Nutrition - Chapter 3

What is the primary function of proteins in the body?

Proteins serve as structural components of cells, perform metabolic reactions, transport molecules, act as enzymes, hormones, and antibodies, and help maintain satiety.

How many common amino acids are there?

There are 20 common amino acids.

What is a peptide?

A peptide is one or more amino acids linked together in chains; a dipeptide has 2 amino acids, a tripeptide has 3, and a polypeptide has 10 or more.

What are the two groups of amino acids?

Amino acids are classified into nonessential and essential groups.

What are nonessential amino acids?

Nonessential amino acids can be synthesized by the body from available simple molecules and other amino acids.

What are essential amino acids?

Essential amino acids cannot be synthesized in adequate amounts and must be obtained from dietary sources.

What are conditionally essential amino acids?

Conditionally essential amino acids are those that may become essential under certain physiological conditions.

What is a limiting amino acid?

A limiting amino acid is an essential amino acid found in the smallest quantity in a food source.

What are complete proteins?

Complete proteins contain all 9 essential amino acids in the correct amounts needed by humans, typically found in animal proteins and soy.

What are incomplete proteins?

Incomplete proteins lack sufficient amounts of one or more essential amino acids, commonly found in plant sources.

What are complementary proteins?

Complementary proteins are proteins from different sources that, when combined, form a complete protein.

What is the Recommended Dietary Allowance (RDA) for protein for adults?

The RDA for adults is 0.8 g/kg body weight per day, approximately 56 g for men and 46 g for women.

What is nitrogen balance?

Nitrogen balance is the difference between nitrogen intake and nitrogen loss; it can be positive, negative, or in equilibrium.

What happens during a negative nitrogen balance?

In a negative nitrogen balance, nitrogen intake is less than nitrogen loss, which can lead to muscle breakdown and loss of body mass.

What is protein malnutrition?

Protein malnutrition includes conditions like Kwashiorkor and Marasmus, resulting from inadequate protein intake.

What are the symptoms of Kwashiorkor?

Symptoms of Kwashiorkor include edema, hair discoloration, altered skin pigmentation, anemia, and increased susceptibility to infection.

What are the symptoms of Marasmus?

Symptoms of Marasmus include extreme hunger, irritability, emaciation, and loss of fat stores due to inadequate caloric intake.

What dietary considerations are important for individuals with Phenylketonuria (PKU)?

Individuals with PKU must follow a low-phenylalanine diet, limit high-protein foods, and consume special dietary supplements.

What are some potential health benefits of vegetarian diets?

Vegetarian diets may lead to lower intake of saturated fat and cholesterol, increased intake of fiber, and reduced mortality from certain heart diseases.

What are common concerns for vegetarians regarding nutrient intake?

Vegetarians may have low levels of iron, zinc, vitamin B12, vitamin D, calcium, and omega-3 and omega-6 fatty acids.

What is the role of proteins in maintaining fluid balance?

Proteins, such as albumin, help pull fluid into capillaries, counteracting blood pressure and preventing conditions like edema.

What is the Acceptable Macronutrient Distribution Range (AMDR) for protein?

The AMDR for protein is 10-35% of total daily calories.

What factors can increase protein requirements?

Increased protein requirements occur during pregnancy, infancy, childhood, and in cases of injury or stress.

What is the impact of inadequate energy intake on protein use?

When energy intake from carbohydrates or fats is inadequate, the body uses protein as an energy source, leading to muscle tissue breakdown.

What are some examples of complementary protein meals?

Examples include legumes with grains, such as hummus with whole-wheat pita or beans with rice.

What is the average protein intake for adults aged 19-30?

The average protein intake for adults aged 19-30 is approximately 91 g per day.

What is the average protein intake for older adults?

The average protein intake for older adults is approximately 66 g per day.

What are the dietary implications of vegetarianism?

Vegetarians should ensure they consume a variety of complementary proteins and may need to take supplements to meet micronutrient needs.