Carbohydrates

5/12/2010

What are carbohydrates food?

• Carbohydrates are the main source of energy for the body.

• Those carbohydrates come from the plant-based foods that we eat.

• We can either use carbohydrates right away for your energy needs or your body can convert them into fat to use later.

• There are three types of carbohydrates: - sugars, starches and fiber.

Chemistry of carbohydrate

• No matter how big they are, all carbohydrates are made of carbon, hydrogen and oxygen with the general formula of Cm(H2O)n.

• Or The empirical or simplest formula of any carbohydrate is (CH2O)n.

• This formula looks like carbon water just as carbohydrate suggests hydrated or watered carbon.

• The formula tells us that all carbohydrates are made of carbon, hydrogen, and oxygen atoms in a 1:2:1 ratio.

For example, a simple little sugar molecule like glucose is made up of six carbon atoms, 12 hydrogen atoms and 6 oxygen atoms. It is shaped like a hexagon and has the formula C6(H2O)6.

D-glucose

• A large starch molecule can be made of many little sugar molecules attached together, which forms a long chain.

• The little m and n in our general formula, Cm(H2O)n, can run into the hundreds.

D-glucose

Simple sugars • are little molecules made up of

one or two sugar units.

• In nutrition, the most basic simple sugar is glucose, C6(H2O)6, and it is the type of sugar our bodies and brains use for energy every day.

• Glucose is called a monosaccharide, which means "single sugar.“.

• Other monosaccharides include fructose, galactose, and ribose.

• Fructose is found in fruits and in vegetables.

• Galactose is found in milk and

• Ribose is best known as a component in ribonucleic acid, which is a part of genetic transcription and is found in the cells in our bodies.

fructose

• it is important to know that the single sugars glucose, fructose and galactose can form different combinations to become disaccharides, a term that means "two sugars." These sugars include:

• Lactose (milk sugar) .

• Sucrose (table sugar).

• Maltose (malt sugar).

• Lactose (milk sugar) is made up of glucose and galactose molecules. People who are "lactose intolerant" can't digest this sugar properly.

• sucrose:- • is comprised of glucose and fructose molecules. • This is the white powdery or granular substance we typically refer to as "sugar" when we are cooking or baking.

• Maltose (malt sugar) is produced during the malting of cereals such as barley.

• An average healthy diet should have half of your daily calories coming from carbohydrates.

• One gram of carbohydrate, whether is it is sugar or starch, contains 4 calories. One slice of bread has about 12 -15 grams of carbohydrates.

• One typical chocolate bar may have about 50 grams of carbohydrates.

• A medium potato has about 35 grams of carbohydrates.

• Simple sugars are water-soluble and sucrose, or table sugar, is easy to digest.

• The individual glucose and fructose molecules are quickly absorbed into the bloodstream via the small intestine.

• This can be a problem for people with diabetes or metabolic syndrome who have to watch their blood sugar, or blood glucose levels.

Chemistry of carbohydrate

• No matter how big they are, all carbohydrates are made of carbon, hydrogen and oxygen with the general formula of Cm(H2O)n.

• Or The empirical or simplest formula of any carbohydrate is (CH2O)n.

• This formula looks like carbon water just as carbohydrate suggests hydrated or watered carbon.

• The formula tells us that all carbohydrates are made of carbon, hydrogen, and oxygen atoms in a 1:2:1 ratio.

Sumary

• Carbohydrates consist of the elements carbon (C), hydrogen (H) and oxygen (O) with a ratio of hydrogen twice that of carbon and oxygen.

• Carbohydrates include sugars, starches, cellulose and many other compounds found in living organisms.

• In their basic form, carbohydrates are simple sugars or monosaccharides.

• These simple sugars can combine with each other to form more complex carbohydrates.

• The combination of two simple sugars is a disaccharide. • Carbohydrates consisting of two to ten simple sugars are

called oligosaccharides, • and those with a larger number are called polysaccharides.

• These simple sugars can combine with each other to form more complex carbohydrates.

• The combination of two simple sugars is a disaccharide.

