Carbohydrates

1. Monosaccharides

   1. Hexose: Glucose (energy), Fructose, galactose

   2. Pentose: Ribose, Xylose

2. Disaccharides

   1. Two Monosaccharides linked together

   2. Sucrose: Glucose + Fructose

   3. Lactose: Glucose + Galactose

   4. Maltose: Glucose + Glucose

3. Oligosaccharides

   1. chains of a few monosaccharides linked together

   2. e.g. fructo-oligosacchairdes (FOS) => 6-7 fructose molecules linked together => in many vegetables

      1. promote growth of beneficial bacteria in large intestine

      2. considered as a type of soluble dietary fiber

MONO- DI- and OLIGOSACCHARIDES are SIMPLE SUGARS!!

1. Polysaccharides

   1. long chains of monosaccharides (more than 9)

      1. typical 100 - few 1000

   2. linear or branched

   3. Starches

      1. amylose (30%) and amylopectin (70% branched)

   4. glycogen

      1. highly branched glucose polysaccharides

      2. stored in the liver and muscle

   5. Dietary fibre

      1. non starch polysaccharides (NSP)

      2. classification in soluble (pectin, gum) and insoluble (hemicellulose, cellulose)

      3. can be partly digested (fermented) by bacteria => digestion products may help maintaining a healthy gastrointestinal tract

Carbohydrates that dont break into sugar and are not absorbed by the small intestine => they pass through digestive system and are fermented in the colon

=> is build through cooling cooked starch-containing foods

=> change of chemical structure

=> benefit for intestine => growing of beneficial bacteria

Pectin (apple skin, vegetables)

Alginates and Carrogeenan (Algae)

Psyllium

Inulin (some plant foods)

Raffinose (legumes)

Cellulose (most plant foods)

Lignin (cereals => e.g. rye)

chitin (shrimp/ insect skin)

Resistant starches

Hemicellulose (cereals, legumes)

AMDR = 45-65%

=> ≤10% of simple sugars (mostly complex sugars)

=> dietary fibre AI = 30 g/ day

=> High in fiber:≥4 g/serving

1. Full calorie sweetener (4 kcal/g) => table sugar, corn syrup, honey, aspartame

2. A few calorie sweetener (1-3 kcal/g) => sugar alcohols (xylitol, mannitol, sorbitol)

3. Zero calorie sweetener (0-1 kcal/g) => stevia, allulose (psicose), saccharin, sucralose

1. natural

   1. sucrose (table sugar), honey, corn syrup

      1. honey and corn syrup are not recommended for infants due to possible contaminations with bacterial spores

2. artificial sweetener

   1. aspartame

      1. energy contribution is negligible because only tiny portions are used to sweeten drinks

      2. 200 times sweeter than sucrose

      3. Dipeptide => energy of a protein

      4. breaks down under heat => don’t use for cooking/ baking

      5. stable for longer than a few days only at pH < 7 => ideal for soft drinks

1. natural:

   1. stevia (from the south american stevia plant)

      1. 200 times as sweet as sucrose

      2. ADI (acceptable daily intake) = 4 mg/kg

   2. Allulose (psicose)

      1. 2/3 as sweet as sucrose

      2. 0.2 kcal/g

      3. in low levels in plant foods: raisins, figs, jackfruit

      4. lower activity of enzymes involved in carbohydrate digestion (amylase, maltase) and decrease glucose absorption (maybe helpful for blood-glucose regulation)

      5. may cause discomfort (flatulence, diarrhea) at high doses: gets fermented by bacteria in the colon

2. Artificial:

   1. saccharin

      1. 300 times sweeter than sucrose

      2. ADI = 5mg/kg

   2. Sucralose

      1. 500 times sweeter than sucrose

      2. ADI = 15 mg/kg

1. natural

   1. sugar alcohols: xylitol, mannitol, sorbitol

      1. < 4kcal/g (usually 2) due to lower absorption efficiency in the small intestine

      2. dont promote tooth decay (bacterias cant break them down) and are therefore used in chewing gum

      3. large quantities can cause diarrhea and bloating => large intestine

      4. xylitol: as sweet as sucrose

      5. mannitol and sorbitol: 1/2 as sweet as sucrose

1. Chewing:

   1. salivary amylase breaks down starch into maltose (not fully, but starts the digestion)

2. Pancreas

   1. produces pancreatic amylase in the small intestine.

