The rise in popularity of plant-based diets is accompanied by many health benefits. Research suggests that eating mostly plants can prevent obesity, decrease the risk of developing diabetes, and lower mortality rates. Plant-based diets are also associated with lower rates of heart disease and cancer. But what happens when eggs are included in plant-based diets?
Defining Plant-Based Diets
If you ask two different people to define “plant-based eating,” you will likely get two different responses. The way that I define “plant-based” is a style of eating that includes mainly plant foods like fruits, vegetables and whole grains. You do not need to completely cut out meat and animal products to be plant-based. In fact, completely cutting out all meat and animal products could mean not getting enough nutrients like vitamin B12, calcium, vitamin D, omega-3s, iron and protein.
News & World Report describes plant-based diets “as an approach that emphasizes minimally processed foods from plants, with modest amounts of fish, lean meat and low-fat dairy, and red meat only sparingly”. The majority of these studies observed vegetarian diet patterns, which include plenty of fruits, vegetables and meatless proteins, like eggs, dairy, whole grains, nuts, seeds and soy. In other words, plants were paired with protein sources, like eggs, to make a nutritious and well rounded meal.
The Nutritional Value of Eggs
In addition to their exceptional nutritional quality, eggs are rich in antioxidants such as vitamins A and E, selenium, lutein, and zeaxanthin. The lipophilic antioxidants present in the egg yolk are highly bioavailable due to lipid content in the yolk. Eggs may provide natural sources of omega-3 fatty acids, vitamin B12, vitamin D, and bioavailable iron that are potentially deficient nutrients in a vegetarian diet.
Eggs in Plant-Based Diets: A Study on Metabolic Syndrome
Chronic low-grade inflammation and oxidative stress that often accompany metabolic syndrome (MetS) are significant factors causing the metabolic condition and associated pathophysiological consequences. MetS, characterized by insulin resistance, hypertension, abdominal obesity, and dyslipidemia, triggers the alteration of cell signaling pathways, resulting in increased levels of inflammatory markers, lipid peroxides, and free radicals, causing cell damage and eventually leading to the clinical symptoms of the condition.
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A recent study evaluated whether the inclusion of whole eggs in plant-based diets would protect against oxidative stress and low-grade inflammation, two common characteristics of MetS. We recently reported that the inclusion of whole eggs in plant-based diets (PBD) increased plasma choline, lutein, and zeaxanthin in individuals with metabolic syndrome (MetS). The objective of the current study was to evaluate whether this dietary pattern would protect against oxidative stress and low-grade inflammation, two common characteristics of MetS.
Study Design and Methods
We recruited 24 men and women with MetS, who, after following a PBD for 2 weeks (baseline), were randomly allocated to consume either two whole eggs with 70 g of spinach/day (EGG) or the equivalent amount of egg substitute with spinach (SUB) as breakfast for 4 weeks. After a 3-week washout, they were allocated to the alternate breakfast. We measured biomarkers of oxidation and inflammation at baseline and at the end of each intervention.
This randomized, controlled, cross-over designed dietary intervention was previously reported. After screening to meet the criteria for MetS, participants were asked to follow a PBD (lactovegetarian) throughout the 13-week intervention. Participants were allowed to consume dairy, vegetables, fruits, and grains while restricting the consumption of meat, poultry, fish, and eggs other than those provided during the treatments. In addition, after a 2-week washout (without eggs and spinach), participants were randomly allocated to consume either two whole eggs per day (EGG) or the equivalent amount (1/2 c) of egg substitute with spinach (70 g) as an omelet for breakfast every day for 4 weeks. The egg substitute was egg whites from the Egg Beaters brand with zero cholesterol as described previously. A registered dietitian advised the participants and ensured compliance with the diet. The intervention scheme was reported earlier. Thirty participants (49.3 ± 8 y) classified with MetS according to National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III) guidelines enrolled in the 13-week diet intervention. At the screening, each participant signed the written informed consent form. With 6 dropouts, 24 participants completed the intervention. This study was registered at Clinicaltrials.gov (protocol NCT04234334) and was approved by the University of Connecticut, Storrs Institutional Review Board under protocol H19-178.
