Introduction to Nutrition - Carbohydrates

They are “bad” for you: A prevalent misconception is that carbohydrates should be entirely avoided for good health.
They will give you diabetes: The myth that carbs cause diabetes lacks substantiation; rather, carbohydrate quality and quantity are significant factors.
They will make you fat: This belief oversimplifies the complex relationship between diet and body weight.

Contribution to Body Fat Accumulation:
- Carbohydrates (CHO) may uniquely contribute to excess body fat accumulation as they can be easier to consume in excess compared to fats or proteins.
- Example: Refined carbs may not satisfy hunger as effectively as fats or proteins.
- Insulin Influence: Carbohydrate consumption leads to the secretion of insulin, a hormone that promotes energy storage and fat accumulation.
General Conclusion: Excess caloric intake from any macronutrient, not just carbohydrates, can lead to body mass gain.
Best Diet for Body Mass Control: High in complex carbohydrates and fiber, and low in dietary fat.

Discuss carbohydrates and the refining process.
Compare and contrast types of dietary carbohydrates:
- “Simple” carbohydrates: Monosaccharides & Disaccharides.
- “Complex” carbohydrates: Oligosaccharides & Polysaccharides.
Discuss blood-glucose regulation including:
- Glycemic index and load.
- Hyperglycemia & Diabetes.

Recommended Dietary Allowance (RDA): 130 g/day (amount required by the brain).
Acceptable Macronutrient Distribution Range (AMDR): 45-65% of total daily kcal.

Carbs form the basis of most modern diets.
Whole Foods: Carbohydrates in whole foods (e.g., fresh fruits, dairy, whole grains) are unprocessed, retaining beneficial nutrients like fiber, vitamins, and minerals.
- Examples of Nutrients in Whole Foods:
- Whole grains, legumes, vegetables: fiber, B vitamins, minerals.
- Fruits: fiber, vitamins A and C.
- Milk: lactose, vitamin B2 (riboflavin), calcium.

**Degree of Processing: ** Refined carbs alter nutrient density, often removing fiber and essential nutrients (e.g., whole wheat into white flour).
Chemical Composition: Carbs can be categorized into Monosaccharides (simple sugars), Disaccharides (two sugars), Polysaccharides (multiple sugars).
Physiological Effect on Blood Glucose: Carbohydrates can be assessed by their glucose response, glycemic index, and glycemic load.

Whole Grains Composition:
- Bran: Contains fiber, B-vitamins, and important antioxidants.
- Germ: Contains protein, minerals, healthy fats, and B-vitamins.
- Endosperm: Contains carbohydrates, protein, and trace amounts of vitamins and minerals.

Milling Process: Involves the detachment of germ and bran from the endosperm, which prolongs shelf life.
- Example of Refined Flour: White flour is mostly composed of endosperm. Some refined grains are fortified with nutrients.

Nutrient	Brown Rice	White Rice	Whole Wheat	White Flour	Cornmeal
Carbohydrate (g)	23	28.2	68.5	71.4	77
Protein (g)	2.6	2.7	14.6	12.1	8
Fat (g)	0.9	0.3	3.2	2.5	3.6
Fiber (g)	1.5	0.4	8.9	2.7	7.3
Magnesium (mg)	43	12	116	29	127
Iron (mg)	0.42	0.2	3.4	4.8	3.4
Moisture (g)	73	68.4	12.2	13.6	10.3

Monosaccharides:
- Glucose (aldohexose)
- Fructose (ketohexose)
- Galactose (aldohexose)
Disaccharides:
- Maltose (glucose + glucose)
- Sucrose (glucose + fructose)
- Lactose (glucose + galactose)

Oligosaccharides: 3-10 monosaccharides linked together, found in foods like beans, onions, bananas, and garlic.
Polysaccharides: More than 10 monosaccharides linked together, categorized into starches, fibers, and glycogen.

Monosaccharide Absorption: Monosaccharides are absorbed through specific carriers in the intestinal microvilli, transported via the portal vein to the liver where galactose and fructose are converted to glucose.
Disaccharide Digestion: Disaccharides undergo hydrolysis (addition of water) to split into monosaccharides.

Lactose Intolerance: Caused by insufficient lactase enzyme in the small intestine leading to digestive issues such as bloating, gas, and diarrhea.
Milk Allergy: An immune response to milk proteins, resulting in symptoms like rashes, wheezing, and gastrointestinal disturbances.

Hormonal Regulation: Insulin and glucagon are crucial in regulating blood glucose levels.
- Insulin: Stimulates glucose uptake, suppresses lipolysis, promotes energy storage as glycogen.
- Glucagon: Promotes glycogenolysis and gluconeogenesis to increase blood glucose from liver stores.
Diabetes Mellitus Types:
- Type 1: No insulin secretion because of pancreatic failure.
- Type 2: Cells become resistant to insulin despite its normal secretion; associated with obesity and lifestyle factors.

Glycemic Index (GI): Indicates how quickly and how much blood glucose rises following carbohydrate consumption.
- High GI (≥70): Foods that raise blood glucose rapidly.
- Low GI (≤55): Foods that have a slower impact on blood glucose.
Glycemic Load (GL): Considers the amount of carbohydrate in a serving; provides a more practical understanding of a food's impact on blood glucose levels.

Health Risks: High free/added sugar consumption is linked to:
- Increased risk of obesity and chronic diseases such as type 2 diabetes and cardiovascular disease.

Recommendations:
- Limit intake of free sugars to less than 10% of total daily calorie intake (approx. 50g for a 2000-calorie diet).
- Major health organizations stress a balance of nutrient-rich foods while advising against added sugars in fa vor of whole food sources.

Carbohydrates are essential for energy, requiring mindful consumption to optimize health outcomes and minimize risks associated with excess intake.
Understanding the types, sources, and effects of carbohydrates enables better dietary choices and promotes lasting health benefits.