If you're new to the nutrition arena getting your head around all the new terminology, definitions and facts can feel daunting. To help you get up to speed quickly and make your life a bit easier, we've compiled an A-Z Fact File of the most commonly used nutritional terms and their meanings.
Use the links below to navigate between different sections of our essential glossary...
The alcohol content of drinks is measured in ‘units’. Each unit is equivalent to around 10mls or 8g of pure alcohol (ethanol). This could be: half a pint of beer/lager/cider, a pub measure of spirit or half a glass of wine.
The Department of Health advises that men and women should drink no more than 14 units of alcohol per week. It is advisable to have alcohol free days in between to allow your body to recover.
Benefits of cutting down on alcohol are:
Food intolerance is the general term used to describe a range of adverse responses to food. It includes a number of different types of reaction including food allergies (reactions that involve the body’s immune system). Most food intolerances are not true allergies, although they may cause uncomfortable or distressing symptoms.
An allergic reaction to a food can be described as an inappropriate reaction by the body's immune system to the ingestion of a food. Foods that commonly induce adverse reactions are milk, gluten-containing cereals, nuts, peanuts, eggs and shellfish.
Coeliac disease is an autoimmune disease caused by an allergic reaction to gluten. It is also triggered by related proteins in other grains (rye and barley).
Lactose intolerance is the most commonly diagnosed adverse reaction to cow's milk among adolescents and adults. Symptoms include flatulence, bloating, diarrhoea and abdominal pain.
Peanut allergy can be very severe and, in some cases, life threatening. Symptoms appear almost immediately after exposure in sensitised people.
It is important that people who think they suffer from a food allergy or other food intolerance seek professional advice from their GP before changing their diet dramatically and risking it becoming unbalanced. Dietary change prior to tests can make diagnosis more difficult, for example in the case of coeliac disease.
BMI is a method of classifying an individual’s weight. It is calculated by dividing an individual’s weight by the square of his or her height:
Weight (Kg)/height x height (metres)
The World Health Organisation (WHO) regards a BMI of less than 18.5 as underweight while a BMI greater than 25 is considered overweight and above 30 is considered obese.
A major limitation of BMI is that it looks at overall weight and does not distinguish between fat and lean tissue. This means that it overestimates adiposity in those who have a higher than normal lean body mass e.g. athletes.
A calorie is a unit of measurement for the amount of energy our body can get from food. In nutrition, calories are usually displayed in units of 1,000. 1,000 calories equals 1 Kilocalorie or 1Kcal. Many nutritionists prefer to use joules as the measurement of energy. 1 calorie equals approximately 4.18 joules (or 1Kcal equals 4.18 Kj). However, most of the general public still prefers to talk in terms of calories (Kcals).
A person's calorie intake should consist of 50-55% carbohydrates, 30-35% fat and 10-15% protein.
The average healthy male requires around 2,500Kcals per day and the average healthy female requires around 1,940Kcals per day.
Caffeine is not an essential nutrient but, like alcohol, it plays an important role in many people's eating and drinking habits. It has been estimated that at least half the world's population consumes tea while in America coffee is the biggest source of caffeine.
Although caffeine is readily accepted as an ingredient in coffee beverages (at about 100mg a cup), caffeine, or derivatives of caffeine, can also be found in many other products such as cocoa, baking chocolate and cola.
To reduce caffeine intake you could either switch to using decaffeinated versions of drinks or exclude sources of caffeine in the diet/
To reduce the undesirable effects of eliminating caffeine in one go it is often best to reduce intake gradually. It takes about 4-6 days to wash out all the effects of caffeine from your system.
Calcium is a mineral needed for strong bones and muscle contraction. Rich sources of calcium include milk, cheese, yoghurt, canned fish, dark green leafy vegetables, cereals, nuts, seeds and soya products e.g. tofu.
In vulnerable people, large intakes of calcium can lead to kidney stones. Other than this group, the risk of calcium toxicity is small.
Recommended intakes depend on age, gender and certain medical conditions. For most adults the recommended intake is 700mg/day.
Carbohydrate is a macronutrient that provides us with energy (4Kcal per gram). The two types of carbohydrate that provide dietary energy are sugars and starch. Dietary fibre is also a type of carbohydrate found in plants. One function of dietary fibre is to keep the digestive system healthy. Some studies have shown that populations with a high intake of fibre-rich foods experience a lower incidence of large bowel cancer.