Blood was drawn from MetS participants at baseline (BL) (week 2) and the end of each treatment (week 6 and week 13). After a 12 h overnight fast, blood samples were collected into EDTA coated vacutainers and were immediately centrifuged at 2000× g for 20 min at 4 °C for the separation of plasma. Blood collected in vacutainers without anticoagulant was left to clot at room temperature for 20 min before centrifuging to separate serum. Serum and plasma aliquots were stored at −80 °C until further analysis.
CRP and liver enzymes alanine transaminase (ALT) and aspartate transaminase (AST) were measured using an automated clinical chemistry analyzer (Cobas C 111, Roche Diagnostics, Indianapolis, IN, USA) as previously described. TAC was measured by assessing the extent of oxidation of the 2,2′-azino-di-3-ethylbenzthiazoline sulfonate (ABTS) radical. GlycA was measured spectroscopically by proton nuclear magnetic resonance (NMR) using the NMR LipoProfile® spectra from plasma samples. This clinical biomarker indicates the glycosylation levels of acute-phase proteins whose elevation reflects systemic inflammation. Plasma MDA and 8-isoprostanes were measured using commercially available ELISA kits from MyBioSource, San Diego, CA, USA and Cayman Chemical Company, Ann Arbor, MI, USA, respectively. OxLDL was measured using a solid-phase capture sandwich ELISA from G Biosciences (St. Louis, MO, USA). PON-1 lactonase activity toward delta-valerolactone (Sigma-Aldrich, Burlington, MA, USA) was determined using a modification of the method described by Khersonsky and Tawfik. We evaluated the parameters of the metabolic syndrome (waist circumference, blood pressure, plasma triglycerides, HDL-C, and fasting glucose) as previously reported. We compared these values to those during screening to determine how many individuals resolved their MetS across the intervention during BL, EGG, and SUB periods.
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Significance was defined as p < 0.05 and data values were reported as mean ± standard deviation. A repeated-measures ANOVA evaluated differences over time (repeated measure) among BL, EGG, and SUB periods. Fisher’s test was used to detect significant differences among groups.
Key Findings
Tumor necrosis factor-alpha, interleukin-6, monocyte protein attractant-1, liver enzymes, and C-reactive protein, as well as total antioxidant capacity, paraoxonase-1 (PON-1) activity, and other biomarkers of oxidation were not different at the end of EGG or SUB or when compared to baseline. However, plasma malondialdehyde (MDA) concentrations were lower (p < 0.05) during the EGG and baseline compared to SUB. In addition, the increases in dietary lutein and zeaxanthin previously observed had a strong positive correlation with PON-1 activity (r = 0.522, p < 0.01) only during the EGG period, whereas plasma zeaxanthin was negatively correlated with MDA (r = −0.437, p < 0.01). The number of participants with MetS was reduced from 24 during screening to 21, 13, and 17 during the BL, EGG, and SUB periods, respectively, indicating that eggs were more effective in reversing the characteristics of MetS.
The plasma concentration of CRP did not change for both EGG and SUB compared to BL. There were no significant changes in the concentration of TNF-α, MCP-1, and IL-6 throughout the intervention. Similarly, AST and ALT remained stable and within normal limits throughout the interventions.
SAA concentrations were not significantly different throughout the 13-week intervention (BL: 5.91 ± 2.65 ng/mL, EGG: 6.25 ± 2.89 ng/mL, SUB: 6.17 ± 2.57 ng/mL). Similarly, no differences were seen in PON-1 activity after EGG (8.03 ± 2.7 U/mL) and SUB (8.04 ± 2.6 U/mL) when compared to BL (7.94 ± 2.8 U/mL). However, a strong positive correlation between PON-1 and dietary lutein and zeaxanthin (r = 0.522, p < 0.05) was observed during the EGG period. Previously, we have reported significant increases in dietary lutein and zeaxanthin after EGG (9190 ± 1527 µg) as well as SUB (9179 ± 2188 µg) when compared to BL (3151 ± 4382 µg). Dietary lutein and zeaxanthin correlated with PON-1, (r = 0.522, p < 0.01).
MDA concentrations were significantly decreased at BL and after EGG intake compared to SUB. There were no differences in the concentration of 8-isoprostanes, GlycA, and oxLDL between diets. We also found a negative correlation between MDA concentration and plasma zeaxanthin. The concentratio of lipid peroxidation product, MDA negatively correlated with the concentration of plasma zeaxanthin after EGG intervention for n = 24 subjects.