• Carbohydrates consisting of two to ten simple sugars are called oligosaccharides,( Oligo = Few) (2- 10 C)

• and those with a larger number are called polysaccharides

Sugars

• Sugars are white crystalline carbohydrates that are soluble in water and generally have a sweet taste.

• Monosaccharides are simple sugars

• Many saccharide structures differ only in the orientation of the hydroxyl groups (-OH).

• This slight structural difference makes a big difference in the biochemical properties, organoleptic properties (e.g., taste), and in the physical properties such as melting point and Specific Rotation (how polarized light is distorted).

• A chain form monosaccharides that has a carbonyl group (c=o) on an end carbon forming an aldehyde group (-CHO) is classified as an aldos

• When the Carbonyl group is on an inner atom forming a ketone , is called as a ketenes

Formaldehyde, the simplest aldehyde

An aldehyde. R is the group attached to the blue aldehyde

group

ketenes

• Physical Properties of sucrose (table sugar). It is a simple sugar (although not a monosaccharide). Monosaccharides and other smaller sugars have the following properties in common with sucrose:

1. They are colorless crystalline solids. They usually appear white.

2. They are soluble in water (why?), only slightly soluble in ethanol and insoluble in nonpolar compounds.

3. They taste sweet. However, each sugar has its own distinct flavor.

4. Most are optically active نشطة ضوئيا

• Sugar contains 4carbons is called =tetroses

• Sugar contains 5 carbons is called =pentoses

• Sugar contains 6carbons is called =hexoses

• Sugar contains 7carbons is called =heptoses

Monosaccharide classifications based on the number of carbons

Tetroses

D-Erythrose D-Threose

Pentose

D-Xylose

D-Ribose D-Arabinose

D-Lyxose

• The ring form of ribose is a component of ribonucleic acid (RNA).

• Deoxyribose, which is missing an oxygen at position 2, is a component of deoxyribonucleic acid (DNA)

• In nucleic acids, the hydroxyl group attached to carbon number 1 is replaced with nucleotide bases.

Ribose

Deoxyribose

Hexoses

• Hexoses, such as the ones illustrated here, have the molecular formula C6H12O6.

D-Allose D-Altrose D-Glucose D-Mannose

D-Idose D-Galactose D-Talose

• Structures that have opposite configurations of a hydroxyl group at only one position, such as glucose and mannose, are called epimers.

• Glucose, also called dextrose, is the most widely distributed sugar in the plant and animal kingdoms and it is the sugar present in blood as "blood sugar".

D-Tagatose(a ketose) D-Fructose

Fructose

Galactose

Mannose

• The chain form of glucose is a polyhydric aldehyde, meaning that it has multiple hydroxyl groups and an aldehyde group.

• Fructose, also called levulose or "fruit sugar", is shown here in the chain and ring forms.

• Fructose and glucose are the main carbohydrate constituents of honey.

D-Fructose

Fructose

Heptoses

• Sedoheptulose has the same structure as fructose, but it has one extra carbon.

Sedoheptulose

Chain and Ring forms • Many simple

sugars can exist in a chain form or a ring form, as illustrated by the hexoses above.

• The ring form is favored in aqueous solutions, and the mechanism of ring formation is similar for most sugars.

• The glucose ring form is created when the oxygen on carbon number 5 links with the carbon comprising the carbonyl group (carbon number 1) and transfers its hydrogen to the carbonyl oxygen to create a hydroxyl group.

• The rearrangement produces alpha glucose when the hydroxyl group is on the opposite side of the -CH2OH group

• or beta glucose when the hydroxyl group is on the same side as the -CH2OH group. Isomers, such as these, which differ only in their configuration about their carbonyl carbon atom are called anomers.

• The little D in the name derives from the fact that natural glucose is dextrorotary, i.e., it rotates polarized light to the right

• Those forming six-sided rings, like glucose, are called pyranoses.

Stereochemistry • Saccharides with identical functional groups but

with different spatial configurations have different chemical and biological properties.

• Stereochemistry is the study of the arrangement of atoms in three-dimensional space.

• Stereoisomers are compounds in which the atoms are linked in the same order but differ in their spatial arrangement.

• Compounds that are mirror images of each other but are not identical, comparable to left and right shoes, are called enantiomers.

