Carbohydrates: DRI, AMDR, and Metabolism

• DRI stands for Dietary Reference Intake
• AMDR stands for Acceptable Macronutrient Distribution Range

Carbohydrates

• DRI: 130 g/day, which is the minimum required for brain function.
• AMDR: 45-65% of total daily calories.
• 4 kcal/g.
• Simple carbohydrates are sugars, while complex carbohydrates are starches and fiber.
• Functions include providing energy and supporting metabolism.
• Digestion begins in the mouth with salivary amylase and continues in the small intestine with pancreatic amylase.
• Blood glucose homeostasis is maintained by insulin, which lowers blood glucose, and glucagon, which raises blood glucose.
• Ketosis occurs when carbohydrate intake is too low, leading to fat breakdown for energy.
• Fiber, fat, protein, food processing, and meal composition affect glycemic response.
• Glycemic Index (GI) ranks foods based on how quickly they raise blood glucose; low GI foods release glucose slowly.
• Adequate Intake of fiber is 38g/day for males and 25g/day for females.
• Fiber supports digestion, reduces cholesterol, and regulates blood sugar.
• Whole grains retain fiber, vitamins, and minerals, whereas refined grains are stripped of nutrients.

Proteins

• DRI: 0.8 g/kg of body weight.
• AMDR: 10-35% of total daily calories.
• 4 kcal/g.
• Essential amino acids must come from the diet.
• Non-essential amino acids can be synthesized by the body.
• Functions include muscle repair, enzyme production, and immune function.
• Complete proteins contain all essential amino acids (e.g., meat, eggs, soy).
• Incomplete proteins lack one or more essential amino acids (e.g., beans, grains).
• Complementary proteins are two incomplete proteins combined to form a complete protein (e.g., rice & beans).
• Digestion begins in the stomach (pepsin) and continues in the small intestine (proteases).
• Vegans do not consume any animal products.
• Lacto-vegetarians consume dairy but no meat.
• Lacto-ovo vegetarians consume dairy and eggs but no meat.
• Kwashiorkor is a protein deficiency with adequate calories, leading to edema and a swollen belly.
• Marasmus is a severe deficiency of both calories and protein, resulting in wasting and extreme thinness.

Fats

• No specific DRI, but essential fatty acids have recommendations.
• AMDR: 20-35% of total daily calories.
• 9 kcal/g.
• Triglycerides are stored fat that provides energy, insulation, and protects organs.
• Saturated fatty acids are found in animal fats and increase LDL cholesterol.
• Unsaturated fatty acids are found in plant oils and include Omega-3 (heart-healthy) and Omega-6.
• Digestion occurs in the small intestine with bile and pancreatic lipase.
• Foods high in cholesterol include egg yolks, liver, and dairy.
• Foods low in cholesterol include fruits, vegetables, and whole grains.

Vitamins and Minerals

• Water-soluble vitamins are excreted in urine, posing a lower toxicity risk (B-complex, Vitamin C).
• Fat-soluble vitamins are stored in fat, posing a higher toxicity risk (Vitamins A, D, E, K).
• Vitamin C functions include immune support and collagen synthesis; deficiency leads to scurvy.
• B-complex vitamins are found in whole grains, meats, leafy vegetables, and legumes.
• B-complex vitamins are needed for metabolism and neurological function.
• Niacin (Vitamin B3) is essential for energy metabolism functioning in NAD+ and NADP+ coenzymes.
• Pyridoxine (Vitamin B6) is involved in amino acid metabolism and neurotransmitter synthesis like serotonin and dopamine.
• Folate (Vitamin B9) is critical for DNA synthesis and cell division, especially important during pregnancy.
• Cobalamin (Vitamin B12) is for DNA synthesis and red blood cell production, supporting nerve function and myelin sheath maintenance.
• Major minerals include Sodium (Na), Potassium (K), and Chloride (Cl) for fluid balance; Calcium (Ca) for bone health and nerve function; Magnesium (Mg) for muscle relaxation; and Phosphorus (P) for bone health and ATP production.
• Trace minerals include Iodine for thyroid function, Iron for oxygen transport (heme & non-heme sources), and Fluoride for dental health.

Hydration

• Increased water intake is needed during exercise, illness, and pregnancy.
• Fruits and vegetables are high in water content.
• Caffeine has a mild diuretic effect but does not significantly dehydrate.

Food Safety and Guidelines

• Common foodborne illnesses include Salmonella (raw poultry, eggs), E. coli (undercooked beef), Listeria (deli meats, soft cheese), and Norovirus (contaminated food).
• Food allergies involve the immune system, while food intolerances do not.
• Dietary Guidelines for Americans are updated every 5 years to promote health and prevent chronic disease.
• Nutrient-dense foods are rich in vitamins, minerals, and fiber with low added sugar and unhealthy fats.