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M101 > W31 Nutrition- Macronutrients > Flashcards

W31 Nutrition- Macronutrients Flashcards

1
Q

What is Nutrition?

A

Science of foods and their actions within the body. This includes:
▪ Relationship between health and disease (malnutrition)

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2
Q

What is Nutrition?

A

Science of foods and their actions within the body. This includes:
▪ Relationship between health and disease (malnutrition)

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3
Q

What is a Diet?

A

Selection of foods and beverages that an individual eats and drinks

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4
Q

What are examples of macronutrients?

A

Water (litres/day)
Carbohydrates*
Proteins
Fats*
*Provide energy for cell metabolism

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5
Q

What are examples of micronutrients?

A
  • Required in SMALL amounts (mg or μg daily)
  • Do not yield energy
  • Vitamins
  • Minerals
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6
Q

Classify the 6 classes of nutrients:

A

Carbohydrates
Proteins
Lipids
Vitamins
Mineral salts
Water

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7
Q

Are macro or micro nutrients energy yielding?
What does the term mean?

A

Macronutrients
Organic nutrients that are broken down to provide energy

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8
Q

For info:
Calculate the Energy Available from Foods

A

Nutrients 1g:
Carbohydrates 4
Proteins 4
Fats 9
▪ 1g of alcohol (not a nutrient) releases 7 kCal

  • 1 slice of bread with 1 tablespoon of peanut butter on it contains 16 g carbohydrate, 7 g protein, and 9 g fat:
    16 g carbohydrate x 4 kcal/g = 64 kcal
    7 g protein x 4 kcal/g = 28 kcal
    9 g fat x 9 kcal/g = 81 kcal
    Total = 173 kcal
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9
Q

What are
Monosaccharides
Disaccharides
Polysaccharides

A

Mono= simple sugars
▪ Smallest sugar Unit
▪ General formula (CH2O)n, where n is 3 to 6.

  • Disaccharides – two linked monosaccharide units
  • Polysaccharides – composed of between a few and thousands of monosaccharides linked together.
  • E.g. cellulose, glycogen, starches, chitin (fungal cell wall component)
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10
Q

Examples of monosaccharides
Features of glucose:

A

Glucose
Fructose
Sucrose

Monosaccharides and food sources

▪ Glucose – enters the cells via an active transport
➢ source of immediate energy (via cellular respiration,
generating ATP – Lecture 6). !1g produces 4 Kcal!
➢ Excess is stored as glycogen (by condensation reactions) by hepatic (liver) and muscle cells
➢ Blood glucose regulation by insulin and glucagon

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11
Q

Examples of Disaccharides (3)
Composed of which mono?

A

Sucrose – composed of a glucose + fructose
Lactose – composed of a galactose + glucose
Maltose – composed of 2 glucose units
▪ Key structural motif of starch. It is released
during starch breaking down (digestion)

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12
Q

Examples of polysaccharides?
What are their features?

A

Glycogen
- multibranched polysaccharide of glucose
✓ in meats (in a limited extent)
* Storage form of glucose, mainly in hepatic and skeletal muscle cells
▪ If glycogen is abundant, glucose excess can be used to make fats

Starch
- long, branched or unbranched glucose chains
✓ in grains, rice, wheat (storage form of glucose in plants)
▪ Broken down during digestion, by salivary and pancreatic amylases into disaccharides (maltose), then hydrolysed into monosaccharides
(glucose) → energy source

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13
Q

What are examples of dietary fibres?
What is their function within the body?

A

Composed of a variety of distinct monosaccharides
✓ Vegetables, fruits, whole grains, and legumes (Structural part of plants)
* Digestion - undigested until the large intestine, where some are broken down by bacteria
* Trap/get rid of bile ( cholesterol levels) and molecules in the gut → regulate bowel activity
▪ Prevention of heart diseases, obesity, as they help lower cholesterol

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14
Q

What are the risks of low-fibre intake diets?

