietary Supplements – Vitamin D. (2019). Retrieved from https://ods.od.nih.gov/factsheets/VitaminD-%20HealthProfessional/
4. Liu, X., Baylin, A., & Levy, P. (2018). Vitamin D deficiency and insufficiency among US adults: prevalence, predictors and clinical implications. British Journal Of Nutrition, 119(8), 928-936. doi: 10.1017/s0007114518000491
5. Wu, J., Cho, E., Willett, W., Sastry, S., & Schaumberg, D. (2015). Intakes of Lutein, Zeaxanthin, and Other Carotenoids and Age-Related Macular Degeneration During 2 Decades of Prospective Follow-up. JAMA Ophthalmology, 133(12), 1415. doi: 10.1001/jamaophthalmol.2015.3590

A new study published last week in the American Heart Association journal Circulation adds more data to the mix on egg consumption and risk for heart disease¹. Recall just a few weeks ago, a study published in the Journal of the American Medical Association (JAMA) made headlines when it seemed to reverse the course of the latest dietary recommendations to say that, once again, eggs and dietary cholesterol were linked with increased heart disease risk². Now, just a few weeks later a new study says exactly the opposite.

In the new study, researchers from Oxford University in the U.K. analyzed data from over 400,000 men and women in Europe over an average follow up of 12 years. The authors reported a small but statistically significant decrease in risk for ischemic heart disease with every 20 gram increment of egg intake (about ½ an egg per day). The researchers also reported similar favorable results for yogurt and cheese consumption, while consumption of red and processed meats was associated with increased risk for heart disease.

Does this mean the science on eggs has changed yet again, just within a matter of weeks? No, it doesn’t. What it does mean is that the science never actually changed with the publication of the study in JAMA. As with any study, it is important to not view it in isolation, but rather in the broader context of the total scientific literature. This is particularly true with studies that are observational in nature, because in this type of research there are often outlier studies that deviate from the clear majority.

Furthermore, if you read the details of the new study the authors rightly pointed out that, as with any new observational study, there are several important factors to consider when interpreting these results:

• The beneficial associations eggs and yogurt may be influenced by reverse causation bias.
• There will always be residual confounding in observational studies that cannot be eliminated; even though the investigators statistically adjusted for many potential confounders including lifestyle factors.
• The results may not be generalizable to populations outside this European cohort.
• Associations with eggs and yogurt were no longer significant after excluding the first 4 years of follow-up.

Importantly, these are factors that should be considered in any observational study, whether the results are favorable or unfavorable to a dietary or lifestyle factor.

That said, these latest findings published in Circulation are more in line with previous meta-analyses of observational cohorts that reported either no relationship with egg consumption and cardiovascular risk^3,4 or small decreases in cardiovascular risk⁵. Given all the caveats and confounding factors that are involved in observational studies, consistency across many studies over time is important.

It’s easy to get wrapped up in the day to day headlines from the next big study, and view the latest study as the next “game changer”. But the truth is science doesn’t change all that quickly, especially nutrition science. Many studies over the course of years or even decades are needed to achieve consensus. This is in fact what happened when the 2015 Dietary Guidelines for Americans no longer listed dietary cholesterol as a nutrient of concern. The evidence required to do so involved 16 studies over the course of many years³.

Lastly, as these studies are all observational in nature it is important to remember that we cannot infer a cause and effect relationship, no matter if the result is favorable or unfavorable to heart disease risk.  Therefore, it is important to view these results in the context of existing randomized controlled trials that consistently show egg intake does not negatively impact cardiovascular disease risk factors, and in some cases, has shown to improve risk factors such as HDL, or “good” cholesterol⁶.

