Meat and Meat Products

Meat and meat products are rich and concentrated sources of nutrients including fats, proteins, vitamin B12, zinc and iron.

Meat is categorised into red meat and white meat. Meat from any source is of similar nutritional value, whether it is white or red. The intensity of colour in meat depends on the amount of myoglobin it contains. It is incorrect to assume that white meat from birds is superior to red meat, or vice versa. Offal meat (i.e. internal organs such as liver and kidney), however, tends to have a higher nutritional value, and red meat is known to contain a rich source of iron.

The distinguishing element among the various sources of meat appears to be the fat content. Some scientists consider red meat (e.g. beef, pork and lamb) to be less healthy because it has a relatively higher fat content compared to white meat. Saturated fat in meat may predispose people to cardiovascular disease.

There are many reasons for people to eliminate meat and meat products from their diet. Some of these reasons may include health concerns, religion, cultural background, income and accessibility of meat.

Red or dark meat is mainly made up of muscles with slow fibres. These muscles are used for extended periods of activity, such as standing or walking, and need a steady energy source. Red meat refers to the muscle meat from cattle, sheep, goat and kangaroo and essentially provides considerable amounts of zinc and vitamin B12.

The pigment that is primarily responsible for the red colour of meat is myoglobin, a protein that can bind and store oxygen in cells. The amount of myoglobin in meat varies according to species, age of animal, amount of exercise, stress, condition of storage, exposure to oxygen, heat and processing.

Tissues and organs that require more oxygen for their functions have more myoglobin, and therefore are redder in colour. Beef is shown to contain more myoglobin in its tissue than lamb and pork.

Myoglobin levels also vary depending on muscle use. More active parts of an animal require more oxygen and will therefore have more myoglobin and consequently, be redder or darker in colour. For example, chicken legs are darker than chicken breasts because their legs are more active.

White meat is made up of muscles with fast fibres. Fast fibre muscles are used for quick bursts of activity, such as fleeing from danger. These muscles source their energy from glycogen, which is also stored in the muscles. White meat is a valuable source of iron and zinc, however, the mineral content per unit weight of white meat is about half the mineral content of red meat per unit weight. Similarly, vitamin B12 content is less in white meat.

Myoglobin content is low in white meat. This explains why chicken breast, pork and veal are slightly pink or white. The colour of fish meat is white because it lives in water and does not need to support its own body weight, and therefore has no myoglobin in its muscles.

Protein

Protein is the fundamental structural and functional element within every cell, and is made up of 20 common amino acids. There are eight amino acids which are not produced in the body and must be supplied by food. These are classified as essential amino acids.

The majority of the foods we eat contribute some amounts of protein to our diet. Animal products have a higher protein content than fruits, vegetables and breads. Muscle meat is a good source of protein. Meat is rich in essential amino acids, particularly sulphur amino acids. White meat contains an equivalent amount of protein to red meat.

Protein from meats, fish and poultry are more easily digested than protein from beans and wholewheat.

Fat

Fat is distributed throughout meat. The fat content of meat varies depending on animal breed, age, amount of exercise and diet. Lean red meat provides 2-5g of fat per 100g of dietary fat. It has almost equal amounts of saturated and monounsaturated fats, and a small amount of polyunsaturated fat.

Lean pork and skinless chicken have the same fat content as lean red meat. Lean pork has more polyunsaturated fat compared with lean red meat, but equal amounts of saturated and monounsaturated fats. There is more monounsaturated fat and polyunsaturated fat in skinless chicken compared to other meats.

The fat content of meat varies as follows:

Red meat: beef (3.5-9.3 %), lamb (7.5-13.3%)White meat: pork (3.7-10.1%), chicken (1.1-9.7 %), turkey (2.0-6.6 %)Processed meat: Burgers and sausages have the highest fat content (up to 25%)

Iron

Iron deficiency is common in Australia. Pregnant women, or those of childbearing age, require more iron than other people. Vegetarians and semi-vegetarians have a higher risk of developing an iron deficiency, as iron obtained from plants has a lower bioavailability. The human body can absorb about 15% of iron from plants (non-haem iron), and about 25% of iron from meat (haem iron). Eating meat in a mixed meal can cause a two-fold increase in the absorption of non-haem iron.

Red meat (e.g. beef and lamb) is the best source of iron. Pork and chicken contain moderate amounts of iron, while fish has the least amount.