Sugar Alcohols, Amino Sugars, and Uronic Acids

• Sugars may be modified by natural or laboratory processes into compounds that retain the basic configuration of saccharides, but have different functional groups.

• Sugar alcohols, also known as polyols, polyhydric alcohols, or polyalcohols, are the hydrogenated forms of the aldoses or ketoses.

• For example, glucitol, also known as sorbitol, has the same linear structure as the chain form of glucose, but the aldehyde (-CHO) group is replaced with a -CH2OH group.

• Other common sugar alcohols include the monosaccharides erythritol and xylitol and the disaccharides lactitol and maltitol.

• Sugar alcohols have about half the calories of sugars and are frequently used in low-calorie or "sugar-free" products.

• Xylitol, which has the hydroxyl groups oriented like xylose, is a very common ingredient in "sugar-free" candies and gums because it is approximately as sweet as sucrose, but contains 40% less food energy.

• Although this sugar alcohol appears to be safe for humans, xylitol in relatively small doses can cause seizures, liver failure, and death in dogs.

Amino sugars

• or aminosaccharides replace a hydroxyl group with an amino (-NH2) group. Glucosamine is an amino sugar used to treat cartilage damage and reduce the pain and progression of arthritis.

Uronic acids • have a carboxyl group (-

COOH) on the carbon that is not part of the ring. Their names retain the root of the monosaccharides, but the -ose sugar suffix is changed to -uronic acid. For example, galacturonic acid has the same configuration as galactose, and the structure of glucuronic acid corresponds to glucose

• Sugar and Cotton are Carbohydrates

Obesity and metabolic syndrome

ترتبط كل من زيادة الوزن والسمنة بظاهرة مقاومة •

الجسم لألنسولين التي سوف تسبب في عوامل

Cluster risk factorsالمخاطر العنقودية لمرض القلب of cardio- vascular المعروفة باسم

metabolic syndrome أو((syndrome X والتي

:تسبب األمراض التالية

.Heart attackالنوبة القلبية 1.

. Strokeالسكتة الدماغية 2.

البطن حول الدهون من عالية كمية•

.مل 100 / ملجم 110 من أعلى الدم سكر تركيز•

.مل 100 / ملجم 150 من أعلى الثالثية جليسيرات•

/ ملجم 40 من أقل الدم في الكثافة عالي الدهني البروتين•

.مل 100

.أعلى أو 85 / 130 الدم ضغط•

المبيض متالزمة المتالزمة هذه تسبب•

Polycystic Ovarian Syndrome

-:التالية المشاكل للمرأة المبيض متالزمة وتسبب•

.الشهرية العادة إختفاء1.

.العفم2.

.الجلدية أمراض3.

.والجسم الوجه في للشعر غزير نمو4.

.الرأس شعر فقد5.

.(2) السكري وداء (2)السكري بداء األصابة قبل ما حالة6.

Complex Carbohydrates

• Complex carbohydrates are long chains of the single sugar units.

• For example, the complex carbohydrate we know as starch is made up of many glucose units.

• These complex carbohydrates can be in the shape of long chains, or the chains can form branches.

• The complex carbohydrates include:

• Starch, the energy storage form of carbohydrates found in plants, especially in the seeds and roots.

• Starch is made up of many glucose units linked together.

• Starchy food examples include rice, wheat, corn, carrots and potatoes.

• Starches are not water-soluble and require digestive enzymes called amylases to break them apart.

The basic chemical formula of the starch molecule is (C6H10O5)n. Starch is a polysaccharide comprising glucose monomers joined in a 1,4 linkages. The simplest form of starch is the linear polymer amylose.

• Glycogen, the energy storage form of glucose found in the muscles and livers of animals.

• We don't consume any carbohydrates when you eat meats; however, the amount of glycogen in animal tissue at the time of slaughter does affect the pH of meat.

• Cellulose, the structural component of plants.

• Cellulose helps plants keep their shape; so, cellulose acts like a plant skeleton.

• We are unable to digest cellulose; however cellulose is one of the important components of fiber, along with lignin, chitin, pectin, beta- glucan , inulin and oligosaccharides.

• Dietary starch and cellulose are the complex carbohydrates that are important in nutrition.