References

1. Key et al. Consumption of Meat, Fish, Dairy Products, Eggs and Risk of Ischemic Heart Disease: A Prospective Study of 7198 Incident Cases Among 409,885 Participants in the Pan-European EPIC Cohort. Circulation. 2019 Apr 22. [Epub ahead of print]
2. Zhong et al. Associations of dietary cholesterol or egg consumption with incident cardiovascular disease and mortality. JAMA. 2019;321(11):1081-1095.
3. Shin JY, Xun P, Nakamura Y, He K. Egg consumption in relation to risk of cardiovascular disease and diabetes: a systematic review and meta-analysis. Am J Clin Nutr. 2013 Jul;98(1):146-59.
4. Rong Y, Chen L, Zhu T, Song Y, Yu M, Shan Z, Sands A, Hu FB, Liu L. Egg consumption and risk of coronary heart disease and stroke: dose-response meta-analysis of prospective cohort studies. BMJ. 2013 Jan 7;346:e8539.
5. Alexander DD, et. al. Meta-analysis of egg consumption and risk of coronary heart disease and stroke. J Am Coll Nutr. 2016. 6:1-13.
6. Blesso CN, Fernandez ML. Dietary Cholesterol, Serum Lipids, and Heart Disease: Are Eggs Working for or Against You? Nutrients. 2018 Mar 29;10(4). pii: E426. doi: 10.3390/nu10040426. Review.

The average American diet does not align with the recommendations of the Dietary Guidelines for Americans.^1,2 With evidence that lower diet quality can impact health,³ research is needed to better understand how substituting nutrient-dense foods within typical eating patterns might improve nutrient intake and diet quality across various population subgroups.  A recent analysis of dietary data from the National Health and Nutrition Examination Survey (NHANES) indicate eggs can contribute significantly to nutrient intake, but consideration of the total dietary pattern is essential.

Using 2001-2014 NHANES dietary data, a recent modeling study evaluated the diet quality of food secure and insecure individuals when eggs were added to the diet.  It was hypothesized that substituting egg dishes for other commonly consumed dishes at certain eating occasions (breakfast, lunch, dinner) could improve daily nutrient intake among vulnerable populations.  The diet model replaced the most commonly consumed main dish (e.g., breakfast cereal) with the most commonly consumed egg dish (e.g., scrambled eggs) on a gram per gram basis.⁴

The data from this study indicate that food secure individuals were more likely to meet recommendations for many nutrients compared to food insecure individuals.  Substituting eggs as a main dish at breakfast, lunch or dinner did not influence total nutrient intake, regardless of food security status.  There was a meaningful decrease in the prevalence of vitamin D inadequacy when eggs were substituted at lunch or dinner for both food secure and food insecure non-participants and increased choline intake for all subgroups.  Of note, when eggs were substituted as the main dish at breakfast, the prevalence of folate inadequacy increased.  Overall, regardless of food security status, these data indicate that when eggs are substituted for other foods in the diet, consideration of the impact on other foods and nutrients is required.

These recent observational data continue to support that eggs can contribute beneficial nutrients to all subgroups of the U.S. population.  Eggs are affordable and are a good or excellent source of eight essential nutrients, including choline which is under-consumed by most Americans.⁵ Importantly, the associations found in these NHANES analyses indicate there may be opportunity to educate about total dietary patterns to best meet dietary recommendations.

1. U.S. Department of Health and Human Services and U.S. Department of Agriculture, 2015-2020 Dietary Guidelines for Americans. 2015.
2. Hiza, H.A., et al., Diet quality of Americans differs by age, sex, race/ethnicity, income, and education level. J Acad Nutr Diet, 2013. 113(2): p. 297-306.
3. Murray, C.J., et al., The state of US health, 1990-2010: burden of diseases, injuries, and risk factors. Jama, 2013. 310(6): p. 591-608.
4. Conrad, Z., et al., Nutrient intake disparities in the US: modeling the effect of food substitutions. Nutr J, 2018. 17(1): p. 53.
5. Wallace, T.C. and V.L. Fulgoni, Usual Choline Intakes Are Associated with Egg and Protein Food Consumption in the United States. Nutrients, 2017. 9(8).