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Plasma TAC was also maintained throughout the intervention (BL: 183.98 ± 36.11 mg VCE/L, EGG: 185.87 ± 40.44 mg VCE/L, SUB: 172.25 ± 35.44 mg VCE/L). TAC is inversely proportional to the concentration of plasma oxLDL after EGG intervention (r = −0.522, p < 0.001) for n = 24 subjects.
Of the 24 adults with MetS criteria enrolled in this study, 4 participants were no longer classified as having MetS after following a PBD for 2 weeks (BL) and 7 after SUB intake. However, EGG intake reversed the metabolic syndrome in 11 participants. Among subjects in the EGG group, seven participants were allocated to the EGG group first and four to the SUB group first. The individual components modified during each treatment were variable among participants.
Implications of the Study
In this study, we found that daily intake of two eggs/day combined with spinach for 4 weeks while following a plant-based diet lowered the lipid peroxidation product MDA without increasing the markers of inflammation. We also found that the inclusion of whole eggs (EGG) helps to reverse MetS when compared to a plant-based diet (BL) or a plant-based diet including egg whites (SUB). These findings strengthen our hypothesis that eggs in combination with a lactovegetarian diet maintain the antioxidant status of a PBD and may reduce oxidative stress biomarkers, therefore preventing the progression of the metabolic conditions of MetS. This is supported by the significant findings reported earlier from this 13-week intervention, that two eggs/day complement a PBD by lowering body weight and BMI and improving HDL-C, especially the large HDL .
MetS features an increased pro-oxidative and pro-inflammation state. The extent of oxidative stress is dependent on the severity of MetS. The imbalance in the antioxidative protection against damaging free radical accumulation triggers aging by damaging cellular functions, altering signaling pathways, and activating endothelial cell injury through inflammatory responses. The prevalence of MetS increases with age. This relation by itself states the urgency of improving dietary intake of antioxidants in the MetS population to prevent age-related comorbidities.
Adherence to the Mediterranean diet benefits MetS by reducing inflammatory and oxidative stress markers while improving insulin sensitivity. Similar effects in MetS are shown with vegetarian and vegan diets compared to omnivorous diets. However, a vegetarian diet puts one at risk for nutrient deficiencies in vitamin B12, vitamin D, calcium, iron, selenium, omega-3, and protein, which are crucial for vital functions.
Although MetS is associated with increased plasma CRP, our participants maintained lower concentrations throughout the intervention. Vegetarian and vegan diets are negatively correlated with CRP. Unlike previous studies of MetS with eggs where inflammatory markers were reduced, we observed no changes in this study. The new and more reliable marker for systemic inflammation, GlycA, with comparatively superior reliability to CRP, also did not change throughout the intervention. No other effects were observed by including eggs or spinach in the diet.
The Multi-Ethnic Study of Atherosclerosis (MESA) has depicted this relationship between reducing CRP and inflammatory cytokines after a fiber-rich vegetarian diet compared to a fat-rich, dietary fiber-devoid omnivore diet. The PBD offers more dietary fiber, which may alter the microbiome and improve bacterial diversity. Low circulating HDL-C is a criterion for MetS and is a well-documented cardiometabolic risk factor. The vital proatherogenic function of HDL involves cholesterol efflux through reverse-cholesterol transport from peripheral tissue to the liver, thus modulating systemic inflammation. Systemic and vascular inflammation generated by disease conditions disrupts the proatherogenic effects of HDL, converting them to dysfunctional HDL. The concentration of the inflammation-related marker SAA and antioxidant enzyme PON-1 carried by HDL are inversely related to each other and are used as indicators for HDL functionality. In this study, the concentration of SAA and the lactonase activity of PON-1 were maintained throughout the intervention, even though an increase in HDL-C was observed after EGG treatment . Antioxidant carotenoids, lutein, and zeaxanthin are mainly transported by HDL, which offers additional protective functions. PON-1 has a critical role in promoting antioxidant properties by protecting LDL from lipid peroxidation. Lipid peroxidation refers to the oxidative degradation of lipid products, causing cellular damage by accumulating free radicals. Evidence attests that oxidative stress is increased in MetS due to the associated fat accumulation. Insulin resistance, dyslipidemia, and abdominal obesity associated with MetS increase the production of free radicals, consequently raising MDA, the primary product of lipid peroxidation.