• Potatoes, dry beans, grains, rice, corn, squash and peas contain a large amounts of starch.

• Vegetables like broccoli, cauliflower, asparagus, lettuces and other greens are not starchy.

• Carbohydrates and Metabolism • The body begins the process of breaking

carbohydrates down into their individual monosaccharides almost before we start to eat them.

• When you smell the delicious aroma of fresh-baked bread or think about that tasty chocolate that you're about to consume, your mouth begins to water.

• Since table sugar is water-soluble, it begins to dissolve in the saliva in mouth.

• Saliva also contains a small amount of amylase, which is an enzyme that starts to break starch down into glucose while you are chewing.

• Carbohydrate digestion is continued in the small intestine where pancreatic amylase is secreted, which breaks down the rest of the carbohydrates.

• The individual monosaccharides are then absorbed into the blood stream.

• Once in the blood, the monosaccharides are either used for energy, stored in the liver and muscles as glycogen, or if there is more energy available than you can use, they are converted and stored as fat.

• The storage of glucose is triggered by insulin, which forces the body to store any extra blood sugar as glycogen.

• People with diabetes or metabolic syndrome either can't produce enough insulin or they are not sensitive enough to the insulin they produce and need to regulate their blood sugar with medications, insulin or dietary changes.

• Body prefers to use glucose as the main source of fuel for daily activity.

• Muscles need glucose to move and organs need glucose to function, including your brain.

• While the body can make glucose from extra dietary protein and fats you may eat, it is suggested that half of your daily calories come from carbohydrates.

• Try to get carbohydrates from healthy sources such as whole grains, fruits and vegetables.

• Cookies, sodas, candy and other sweets are not so healthy

• An average healthy diet should have half of your daily calories coming from carbohydrates.

• One gram of carbohydrate, whether is it is sugar or starch, contains four calories.

• One slice of bread has about 12 -15 grams of carbohydrates.

• One typical chocolate bar may have about 50 grams of carbohydrates.

• A medium potato has about 35 grams of carbohydrates.

• Although all carbohydrates have 4 calories per gram, some sources of carbohydrates are better for your diet than others.

• Fruits, vegetables, legumes, nuts, seeds and grains are healthier than candy, sodas and pastries.

• Why? The healthy carbohydrate sources have great amounts of vitamins, minerals, Phytochemicals and fiber, all of which are vital to good health.

• Candy, sodas, pastries and other junk foods usually are poor sources of nutrients and sometimes we refer to these foods as having "empty calories.“

• This means the foods have lots of calories with little or no nutrition.

• Since you need half of your calories from carbohydrates, you can calculate how many you need per day.

• For example, let's say a person needs 2,000 calories per day. That means that 1,000 calories should come from carbohydrates (2,000 X 0.5).

• Since each gram of carbohydrate has 4 calories, then you divide 1,000 by four (1,000/4) to get 250.

• A person who needs 2,000 calories each day needs about 250 grams of carbohydrates per day.

• Of those 250 grams, about 10 percent can come from added table sugar and sweeteners.

• That would be about 25 grams for a 2,000 calorie per day diet.

• That would equal about half of a candy bar, or less than one can of sugary soda.

• Unfortunately many people exceed that amount every day.

• In order to meet your carbohydrate requirement each day, you need to know how many carbohydrates are in all of the foods you eat.

• It really is impossible to list every carbohydrate containing food here, however, here are some approximate amounts from common examples:

• One slice of bread - 12.5 grams total, of which 10 grams are starch and less than one gram is fiber.

• One cup of pasta - 43 grams total, of which 36 grams are starch and 2.5 grams are fiber.

• One medium apple - 19 grams total, of which eight grams are starch and three grams are fiber

• One Snickers candy bar - 63.5 total grams, of which 53 grams are sugar, two grams are fiber.

• One cup of raisin bran cereal - 43 grams total, of which seven grams are fiber, 17 grams are starch and 16 grams are sugar .

• One cup of sugar frosted corn flake cereal - 28 grams total, of which 15 grams are starch, one gram is fiber, 12 grams are sugar.

