View source for 3. Principles of healthy diet

Component of diet

* Nutrients
** Macronutrients
*** Lipids
*** Proteins
*** Carbohydrates
** Micronutrients
*** Vitamins
*** Minerals
* Dietary fibre
* Bioactive components
** Alkaloids
** Flavonoids
** Carotenoids
* Food additives
** Spices
** Preservatives
** Colouring
** Sweeteners
** Thickeners
** Stabilizing agents

Macronutrients

* Proteins should be 12 – 15% of the total calorie intake
* Carbohydrates should be 55 – 60% of the total calorie intake
* Fat should be 25 – 30% of the total calorie intake

Calories

* Males 19-30 years – 2500 kcal/day
* Females 19-30 years – 1900 kcal/day
* Requirements increased with increased level of activity

Fats

* 25 – 30% of total calorie intake
** Trans fats – < 2 % of total calorie intake
* Types of fats and their sources
** Unsaturated fats
*** Monounsaturated fats (oleic acid)
**** Olive oil
**** Almonds
**** Butter
**** Avocado
*** Polyunsaturated fats
**** Omega-3 (α-linoleic acid, DHA, EPA)
***** Flax seeds
***** Linseed oil
***** Walnuts
***** Olive oil
***** Fish oil
**** Omega-6 (linoleic acid)
***** Grapeseed oil
***** Corn oil
***** Walnuts
***** Soybean oil
***** Margarine
** Saturated fat (palmitic acid)
*** Butter
*** Meat fat
*** Palm oil
*** Coconut oil
** Trans fatty acids
*** Industrially produced
*** Naturally in beef, lamb, diary
* Effects of lipids on health
** Lipid-free diet ->
*** dermatitis, coagulopathy, avitaminosis of lipid soluble vitamins
** Excess lipids in diet ->
*** obesity, atherosclerosis, hypertension
** Saturated fatty acid intake -> increased serum cholesterol
** Monounsaturated fatty acid intake -> no change in serum cholesterol
** Trans fats intake -> increased risk for cardiovascular disease, serum cholesterol and cancer
* Essential lipids are necessary in the diet
** Omega-6
*** Linoleic acid
*** Precursor for arachidonic acid
*** Arachidonic acid is pro-inflammatory
** Omega-3
*** α-linoleic acid
*** Precursor for EPA and DHA
*** EPA, DHA are anti-inflammatory
** Omega-6:Omega-3 ratio is important.
*** Optimal is 4:1.
*** Ratio in western diet: 15:1 (too much omega-6)

Dietary cholesterol

* Found in egg yolk, milk fat, animal fat, meat
* Factors which influence the composition and concentrations of serum lipoproteins
** Dietary intake of cholesterol
** The composition of the diet, especially the fats
*** Saturated fat intake -> increased LDL
*** Monounsaturated fat intake -> no change in LDL
*** Polyunsaturated fat intake -> small decrease in LDL, but they have other anti-atherosclerotic effects
** The energy balance

Proteins

* 12 – 15 % of total calorie intake
* 0,8 g/kg of bodyweight
* Increased need in:
** Childhood
** Old age
** Pregnancy, lactation
** Tissue regeneration (infection, burns, postoperative)
** Exercise
* Protein turnover occurs in all proteins in the body
** Around 300g of protein turnover occurs each day
* Essential amino acids are necessary in the diet
** Histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine
** “Complete proteins” – proteins containing essential amino acids in sufficient amounts
*** Proteins of animal origin
*** Soy protein
** “Incomplete proteins” – proteins not containing all essential amino acids, or containing all essential AAs but not in sufficient amount
*** Most proteins of plant origin
* Biological value of protein = how much of ingested protein is incorporated into proteins in the body
** Determined by which essential amino acid is present in the lowest quantity

{| class="wikitable"
|'''Food'''
|'''Biological value'''
|-
|Breast milk
|100%
|-
|Egg
|100%
|-
|Milk
|90%
|-
|Beef
|90%
|-
|Chicken
|80%
|-
|Potatoes
|70%
|-
|Rice
|60%
|}
Carbohydrates

* 55 – 60% of total calorie intake
* Low carb intake -> gluconeogenesis, lipid metabolism
* High carb intake -> obesity, diabetes mellitus type 2, caries
** Carbs taste good (high palatability) -> excessive calorie intake
** Empty calories – foods with many carbs usually don’t contain many nutrients
* Types
** Monosaccharides
*** Glucose
*** Fructose
*** Galactose
** Disaccharides
*** Sucrose
*** Lactose
*** Maltose
** Oligosaccharides
*** Maltotriose
*** Fructotriose
** Polysaccharides
*** Starch
*** Glycogen
*** Cellulose
* Glycaemic index (<abbr>GI</abbr>) = the increase in blood glucose in the 2 hours after ingestion, compared to glucose
** Diets high in carbs with high GI -> diabetes mellitus, dyslipidaemia
*** Causes glucose spike and insulin spike after eating
*** Dates
*** Instant rice
*** Corn flakes
*** Whole wheat bread
** Diets high in carbs with low GI -> decreased cholesterol and triglyceride
*** Peanuts
*** Soymilk
*** Apple, pear
*** Long-grain rice
* Simple carbohydrates
** Quickly broken down
** High glycaemic index
** Found in
*** Fruits
*** Milk
*** Vegetables
* Complex carbohydrates
** Slowly broken down
** Low glycaemic index
** Found in
*** Bread
*** Legume
*** Rice
*** Pasta

Dietary fibres

* 25 – 35 g/day
* = Large and complex mixtures of polysaccharides that aren’t digested and absorbed
* Types
** Cellulose
** Gums
* Effect on health
** Increases satiety
** Slow down glucose absorption
** Increase stool mass
** Increase GI bacterial health
** Protects against <abbr>CRC</abbr>
** Protects against type 2 diabetes

[[Category:Public health 4 - Preventive medicine]]