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Dietary cholesterol, which is only found in animal products, has a less significant impact on plasma cholesterol levels compared to the amount and types of fatty acids consumed. Many experts suggest a maximum intake of 300 mg/day, although establishing an upper limit has become a matter of debate.

Various dietary factors can affect coronary heart disease. Moderate alcohol consumption (up to 1 drink/day for women and up to 2 drinks/day for men) has been linked to a reduced risk of CHD due to its positive correlation with HDL-C levels. However, health professionals are hesitant to recommend increased alcohol consumption due to the potential risks associated with alcohol abuse. Red wine may offer additional cardioprotective benefits apart from its alcohol content, such as the presence of phenolic compounds that inhibit lipoprotein oxidation.

Dietary fats have different effects on the body, as summarized in Figure 27.15. Recent studies, including meta-analyses, have raised concerns regarding the current guidelines for dietary fat in preventing CHD.

The primary function of dietary carbohydrates is to provide energy. Despite a decrease in reported caloric intake in the United States since 2003, there has been a significant increase in obesity rates. Some attribute this increase to higher carbohydrate consumption, although it is important to consider the impact of sedentary lifestyles and calorie-dense foods with larger portion sizes. Carbohydrates themselves are not inherently fattening.

Dietary carbohydrates can be classified into simple sugars (monosaccharides and disaccharides), complex sugars (polysaccharides), and fiber. Glucose and fructose are the main monosaccharides found in food. Glucose is abundant in fruits, sweet corn, corn syrup, and honey, while free fructose is present in honey and fruits like apples.

High-fructose corn syrup (HFCS) is produced by enzymatically converting glucose into fructose in corn syrups, which are then mixed with pure corn syrup to achieve desired sweetness. In the United States, HFCS 55 (containing 55% fructose and 42% glucose) is commonly used as a substitute for sucrose in beverages, including soft drinks, while HFCS 42 is used in processed foods. The composition and metabolism of HFCS and sucrose are similar, with the main distinction being that HFCS is consumed as a mixture of monosaccharides. Studies have generally shown no significant difference in postprandial glucose or insulin responses between meals containing sucrose or HFCS. It is worth noting that while the use of HFCS has increased in parallel with obesity rates, a causal relationship has not been proven.

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5. Dietary cholesterol: Cholesterol is found only in animal products. The effect of dietary cholesterol on plasma cholesterol (Fig. 27.14) is less important than the amount and types of fatty acids consumed. Many experts recommend ≤300 mg/day. However, having an upper limit has become controversial.
concentrations to an increase in dietary cholesterol intake.
C. Other dietary factors affecting coronary heart disease
Moderate consumption of alcohol (up to 1 drink/day for women and up to 2 drinks/day for men) decreases the risk of CHD, because there is a positive correlation between moderate alcohol (ethanol) consumption and the plasma concentration of HDL-C. However, because of the potential dangers of alcohol abuse, health professionals are reluctant to recommend increased alcohol consumption to their patients. Red wine may provide cardioprotective benefits in addition to those resulting from its alcohol content (for example, red wine contains phenolic compounds that inhibit lipoprotein oxidation; see p. 235). [Note: These antioxidants are also present in raisins and grape juice.] Figure 27.15 summarizes the effects of dietary fats. [Note: Recent studies (including meta-analyses) have raised questions concerning the current guidelines for dietary fat in the prevention of CHD.]
VI. DIETARY CARBOHYDRATES
The primary role of dietary carbohydrates is to provide energy. Although self-reported caloric intake in the United States peaked in 2003 and is now declining, the incidence of obesity has dramatically increased (see p. 349). During this same period, carbohydrate consumption has significantly increased (as fat consumption decreased), leading some observers to link obesity with carbohydrate consumption. However, obesity has also been related to increasingly inactive lifestyles and to calorie-dense foods served in expanded portion size. Carbohydrates are not inherently fattening.
A. Classification
Dietary carbohydrates are classified as simple sugars (monosaccharides and disaccharides), complex sugars (polysaccharides), and fiber.
1. Monosaccharides: Glucose and fructose are the principal monosaccharides found in food. Glucose is abundant in fruits, sweet corn, corn syrup, and honey. Free fructose is found together with free glucose in honey and fruits (for example, apples).
a. High-fructose corn syrup: High-fructose corn syrups (HFCS) are corn syrups that have undergone enzymatic processing to convert their glucose into fructose and have then been mixed with pure corn syrup (100% glucose) to produce a desired sweetness. In the United States, HFCS 55 (containing 55% fructose and 42% glucose) is commonly used as a substitute for sucrose in beverages, including soft drinks, with HFCS 42 used in processed foods. The composition and metabolism of HFCS and sucrose are similar, the major difference being that HFCS is ingested as a mixture of monosaccharides (Fig. 27.16). Most studies have shown no significant difference between sucrose and HFCS meals in either postprandial glucose or insulin responses. [Note: The rise in the use of HFCS parallels the rise in obesity, but a causal relationship has not been demonstrated.] (B) leads to absorption of glucose plus fructose.
2.