• 240 ml serving of low fat milk - 12 grams total, of which 12 grams are lactose .

• One cup broccoli - six grams total, of which 2.5 grams are fiber and 1.5 grams are sugar.

• One cup green beans - eight grams total, of which four grams are fiber

• One cup sweet corn - 31 grams total, of which 21 grams are starch, three grams are fiber

• Two cups lettuce - two grams total, of which one gram is fiber

• One cup asparagus - four grams total, of which two grams are fiber

• One medium orange - 15 grams total, of which three grams are fiber

• One half medium grapefruit - nine grams total, of which 1.5 grams are fiber

• One medium chocolate chip cookie - 16 grams total, of which seven grams are sugar

• One cup strawberries - 12 grams total, of which three grams are fiber

• One cup blueberries - 21 grams total, of which four grams are fiber and 15 grams are sugar

• One medium tomato - five grams total, of which 1.5 grams are fiber

• One medium potato with skin - 29 grams total, of which three grams are fiber, 25 grams are starch

• One cup carrots - 12 grams total, of which 3.5 grams are fiber and two grams are starch

• One slice of an apple pie - 40 grams total, of which 18 grams are sugar

• One cup of orange juice - 26 grams total, of which 21 grams are from fruit sugars

• One cup of dry beans like pinto beans or navy beans - 47 grams total, of which 19 grams are fiber, 28 grams are starch

The Importance Of Carbohydrates

Carbohydrates take the form of sugars, oligosaccharides, starches and fibres and are one of the three major macro-nutrients which supply the body with energy (fat and protein being the others). There is now good evidence that at least 55% of our daily calories should come from carbohydrates(1).

Whereas it is important to maintain an appropriate balance between calorie intake and expenditure, scientific studies suggest that:

• A diet containing an optimum level of carbohydrates may help prevent body fat accumulation

• Starch and sugars provide readily accessible fuel for physical performance

• Dietary fiber, which is a carbohydrate, helps keep the bowel functioning correctly

• Apart from the direct benefits of carbohydrates for the body, they are found in a wide range of foods which themselves bring a variety of other important nutrients to the diet. For this reason it is recommended that carbohydrates be supplied from diverse food sources to ensure that the overall diet contains adequate nutrients

• It is also important to remember that carbohydrates contribute to the taste, texture and appearance of foods and help to make the diet more varied and enjoyable.

Sugars

• Glucose and fructose are simple sugars or monosaccharides and can be found in fruits, berries, vegetables and honey.

• When two simple sugars combine, they form disaccharides.

• Table sugar or sucrose is a combination of glucose and fructose and occurs naturally both in sugar beet, sugar cane and fruits.

• Lactose is the main sugar in milk and dairy products and maltose is a disaccharide occurring in malt

• Polyols are so-called sugar alcohols. They do occur naturally but most are made commercially by the transformation of sugars.

• Isomalt is the most commonly used polyol and is derived from sucrose. Polyols are sweet and can be used in foods in a similar way to sugars although they can have a laxative effect when eaten in large quantities

Oligosaccharides

• When 3 to 9 sugar units combine they form oligosaccharides.

• Maltodextrins contain up to 9 glucose units and are produced commercially by the partial hydrolysis (or breakdown) of starch.

• They are less sweet than mono- or disaccharides.

• Raffinose, stachyose and fructo-oligosaccharides are found only in small amounts in certain pulses, grains and vegetables.

Polysaccharides

More than 10 and sometimes even up to several thousand sugar units are needed to form polysaccharides.

Starch is the main energy reserve in root vegetables and cereals.

It comprises long chains of glucose and occurs as granules whose size and shape vary according to the plant in which it is contained.

• Non-starch polysaccharides are the main components of dietary fiber.

• They include; cellulose, hemicelluloses, pectins and gums.

• Cellulose is the major component of plant cell walls and consists of several thousand glucose units.

• The separate components of dietary fibber have different physical structures and properties.

Carbohydrates In The Body

The main function of carbohydrates is to provide energy, but they also play an important role in the structure and function of the body organs and nerve cells

• Energy source and storage • Starches and sugars are the main energy-

providing carbohydrate sources and supply 4 kilocalories (17 kilojoules) per gram.