At least half the energy from diet should be from carbohydrate sources (mainly starchy carbohydrates).
Food sources are breads, cereals, rice and potatoes, beans, pulses, fruits, some vegetables, milk and dairy products.
Starchy carbohydrates (breads, cereals, rice, pasta and potatoes) are an important source of carbohydrate and also tend to be rich in many other nutrients like vitamins and minerals. You should choose wholegrain varieties as this will help manage steady blood sugar levels and keep you feeling fuller for longer.
There are two main types of diabetes:
Type 1 diabetes occurs when the body produces no insulin. It is often referred to as insulin-dependent diabetes. It usually develops before the age of 40, often during teenage years. If you have type 1 diabetes you will need to take insulin injections for life. You must also ensure your blood glucose levels stay balanced by eating a healthy diet and by carrying out regular blood tests.
Type 2 diabetes occurs when not enough insulin is produced by the body or when the body’s cells do not react to insulin. This is called insulin resistance. If you have type 2 diabetes you may be able to control your symptoms simply by eating a healthy diet and monitoring your blood glucose level. However, as type 2 diabetes is a progressive condition, you may eventually need to take insulin medication, usually in the form of tablets.
General healthy eating guidelines also apply to those with diabetes. Large intakes of sugars should be avoided, although they do not need to be removed from the diet.
Essential fatty acids cannot be synthesized by the body. There are 2 essential fatty acids - omega 3 and omega 6 - which are very important because they help the cardiovascular, reproductive, immune and nervous systems to function. In particular they are involved in the manufacture and repair of cell membranes, which in turn enable the cells to obtain optimum nutrition. They are also the precursors for a group of compounds called eicosanoids.
Foods rich in omega 6 are walnuts, sunflower seeds, sunflower oil and wheatgerm. Foods rich in omega 3 are oily fish, salmon, mackerel, sardines, whitebait, herrings, linseed oil, wheatgerm, walnuts, rapeseed oil and soya beans.
There are 3 types of fat - saturated fat, unsaturated fat and trans fats. Unsaturated fat can also be broken down into monounsaturated and polyunsaturated fat.
Saturated fat is normally solid at room temperature. It is found mostly in meat and dairy products (such as whole milk, butter and cheese) as well as in coconut and palm oils.
Trans fat can be found in some margarines, many fast foods, commercially baked goods, snack foods and other foods made with or fried in partially hydrogenated oils.
Polyunsaturated fats are normally liquid at room temperature and kept in the refrigerator. They are found in certain plant oils such as safflower, sunflower and soybean.
Monounsaturated fats are normally liquid at room temperature but start to solidify at refrigerator temperatures. They are found in oils such as olive oil, rapeseed oil and sesame oil. Monounsaturated fats are preferable for cooking.
Saturated and trans fats are considered to be bad for you because they raise blood cholesterol levels and are therefore linked to heart disease.
All types of fat provide 9Kcal per gram and are therefore twice as energy dense as carbohydrate and protein. Fat should provide no more than 30-35% of our energy intake.
High cholesterol levels are associated with increased risk of heart disease and stroke. Reducing saturated fat intake, increasing fibre intake and being more active can all help reduce blood cholesterol levels.
Iodine helps make the thyroid hormones which control the body’s metabolic rate.Iodine is a trace element found in seawater and some types of soil. Good food sources include sea fish and shellfish. Plant foods can also be a good source, depending on the iodine content of the soil. Adults need 0.14mg of iodine a day.
Dietary iron is found in two forms - haem iron (from animal sources) and non-haem iron (from plant sources). Haem iron is the most bioavailable form of iron. The main food sources are red meat, liver, offal, fortified cereals, shellfish, wholegrain breads, pasta and cereal, pulses and green leafy vegetables. Vitamin C will enhance iron absorption. Iron is involved in red blood cell formation, oxygen transport and utilisation.
A lack of dietary iron may result in iron deficiency anaemia. Loss of blood due to injury or large menstrual losses increases iron requirements in the short-term. The recommended intake is 8.7mg/day for men and 14.8mg/day for women.
