Omega-3 enriched eggs, organic eggs, cage-free eggs, pasteurised eggs, carrot eggs, kampung eggs, standard brown eggs, etc – is there any real difference in their nutritional and cholesterol content?
It is thus no wonder that the consumption of eggs in Singapore has risen steadily over the years, although some people avoid what they believe is a “cholesterol-rich” food.
A check with the Agri-Food & Veterinary Authority (AVA) shows that the yearly per capita consumption of hen eggs has risen from 291 eggs in 2006 to 338 eggs in 2016.
Around 76 per cent of the eggs eaten here are imported mostly from Malaysia, while farms in Singapore supply the rest.
A spokesman for local supplier Seng Choon Farm said the farm can produce up to 750,000 eggs a day.
Another major player, Chew’s Agriculture (pictured below), produces half a million eggs daily for the Singapore market, up from 300,000 in 2010.
Eggs are one of the richest sources of dietary cholesterol. They also contain nutrients that may help lower the risk of heart disease.
Some eggs sold in supermarkets are described as designer eggs as certain nutrients have been enhanced by changing the hen’s diet.
Chew’s Agriculture general manager of production Tan Chee Nam said: “With nutritional knowledge and technical know-how, we can manipulate feed formulation to manufacture specific poultry feed for the mother hens.”
This is so that these mother hens, known as layers, can lay eggs that may have the value-added nutrients, he added. For example, adding flaxseed, canola meal, fish oil additives or algae additives to the feed can raise the content of omega-3 fatty acids in the eggs.
When the layers digest these additional ingredients, some of the fatty acids transfer to the yolk.
Lab tests are done to ensure that the eggs do contain a higher amount of the fatty acids.
To get organic selenium eggs, the farm includes organic selenium additives in the feed, said Mr Tan. Certain additives may be included to lower the cholesterol content of the eggs. He also said the AVA does not allow antibiotics or hormones to be given to chickens.
Seng Choon‘s carrot eggs are enhanced with the antioxidant lutein from plant-based feed ingredients, said a spokesman.
Ms Ong Ke Min, a nutritionist at nutrition consultancy Health Can Be Fun, said the diet of hens which lay these eggs includes food sources that have a high lutein content, such as carrots and corn.
Consumers can buy cage-free eggs, though most chickens live in cages for their entire lives. Mr Tan said most of the hens at Chew’s Agriculture are housed in an environmentally-controlled battery cage.
Cage-free hens are transferred to a barn-like environment when they are 17 weeks old, before they start laying eggs. They can roam about to get feed and drinking water.
The AVA carries out checks to ascertain that labels on egg products carry mandatory information such as the ingredient list and net quantity. It also inspects the hens, eggs, water and feed to ensure the eggs produced are safe for public consumption.
An AVA spokesman said the industry is responsible for ensuring the accuracy of information on food labels. He said: “Consumers should exercise discretion when choosing food based on the information provided on the labels.”
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Which type of eggs is the healthiest?
Raffles Diabetes & Endocrine Centre principal dietitian Bibi Chia said eggs generally have a similar nutrient content.
Smaller first-born eggs are not superior to other types of eggs, she added. “A large 50g egg has 70 calories and about 7g of protein.”
Standard eggs have 185mg of cholesterol. Low-cholesterol eggs have about 150mg of cholesterol.
Ms Chia said designer eggs may have more of ingredients such as omega-3 fatty acids. But these ingredients are not necessary as they can be obtained from sources such as fish, walnuts and canola oil.
According to the American Egg Board, an egg has 14 essential nutrients, including vitamin D and choline.
Vitamin D is critical for bone health and immune function, as well as supporting healthy brain development of the foetus during pregnancy. Choline is essential for normal functioning of all cells.
Eggs also contain lutein and zea-xanthin. These antioxidants are believed to reduce the risk of cataracts and slow the progression of age-related macular degeneration.
1. Cage-free eggs
These eggs are laid by hens not housed in enclosures. They roam in a building, room or open area that includes nest space and perches. Unlike hens that produce free-range eggs, they do not usually have access to the outdoors.