• To utilize this energy all carbohydrates need to be broken down to glucose after which they are transported to their place of use.

• Disaccharides are broken down by digestive enzymes into simple sugars.

• The body also needs the help of digestive enzymes to break down the long chains of starches into their constituent sugars, which are then absorbed into the bloodstream.

• Glucose can also be converted to glycogen, a polysaccharide similar to starch, which is stored in the liver and the muscles and is a readily available source of energy for the body.

• The brain needs to use glucose as an energy source, since it cannot use fat for this purpose.

• It is for this reason that the level of glucose in the blood must be constantly maintained above the minimum level.

• Glucose may come directly from dietary carbohydrates or from glycogen stores.

• Several hormones, including insulin, work rapidly to regulate the flow of glucose to and from the blood to keep it at a steady level.

The glycaemic index (GI)

• When a carbohydrate food is eaten there is a corresponding rise and subsequent decrease in blood glucose level known as the glycaemic response.

• This response is relevant, for example, to appetite control, sports nutrition and those with diabetes.

• A number of factors influence the rate and duration of the glycaemic response. It depends on:

1. The specific food:

• The nature and the form of the carbohydrate as some are more digestible than others The cooking and processing methods used which can change the digestibility. Other nutrients in the food such as fat or protein that can slow the digestion rate.

2. The individual person:

• their metabolism

• the time of day the carbohydrate is ingested

• The impact of different carbohydrate-containing foods on the glycaemic response of the body is classified according to a standardized amount of glucose.

• This measurement is called the glycaemic index, (GI).

Gut function and dietary fiber • The body is unable to digest dietary fibre and

some oligosaccharides in the small intestine.

• Fibre helps to ensure good gut function by increasing the physical bulk in the bowel and stimulating the intestinal transit.

• Once the indigestible carbohydrate passes into the large intestine, some types of fiber such as gums and pectins and the oligosaccharides are fermented (broken down) by the gut microflora.

• This also increases the overall mass in the bowel and has a beneficial effect on the make up of this microflora.

Body Weight Regulation

• People eating a diet high in carbohydrates are less likely to accumulate body fat compared with those who follow a low carbohydrate/high-fat diet.

• The reasons for this observation are threefold: It could be due to the lower energy density of high carbohydrate diets, as carbohydrates have less calories weight for weight than fats. Fiber-rich foods also tend to be bulky and physically filling therefore less calories may be consumed.

• Studies have found that carbohydrates, both in the form of starch and sugars, work quickly to aid satiety and that those consuming high carbohydrate diets are therefore less likely to overeat.

• The inclusion of plenty of carbohydrate rich foods appears to help regulate the appetite.

• Many foods with a lower glycaemic index may be particularly satisfying as they are slowly.

• It has also been confirmed that very little dietary carbohydrate is converted to body fat mainly because it is a very inefficient process for the body.

• Instead carbohydrate tends to be preferentially used an energy by the body

• It is increasingly evident that diets high in carbohydrate, as compared with those high in fat, reduce the likelihood of developing obesity.

• Starch and sugars have not been found to have different effects on weight control.

• In fact, in several studies, high sugar consumers have been found to be slimmer than low sugar consumers.

Diabetes

• Diabetes is a metabolic disorder whereby the body cannot regulate blood glucose levels properly.

• There is no evidence that sugar consumption is linked to the development of any type of diabetes.

• However there is now good evidence that obesity and physical inactivity increase the likelihood of developing non-insulin dependent diabetes, which usually occurs in middle age

• Weight reduction is usually necessary and is the primary dietary aim for people with non-insulin dependent (Type II) diabetes.

• Consuming a wide range of carbohydrate foods is an acceptable part of the diet of all diabetics, and the inclusion of low glycaemic index foods is beneficial as they help regulate blood glucose control.

• Most recommendations for the dietary management of diabetes allow a modest amount of ordinary sugar as the inclusion of sugar with a meal has little impact on either blood glucose or insulin concentrations in people with diabetes.

Dental Health

• The incidence of tooth decay is influenced by a number of factors.