The Debate Around Plant-Based Eggs
The rising trend of alternative vegetarian proteins shows no signs of slowing down. Plant-based chicken tenders, sausage patties, and even beef jerky have begun showing up on grocery store shelves at breakneck speed. The latest food to get a plant-based makeover? Eggs.
What are Plant-Based Eggs?
Though they may seem like a relatively recent invention, egg-free eggs have been around for a while. Several varieties are available, each with its own ingredient list. Many older iterations of faux eggs are intended primarily for use as a binder in baking, not as solo foods. These often begin with a base of flax or chia seed. You can even make your own:
Combine 1 tbsp. flaxseed meal with 2 1/2 tbsp. water.
Let rest for 5 minutes.
Add to your recipe.
For eating on their own, a fresh harvest of faux eggs has recently hit the market with more options rolling out in 2021. Some brands, such as Follow Your Heart’s VeganEgg, have a soy milk powder base that has to be reconstituted with liquid before use. Volumizing agents and emulsifiers like cellulose and carrageenan add to the mix to mimic a fluffy egg-like texture, while nutritional yeast, salt, and herbs help recreate the savory flavor of eggs.
For my own DIY test kitchen experiment with faux eggs, I tried JustEgg, a stand-alone product intended for eggy eating (not just baking). JustEgg comes in both pourable and precooked form. It’s made with a blend of mung bean protein and canola oil, plus spices and other flavoring agents to give it that signature eggy taste.
The Pros and Cons of Plant-Based Eggs
If you’re considering trying egg-less eggs, you probably have nutrition and ethical concerns in mind. These products do stand out for certain dietary and planetary pros.
Pros
Without animal products, vegan eggs contain no cholesterol. For heart health, this may be a plus, as the Dietary Guidelines for Americans recommends consuming as little dietary cholesterol as possible.
For many people, the environmental benefits behind plant-based eggs are another major selling point. Egg-laying hens, even free-range ones, are a source of greenhouse gases, which contribute to climate change. Choosing plant proteins over animal proteins reduces this footprint. Meanwhile, without any animals involved, animal cruelty is a nonissue with vegetarian eggs.
Cons
Just because faux eggs are made with plants doesn’t mean they’re a superior nutritional alternative to chicken eggs. For one thing, fake eggs have less protein. Compared with roughly 6 grams in a large egg, one serving of JustEgg’s liquid product contains 5 grams, while a serving of VeganEgg provides only 3 grams.
Then there’s the matter of sodium. A single serving of JustEgg packs 170 milligrams (mg) of sodium, and a serving of VeganEgg comes with 150 mg. A large chicken egg’s sodium content? A mere 65 mg.
Faux eggs are also a far more processed food than chicken eggs. A diet high in ultra-processed foods has been linked to an increased risk of obesity and cancer. Not surprisingly, the level of processing it takes to achieve faux eggs is reflected in their ingredient lists. Compared with the one-word ingredient label of chicken eggs, this can be off-putting. However, even unpronounceable ingredients aren’t necessarily cause for alarm. “Some people may not be happy about unfamiliar ingredients on the ingredient list, like transglutaminase. The FDA (Food and Drug Administration) classifies transglutaminase as GRAS (generally recognized as safe), and the USDA deems the ingredient safe to use in meat and poultry products,” says Taub-Dix.
Taste and Culinary Performance
Nutrition stats aside, the question on everyone’s mind when it comes to faux eggs is: How do they taste?
Quiche
First on the agenda in my personal food laboratory was quiche, an easy breakfast, lunch, or dinner. I whipped up my first-ever vegan quiche with JustEggs’ liquid mixture, a sprinkle of cheese, and a dusting of salt and pepper. After baking for 20 minutes, my creation emerged from the oven looking - I kid you not - exactly like regular baked eggs. Food science is magic. I poked at it with a fork to test its texture. Indeed, it matched what I’d expect from my usual quiche almost perfectly, down to the top layer of crispy eggy crust. In fact, the JustEgg mixture seemed to even hold together better, with a thicker, less goopy structure than regular eggs.
Now for the moment of truth: How did it taste? The flavor of the eggless quiche was definitely very close to real eggs, but not exactly spot-on, with a little too much savory. Still, I’d never believe what I was eating was made of beans.
