Glossary of Terms

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Age-related Macular Degeneration

Age-related macular degeneration is a deterioration of the eye’s macula. The macula is a small area in the retina — the light-sensitive tissue lining the back of the eye. The macula is the part of the retina that is responsible for your central vision, allowing you to see fine details clearly. As the name suggests, the condition is more common with advancing age.

Beta cells

The cells in the pancreas that produce insulin. They are found grouped together in the Islets of Langerhans.

Blood glucose level

The concentration of glucose (a type of sugar) in the bloodstream. Essentially all carbohydrates in food are ultimately converted to glucose.
Glucose is a universal fuel for most organs and tissues in our bodies

  • • The only fuel source for our brain, red blood cells and a growing foetus, and
  • • The main source of energy for our muscles during strenuous exercise

Blood pressure

The pressure of the blood on the walls of the blood vessels caused by the beating of the heart. Every body has blood pressure, although not everyone’s blood pressure is high. Hypertension is defined as having blood pressure above 140/90 mm HG. An abnormal blood pressure is considered to be 120/80.

Carbohydrate,

A vital source of energy found in all plants, is the starchy part of foods like rice, bread, legumes, potatoes, and pasta and the sugars in foods like fruit, milk and honey. Cheap, plentiful and sustainable, it is the most widely consumed substance in the world after water and the basis for a healthy diet. Some foods contain a large amount of carbohydrate (such as cereals, potatoes, and legumes) while other foods such as carrots, broccoli and salad vegetables are very dilute sources. The simplest form of carbohydrate is glucose, which is a universal fuel for our body cells, the only fuel source for our brain, red blood cells and a growing foetus, and the main source of energy for our muscles during strenuous exercise.

Cholesterol

A soft, waxy substance found in the blood and in all the body’s cells. It’s an important part of a healthy body because it is part of the walls around all of our cells, and is a major component of many of the hormones our body’s produce. Most of the cholesterol in our body does not come from the foods we eat, but is in fact manufactured by the liver. High levels of cholesterol in the blood may lead to blocked arteries, heart attack and stroke. Cholesterol and other fats can’t dissolve in the blood. They have to be transported to and from the cells by special carriers called lipoproteins. There are several kinds, but the most common ones are low-density lipoprotein (LDL) and high-density lipoprotein (HDL).

Coeliac disease

A condition where the lining of the small intestine is damaged due to an immune reaction from your own body to a small protein known as gluten. Gluten is found in certain grain foods like wheat, rye, triticale and barley, and in much smaller amounts in oats (as a contaminant). The only treatment for coeliac disease at present is a gluten-free diet.

Diabetes

Type 1 diabetes is characterised by high blood glucose levels due to the body’s complete inability to produce insulin. It occurs when the body’s immune system attacks the insulin-producing Beta cells in the pancreas and destroys them. The pancreas then produces very little or no insulin. Type 1 diabetes occurs most often in young people but can develop in adults.

Type 2 diabetes is characterised by high blood glucose levels caused by an insufficiency of insulin and the body’s inability to use insulin efficiently. It is thought to occur when the body becomes resistant to insulin. The pancreas compensates initially by producing more insulin, then eventually becomes exhausted and produces insufficient insulin. Type 2 diabetes occurs most often in middle-aged and older people but is being seen increasingly in younger adults and teenagers.

Gestational diabetes can occur during pregnancy, but usually goes away after the baby is born. Hormones released by the placenta during pregnancy reduce the effectiveness of the mother’s insulin. It is usually managed successfully with healthy eating and regular physical activity, but in some cases extra insulin is needed.

Dyslipidaemia

Abnormal levels or composition of the blood fats known as cholesterol and triglycerides.

Fat

Fat provides lots of kilojoules/calories – more than protein or carbs per gram – so you only need a small amount each day. The message today is know your fats. Focus on the good ones (mono- and poly-unsaturated fats) and give the bad fats (trans fats and saturated fats) the flick.

Saturated fats are solid at room temperature. These are the fats on meat or chicken skin, and in butter, cheese, palm oil and coconut oil. We don’t actually need to eat any saturated fat, since the body can make all it requires, but it is fairly difficult not to eat some, since all fats are actually mixtures of saturated and unsaturated fats.