• These include: degree of oral hygiene and plaque removal carried out,

• availability of fluoride,

• type of food eaten,

• frequency of consumption of any fermentable carbohydrate

• genetic factors

• Foods containing sugars or starch can be broken down by the enzymes and bacteria in the mouth to produce acid which attacks the enamel of the teeth.

• However it is not the amount of sugar or other carbohydrate that is important but how often they are consumed.

• After an acid challenge, saliva provides a natural repair process which rebuilds the enamel.

• When carbohydrate-containing foods are consumed too frequently, or nibbled over time, this natural repair process is overwhelmed and the risk of tooth decay is increased

• However in recent years the availability of fluoride and the widespread use of good oral hygiene practices have been widely heralded as responsible for the low rate of tooth decay in today's children and adolescents.

• This improvement has happened independent of any change in sugar or fermentable carbohydrate intake.

• Keeping plaque bacteria at bay and strengthening the teeth with fluoride reduces the risk of decay.

• The research now available in the 1990's allows a more rational approach to the role of sugar and other carbohydrates in dental caries.

• It is now recommended that programmes to prevent dental caries focus on fluoridation, adequate oral hygiene and a varied diet, and not on sugar intake alone.

Getting Active

• There is now substantial evidence that carbohydrates can improve the performance of athletes.

• During high intensity exercise, carbohydrates are the main fuel for the muscles.

• By consuming high levels of carbohydrate before, during and after training or an event, glycogen stores are kept well stocked.

• These stocks help the athlete to perform for longer and help their bodies sustain the effort.

• The vital role of physical activity in maintaining health and fitness in the general population is now recognized.

• There is no doubt that many people would benefit from increasing their activity level as it helps in the regulation of body weight.

• It also reduces the risk of developing diseases such as heart disease and diabetes.

• For those who want to keep fit and active, a well-balanced high-carbohydrate diet is recommended.

Carbohydrate Recommendation • Carbohydrates in all shapes and forms are good for

your health.

• They can help to control body weight, especially when combined with exercise, are vital for proper gut function and are an important fuel for the brain and active muscles.

• Neither starch nor sugar have been found to have any special role in the development of serious diseases such as diabetes, and the role of sugar in the development of tooth decay is less important in today's fluoride and oral hygiene aware populations.

• The recent report from the World Health Organization and the Food and Agriculture Organization of the United Nations on Carbohydrates in Human Nutrition makes many recommendations for health professionals and research scientists, but the most important messages for the public are:

• the most important messages for the public are:

1. That the many health benefits of dietary carbohydrates should be recognized and promoted. Carbohydrates provide more than energy alone.

2. An optimum diet contains at least 55% of energy from carbohydrates for all those over two years of age.

3. A wide range of carbohydrate-containing foods should be consumed so that the diet is sufficient in essential nutrients and dietary fiber.

References

• WHO/FAO (1998) Carbohydrates in human nutrition. FAO food and nutrition paper no. 66. FAO, Rome. Foster-Powell, K., Brand

• Miller, J. (1995), International tables of glycaemic index. American Journal of Clinical Nutrition. 62: 871S-93S. Hellerstein, M.K.,

• Christiansen, M., Kaempfer, S. et al (1991). Measurement of de novo hepatic lipogenesis in humans using stable isotopes. J. Clin.

• Invest. 87: 1841-1852. World Health Organisation (1998) Obesity - preventing and managing the global epidemic. Report of the WHO consultation on obesity. Geneva, June 97. Bolton-Smith C & Woodward

• M (1994). Dietary composition and fat to sugar ratios in relation to obesity. Int J Obesity 18;820-828. US Department of Health and Human

• Services (1996). Physical activity and health: a report of the Surgeon General, Atlanta, Georgia, USA. 7. Fejershov O. Concepts of dental caries and their consequences for understanding the disease. Community Dent. Oral Epidemiol. 1997; 25: 5-12.

Further Reading

• Dietary Starches and Sugars in Man: A comparison (1989). Edited by J. Dobbing, ILSI Human Nutrition Review series.

• ILSI Europe Concise Monographs Series: Nutritional and Health Aspects of Sugars: Evaluation of New Findings (1995).

• ILSI Europe Concise Monographs Series: Caries Preventative Strategies (1995).