A
  1. Constipation and haemorrhoids
  2. Increased risk of heart diseases and some types of tumours
    ▪ E.g. colon cancer
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15
Q

What is Glycaemic Index (GI)?

What foods have a High GI?
What foods have a Low GI mean?

A

Degree to which a food increases blood sugars and elicit insulin response.
Different carbohydrates are digested and absorbed at different rates.

High GI (processed carbs, white bread, potatoes, watermelon)
→ raise blood sugar high and rapidly.
Low GI (fruit, legumes, whole wheat)
→ raise blood sugar slowly and to a lesser extent.
With type 2 diabetes, the diet must include low GI foods

▪ Help stabilise long-term blood glucose levels
Not all low-GI foods are healthy choices
▪ Chocolate and crisps are low GI, high in fat → carbohydrates absorption

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16
Q

What is hypoglycemia?

A

Sugar Deficiency → hypoglycemia
➢ Energy deficit → CNS suffering, dizziness, mental and physical weakness
➢ Protein breaking down to produce energy → kidney stress, digestive problems

17
Q

What are some effects of high free sugar intake on health?

A

➢ Obesity → weight gain and obesity
➢ Increased chronic diseases risk (type 2 diabetes, cancers, hypertension, heart diseases)
➢ Dental Caries bacterial fermentation of added sugars producing acids, contributing to tooth decay

18
Q

What are proteins?

A

They are polymers (polypeptide) chains of amino
acids (monomers) linked by peptide bonds

19
Q

What are the 3 types of amino acids?

A
  1. Non-essential amino acids
    ▪ can be synthesised by the body
  2. Essential amino acids
    ▪ CANNOT be synthesised by the body
    MUST be provided in the diet
  3. Conditionally Essential Amino Acid.
    In some cases, some nonessential amino acids become essential (e.g. in newborns)
20
Q

What are complete proteins?
What are incomplete proteins?

A

▪ Containing all the essential amino acids in the required proportions
✓ meat, fish, soya beans, milk, and eggs.
Incomplete proteins

▪ Do NOT contain all the essential amino acids in the correct proportions.
✓ mainly of vegetable origin (cereals, peas, beans, and lentils).
▪ A diet based on a wide variety of incomplete proteins can avoid amino acid deficiencies. Essential consideration for strict vegetarian or vegan diets.

21
Q

What is a Protein Deficiency?
What can it cause? (3)
What is it caused by? (3)

A

A diet consistently supplying too little protein or lacks essential amino acids

E.g. Marasmus and kwashiorkor (swollen abdomen), clinical syndromes in children/infants
It can cause:
1. severe weight loss
2. slowed growth
3. impaired brain functions, etc
➢ Eating disorders (anorexia nervosa), cancer, difficult to absorb nutrients (after gastric bypass)

22
Q

Where is the only source of nitrogen in the body attained from? What is it needed for?

A

Proteins
For amino acids and nitrogen-containing compounds)

23
Q

What is Excess of Protein?

A

Diet consistently suppling too much protein (especially from animal sources). A risk factor for:
* To produce proteins, a diet needs to provide essential amino acids
* Proteins are the only source of nitrogen (for amino acids and nitrogen-containing compounds)

24
Q

What are the steps of Protein digestion and absorption? (breakdown) and where do the stages take place?

A
  • Protein digested into shorter polypeptides (Cells of the stomach)
    Then polypeptidases digest them into amino acids (Pancreas)
    Then the amino acids are absorbed through the lining of the small intestine (Cells of the small intestine)
25
Q

Amino acid absorption:

A

Intestinal cells uptake amino acids and:
- Released into the bloodstream
- Used to make proteins
- Converted to glucose, if needed
- Broken down to provide energy via deamination producing ammonia (NH3) that is then converted to urea

26
Q

What are examples of Lipids?
Why are they important? (2)

A

Fats, oil steroids, waxes
* Major fuel source during light/moderate exercise
▪ More energy per gram than carbohydrates (9 vs 4 kCal/g)
* Major store of energy from food (Triglycerides)
▪ Adipose cells uptake lipids and expand in size.