Unsaturated fat is liquid at room temperature. These good mono- and polyunsaturated fats provide you with essential fatty acids that form your cell membranes; help you absorb the fat-soluble vitamins A, D, E and K; form part of your body’s hormones; provide insulation; and help you absorb some anti-oxidants from fruit and vegetables.

Trans-fats are produced during manufacture and behave like saturated fat in a product (increasing its firmness), as well as in our bodies (increasing the risk of heart attack). Foods high in trans fats include fried fast foods, some margarines, crackers, cookies and snack – so read the label before you buy these foods.

Fatty liver

The build up of excessive amounts of triglycerides and other fats inside liver cells; also known as steatohepatitis or NASH (Non-Alcoholic Steato-Hepatitis).

Fibre

Dietary fibre only comes from plant foods – the outer bran layers of grains (corn, oats, wheat and rice and in foods containing these grains), fruit and vegetables and nuts and legumes (dried beans, peas and lentils). We need about 30 grams of fibre a day for bowel health and to keep regular. There are two types of fibre—soluble and insoluble—and there is a difference.
Soluble fibres are the gel, gum and often jelly-like components of apples, oats and legumes. By slowing down the time it takes for food to pass through the stomach and small intestine, soluble fibre can lower the glycemic response to a food. Good sources include: oatmeal, oat bran, nuts and seeds, legumes (beans, peas and lentils), apples, pears, strawberries and blueberries.
Insoluble fibres are dry and bran-like and commonly called roughage. All cereal grains and products that retain the outer coat of the grain they are made from are sources of insoluble fibre, eg wholemeal bread and All-Bran®, but not all foods containing insoluble fibre are low GI. Insoluble fibres will only lower the GI of a food when they exist in their original, intact form, for example in whole grains of wheat. Here they act as a physical barrier, delaying access of digestive enzymes and water to the starch within the cereal grain. Good sources include: wholegrains, wholewheat breads, barley, couscous, brown rice, bulghur, wheat bran, seeds, and most vegetables.

Fructose or fruit sugar

An alternative sweetener that is nearly twice as sweet as table sugar but provides the same amount of kilojoules. As the name suggests, it is found naturally in most fruits.

Glucose

When you eat carbohydrate foods such as bread, cereals and fruit, your body converts them to glucose (a monosaccharide sugar that’s present in most animal and plant tissues) during digestion. It is this glucose that is absorbed from the intestine and becomes the fuel that circulates in the bloodstream. As the level of blood glucose rises after you have eaten a meal, your pancreas gets the message to release insulin which then drives the glucose out of the blood and into the cells. Once inside the cells it is channelled into several pathways simultaneously – to be used as an immediate source of energy, converted into glycogen (a storage form of glucose) or into fat.

Blood glucose (blood sugar) is the amount of glucose in the blood stream. If you haven’t eaten in the past few hours (and you don’t have diabetes), your blood glucose level normally falls within the range of 3.5–6 mmol/L. If you eat, this will rise, but rarely above 10 mmol/L. The extent of the rise will vary depending on your glucose tolerance (your own physiological response) and the type of food you have just eaten. Although blood glucose levels will fluctuate over the course of the day, they will normally remain with this fairly narrow range. Keeping levels within the normal range is important for your health whether you have diabetes or not.

The test that measures your average blood glucose level over the past 2–3 months has a variety of names. It’s mostly described asHbA1c (hemoglobin A1c or glycated hemoglobin). It indicates the percentage of hemoglobin (the part of the red blood cell that carries oxygen to the cells and sometimes joins with glucose in the bloodstream) that is ‘glycated’. Glycated means has a glucose molecule riding on its back. This is proportional to the amount of glucose in the blood. The higher the level of HbA1c, the greater the risk of developing diabetic complications. People with diabetes should aim to keep their HbA1c at or less than 7%.

Glucagon

Between meals your blood glucose levels will start to fall. As this happens, the pancreas releases the hormone glucagon into the blood. This hormone promotes the conversion of glycogen stored in the liver and muscles to glucose and raises your blood glucose level to keep it within the normal range.

