CUKRY - SACHARIDY...Carbohydrates Primary function: energy source Types and dietary sources of...
Transcript of CUKRY - SACHARIDY...Carbohydrates Primary function: energy source Types and dietary sources of...
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Objectives of the lesson
1. Carbohydrates and gut microbiota
2. Proteins – are they a nutrtional problem?
3. Vitamins in a nutshell
Lesson 2
© Katarína Babinská, MD, PhD. MSc., 2019
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Clinical case
• Patient: Joanna, 36 y old
• Overweight (BMI 28)
• Problems with glycemia
– fasting normal
– abnormally high levels after meal
• Complains of chronic constipation
• Need to modify carbohydrate intake?
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Carbohydrates
Primary function: energy source
Types and dietary sources of carbohydrates
1. Monosaccharides (1 carbohydrate unit in molecule)
• glucose, fructose, galactose (fruit, vegetables, honey)Glucose
2. Disaccharides (2 carbohydrate units in molecule)
• saccharose (sugar, sweets, soft drinks)
• lactose (milk, milk products)
3. Polysaccharides (10 and more carbohydrate units)
• starch – main carbohydrate in human diet
(cereals, legumes, potatoes, fruit, vegetables)
- energy value of carbohydrates 17,1 kJ (4,1 kcal)/ 1g
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Proteins Fats Carbohydrates
25- 30 %
10- 15 %
55 - 60 %
Recommended intake of
carbohydrates
• 55 – 60 % of daily energy intake
• of that mono and disaccharides:
maximum 10 % of energy
Foods rich in simple carbohydrates (mono/disachcarides)
(candies, soft drinks, crackers, sweet bakery....)
- if consumed in excess
• low nutritional value:
- rich in calories,
- but often poor in vitamins, minerals, etc. („valuable“ nutrients)
• risk of tooth decay
(oral bacteria – carbohydrate fermentation - acid formation –
enamel destruction)
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Mono / disaccharides
- fast source of energy
- rapidly digested and absorbed in the gut
- rapid increase of glycaemia
- rapid increase in insulin secretion with adverse metabolic effects:
preferred fuel - glucose,
therefore fat deposition
faster onset of hunger –
blood glucose drops rapidly
down
CVD, DM risk
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Polysaccharides
- „easily digested“ – similar metabolic effect as simple carbohydrates (or
slightly lower)
- e.g. white bread !!!
Slowly digested poysaccharides
- slower and prolonged increase in glucose level
- glycaemia does not reach that high levels
- metabolically more
advantageous
- „longer term“ source of
energy - longer feeling of
satiety
- dietary fibre containing
carbohydrates
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Glycaemic index (GI)
• Indicates to what extent a food item causes elevation of blood glucose level
• high glycaemic index GI – food significantly increases glycaemia
• foods with lower GI – less increase of glycaemia
Glycemic load
- takes into account both the
amount of carbohydrate in the
food in relation to its impact on
blood sugar levels.
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Fructose and health
• often added as a sweetener
• of major concern
• associations with
• icreased fat deposition in the
liver and skeletal muscle
• insulin resistance, obesity,
and the associated risk of
DM 2
• shown in animal studies, not
that much in human studies
• more research needed
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Dietary fibre
- several chemical compounds (mostly polysaccharides - macromolecules)
collectively referred to as ditary fibre
a/ water soluble b/ water insoluble
- indigestible component of diet
- it cannot be broken down by digestive juices
- the GI secretions lack enzymes for digestion of fibre
- is not absorbed in the intestines
- fermented by microorganisms (mainly) bacteria living in the GI system
Food sources
- plant foods (cereals, legumes, vegetables, fruits, nuts)
- recommended intake 20 - 30 g/day
- „protective nutrient“ - displays many positive effects
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Water soluble fibre - in GIT absorbs water, creates a gel
• reduces glucose absorption – prevents too fast increase in glycaemia
• helps to reduce blood cholesterol (enhances excretion of bile acids via faeces)
Effects of dietary fibre in the human body
Water insoluble fibre
absorbs water in alimentary tract, increases the volume of its content
stimulates intestinal motility
lowers the passage time, thus the exposure of mucosa to harmful substances
aids defaecation – prevents constipation
triggers the feeling of satiety (obesity prevention –see a scheme in the next slide)
Dietary fibre - effective in prevention of cardiovascular diseases, cancer, obesity,
constipation
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Dietary fibre and gut microbiota dietary fibre - „food for the microbes“ living in GIT
Intestinal microbiota
more microbial cells than cells of the human body, 1-2 kg
mostly anaerobes, main representatives: Bacteroidetes, Firmicutes
Functions
ferment the dietary fibre - formation of short chain fatty acids – utilized as energy
for intestinal mucosal cells
growth of fermenting bacteria – lower pH
and suppress growth putrid or pathogenic
bacteria
quantity of bacteria - the content of
large intestine – enhanced motility
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The gut – brain axis
synthesis of bioactive compounds -
effects on
the intestinal epithelium
local mucosal immune system
the enteric nervous system
- transmission of signals
from the gut to the brain
= gut-brain axis
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Dysbiosis
- abnormal composition of gut microbiota
- associated with acute diarrhoea
- linked to chronic diseases (obesity, diabetes
mellitus, Crohn´s disease, etc.)
