The surfaces of influenza viruses include, among other molecules, two glycoproteins named hemagglutinin (H) and neuraminidase (N), coded for by the viral segmented RNA genome. Each of these molecules is required for successful infection and spread in a host animal. The hemagglutinin attaches influenza to sialic acid on the surfaces of cells, enabling them to enter and infect cells. After the virus has replicated, neuraminidase (also called sialidase) removes sialic acid from the cell, enabling the newly assembled virions to be released in order to spread and infect other cells. The hemagglutinin (H) and neuraminidase (N) of influenza A are classified into various numbered serotypes or subtypes, such as H1N1, H2N2, H3N2, H5N1, and so forth. For more about neuraminidase, including references for the points made in this paragraph, please see Influenza at Wikipedia
Why is protein important?
From hair to fingernails, protein is a major functional and structural component of all our cells. Protein provides the body with roughly 10 to 15 per cent of its dietary energy, and is needed for growth and repair.
Proteins are large molecules made up of long chains of amino acid subunits. Some of these amino acids are nutritionally essential as they cannot be made or stored within the body and so must come from foods in our daily diet.
Although all animal and plant cells contain some protein, the amount and quality of this protein can vary widely.
Animal protein
Protein from animal sources contains the full range of essential amino acids needed from an adult's diet. But red meat, in particular, should be eaten in limited amounts due to the high level of saturated fat it contains, which may raise blood levels of 'unhealthy' LDL cholesterol.
A high intake of saturated fat can lead to an increased risk of cardiovascular disease and other related disorders. As an alternative source of animal protein, choose poultry, fish and shellfish.
The 2007 World Cancer Research Fund report recommended meat eaters limit their consumption of red meat to no more than 500g a week, with very little processed meat, as these have both been linked to certain forms of cancer.
Fish is a good source of animal protein. Oil-rich fish such as salmon, mackerel, herring, tuna, trout and sardines are all rich in omega-3 fatty acids, which help to reduce the risk of developing cardiovascular disease.
Shellfish is also a good source of protein and is low in fat.
Aim to eat a couple of portions of fish every week, with at least one portion being an oily fish.
Did you know...?
Eggs contain all eight essential amino acids, making them a perfect source of protein. However, you'd have to eat at least eight eggs a day to get all the protein you need. Be sensible; include them as part of a balanced and varied diet.Advice for vegans and vegetarians
Vegetarians rely on plant sources for their daily protein. Plants don’t contain the full range of essential amino acids and so are not as high in nutritional value as animal protein. But by eating a well-balanced diet that contains a variety of different foods, it's possible to consume the required amino acids, regardless of the time of day they’re eaten or in what combinations within a meal.
Foods such as nuts, seeds, beans, pulses, vegetable protein foods and soya products all contain protein. There are also small amounts in grains and dairy products. Due to this variety of protein-rich foods available in the UK, protein deficiency is rare.How much is enough?
Health professionals suggest men should eat 55.5g protein a day and women 45g. In practical terms, eating a moderate amount of protein - in one or two meals every day – should give you all the protein you need. Most people in the UK eat far more protein than they actually need. It's easy to understand the excitement. Protein is an important component of every cell in the body. Hair and nails are mostly made of protein. Your body uses protein to build and repair tissues. You also use protein to make enzymes, hormones, and other body chemicals. Protein is an important building block of bones, muscles, cartilage, skin, and blood.
Along with fat and carbohydrates, protein is a "macronutrient," meaning that the body needs relatively large amounts of it. Vitamins and minerals, which are needed in only small quantities, are called "micronutrients." But unlike fat and carbohydrates, the body does not store protein, and therefore has no reservoir to draw on when it needs a new supply.
So you may assume the solution is to eat protein all day long. Not so fast, say nutritionists.
The truth is, we need less total protein that you might think. But we could all benefit from getting more protein from better food sources.