2. Certified organic eggs
These eggs are usually laid by cage- free or free-range hens raised on certified organic feed and with access to the outdoors. The feed is grown without synthetic pesticides, fungicides or fertilisers. The American Egg Board said that 100 per cent of the ingredients must be certified organic. Organic eggs may also come from caged chickens, said dietitian Ms Chia.
3. Free-range eggs
These eggs are laid by hens not housed in enclosures and which have access to the outdoors. In addition to eating grains, these hens may forage for wild plants and insects.
4. Omega-3 enriched eggs
These eggs provide more omega-3 fatty acids as they are laid by hens fed a diet rich in omega-3 fatty acids, said the American Egg Board.
Each egg packs 100mg to over 600mg of the beneficial fatty acid. Egg yolks already contain some naturally-occurring omega-3 fatty acids, like docosahexaenoic acid (DHA). DHA, which is found in oily fish, is needed for the proper development and maintenance of brain cells.
5. Pasteurised eggs
These eggs are heated to a temperature just below the coagulation point to destroy salmonella, a bacterium that can cause food- borne illness. These eggs can be used for lightly-cooked or uncooked food preparations, such as mayonnaise, cream or mousse.
Pasteurised eggs are sometimes recommended for young children, the elderly and people with weakened immune systems to lower their risk of contracting a salmonella infection.
6. Brown eggs
The colour of the shell has nothing to do with the nutritional value, quality or flavour of the egg. The colour depends on the breed of the hens.
The American Egg Board said hens with white feathers and white ear lobes lay white eggs, while those with red feathers and red ear lobes lay brown eggs.
7. Kampung eggs
These come from kampung chickens. The nutrient content of these eggs is similar to that of normal eggs, said Ms Chia. Many people assume that the chickens are free-roaming but they are not, she said.
The term kampung chicken refers to a breed of chicken found in Malaysia and Indonesia.
Should you be eating an egg a day?
Ms Ong said there is no need to avoid eggs as recent studies show that cholesterol in food has a much smaller effect on a person’s harmful cholesterol levels than saturated fats and trans fats.
Dr Charles Chan, a cardiologist at Gleneagles Hospital, said: “While eggs are high in cholesterol, they are also high in omega-3 fatty acids.
“The effect of egg consumption on blood cholesterol is minimal when compared to the effect of trans fats and saturated fats.”
He said most healthy people can eat up to seven eggs a week with no increase in the risk of heart disease.
Results from the latest studies have led major health advisory groups to relax their recommendations on egg consumption. Dr Chan said: “What has changed is the shift in focus towards a healthy eating pattern, rather than on the avoidance of foods such as eggs.”
There is also a lack of epidemiological data to suggest that egg consumption increases the risk of coronary heart disease, he added.
“In fact, egg consumption may be beneficial,” he said, pointing to the Japanese diet, which frequently incorporates eggs, and is typically low in total fat and saturated fat.
“Interestingly, the incidence of declining heart disease in Japan has mirrored the increase in consumption of eggs per capita.”
More studies are starting to show that an egg a day might not affect the cholesterol levels of people with high cholesterol, if the rest of their diet is healthy and low in saturated fat, said Ms Chia.
Dr Chan pointed out that there is no need to avoid egg yolk, which contains all the fat in the egg.
“Eating purely egg whites has become popular with people who want to avoid excess cholesterol. But taking both the fat and protein can have a positive effect on blood sugar,” he said.
“Consuming the fat satiates your appetite but slows down the absorption of food. By eating only the egg white, you’ll miss out on healthy nutrients.”
According to the American Egg Board, egg whites contain some high-quality protein, riboflavin and selenium, but a big proportion of an egg’s nutrients is found in the yolk.
Ms Natalie Goh, chief dietitian at Mount Elizabeth Novena Hospital, agrees that healthy adults can eat an egg a day.
Recent scientific reports have said that people who eat four to six eggs a week were not observed to have a higher risk of cardiovascular disease, she said.
But the picture is less clear for those who eat more than one egg a day, she said. Like all foods, she added, eggs should be eaten in moderation, as part of a balanced diet.
A version of this article first appeared in The Straits Times in 2017.
(Photos: SPH; Video: The Straits Times)