Iron deficiency is progressive. Anaemia develops at its final stage. When iron stores in the body are depleted, the amount of iron circulating in the blood is decreased, causing a fall in red blood cell production. Mild iron-deficiency anaemia leads to reduced work capacity, slower response to exercise, impaired immune function, and changes in mood and cognitive performance. In children, iron-deficiency anaemia is associated with psychomotor development. In pregnancy, iron-deficiency anaemia causes prematurity, low birth weight and increased perinatal mortality.

Zinc

Zinc is a trace mineral that can be found in almost every cell in the body. Zinc is essential to the human body because it stimulates enzyme activities, provides a healthy immune system, is used for wound healing, sustains senses of smell and taste, and is used for DNA synthesis. Zinc is also important for normal growth and development during pregnancy, childhood and adolescence.

Meat is a major source of readily available zinc. The liver and kidney are richer sources than muscle meat, and pig liver is richer in zinc than sheep or beef liver. Zinc from animal sources (including eggs) is better absorbed than zinc from plant foods (e.g. wholemeal bread).

B vitamins

Vitamin B1 (thiamin) occurs naturally in pork, duck, oyster, and other meats. A deficiency of vitamin B1 can cause beri-beri and Wernicke-Korsakoff syndrome, which result in neurological and cardiovascular dysfunction. These two syndromes are normally seen in alcoholics, and seldom seen in vegans. Vegans can derive their vitamin B1 from plant sources (e.g. nuts, pulses, oatmeal, fortified breakfast cereals, etc).

Offal is the best source of vitamin B2 (riboflavin). Riboflavin aids the metabolism of carbohydrates, fats, and proteins. It plays an important role in reproduction, and in the growth and repair of joints, skin, hair, and nails. It also enhances the immune system's ability to fight disease.

Vitamin B3 (niacin) is found in foods that are high in protein (e.g. liver, kidney, poultry and fish). Vitamin B3 helps to remove toxic and harmful chemicals from the body. It helps produce various sex and stress-related hormones in the body. Vitamin B3 helps improve circulation and reduce blood cholesterol levels.

Vitamin B12 (Cobalamin) is necessary for cell division and blood formation. Vitamin B12 is synthesised by microorganisms and is found in bacterially fermented foods, meat, and offal from ruminant animals. Offal, particularly liver, contains more vitamin B12 as this is where the vitamin is stored. Occasionally, cobalamin is found in soil and water because they are contaminated with microbes that produce vitamin B12. This is how plants derive an inactive form of this vitamin. Shellfish, fish and meat are also rich in vitamin B12.

A study conducted in Perth, Australia showed that the per capita consumption of red meat had fallen steadily, while white meat consumption rose. One of the factors that contributed to this pattern was rising concerns about fat, cholesterol, nutritional value, calories, fibre, waste and artificial additives. Lean meat is rapidly becoming the preferred choice, but it is often more expensive.

Meat definitely has great nutritional value but consumers must be reminded that too much of a good thing can be harmful. Human population studies show that red and processed meats are associated with an increased risk of colorectal cancer, but white meat is not. The evidence is not yet conclusive, but consuming a lot of preserved meat probably increases the risk of colorectal cancer.

Scientific studies have demonstrated that the key factor in disease outcomes is the dietary patterns rather than the individual food components. Dietary patterns that mainly contain processed meats are more associated with some diseases including CVD, colon cancer and type II diabetes, than dietary patterns that mainly contain poultry.

 

The NHMRC Dietary Guidelines for Australians on meat consumption are:

Males aged 19-60 years: 1 serve of lean meat, fish, poultry, nuts and legumes each dayFemales aged 19-60 years: 1 serve of lean meat, fish, poultry, nuts and legumes each dayPregnant women: 1 ½ serves of lean meat, fish, poultry, nuts and legumes each dayLactating women: 2 serves of lean meat, fish, poultry, nuts and legumes each day

Note: A sample serve is 65-100 grams of cooked meat or chicken (e.g. ½ cup mince, 2 small chops, or 2 slices of roast meat) or 80-120 grams of cooked fish fillet.

The NHMRC Dietary Guidelines for Australians recommends that lean red meat be consumed 3-4 times a week, and fish 1-2 meals per week.

Individuals that have high iron needs (e.g. girls, women, vegetarians and athletes) might require high-iron replacement foods.

Enjoy lean red meat 3-4 times each week.Choose lean meat, or trim the fat off your meat.Eat less sausages and processed meats.Try to eat 1-2 fish meals a week.

