Module 5 -NUTR 120, First half

Fructose Overview

• Definition: Fructose, commonly known as fruit sugar, is less cariogenic than sucrose and does not lead to tooth cavities.

• Sources: It is found in food items such as honey, fruits, and high fructose corn syrup (HFCS), with HFCS comprising about 55% corn syrup. As a liquid sweetener, it has become prevalent in food products due to its lower cost compared to sucrose (cane sugar).

Trends in Fructose Intake

• Historical Context: The intake of fructose has dramatically increased from negligible levels in the 1970s to accounting for one-third of all sugar intake in contemporary diets. This rise is reflected in the average consumption of about 62 pounds of fructose per person annually in the U.S.

• Health Impact: The increased fructose intake is linked to the obesity epidemic due to the unique metabolic processing of fructose in the human body.

  • Insulin Response: Unlike other sugars, fructose does not stimulate insulin secretion from the pancreas, leading to differences in how it affects body weight and fat composition.

  • Leptin Secretion: Fructose also does not trigger leptin secretion, which is involved in regulating energy balance and body weight.

  • Liver Fat Synthesis: It promotes fat synthesis in the liver, resulting in elevated triglycerides (TG) and a higher risk for coronary heart disease (CHD).

  • Blood Pressure: There is an association between higher fructose consumption and increased blood pressure, contributing to the risk of CHD.

Fructose and Weight Gain

• Soda Consumption: For example, a typical 16-ounce soda, which contains about 200 kcal primarily from fructose, could contribute to an annual weight gain of around 20 pounds. This illustrates the caloric density and potential for overconsumption associated with sugary beverages.

• Disaccharides and Pure Sugars: Sucrose, the disaccharide that comprises glucose and fructose, is isolated from sugar beets or cane and is a powerful source of calories, often leading to increased caloric intake without enhancing satiety.

Sugar and Health Issues

• Obesity: The trend toward low-fat foods in the 1980s led to manufacturers replacing fat with sugars, often resulting in equivalent or higher calorie content. This practice has contributed to weight gain as excess calories, regardless of their source, can lead to obesity.

• Satiety Effects: Carbohydrates, especially sugars, have a lower impact on satiety compared to fiber-rich foods, making it easier to overconsume them, thus promoting weight gain.

• Nutritional Value: Sugars offer empty calories, devoid of significant vitamins or minerals, and often displace nutrient-rich whole foods in the diet.

Heart Disease Connection

• Metabolic Syndrome: This condition is defined by a cluster of five features: abnormal obesity, high fasting glucose, elevated triglycerides, low HDL cholesterol levels, and high blood pressure. Its prevalence is rising and it is linked with diets rich in sugars and refined grains.

Lactose Intolerance and Milk Allergy

• Lactose: Composed of glucose and galactose, lactose is the sugar found in milk. While infants are born with lactase (the enzyme needed to digest lactose), many individuals develop lactase deficiency as they age. Ethnic backgrounds influence the prevalence of lactose intolerance, with significant variances noted across populations.

• Undigested Lactose: When lactose is undigested, it attracts water in the intestines, leading to bloating and cramps, and is fermented by intestinal bacteria producing gas.

• Milk Allergies: In contrast to lactose intolerance, a milk allergy is an immune response to milk proteins, which can lead to serious reactions, including anaphylaxis in extreme cases.

Carbohydrate Types and Dietary Fiber

• Carbohydrate Classification: Carbohydrates include digestible simple sugars (monosaccharides, disaccharides) and complex carbohydrates (oligosaccharides, starches), as well as nondigestible fibers.

• Dietary Fiber Types:

  • Soluble Fiber: Forms a gel-like substance in the gut, slowing food movement and fermenting to produce short-chain fatty acids (SCFAs), which can benefit cholesterol levels and colon health.

  • Insoluble Fiber: Increases fecal bulk and reduces transit time, contributing to digestive regularity.

Fiber's Role in Health

• Cholesterol Management: Soluble fibers bind bile acids and cholesterol in the gut, preventing deren absorption and promoting excretion, which can lead to lower total and LDL cholesterol levels.

• Weight Management: High-fiber foods are more filling and can help in weight loss by reducing overall caloric intake. Additionally, fibers delay gastric emptying, leading to prolonged satiety.

Summary Takeaways

• Nutrient Density: It is important to choose nutrient-dense foods over calorie-dense options to support overall health.

• Beverage Choices: Opting for lower-calorie, nutrient-rich beverages can contribute to better health outcomes and weight management.