Nutrition Science

Nutrition research is the underpinning of our programs and outreach. ENC is dedicated to providing accurate and up-to-date information on eggs, nutrition and health. Below is a collection of both ENC-funded research and relevant studies.

To learn more about our competitive research program, click here.

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Fat Soluble Bioactives in Egg Yolk Show Anti-Inflammatory Potential

Eggs broken with yolk over white background

Is the unique combination of vitamins, carotenoids and phospholipids in egg yolks inflammatory protective?

Eggs are an example of a food that is naturally health promoting, despite containing a moderate amount of saturated fat, due to a combination of balancing bioactive components in the yolk.

Researchers at Ohio State University were interested in understanding various components of egg yolk with respect to an important inflammatory signal called NF-kappa B (NF-kB]. They presented research findings at the annual scientific sessions of the American Society for Nutrition [Shen, 2015].

In order to determine potential anti-inflammatory components, egg yolk was specially separated into two fractions 1) the polar-rich fractions of yolk and 2) the non-polar fractions. Although lower in fat, the polar-rich egg yolk still contained about 80% of the cholesterol and half of the triglyceride fat found in whole egg yolk.

The polar-rich yolk differed substantially from the non-polar egg yolk in that it retained much more cholesterol and triglyceride fat than the non-polar egg yolk, but it also retained the potentially bioactive vitamins and the carotenoids lutein/zeaxanthin.

In other words, although the non-polar egg yolk component was substantially reduced in cholesterol and triglyceride, it did so at the expense of losing fat-soluble vitamins and carotenoids with anti-inflammatory potential.

When the researchers measured the potential to reduce inflammation in pre-adipocyte (fat) cells, they found whole egg yolk to be neutral, but the lower-fat, carotenoid-rich polar yolk version to be anti-inflammatory. Although the non-polar fraction was much lower in fat, it showed no statistical effect on inflammation, likely due to the loss of lipid soluble vitamins and lutein/zeaxanthin.

They concluded that:

“partially delipidated EY-P [egg yolk-polar] fraction leads to the inhibition of NF-kB activation and its downstream inflammatory targets.”

NF-kB is a particularly important regulator of chronic inflammation, having been shown to impact inflammatory mediated central adiposity and type-2 diabetes [Harte, 2013].

Studies such as this by Shen et al. demonstrate that the final impact of specific foods on human health depends on the combination of nutrients and other bioactive components found naturally in food acting holistically.

 

Reference Citations

Shen, Q, K Riedl, RM Cole, C Lehman, L Xu, H Alder, M Belury, SJ Schwartz, and O Ziouzenkova. “Egg yolks attain anti-inflammatory properties after partial delipidation.”  Poster presented at: Experimental Biology, American Society for Nutrition Annual Scientific Session: 2015 April 29; Boston MA. This study was funded by grants from the American Egg Board.

Harte, AL, G Tripathi, MK Piya, TM Barber, JC Clapham, N Al-Daghri, D Al-Disi, W Kumsaiyai, P Saravanan, AE Fowler, JP O’Hare, S Kumar, and PG McTernan. “NF kappa B as a Potent Regulator of Inflammation in Human Adipose Tissue, Influenced by Depot, Adiposity, T2DM Status, and TNFa” Obesity 2013;21(11); 2322–2330.

 

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Barbara Lyle, PhD, is President of B Lyle, Inc. a nutrition and innovation firm and blogger for the Egg Nutrition Center.

 

Views expressed by the author may not be those of the Egg Nutrition Center.

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Eggs Improve Carotenoid Value of Raw Vegetables

Mixed Egg Salad

Eggs offer potential to improve the nutritive value of a salad, in more than one way.

Egg yolk is among the few commonly consumed foods containing the carotenoid lutein and its stereoisomer zeaxanthin. Spinach and other dark leafy greens may have a higher content per serving, but lutein/zeaxanthin is absorbed and utilized better from egg yolk [Chung, 2004].

Researchers at Purdue University are studying ways to improve carotenoid absorption and tested whether eggs improved absorption of carotenoids, like lutein/zeaxanthin, from raw mixed-vegetable salad. They reported findings at the Experimental Biology 2015 meeting of nutrition scientists.

Drs. Jung Eun Kim, Wayne Campbell and colleagues, fed sixteen healthy college-age men raw vegetable salad or the same salad with either 10.5 or 18 g scrambled eggs (i.e., 7.5 g or 15 g egg, which is equivalent to about 1 ½ or 3 eggs, respectively). All salads contained the same amount of tomatoes, shredded carrots, baby spinach, romaine lettuce, and Chinese wolfberry.

To determine carotenoid absorption, carotenoid levels were measured in the men’s blood over a 10 hour period after eating salads with or without eggs.

Carotenoid levels in blood were 3-9 fold higher for various carotenoids when the men ate salad with 3 eggs compared to plain salad. And it was more than just lutein/zeaxanthin that increased. Carotenoids in the salad also include beta-carotene, alpha-carotene, and lycopene. And all of these carotenoids were absorbed better with the high egg salad.

These findings are consistent with other research by this group showing that adding certain oils to mixed raw vegetables enhances carotenoid absorption.