But also,
* Primary component of cell membranes and nerve sheaths (myelin)
* Providing cushioning and thermal insulation for the organs
* Required for the synthesis of steroid hormones
* Serve as a vehicle for the absorption of lipid soluble vitamins

27
Q

What are 3 types of fatty acids?
What are their functions?

A
  1. Triglycerides
    * Primary lipid in food and in body
  2. Phospholipids
    * Amphipathic molecule
    * Cell membrane component
  3. Sterols (Cholesterol)
    * Components of vitamins, hormones, cell membrane
28
Q

What are Fatty acids?
How do they differ? (3)

A

Aliphatic building blocks of triglycerides, phospholipid and glycolipids.

  1. Chain length- 4 to 24
  2. Degree of saturation- presence & No. of double bonds in the chain
    ➢ Saturated – No double bonds
    ➢ Monounsaturated – having one double bond
    ➢ Polyunsaturated – having two or more double bonds
  3. Locations of Double Bonds- presence & No. of double bonds in the chain
    ➢ Saturated – No double bonds
    ➢ Monounsaturated – having one double bond
    ➢ Polyunsaturated – having two or more double bonds
29
Q

What are the properties of saturated fatty acids?

A
  • more solid at room temp
  • more stable/resistant to oxidation
  • animal-based food (milk, cheese, butter, eggs, fatty meat)
  • factor risk for heart diseases
30
Q

What are the properties of unsaturated fatty acids?

A
  • plant-based food (avocados, olives, vegetable oils, etc), seafood
  • the more unsaturated points, the less stable/resistant to oxidation
  • the more unsaturated points has, the more liquid it is (at room temp.)
31
Q

Which fatty acids can the body not make?
How are they alternatively provided?
Which category of people usually have fatty acid deficiencies and what are the effects?

A

Linolenic acid (an omega-3) and linoleic
acid (an omega-6)

▪ These essential fatty acids MUST be
provided by the diet (vegetable oils,
seeds, nuts, fish, and seafoods)

Infants
▪ Impaired growth, reproductive failure,
skin lesions, kidney and liver disorders

32
Q

Trans fatty acids:
What is Hydrogenation of unsaturated fatty acids?
What are the health effects?

A

Some unsaturation points are saturated by adding hydrogen molecules, (reducing the double bonds in the structure)

Increase LDL cholesterol in blood which leads to Increased risk of heart diseases

  • Partially hydrogenation in food industry, to prevent oxidation, and ensure a longer shelf life
    ▪ Some double bonds that remain after processing change their configuration from cis to trans.
    ▪ Trans unsaturated fatty acids - in which the H are located on opposite sides of a double bond

Contained in:
* Deep-fried food
* Packaged food snack
* Bakery products
* Crackers
* Fast food

33
Q

Where does lipid digestion take place?

A
  • Mouth-lingual lipases released by salivary glands
    -Important in infants - minor role in adults
    triglycerides
  • Stomach - little lipid digestion by gastric lipases
  • Small Intestine – lipids activate the cholecystokinin (CCK) that release bile from the gallbladder

▪ Bile emulsifies fat for digestion - promotes the dispersal
of fats in watery fluids, so that
▪ Pancreatic & intestinal lipases can degrade triglycerides

Emulsifiers are required to make lipids accessible to lipases

34
Q

How are lipids absorbed?

A

Once lipid digestion occurs,
▪ Medium chain fatty acids and glycerol are absorbed into the bloodstream

▪ Long-chain fatty acids and monoglycerides
combine with the bile, forming micelles,
diffuse into intestinal cells and are
reassembled into triglycerides
▪ Triglycerides and phospholipids are packaged with proteins as chylomicrons

▪ Chylomicrons are transport vehicles
released into lymph vessels and reach the
bloodstream (thoracic duct)

▪ Triglycerides are stored in the adipose tissue
▪ In energy deficit, triglycerides are hydrolysed to release energy Images

M101 (41 decks)

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