Glycemia is the concentration of glucose in the blood. Hence the adjective, glycemic.

Glycemic Index (GI)

The Glycemic Index is a relative ranking of carbohydrate in foods according to how they affect blood glucose levels. Carbohydrates with a low GI value (55 or less) are more slowly digested, absorbed and metabolised and cause a lower and slower rise in blood glucose and, therefore usually, insulin levels.

Glycemic Load (GL)
Glycemic Load is a measure of both the quality (GI value) and quantity (grams per serve) of a carbohydrate in a meal.
Glycemic load is determined by multiplying its glycemic index by the grams of carbohydrate per serve and dividing by 100.

Glycemic Load =  Glycemic Index x Amount of carbohydrate per serve (g)
                                                          100

A glycemic load of 20 or more is high, 11 to 19 is medium, and 10 or under is low. However, the simplest way to use the GL is to choose foods with the lowest GI within a food group or category, and to be mindful of your serve size.

Glycemic potential

A food or meal’s predicted blood glucose raising effect.

Glycemic response or glycemic impact

These terms describes the change or pattern of change in blood glucose after consuming a food or meal. Glucose responses can be fast or slow, short or prolonged. It is primarily determined by the food’s carbohydrate content. Other factors include how much food you eat, how much the food is processed and even how the food is prepared (for example, pasta that is cooked al dente has a slower glycemic response than pasta that is overcooked).

Glycogen

The name given to the glucose stores in the body. It can be readily broken down into glucose to maintain a normal blood glucose concentration. In an adult male, approximately two-thirds of the body’s glycogen is found in the muscles and one-third in the liver. The total stores of glycogen in the body are relatively small however, and will be exhausted in about 24 hours during fasting or starvation.

Hypoglycemia (also called an insulin reaction)

Occurs when a person’s blood glucose falls below normal levels – usually less than 4 mmol/L. People with diabetes know all about it. Hypoglycaemia is treated by consuming a carb-rich food such as a glucose tablet. It may also be treated with an injection of glucagon if the person is unconscious or unable to swallow. If you don’t have diabetes, but you have vague health problems ranging from tiredness to depression and think you may have hypoglycemia or someone tells you that you probably have ‘low blood sugar’, see your doctor and get a proper diagnosis. Hypoglycemia is far less common that once was thought in people who do not have diabetes.

Impaired glucose tolerance

Sometimes called pre-diabetes or impaired fasting glucose. It is a condition in which blood glucose levels are higher than normal, but are not high enough for a diagnosis of diabetes. People with impaired glucose tolerance are at increased risk of developing diabetes, heart disease and stroke.

Insulin

A hormone produced by the pancreas that helps the body use glucose for energy. Although the body needs glucose, it doesn’t want it all in one hit, so it pumps out insulin to drive the glucose out of the blood and into the tissues. The pancreas should automatically produce the right amount of insulin to move glucose into the cells. People with type 2 diabetes do not always produce enough insulin. People with type 1 diabetes produce no insulin at all. When the body cannot make enough insulin, it has to be taken by injection or through use of an insulin pump. It can’t be taken by mouth because it will be broken down by the body’s digestive juices.

Insulin is not only involved in regulating blood glucose levels, it also plays a key part in determining whether we burn fat or carbohydrate to meet our energy needs – it switches muscle cells from fat burning to carb burning. For this reason lowering insulin levels is one of the secrets to life-long health.

Insulin resistance

Insulin is a hormone that is critical for the body’s use of glucose as energy. Insulin resistance (IR) is a condition in which the body’s cells become resistant to the effects of insulin. That is, the normal response to a given amount of insulin is reduced. As a result, higher levels of insulin are needed in order for insulin to do its job.
With insulin resistance, the pancreas produces more and more insulin until the pancreas can no longer produce sufficient insulin for the body’s demands, then blood sugar rises. Insulin resistance is a risk factor for development of diabetes and heart disease and polycystic ovarian syndrome (PCOS).