This means that eggs provided benefits in two ways: as a direct source of lutein/zeaxanthin and by improving the carotenoid value of raw vegetables.

Research related to lutein/zeaxanthin and eggs is cited at the ENC website.

 

 

 

Views expressed by the author may not be those of the Egg Nutrition Center.

Barb Barbara Lyle, Ph.D. is President of B Lyle, Inc. a nutrition consulting and innovation firm, and guest blogger for the Egg Nutrition Center.

Diet Quality Characterized in 187 Countries

Hand with plate and globe

New global data show that while consumption of “healthy” food items increased in many countries, consumption of “unhealthy” items worsened across the world.

A study in The Lancet Global Health examined 20-year trends in diet patterns from around the world based on over 300 diet surveys estimated to represent 89% of adults worldwide (Imamura, 2015). The Global Burden of Diseases Nutrition and Chronic Diseases Expert Group co-author Dr. Dariush Mazaffarian noted the importance of examining “healthy” food patterns separately from “unhealthy” food items, in order to fully inform policies and priorities (online interview).

In examining diets, the research team noted that ‘’national diet quality based on healthy versus unhealthy items was largely masked when only overall diet patterns were considered.”   Therefore, diet trends were characterized separately for 10 “healthy” items, for 7 “unhealthy” items, and then a combined pattern for all 17 items.

The “healthy” pattern scored consumption of: fruits, vegetables, beans and legumes, nuts and seeds, whole grains, milk, total polyunsaturated fatty acids, fish, plant omega-3s and dietary fiber.

The “unhealthy” pattern scored consumption of: unprocessed red meats, processed meats, sugar-sweetened beverages, saturated fat, trans fat, dietary cholesterol, and sodium.

In light of the recent acknowledgement by the US Dietary Guidelines Advisory Committee (DGAC, 2015) that scientific evidence has evolved to the point in which dietary cholesterol is not a nutrient of concern for overconsumption, it would be informative to know whether results from this global diet study change if dietary cholesterol is removed from the “unhealthy” pattern score.

Results of the current study showed:

“[O]lder adults had better dietary patterns than did younger adults…women also had better dietary patterns than men…”

 “Higher national income was associated with better quality for the healthy dietary pattern…and with much worse quality for the unhealthy dietary pattern.”

In concluding remarks, the authors noted

“Increases in unhealthy patterns are outpacing increases in healthy patterns in most world regions. In view of the disease burden associated with suboptimum diet quality, these findings emphasise the need to better elucidate the societal, policy, and food industry determinants of these differences and trends, and to implement policies to address these inequities and improve diet quality globally.”

This study illustrates the importance of considering patterns of foods consumed rather than overall single diet quality scores, single food approaches, or single nutrient assessments. That’s good advice when considering diet globally, locally, and also individually. A summary article and global map of diet quality is available at the Medical Research Council.

References Citations

F Imamura, R Micha, S Khatibzadeh, S Fahimi, P Shi, J Powles, D Mozaffarian, on behalf of the Global Burden of Diseases Nutrition and Chronic Diseases Expert Group (NutriCoDE). “Dietary quality among men and women in 187 countries in 1990 and 2010: a systematic assessment.” The Lancet Global Health. March 2015. (3):e132-e142.

Scientific Report of the 2015 Dietary Guidelines Advisory Committee. February 2015.

photo2-150x150 Barbara Lyle, Ph.D. is President of B Lyle, Inc. a nutrition consulting and innovation firm, and guest blogger for the Egg Nutrition Center.

 

Views expressed by the author may not be those of the Egg Nutrition Center.

Nutrition Science for Policy Making

Young student woman medical / scientific researcher / doctor looking at a test tube of liquid in science laboratory, blood test

Nutrition research informed by policy needs, will have greater impact.

Nutrition and diet policies, like the Dietary Guidelines for Americans, are based on a body of scientific evidence built from many individual research studies. In a commentary in The Lancet, Drs. Kelly Brownell, from Duke University, and Christina Robert, from Harvard University, advocate for enhancing links between science and policy (Brownell, 2015) citing that “only a small proportion of research has the policy impact it might have.”

“We define strategic science as research designed to address gaps in knowledge important to policy decisions, derived from the reciprocal flow of information between researchers and policy makers…”

They proposed a four-step, reciprocal model to impactful science.

  1. “Identify change agents and create reciprocal information flow between researchers and these actors”
  1. “[D]evelop strategic questions… that need to be addressed for the policy process to be fully informed”
  1. “[U]ndertake strategic studies…” with strategic policy informed questions driving “research designs, hypotheses, and analyses.”
  1. “Shortening the review and publication process … to bring research in step with the real-time needs of policy makers.”

In summary, Brownell and Roberto point out the:

“unrealised potential to contribute to the common good by having the evidence base communicated more effectively to policy makers, and for scientists to be aware of the important questions in the policy world.”

Better interaction between researchers and policy domains would improve the speed by which long-standing, as well as new questions about nutrition and health, are translated into policies and advice for the public. Nutrition researchers can start by informing their research programs based on stated gaps in policy documents, like the Dietary Guidelines Advisory Committee 2015.

Brownell, KD and CA Roberto. “Strategic science with policy impact“. The Lancet. February 18, 2015.

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