Lecture 6 - Carbs Flashcards
What are the different classifications for carbs?
- monosaccharides
- disaccharides
- polysaccharides
Starch and non starch
-dietary fibers
soluble and non soluble
Intrinsic vs extrinsic sugars
depends where you find them and if they are attached to something then it is intrinsic. For instance, sugars that are contained within plant cell walls. Extrinsic are in a free solution and provide substrate for oral bacteria. lead to formation of dental plaque and caries. Easy to consume and so easy to get obese. Omly exception is lactose.
What is an oligo saccharide?
Contains 3-9 monosaccharide units wheras poly has more than 10.
What are sugar alcohols?
They are formed by the reduction of the aldehyde group of a monosaccharide to a hydroxyl (-OH) group.
Where are sugar alcohols absorbed?
They are absorbed in the GIT and metabolised slowly.
glycemic index of sugar alcohols in comparison to other CHOs?
They have a lower glycemic index than other CHO. They have a minor effect on the concentration of glucose in blood and so it widely used in foods suitable for those who have diabetes.
Energy yield of sugar alcohol in comparison to glucose?
approximately half of glucose. Not exactly suitable in weight reducing diets.
What is xylitol?
It is a sugar alcohol that is formed by the reduction of the 5C sugar xylose (an isomer of ribose). It is tooth friendly as it has anti cariogenic actions.
What is the glycemic index?
It is a means of comparing quantitatively the blood glucose responses from ingestion of equivalent amount of digestable CHO from different foods.
The effect of 50g CHO in a particular food on blood glucose levels compared to 50g of glucose.
If CHO has a high glycemic index then?
greater insulin secretion after the meal
What is the glycemic load?
The index times the amount of CHO in a standard serving size of that food. Index of glycemic response.
What is glycemic response?
The rate, magnitude and duration of the rise in blood glucose that occurs after food is consumed.
How are fibers broken down?
They can not be digested by the human body but they can be fermented to some extent by intestinal bacteria. The products produced can be absorbed and metabolised as metabolic fuel. There are beneficial health effects.
What is dietary fiber?
Mixture of indigestible CGO and lignin that is found intact in plants.
What is functional fiber?
Isolated indigestable CHO that has been shown to have beneficial effects on humans.
What is total fiber?
Sum of dietary and functional fiber
What is soluble fiber?
Dissolves in water to form viscous solutions that can be broken down by intestinal micro flora (pectins, gums)
What is non soluble fiber?
Does not dissolve in water and cannot be broken down by bacteria in the large intestine (cellulose, lignin)
Sources of soluble fiber?
oats, apples. beans, seaweeds
Sources of insoluble fiber?
wheat bran, rye bran, and vegetables.
Health benefits of insoluble fiber?
Soften stools and decrease transit time.
Health benefits of indigestable CHO?
stimulate GI motility, promote a healthy microflora, slow nutrient absorption and increase intestinal gas.
How do dietary fibers reduce the risk of colorectal cancer?
Fibers absorb bile acids and reduce exposure of colonic enterocytes to carcinogens.
What does breast milk consist of?
proteins, fats CHO, vitamins and minerals. It also has immune cells
What are the bioactive components of breast milk?
- ) Anti inflammatory
- ) Anti infective
- ) probiotic action
Evidence is that it contains its own microbiota
What is cellulose?
insoluble and is a polymer of glucose. It cannot be hydrolysed by human enzymes.
What is hemicellulose?
insoluble and branched polymer of pentose and hoxose.
What is inulin?
Insoluble and polymer of fructose. Storage CHO for many root veg like artichoke.
What is pectin?
Soluble and a complex polymer of a variety of monosaccharides including some methylated sugars.
What are plant gums?
Soluble and complex polymer of mixed monosaccharides. Like gum arabic.
What are mucilages?
Soluble and a complex polymer of mixed monosaccharides found in seaweeds and other algae.
What is saccharin?
200-700 times sweeter than sugar
What is aspartame?
made of aspartic acid and phenylalanine. Dangerous to people who have phenylketonuria (PKU)
What is sucralose?
Derived from sugar
What is acesulfame K
200 times sweeter than sugar and heat stable
What is neotame?
7000-13000 times sweeter than sugar and it is similar to aspartame with stronger chemical bonds.