Scrambled Eggs
Next, it was time to try faux eggs in their most basic preparation: scrambled. Going into the pan, the bean-based liquid looked indistinguishable from beaten eggs. As the mixture cooked, it even clumped up just like real eggs. Texture-wise, though, the mixture seemed a bit stickier. It even stuck to the pan like real scrambled eggs. Plus, since the faux eggs didn’t brown, it was hard to know when they were done. Upon tasting my scramble, I wasn’t sold on taste. Due to their added flavoring, the vegan eggs didn’t need salt, but they left an unpleasant aftertaste that lingered.
Muffins
I’m constantly whipping up muffins for breakfast, so a taste test using these baked goods was a near-guarantee for me. Instead of cracking an egg into my favorite banana muffin recipe, I poured in a bit of JustEgg. To my surprise, there was no noticeable difference in the finished product, either in flavor or texture. Baking gets my vote as the best place to use vegan eggs.
The Future of Plant-Based Eggs
Both real eggs and faux eggs offer advantages for health and nutrition. As a non-vegan, I’m personally not ready to “fly the coop” just yet by replacing chicken eggs with faux eggs. For goals like reducing cholesterol, scaling back on animal protein, or to reduce your planetary footprint, plant-based eggs can make an ideal choice.
As food technologists work to overcome these challenges, plant-based eggs are likely to get better and better. But the ultimate goal might be to surpass, not merely match, the performance of real eggs. In the future, scientists could adjust the amino acid composition of proteins or boost the calcium or iron content in plant-based eggs to match nutritional needs. “We ultimately could engineer something that’s way healthier than what’s available now,” says Bianca Datta, a food scientist at the Good Food Institute, an international nonprofit focused on advancing alternative proteins.
The Other Side of the Coin: The Case Against Eggs
A common question I hear as a dietitian (second only to “Where do you get your protein?” of course) is “What’s wrong with eggs?”
The Nutritional Drawbacks of Eggs
Let’s start with the obvious egg facts. Eggs have zero dietary fiber, and about 70 percent of their calories are from fat-a big portion of which is saturated. They are also loaded with cholesterol-about 213 milligrams for an average-sized egg. For reference, people with diabetes, cardiovascular disease, or high cholesterol should consume fewer than 200 milligrams of cholesterol each day. (Uh oh.) And, humans have no biological need to consume any cholesterol at all; we make more than enough in our own bodies.
Why so much fat and cholesterol in such a tiny package? Think about it: eggs hold every piece of the puzzle needed to produce a new life. Within that shell lies the capacity to make feathers, eyes, a beak, a brain, a heart, and so on. It takes a lot of stuff to make such a complex being.
In addition to these excessive (for humans) natural components of an egg, other human-health hazards exist.
Eggs and Disease
But how do eggs affect real people in real life? Luckily, researchers have conducted good studies to help answer that question.
Eggs and Cancer
In a 1992 analysis of dietary habits, people who consumed just 1.5 eggs per week had nearly five times the risk for colon cancer, compared with those who consumed hardly any (fewer than 11 per year), according to the International Journal of Cancer. The World Health Organization analyzed data from 34 countries in 2003 and found that eating eggs is associated with death from colon and rectal cancers. And a 2011 study funded by the National Institutes of Health showed that eating eggs is linked to developing prostate cancer. By consuming 2.5 eggs per week, men increased their risk for a deadly form of prostate cancer by 81 percent, compared with men who consumed less than half an egg per week. Finally, even moderate egg consumption tripled the risk of developing bladder cancer, according to a 2005 study published in International Urology and Nephrology.
Eggs and Diabetes
A review of 14 studies published earlier this year in the journal Atherosclerosis showed that people who consumed the most eggs increased their risk for diabetes by 68 percent, compared with those who ate the fewest.
Egg consumption also increases the risk of gestational diabetes, according to two 2011 studies referenced in the American Journal of Epidemiology. Women who consumed the most eggs had a 77 percent increased risk of diabetes in one study and a 165 percent increased risk in the other, compared with those who consumed the least.
Eggs and Heart Disease
Researchers published a blanket warning in the Canadian Journal of Cardiology, informing readers that ceasing egg consumption after a heart attack would be “a necessary act, but late.” In the previously mentioned 14-study review, researchers found that people who consumed the most eggs increased their risk for cardiovascular disease by 19 percent, and if those people already had diabetes, the risk for developing heart disease jumped to 83 percent with increased egg consumption.