Over the coming months, as part of our nutrition theme, we'll be featuring some main food groups, outlining their role in sports nutrition, and sharing ideas of how they can be added to the diet. To kick us off, this week we cover milk and eggs, two of the best (and cheapest) sources of protein available.
Nature's best
Both milk and eggs contain all the
essential amino acids in the correct proportions. As the main food to sustain animal life before birth (eggs) and after birth (milk), it is unsurprising that both foods are nutrient rich. In addition to protein, eggs are also a good source of vitamins B2, B12, D, E, folic acid, iron and a substance called choline which is involved in fat transport and in the production of phospholipids, an important component of cell membranes. With a perfect blend of amino acids, as well as high levels of calcium (essential for bone health and the prevention of stress fractures), and other nutrients involved in metabolism and tissue growth, milk is the perfect recovery drink.
Unfortunately, despite their nutritional value, both eggs and milk have received bad press. Eggs are high in cholesterol, though there is little evidence, if any, to link consumption of eggs with heart disease. Milk is often advised against because of its high fat content, though a glass of full fat milk contains less saturated fat than a couple of biscuits. Cow's milk is also, unfortunately, not tolerable by all, and dairy allergies and lactose intolerance is common. Both foods do have important roles to play in the diet, and below we suggest some alternatives.
EGGS
The eggs of almost all birds, reptiles and turtles are edible, and most are eaten somewhere in the world. Indeed, many are a delicacy. The egg of the common hen, however, is by far the mostly widely available and commonly eaten egg in the West, and it is hen eggs that we will focus on in this piece.
The majority of the egg's nutritional value is found in the yolk, though the white is also a good source of protein, has no cholesterol, and contains very little fat.
Cholesterol and eggs
Eggs are high in cholesterol, but eating eggs doesn't usually contribute significantly to blood cholesterol levels; foods high in saturated fat have a much greater affect. Egg are low in saturated fat, and egg whites don't contain any cholesterol, and can be used unsparingly in the diet.
Checking for freshness
Shops should only sell eggs less than 21 days old. They are safe to eat up to 28 days, if kept in the correct conditions, though fresher eggs are better for certain dishes. If you are unsure about the age of an egg, there are a number of ways of checking its freshness. The simplest way is to place an unbroken egg in a glass of water. Fresh eggs will sink straight to the bottom; older, but still safe to eat eggs will sit in the middle of the water, and old eggs, which should be thrown away, will float to the top. The appearance of the yolk and white of the egg will change with age. When broken onto a plate, a fresh egg will have two distinct layers to its white, and a rounded yolk. The layers of the white merge and the yolk flattens with age. The final test for freshness is the smell test. Bad eggs have an unmistakable, unpleasant, sulphorus smell.
Storing eggs
The shell of the egg is porous, making it
vulnerable to bacteria and odour contamination. Storing eggs in their
box, or in a special egg compartment in the fridge, away from fish, will
help protect them from smells. Fresh eggs can be stored in a well
ventilated place, at less than 20°, for up to a week, or in the fridge
for 3 to 4 weeks. Refrigerated eggs should be brought back to room
temperature before cooking.
Beaten eggs, in a container
loosely covered with cling film, can be stored in the fridge for 1 to 2
days. Whole, shelled eggs can be stored in an airtight container in
the fridge for 1-2 days. Egg whites can be frozen in an airtight
container. They should be defrosted in the fridge and used immediately.
Cooked eggs can only be stored if they are fully cooked. Shelled eggs
can be loosly wrapped in cling film and stored in the fridge for 1-2
days. Hard boiled eggs which are left in their shells will develop an
unappetising blue-grey ring around the yolk.
Egg safety
Some eggs may contain the salmonella bacteria, which, if not completely cooked or pasturised, can cause serious illness resulting in abdominal pain, vomiting and diarrhea. Mayonnaise, ice cream and mousse are based on raw eggs. While commercial versions of these product use pasturised eggs, home-made versions may carry a salmonella risk. At-risk individuals (children, pregnant women, the elderly), as well as athletes in the run-up to an important competition, should minimise their salmonella risk, and avoid raw or undercooked eggs.
Cooking eggs
Eggs' real value comes in their versatility. They can be boiled, fried, poached or even baked on their own, mixed with some milk and seasoning (and optional other ingredients) and scrambled, or simply turned into an omelet. They can be eaten hot or cold, and used to increase the protein content of a number of dishes. They also form the basis of quiches, frittatas and tarts. Egg-based recipes such as quiches and omelets are also a great way to use up leftovers, though beware of the high saturated fat content of any recipe using pastry.
While frying is the simplest way to cook an egg, it's also the least healthy option, because of the fat involved in the cooking process. Poaching or boiling are much better options. Poached egg on toast makes a simple, cheap and nutritious recovery snack, while cooked hard boiled eggs are a great addition to salads and sandwiches.
The Bord Bia (Irish Food Board)
website has a range of great egg recipes that you might like to try.
MILK
Cow's milk, with its slightly sweet, mild and subtle flavour is the most popular form of milk used for human consumption, though the milk of other animals, including goats and sheep, and milk made from plants such as soya, rice and almonds can also be consumed. Commercially available milk usually comes from Frisian cows, though the milk of Jersey and Guernsey cows, richer in flavour, higher in fat and darker in colour, is also popular.
Recovery food
As mentioned previously, milk's perfect balance of protein makes it an ideal recovery drink. It also contains some sugars for refueling, and a lot of water and the electrolytes sodium and potassium to help with rehydration.
Milk makes a tasty recovery drink on it's own, as part of a banana or chocolate milk-shake, or added to a fruit smoothie.
Milk and saturated fat
Full fat milk has gained a lot of bad press, particularly in relation to it's saturated fat content. While it is true that whole or full-fat milk contains just over twice the fat content of semi-skimmed milk, it's worth putting the fat values into context. A 200ml glass of full fat milk contains 7.8 g of fat; approximately the same as two chocolate digestive biscuits. Semi-skimmed milk is a good choice, as it has approximately the same protein, carbohydrate, vitamin and mineral content as whole milk, with half the fat, but those who prefer the taste of full fat milk shouldn't get hung up on it's fat content - just skip one of the chocolate digestives instead!
Skimmed milk typically has half the calories, a fraction of the fat and most of the vitamins and calcium of full fat milk, but is low in the fat-soluable vitamins A and D. It is therefore not suitable for young children.
Alternatives
Goat's milk is a good alternative for those with a diary alergy. It has a stronger flavour and is less widely available, but has a similar nutritional content, is easier to digest and contains less lactose than cow's milk. Soya milk, made from pulverized soya beans, is suitable for vegans and those with lactose intolerance. It has a thicker consistency than cow's milk, and has a slightly nutty flavour. It curdles in very hot coffee and tea.
Buttermilk, traditionally made from the thin, unstable liquid left over after making butter, but more recently made from fermented skimmed milk and milk solids, is particularly low in fat. It is, however, not to everyone's taste.
Storing milk
Milk should be stored in the fridge. It usually lasts no more than 3-4 days in the fridge after opening, irrespective of its use-by date, and can quickly sour when the weather is very warm.
Calcium and iron - not the perfect mix
Calcium is one of the substances which can affect iron absorption. To maximise absorption, avoid drinking milk at the same time as you take iron supplements or eat iron rich foods.
Do you have any milk or egg-based recipes that you'd like to share? We'd love to hear from you. Just add suggestions as comments below.