 

Milk and Milk Products (Dairy Products)

Children and adolescents should be encouraged to consume milk products because this is the period of their lives in which they are building their peak bone mass and developing lifelong habits. This article highlights the benefits of milk and milk products, as well as common misconceptions.  

A production plant for processing dairy products is called a dairy or a dairy factory. Dairy products are generally defined as food products that are produced from milk. They are rich sources of energy. Raw milk for processing generally comes from cows, but occasionally from other mammals such as goats, sheep, and water buffalo. Water is the main constituent of milk (about 90%).

Milk of various types (including whole milk, skim milk, buttermilk), yoghurt, cheese (e.g. Swiss cheese, cheddar cheese, cottage cheese), and ice cream are dairy products. Of all milk products, milk, yoghurt and cheese are the best sources of calcium.

Dairy products and alternatives such as calcium-fortified soy products are nutritious foods, and provide benefit when consumed as part of a nutritionally balanced diet which includes all of the 5 food groups:

Meat/chicken/fish/alternatives; andA small amount of fats and oils.

The functions of a food are served specifically through its nutritionally important components, including proteins, carbohydrates, lipids, minerals, vitamins and water. Cow's milk is the preferred choice for most people. It provides 67 kilocalories and has a protein content of 3.2 grams per 100 millilitres. Milk proteins include casein (about 80%) and whey (about 20%). Whey has a higher nutritional value than casein.

Once fat and casein have been removed from milk, it consists mainly of whey, which contains the soluble milk salts, milk sugar and the remainder of the milk proteins. Whey proteins consist of a number of specialised proteins, the most important being beta lactoglobulin (50% of whey) and lactoglobulin.

Milk proteins have a high biological value but, unlike egg proteins, they lack sulphur-containing amino acids. The proteins in cow's milk have balanced amino acid profiles and good digestibility, making it the obvious choice when it comes to feeding the family. Casein in cow's milk combines with calcium to form caseinogen. A higher proportion of calcium and casein in cow's milk makes it more difficult to digest than human milk. Some people cannot drink fresh milk because they are lactose intolerant, but can consume sour milk because it contains less lactose.

The nutrient composition of milk makes it a time-tested liquid that is indispensable for the maintenance of optimal nutrition, especially for the young. The major nutrients in milk aside from protein include the following:

Fat

Milk and milk products also contain fat. Cow's milk contains fat that is in the form of glycerides. The fat in cow's milk is a poor source of essential fatty acids.

The fat content of milk varies:

Whole milk contains 3.9 g fat per 100 ml,Semi-skimmed milk provides 1.7 g fat per 100 mlSkim milk provides 0.2 g fat per 100 ml1% milk, a blend of skimmed and semi-skimmed milk, has recently become available. It contains 1 g fat or less per 100 ml.

Carbohydrates

The main carbohydrate in milk is a disaccharide called lactose. It is made up of two simple sugars – glucose and galactose – and is sweeter than sucrose (found in cane sugar). Lactose supports the absorption of calcium and phosphorus and the synthesis of some B complex vitamins in the small intestine. In the human body, an intestinal enzyme called lactase digests lactose. Some people are unable to produce enough lactase, inhibiting lactose digestion. This undigested lactose is then broken down in the large intestine by bacteria, causing the formation of gas, bloating, pain and diarrhoea. This condition is called lactose intolerance.

Lactose intolerance is the inability to digest significant amounts of lactose, the major sugar found in milk. Lactose intolerance poses a problem for some people, but can be managed. People who have trouble digesting lactose should avoid dairy products that are not compatible with their system. Many people with this condition can enjoy milk, ice cream and other such products if they eat them in small amounts or eat other food at the same time. Additionally, lactase liquid or tablets can help digest the lactose.

Lactase deficient individuals may tolerate milk with cereals or cooked as custard more than liquid milk. Some dairy foods contain less lactose than others, and may be better for people who suffer from lactose intolerance. These include:

Fermented milk products, including some yoghurts, mature cheeses (like cheddar cheese) and butter, generally pose no problems.Since heating breaks down some of the lactose, heated milk products such as evaporated milk may be preferred to unheated foods.

Vitamins and minerals

Milk and milk products are an excellent source of vitamins and minerals, particularly calcium. Milk has significant amounts of vitamin A and B vitamins such as thiamine, riboflavin and nicotinic acid, but is a poor source of vitamin C and vitamin E. It also contains vitamin B12.