A macronutrient is a nutrient that the body needs in relatively large quantities and they form the major part of our diet. The three macronutrients are carbohydrate, fat and protein.
Magnesium is a mineral that helps with energy production. It is also needed for healthy bones and teeth and proper nervous system functioning. Magnesium is found in a wide variety of foods including green leafy vegetables, nuts, brown rice, fish, meat and dairy foods.
The amount of magnesium you need is:
A micronutrient is a nutrient that the body needs in small quantities. Vitamins and minerals are both micronutrients.
Potassium is a mineral that works with sodium in the body to control fluid balance. Potassium is found in most foods but bananas, vegetables, pulses and nuts are particularly good sources. Adults need roughly 3,500mg of potassium a day.
Protein is essential for growth and repair of the body and maintenance of good health. It also provides energy (4Kcal per gram). The amount of protein we need changes during a lifetime. Protein should provide the body with approximately 10-15% of its dietary energy.
Different foods contain different amounts and combinations of amino acids (the building blocks of proteins). Protein from animal sources (e.g. meat, fish, eggs and dairy products) contains the full range of essential amino acids needed by the body. There are also non-animal sources of protein such as pulses and cereals.
The reference Nutrient intake is the amount of a nutrient that is sufficient to meet the needs of 97.5% of the population.
Selenium is an essential mineral and micronutrient. It functions as an antioxidant (involved within the glutathione peroxidise system) helping to protect against heart disease and some cancers. Good sources are meat, fish, brazil nuts, eggs and grains.
The amount of selenium you need is:
Low calorie sweeteners provide a sweet taste to food or drinks with the benefit of little or no calories. They can be added to foods or drinks (in tea, coffee or baking) and are used in many low calorie and sugar-free foods and beverages such as soft drinks, chewing gum, confectionery, frozen desserts, dessert mixes, yoghurts and puddings.
In the EU, all low calorie sweeteners must undergo thorough safety testing before being approved by the European Commission. Food manufactures also have to provide evidence that the sweetener they use in their food does not have any adverse effects.
Examples of commonly used sweeteners include sucralose, saccharin and aspartame.
A diet that is high in salt can cause raised blood pressure. 75% of the salt we eat is already in everyday foods such as bread, breakfast cereal and ready meals.
Nutrition labels on food packaging will show the amount of salt in food. A food is considered high in salt if it contains more than 1.5g salt per 100g (or 0.6g sodium).
Some foods high in salt are anchovies, bacon, cheese, gravy granules, ham, olives, pickles, prawns, salami, salted and dry roasted nuts, salt fish, smoked meat and fish, soy sauce, stock cubes and yeast extract.
Adults should eat no more than 6g of salt a day - that's around one full teaspoon.
Vitamin A is a fat soluble vitamin. It is found in two forms - vitamin A (retinol) and provitamin A (beta-carotene).
Food sources for provitamin A are brightly coloured fruit and vegetables such as apricots, mangoes, peppers, tomatoes, carrots, spinach and green vegetables such as broccoli.
Food sources for retinol are liver, cheese, oily fish, eggs, butter and margarine.
If you are pregnant or planning to get pregnant, do not eat liver or liver products (e.g. pate), as they contain high levels of vitamin A and may harm the unborn baby.
In general, the amount of vitamin A adults need is:
Also known as thiamin, this is a water soluble vitamin. Main sources of vitamin B1 are wholegrain cereals, wholemeal breads, liver, kidneys, red meat and pulses. The recommended nutrient intake is 0.4mg/1,000Kcals for men and women. Deficiency will result in loss of appetite and energy, beri-beri and pain in the calf muscles. Excess intake of thiamin will not result in any toxic effects as the excess will be excreted in the urine.
Vitamin B6 is a water soluble vitamin, essential for the formation of red blood cells and the metabolism and transport of iron. Together with folate and vitamin B12, vitamin B6 is required for maintenance of normal blood homocysteine levels. Raised homocysteine is a risk factor for cardiovascular disease. It also promotes carbohydrate, fat and protein metabolism, promotes healthy skin and hair formation. Food sources are poultry, white fish, milk, eggs, whole grains, soya beans, peanuts and some vegetables.
The Department of Health advices that you should be able to get all the vitamin B6 you need by maintaining a balanced diet. Do not take more than 10mg of vitamin B6 a day in supplements.
