In a recent review published in The New England Journal of Medicine, researchers presented modern nutritional ideas, emphasizing calorie and macronutrient intake.
Poor dietary intake is a primary contributory factor for chronic illness among United States (US) adults and the top modifiable cause. Suboptimal diets account for considerable global mortality. Interventions based on food as medicine are increasingly being investigated as a strategy to prevent and treat various chronic disorders. Unlike conventionally licensed drugs with well-defined molecular targets, dietary intake includes various food elements with actions spaced throughout the lifespan. Providing suggestions to patients, particularly those with comorbidities, on the type and quantity of foods to consume is more complicated than health professionals' advice.
In the present review, researchers described the role of macronutrients such as carbohydrates, proteins, and fats in health and well-being.
Guidance on Energy and Macronutrients across the Life Span. Image Credit: Lightspring / Shutterstock
Dietary Macronutrients and Their Recommended Dietary Allowances
After digestive processes and nutrient absorption, proteins, carbohydrates, and fats release metabolic substrates such as amino acids, glycerol, free fatty acid molecules, and glucose. The substrates can replace proteins in lean tissues, triglycerides in fatty tissues, and glycogen stores, which are catabolized in the body while providing energy for biochemical activities. Energy-producing processes take oxygen and emit carbon dioxide, heat, and water. All calories in macronutrients consumed are not accessible to the body.
The average net digestion losses from mixed meals are 2.0%, 5.0%, and 8% for carbohydrates, fat, and protein, respectively. Adult recommended daily allowances (RDAs) are 130 g/day of carbohydrates, 0.8 g/kg/day of protein, 14 g/1,000 kcal/day of total fiber, and 2.7 to 3.7 liters/day. Carbohydrates comprise sugars and starches, whereas total fiber is the sum of dietary and functional fiber. Pregnant and nursing women have higher RDA values, whereas physically active or exposed to hot settings necessitate greater total water intake.
Energy balance is essential for maintaining a steady weight in animals and humans. Proteins, derived from amino acids, are human beings' primary structural and functional components. Animal sources include all nine essential amino acids, but plant proteins are typically lacking. Graded protein sources include cow milk, meat, eggs, rice, and soy protein. Eating plant-based meals allows vegetarians and vegans to meet their protein requirements. Nutritionists assess protein needs using nitrogen-balance techniques, with healthy young individuals requiring 0.6 g/kg body weight daily.
Insufficient energy intake from fats and carbohydrates might result in a negative nitrogen balance. The human body fat is primarily composed of triglycerides. Saturated fatty acids are sourced from animals, whereas cis-unsaturated fatty acids come from plants. Two essential fatty acids, linoleic and α-linolenic, promote development and avoid symptoms. Higher levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are associated with a decreased risk of cardiovascular disease.
The human diet comprises sugars and carbohydrates, and excessive sugar consumption is associated with excess energy, poor food quality, weight gain, and obesity. Fibers, nondigestible plant carbs, and lignin are critical for better glycemic management, laxation, and weight reduction. High fiber consumption lowers the risk of non-communicable illnesses and death.
Macronutrient Components of typical US diets and healthy USDA dietary patterns
Healthy eating habits are vital for preserving health and reducing the risk of chronic illnesses. A balanced diet includes vegetables, fruits, grains, dairy, protein foods, and oils. These eating patterns are linked to lower any-cause mortality and include less processed and red meat, refined carbohydrates, sweets, and high-fat dairy.
Meal patterns contain the five dietary groups (vegetables, fruits, grains, proteins, and dairy). To achieve macronutrient requirements, nutrient-dense meals and beverages with negligible added sugars and saturated fats are advised. Adults should consume between 10% and 35% of their calories from protein, 20% and 35% from fat, and 45% and 65% from carbohydrates. The typical US diet contains 2,144 calories, 81 grams of protein, 244 grams of carbohydrates, 88 grams of fat, and 17 grams of dietary fiber. The typical US diet contains polyunsaturated fats such as linoleic acid (18g) and α-linolenic acid (1.9g).
The US Department of Agriculture's (USDA) healthy diet patterns include Mediterranean and vegetarian diets. The Mediterranean diet has 1,998 kcal of calories, 89 g of protein, 259 g of carbs, 31 g of dietary fiber, and 72 g of fat. The vegetarian diet has 1,999 kcal of calories, 71 g of protein, 274 g of carbs, 35 g of dietary fiber, and 75 g of fat. Alcohol contributes to daily calorie consumption, but limiting alcohol intake benefits health.
Based on the review findings, the quantity and type of foods consumed are crucial drivers of growth, development, and health sustenance throughout life. Macronutrient components drive these processes. Recognizing their importance is critical for delivering appropriate treatment to all patients, particularly the growing number of individuals with disorders in which nutritional components play an essential role in pathophysiology.
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