Insulin sensitivity

If you are insulin sensitive, your muscle and liver cells take up glucose rapidly without the need for a lot of insulin. Exercise keeps you insulin sensitive: so does a moderately high carbohydrate intake.

Ketones

Our bodies need to maintain a minimum threshold level of glucose in the blood to provide energy for our brain and central nervous system. If for some reason, glucose levels fall below this threshold, (a very rare state called hypoglycemia) the brain will make use of ketones – a by-product of the breakdown of the body’s fat stores. Ketones are strong acids, and when they are produced in large quantities they can upset the body’s delicate acid-base balance. They are normally released into the urine, but if levels are very high or if the person is dehydrated, they may begin to build up in the blood. High blood levels of ketones may cause fruity-smelling breath, loss of appetite, nausea or vomiting, and fast, deep breathing. In severe cases, it may lead to coma and death. In a pregnant woman, even a moderate amount of ketones in the blood may harm the baby and impair brain development. Large amounts of ketones in the urine may signal diabetic ketoacidosis, a dangerous condition that is caused by very high blood glucose levels.

Ketosis

The metabolic state when the body is burning fat for fuel. Normally carbohydrates are the main source of fuel for your brain, heart and many other organs.

Kilojoule or kJ

The metric system for measuring the amount of energy produced when food is completely metabolised in the body. The Calorie is the imperial measure of energy, and can be calculated from the number of kilojoules by dividing by 4.2.

Lipids or fats

These are found in the blood and the walls of all of the body’s cells. The most common lipids are cholesterol and triglycerides (sometimes called triacylglycerols).

LDL cholesterol see Cholesterol

Metabolic rate
Metabolic rate (or metabolism) refers to the amount of energy the body uses each day and is measured in kilojoules/calories.

Millimole (mmole)

A unit for measuring the concentration of glucose, cholesterol, triglycerides and other substances in a certain volume of blood – usually 1 litre (L).
Mono-unsaturated fat is found in large quantities in olive and canola oil, and some nuts and seeds. Like all fats, mono-unsaturated fats are high in kilojoules. Mono-unsaturated help lower LDL cholesterol levels and are thought to help reduce the risk of heart attack and stroke

Polycystic Ovarian Syndrome
A hormonal imbalance in the ovaries that affects fertility, physical health and emotional wellbeing.

Starches

Long chains of sugar molecules. They are called polysaccharides (poly meaning many). They are not sweet-tasting. There are two sorts – amylose and amylopectin.

  • • Amylose is a straight-chain molecule, like a string of beads. These tend to line up in rows and form tight compact clumps that are harder to gelatinise and therefore digest.
  • • Amylopectin is a string of glucose molecules with lots of branching points, such as you see in some types of seaweed. Amylopectin molecules are larger and more open and the starch is easier to gelatinise and digest.

Sugars

A type of carbohydrate. The simplest is a single-sugar molecule called a monosaccharide (mono meaning one, saccharide meaning sweet). Glucose is a monosaccharide that occurs in food (as glucose itself and as the building block of starch). If two monosaccharides are joined together, the result is a disaccharide (di meaning two). Sucrose, or common table sugar, is a disaccharide, as is lactose, the sugar in milk. As the number of monosaccharides in the chain increases, the carbohydrate becomes less sweet. Maltodextrins are oligosaccharides (oligo meaning a few) that are 5 or 6 glucose residues long and commonly used as a food ingredient. They taste only faintly sweet. Sugars found in food:

Monosaccharides (single-sugar molecules)
glucose
fructose
galactose

Disaccharides (two single-sugar molecules)
maltose = glucose + glucose
sucrose = glucose + fructose
lactose = glucose + galactose

Triglycerides also known as triacylglycerols or blood fats

Another type of fat linked with increased risk of heart disease. Having too much triglyceride often goes hand in hand with having too little HDL cholesterol. Having high levels of triglycerides can be inherited, but it’s most often associated with being overweight or obese. Normal ranges for triglycerides are 1.0–2.3 mmol/L, people with diabetes should aim to keep their triglyceride levels under 2.0 mmol/L as they are at greater risk of cardiovascular disease.

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