Toxicity may result in loss of nerve sensation and unusual gait (walking stride). Deficiency will result in irritability, convulsions and aneamia.
The recommended intake of vitamin B6 is 1.4mg/day for men and 1.2mg/day for women.
This is a water soluble vitamin. Main food sources are meat, fish, shell fish, poultry, liver, eggs, dairy products, yeast extract and fortified breakfast cereals, soya proteins and milk.
A lack of vitamin B12 could lead to vitamin B12 deficiency anaemia. It is involved in fat, protein and carbohydrate metabolism and the formation of red and white blood cells. It is also required for normal growth and development of nerve, gut and skin tissues. Recommended nutrient intake for men and women is 1.5mg/day.
Folic acid is the synthetic form of folate and is a water soluble B vitamin. It is used in supplements and for food fortification.
There is conclusive evidence that supplements of 400μg/day of folic acid taken before conception and during the first 12 weeks of pregnancy prevent the majority of neural tube defects (e.g. spina bifida) in babies. Therefore, it is recommended that all women of childbearing age who are planning a pregnancy take a daily supplement as it is difficult to achieve 400μg/day from diet alone.
Main food sources of folate are liver, meat, green vegetables (e.g. sprouts), yeast extract, pulses and fruit. In various parts of the world such as the USA, Canada and Chile, folic acid is added by law to flour and bread. The UK is still considering this fortification as there are concerns that high intakes of folic acid may mask vitamin B12 deficiency in older people.
A water soluble vitamin. Vitamin C has antioxidant properties, potentially protecting cells from oxidative damage caused by free radicals. Vitamin C is also involved in the synthesis of collagen. This is required for the normal structure and function of connective tissues (skin, cartilage and bones). It is also involved in the normal structure and function of blood vessels and neurological function. Vitamin C increases the absorption of non-haem iron (iron from plant sources) in the gut. Main food sources are fresh fruit (especially citrus fruits), green leafy vegetables, broccoli, potatoes, peppers, tomatoes, berries and currants.
Deficiency will result in weakness, slow wound healing, infections, bleeding gums and anaemia.
The recommended intake to avoid deficiency is 40mg per day.
Dietary vitamin D exists as either ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3). Dietary sources are relatively insignificant compared with the synthesis in the skin from exposure to sunlight or ultraviolet rays, because there are not many rich food sources of vitamin D.
Vitamin D is a fat soluble vitamin. Main food sources are liver, oily fish, eggs, fortified dairy products, cereals and margarine. Vitamin D increases calcium absorption from the intestine and promotes and helps regulate bone formation. Lack of vitamin D will result in rickets in children and osteomalacia in adults.
It is recommended that pregnant and lactating women and people aged 65 years and over take vitamin D supplements (10µg per day). For other ‘at risk’ groups, for example ethnic groups that have limited sun exposure because of their style of dress, supplements may also be necessary. Infants are recommended to receive supplements containing 7-8.5µg of vitamin D.
Vitamin K is a fat-soluble vitamin. It is an essential component in the body’s normal blood clotting process. The main food sources are dark green leafy vegetables (such as cabbage, sprouts, cauliflower and spinach). Besides getting vitamin K from food, we also get it from our own bodies as it is produced by bacteria in the bowel. Anybody who undergoes a long course of treatment with antibiotics is at risk of a vitamin K deficiency as the antibiotics will kill off the gut flora, thus putting them at risk.
The dietary reference value for vitamin K is between 0.5-1.0µg/kg/day.
When the number of calories consumed through food equals the calories the body expends (through normal physiological processes and physical activity) body weight will remain the same.
If weight loss is desired the calories consumed must be less than the calories expended. A calorie shortage of 500 Kcal per day will produce roughly 1lb of weight loss per week.
Even a small calorie excess can eventually cause weight gain. A surplus 100Kcal per day (such as 1 biscuit) over a year would lead to weight gain of about 10lb.
Zinc is a trace element that has several important functions in the body including cell reproduction. It is also involved in the metabolism of carbohydrates, fats and protein and helps with the healing of wounds.
Good food sources of zinc include meat, shellfish, dairy foods and cereals. The amount of zinc you need is about:
4-7mg a day for women