      1. continue digestion starch poly- and oligosaccharides into mono- and disaccharides

3. small intestine

   1. disaccharidase breaks down disaccharides

      1. lactase: lactose => glucose + galactose

      2. sucrase: sucrose => glucose + fructose

      3. maltase: maltose => glucose + glucose

4. gut cells

   1. enterocytes: absorbs the sugar and transports them to body cells via bloodstream

5. Liver and muscle

   1. store the glucose (glycogen)

6. large intestine:

   1. carbohydrates that are not absorbed get fermented by bacteria

   2. excessive passage can result in gas production, bloating, abdominal discomfort

      1. lactose intolerance

1. energy source (glucose)

   1. glucose is used to make energy

   2. if a person eats too much: glucose can be converted to fatty acids => stored as fat in adipocytes

2. Antiketonic

   1. sufficient dietary carbohydrates prevent high fat use for energy

      1. ketones result from incomplete use of fat for energy (also if diabetic is not controlling the disease well)

3. sparing of protein breakdown

   1. sufficient dietary carbohydrates decrease use of proteinss which are used to make new glucose (gluconeogenesis)

      1. normally the insulin after consumption of foods prevents gluconeogenesis => body doesn’t need to produce glucose because its available from the diet

   2. structural and regulatory functions

      1. structures on the cell surface: responsible for different blood groups

1. prebiotic effect to promote the growth of beneficial bacteria in the large intestine

2. contribute in satiety: lower energy intake, better weight management because of lower energy intake

3. not yet proven: possible benefits: lower risk of colorectal cancer and lower risk of diverticulosis

4. insoluble fibres

   1. increase the rate of transit through the colon and help to prevent constipation (stool softening, together with fluid)

5. soluble fibres

   1. can lower the absorption rates of some nutrients (glucose => possible benefit for diabetics)

   2. can lead to lower LDL cholesterol, by decreasing the absorption of cholesterol and bile acids in the gut

1. Lactose intolerance

   1. deficiency of lactase enzyme in the small intestine => lactose continue into the large intestine, where it will be fermented by bacteria

   2. production of gas, bloating, abdominal discomfort

2. empty calories

   1. excessive energy intake but low intake of other nutrients required for body growth (protein, fat, vitamins, minerals), because of the consumption of too many simple sugars (soft drinks, fast food)

      1. concern for children!

   2. high sugar increases risk of dental caries

3. ketogenic diets

   1. Carbohydrate intake < 25% of daily calories (normal 45-65)

   2. possible health benefits

      1. maybe better blood glucose control in diabetics

      2. benefits for some epileptics in terms of helping control the frequency of their seizures

   3. possible health problems

      1. low intake of fruits and vegetables: lack of nutrients

      2. likely to have high intake of saturated fats from animal products, potentially leading to increased cardiovascular disease risk over the long term

      3. depending on the level of ketosis: may unpleasant symptoms such as fatigue, dizziness, headache, constipation due to increased dehydration, insomnia, possible nausea

   4. Diabetes

1. ketogenic diets

   1. Carbohydrate intake < 25% of daily calories (normal 45-65)

   2. possible health benefits

      1. maybe better blood glucose control in diabetics

      2. benefits for some epileptics in terms of helping control the frequency of their seizures

   3. possible health problems

      1. low intake of fruits and vegetables: lack of nutrients

      2. likely to have high intake of saturated fats from animal products, potentially leading to increased cardiovascular disease risk over the long term

      3. depending on the level of ketosis: may unpleasant symptoms such as fatigue, dizziness, headache, constipation due to increased dehydration, insomnia, possible nausea

=> early: excess of insulin production (hyperinsulinemia), an attempt by the body to compensate for growing resistance to insulin action

=> over time (years/ decades): insulin production decreases due to pancreatic beta-cell dysfunction and loss of beta-cell mass

1. type 2 diabetics may also require insulin injections to help control blood glucose levels

2. over 90% of all diabetics are type 2

3. other forms

   1. type 1 (no insulin production, or extremely low amounts)

   2. type 1/2 hybrid forms

   3. gestational diabetes (pregnancy)

4. both genetic and environmental factors are involved in type 2 and type 1

5. factors for type 2

   1. obesity (especially with visceral adiposity), low physical activity

1. try to keep blood glucose as close to normal as possible

2. controlling atherogenic dyslipidemia (high serum cholesterol, high serum fasting triglycerides, hypertension)

   
   

3. Recommendations

   1. weight loss

      1. increase physical activity

      2. decrease caloric intake

   2. prevent cardiovascular diseases

      1. decrease intake of saturated fats from animal products

      2. increase omega-3 food

      3. increase consumption of plant foods

      4. distribute carbohydrate-rich foods over several daily meals, rather than combining them into one or two meals

   3. better glucose blood levels

      1. avoiding foods that contain simple sugars (drinks like sodas, fruit juices)

      2. more complex carbohydrates (also the rest of the population)

      3. check the glycemic index of foods => eat low GI foods and overall low glycemic load

=> Glycemic index is a measure of the extent to which consumption of food can increase blood glucose

GI = relative area under the curve (AUC) of glucose concentration after food intake

=> relative index because it involves comparison of food serving that contains 50 g of digestible carbohydrate with 50 g of a standard food (glucose or white bread)

≤ 55

≥ 70 or higher

=> multiplying the Glycemic index with the amount of carbohydrate in a food: 100

=> different varieties of the same plant food can have different GI numbers: white bread is typically classified as a high GI food, whole wheat bread as intermediate GI and heavy rough-grain bread as a low GI

1. GI scale applies to single foods and not to the food combinations that are typical of meals where interactions among different foods could potentially affect the GI and GL

2. the same food can affect blood glucose levels variability among different individuals

   1. GI represent averages from studies done on different subjects

3. diabetic can get too focused on GI and ignore other important dietary recommendations (total caloric intake, dietary fibre)