3. Principles of healthy diet

From greek.doctor

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