The important minerals in milk are calcium, phosphorus, sodium and potassium. It is, however, a poor source of iron. Calcium is a mineral that the body needs for numerous functions, including building and maintaining bones and teeth, blood clotting, the transmission of nerve impulses, and regulation of the heart's rhythm.

How much calcium do you consume?

Calcium is found in many foods, in particular dairy products and to a lesser degree bony fish, nuts and legumes, fruit and vegetables. It plays an important role in building and maintaining healthy bones and teeth.

Individuals need to consume sufficient amounts of calcium throughout their lifespan.  Calcium requirements increase throughout childhood, peak during puberty, then stabilise until an individual is approximately 50 years old, when bone mass deteriorates and more calcium is required.

Click here to calculate your required calcium intake

Milk and dairy products are the major food source of calcium and protein in most developed countries, including Australia. One litre of milk can provide approximately 1200 mg of calcium, representing more than the daily requirement for calcium. Calcium in milk is in a bioavailable form and is readily absorbed. The absorption of calcium is enhanced by vitamin A and lactose.

Adequate intake of calcium is necessary for growth in childhood, and for the prevention of diseases like osteoporosis in adulthood. Research evidence points to an association between decreased calcium intake and osteoporosis.

  

Calcium is also needed in the diet to control hypertension. A number of studies have reported an inverse association between dietary calcium intake and blood pressure. The most powerful research strategy is the randomised controlled trial. Findings from such clinical trials indicate that an increased calcium intake lowers blood pressure and the risk of hypertension. However, another trial in which researchers followed 193 men and women split into two groups, one taking a placebo and the other taking calcium carbonate tablets twice daily, reported that calcium had no significant effect on blood pressure.

Despite its nutritional value, some people are sceptical of milk consumption, mainly because of the fat and cholesterol content, and the risk of atherosclerosis (clogging of the arteries) or coronary heart disease (CHD). However, there is insufficient scientific evidence to support this caution. In 2004, Dairy Australia Seminar Series, a review of the epidemiological evidence on milk and cardiovascular disease presented by Professor Peter C Elwood, showed that milk drinkers have a reduced risk of cardiovascular disease (CVD) compared to those who drink little or no milk, despite the fact that most of the milk drank was regular fat milk. The review further concluded that there was no evidence of an increase in vascular disease; rather, the incidence of stroke and heart disease was about 15% lower in the subjects with the highest intakes of milk. Evidence from cohort studies suggests that though milk consumption raises cholesterol level, milk is protective against vascular disease.

The biggest setback to using milk and dairy products is that the public in general, and teenagers and women in particular, tend to avoid milk and dairy products because of their fat content.

A 300 ml glass of full cream milk contains 10 g of fat, of which 6.3 g is saturated fat, and can contribute about 770 kJ of energy. In contrast, a 300 ml glass of skim milk only contains 0.6 g of fat (a reduction of 94%), 0.3 g of saturated fat, and 440 kJ (a reduction of 43%). Therefore, consuming skim milk and low fat yoghurt instead of whole milk will allay the fear of health risks associated with dairy fat.

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It has been documented that, in most countries, milk consumption has fallen over the past 20–25 years. A reduction in milk consumption may impact on nutritional needs, especially of calcium. It appears that the positive nutritional and health contributing values of dairy products far outweigh concerns regarding cholesterol.

Like any other food, overconsumption may be associated with health risks. The key word in the choice and consumption of any food is moderation. At moderate levels, calcium and dairy products have benefits beyond bone health, including possibly lowering the risk of high blood pressure and colon cancer.

A daily intake of three glasses of skim milk, over cereal at breakfast, in hot beverages and in milk dishes like custard, and one or more portions of low fat yoghurt or low fat cottage cheese, is sufficient to meet your milk requirements. The US Department of Agriculture's Food Guide Pyramid recommends that individuals two years and older eat 2–3 servings of dairy products per day.

A serving is equal to:

1 cup (8 fl oz; 250 ml) of milk 8 oz (250 g) of yoghurt1.5 oz (40 g) of natural cheese (e.g. cheddar) 2.0 oz (60 g) of processed cheese

It is generally recommended that children, pregnant women, older people and those who are unwell avoid unpasteurised milk and milk products. Individuals who are allergic or intolerant to milk and dairy products may try to avoid them. For such people, eating dairy products such as yoghurt in small quantities may be helpful.

Milk and milk products should be stored in a refrigerator to slow down the growth of micro-organisms, such as mould on cheese. Milk, cheese and yoghurt should be stored and used by the date specified on the packaging.