- increasing evidence shows that it may play role
in pathomechanisms of some CNS disorders
(depression, schizophrenia, autism, etc.).
- microbial colonization occurs after birth
- birth „per vias naturales“ - crucial
- Cesarean section – different microbiota in early
age – may adversely impact development of
the nerveous system, immune system
Gu
t-bra
in a
xis
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Clinical case
• Patient Anna – she´s vegan
• She came to doctor´office for an advice:
„What to eat, in order to have adequate protein
intake?“
Recommendation:
• Eat a variety of foods
• Combine various plant foods rich in protein:
- legumes - soy products
- cereals - nuts
• Why?
Proteins
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Function
• synthesis of tissues (body proteins)
• synthesis of enzymes, hormones, antibodies, plasma proteins....
• source of energy (under some circumstances)
Proteins
Structure
• macromolecules composed of amino - acids (AA)
• human body - built from 20 different amino acids
Amino acids
1. essential
– cannot be synthesized in the human body,
– provided only by food
• adults - 8 essential AA • child - 10 essential AA
2. non - essential – can be synthesized in the body from essential AA
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Plant sources
- soy, legumes, bread, cereals, potatoes
- incomplete protein (= protein with lower biological value) = less adequate AA composition
usually poor in some essential amino acids
synthesis of body proteins is inefficient if any of the essential AA is missing !
Animal sources
- meat, fish, eggs, milk, milk products, cheese
- complete protein (protein with higher biological value)
= adequate AA composition
contains all essential AA in adequate amount
more efficient utilization of AA in synthesis of body proteins
Main food sources of protein
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Energy value of protein
17,1 kJ/ 1 g
Protein requirements
• some body protein is degraded daily (obligatory loss) – needs to be replaced
• recommended protein intake: 10-15 % of daily energy intake
• higher protein requirements (tissue synthesis)
- children and adolescents,
- pregnant and lactating females
- sportsmen
- patients (mainly chronic diseases)
Proteins Fats Carbohydrates
10-15 %
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Proteins - summary
protein rich food may be rich in saturated fats
It is recommended to prefer low fat alternatives
- full milk yoghurt / low fat yoghurt
- fatty meat / lean meat, etc.
people consuming exclusively plant food shouldcare about the variety of their diet
by consumption of a variety of different plant foods adequate amount of AA can be supplied(e.g. in vegetarian diet)
I´m a vegetarian. Is my
protein intake
adequate?
the intake of protein in economically developed countries is generally adequate
or slightly higher protein than recommended
exception may be some high risk groups (vegetarians, elderly, low income)
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Vitamins
• involve 13 substances
– fat soluble vitamins (A, D, E, K)
– water soluble vitamins (vitamin C and the B complex: B1, B2, B6, B12,
niacin, folate, biotin, pantothenic acid)
Function
• components of enzyme systems (co-factors)
• involved in the regulation of metabolism
• Individual vitamins often associated with a
specific function
– Vit A – vision
– Vit K – blood clotting
– Vit B12 – erythropoiesis
– Vitamin E – antioxidant
– Vitamin D – bone formation, etc.
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Sources of vitamins
• nutrition
– should be the only/main source of vitamins
(except vitamin D – sun exposure)
• Some vitamins can be produced in the human body
vitamin K, B12– in small and insufficient amount
– produced by bacteria in large intestine – minimum absorption
vitamin D - sufficient amount produced in exposure to sunlight
vitamin A - produced in the body if sufficient amount of provitamine
available (b-carotene)
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Vitamin pills
- contain „only“ vitamins
- do not fully replace healthy diet
- diet contains also other bioactive substances with biologically – strenghten the
effects of vitamins
- suitable in some circumstances – disease, diet, the elderly, pregnant women...
Do I need vitamin pills?
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Risks of insufficient vitamin intake
Avitaminosis
- absolute deficiency – at present time rare in developed countries
- results in disorders with typical symptoms – currently very rare
vit. A – night blindness, blindness
vit. D – rhachitis
Hypovitaminosis
- intake of many vitamins, mainly B and C is lower than the recommendations
- large part of population are vitamin D deficient
- typical are mild forms of deficiencies – rather common
- no clinical symptoms present, can be diagnosed by examination of blood levels
- causes metabolic abnormalities and increased risk of non-communicable
diseases (cardio-vascular, osteoporosis, etc.)
Risks of excessive vitamin intakes
- Hypervitaminosis – acute or chronic toxicity
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Simple recommendation to supply
sufficient amount of vitamins:
...eat a variety of foods...
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Questions to study
• Carbohydrate types and glycemia
• Health risks associated with overconsumption of mono and
disaccharides
• Fructose and health
• Dietary fibre, health effects, recommended intake, food sources
• Gut microbiota, main representatives, health effects
• Gut brain axis – what is, communication pathways, health effects
• Proteins – dietary sources
• Complete, incomplete protein – what determines the quality?
• Vitamins: hypovitaminosis – current problem and its consequences
• Vitamin pills – what is their disadvantage in comparison to natural
vitamin sources