CHEM215 Lecture Notes - Lecture 11: Lignin, Attention Deficit Hyperactivity Disorder, Dietary Fiber
Carbohydrates and Health:
• Common misconceptions:
-carbohydrates cause obesity - bread and bananas are fattening
-low carb diets help you lose fat fast
-sugar causes diabetes, heart disease and behaviour problems in children
-fibre has no calories.
• Function of carbohydrates:
-provides 40-80% of energy worldwide —> provides 17kJ/g.
-fuel for nervous system, red blood cells
-transported as glucose in blood to muscles
-stored as glycogen in liver and muscles and as triglycerides in fat (rarely)
• Other reasons to include carbs in food:
-flavour (sweetness)
-satiety and satiation
-bowel health and gut microbiota
-bowel regularity.
Sugar and health:
• Current research does not show a link between moderate consumption of sugars
and serious diseases such as diabetes, heart disease, hyperactivity and cancer. But
what does moderate mean? This is why we have a dietary guideline for sugar.
• Obesity: 63% (almost 2/3) of Australians adults are overweight or obese based on
BMI. 1 in 4 Australian children are overweight or obese. Being overweight
or obese is third only to smoking and high blood pressure as a contributor to
our overall burden of disease.
• Australian health survey: Australians consume on average 60g of free sugars per
day (=14 tsp). Most of these free sugars (81%) came from added sugars with only a
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small portion coming from things such as fruit juice and honey. This survey found
that children and teenagers were most likely to exceed the recommendation.
• Good news for unrefined carbohydrates:
1. any diet type resulting in reduced energy intake will result in weight loss
2. Short term low-carb high-fat studies show both favourable and less desirable
effects
3. Sustained adherence to a ketogenic LCHF diet appears to be difficult. A non-
ketogeneci diet supplying 100-150g CHO/day may be more practical
4. There is a lack of data supporting long-term efficacy, safety and health benefits of
LCHF diets.
5. Lifestyle intervention in people at high risk of developing type 2 diabetes, while
maintaining a relative CHO-rich diet results in long-term prevention of
progression to type 2 diabetes and is generally seen as safe.
Dietary fibre:
• Fibre is the undigested plant food - has no signal definition.
• However best described as the edible part of plants or analogous
carbohydrate resistant to digestion/absorption in the small intestine.
• Fibre may be completely or partially fermented in the large bowel and includes
polysaccharides, oligosaccharides and lignin.
• Bacterial metabolism of soluble fibre and resistant starch: bacteria digest and
produce short-chain fatty acids, and these enhance the health of cells in the large
intestine by decreasing the survival of pathogenic bacteria. Fibre and resistant
starch can also provide a bit of fuel which is absorbed into the blood stream to
yield energy.
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Document Summary
Carbohydrates cause obesity - bread and bananas are fattening. Low carb diets help you lose fat fast. Sugar causes diabetes, heart disease and behaviour problems in children. Fibre has no calories: function of carbohydrates: Provides 40-80% of energy worldwide > provides 17kj/g. Stored as glycogen in liver and muscles and as triglycerides in fat (rarely: other reasons to include carbs in food: Sugar and health: current research does not show a link between moderate consumption of sugars and serious diseases such as diabetes, heart disease, hyperactivity and cancer. This is why we have a dietary guideline for sugar: obesity: 63% (almost 2/3) of australians adults are overweight or obese based on. 1 in 4 australian children are overweight or obese. Being overweight or obese is third only to smoking and high blood pressure as a contributor to our overall burden of disease: australian health survey: australians consume on average 60g of free sugars per day (=14 tsp).
