3. Principles of healthy diet
Component of diet
- Nutrients
- Macronutrients
- Lipids
- Proteins
- Carbohydrates
- Micronutrients
- Vitamins
- Minerals
- Macronutrients
- 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
- Omega-3 (α-linoleic acid, DHA, EPA)
- Monounsaturated fats (oleic acid)
- Saturated fat (palmitic acid)
- Butter
- Meat fat
- Palm oil
- Coconut oil
- Trans fatty acids
- Industrially produced
- Naturally in beef, lamb, diary
- Unsaturated fats
- 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
- Lipid-free diet ->
- 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)
- 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
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
- Monosaccharides
- Glycaemic index (GI) = 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
- Diets high in carbs with high GI -> diabetes mellitus, dyslipidaemia
- 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 CRC
- Protects against type 2 diabetes