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

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 (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
• 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