Nutrition Chapter 6 : Proteins, Amino Acids, and Vegetarian Diet

Complete protein

all 9 of the essential aa, along with some of the 11 nonessential aa.

Vegetarian = a person who does not eat meat, fish, poultry, or (sometimes) food products made from these.

1. 3% of American adults follow a vegetarian diet. 2. The vegetarian food market is a $1.5 billion industry. 3. Most sit-down restaurants and even some fast-food restaurants offer vegetarian options on their menus.

A high-quality protein determined by:

1. Body's ability to digest the protein (the protein's digestibility) 2. Types and amounts of amino acids (essential, nonessential, or both)

Reasons for Choosing a Vegetarian Diet

1. Compassion for animals: Many people deplore the treatmentof farm animals. 2. Religious convictions: Buddhism and Hinduism, forbid or discourage consumption of animal-based foods. 3. Financial constraints: Meat, poultry, and fish are relatively expensive foods and consumption of them is associated with wealth.

Plant proteins "upgraded" to complete proteins by:

1. Consuming modest amounts of soy or animal protein, or 2. Being complemented with other plant proteins which provide enough of the limiting amino acid

Proteins : are the predominant structural and functional materials in every cell

1. Contain carbon, hydrogen, oxygen (like carbohydrates and fats) 2. Also contain nitrogen 3. Each amino acid has: Acid group (COOH), Amine group (NH2), and Side chain (unique) 4. All proteins consist of some combination of 20 unique amino acids

Eating Too Little Protein Can Lead toPoor Bone Health and Malnutrition

1. Kwashiorkor: severe deficiency of dietary protein Signs: edema, muscle loss, skin rashes, hair changes, water and electrolyte imbalances 2. Marasmus: severe deficiency of calories Signs: emaciation, lack of growth, loss of fat stores 3. Marasmic Kwashiorkor: worst of both conditions 4. Medical treatment and food: three-step approach

Eating too much protein:

1. May increase risk of heart disease, kidney stones, calcium loss from bones 2. Can displace other nutrient- and fiber-rich foods associated with a reduced risk of chronic diseases: *Whole grains, fruits, vegetables

You Can Determine Your Personal Protein Needs

1. Protein recommendations (DRI): 10 to 35 percent of total daily calories from protein *Average intake in the United States = 15 percent 0.8 g of protein/kg of body weight needed daily 2. Calculating your daily protein needs: Convert weight to pounds by dividing by 2.2 lbs/kg: * If you weigh: 130 lbs ÷ 2.2 = 59 kg 59 kg X 0.8 g = 47 g of protein/day

How Does Your Body Use Proteins?

1. Proteins help maintain acid-base balance: Buffers: substances that help maintain the proper pH in a solution by attracting or donating hydrogen ions 2. Proteins transport substances throughout the body: Transport proteins shuttle oxygen, waste products, lipids, some vitamins, and sodium and potassium through your blood and into and out of cells through cell membranes 3. Proteins contribute to a healthy immune system: Specialized protein "soldiers" called antibodies eliminate potentially harmful substances 4. Proteins can provide energy 5. Protein improves satiety and appetite control

How Does Your Body Use Proteins?

1. Proteins provide structural and mechanical support and help maintain body tissues: 1. Collagen: a ropelike, fibrous protein that is the most abundant protein in your body 2. Connective tissue: the most abundant tissue type in the body; made up primarily of collagen, it supports and connects body parts as well as provides protection and insulation *Proteins build most enzymes and many hormones *Proteins help maintain fluid balance

Concerns about Consuming Adequate Amounts of Vitamin B12

1. Vitamin B12 is derived only from food of animal origin. 2. Deficiency is less of a risk for lacto-ovo-vegetarians. 3. The ADA recommends that vegetarians and vegans consume at least three good food sources of vitamin B12 daily, such as: Eggs,Cow's milk, yogurt, or cheese, Vitamin B12-fortified soy milk, breakfast cereal, or nutritional yeast

Incomplete protein

A protein that is low in one or more of the essential aa.

Building Proteins from Amino Acids

Amino acids are joined by peptide bonds: 1. Dipeptide: two amino acids joined, 2. Tripeptide: three amino acids joined, 3. Polypeptide: many amino acids joined together *Proteins typically consist of 100 to 1,000 amino acids in a specific sequence. *Fold into a distinct 3-D shape based on the interaction of the side chains with each other and the environment: 1. Hydrophobic side chains cluster to the interior 2. Hydrophilic side chains assemble on the outside surface. *The shape of a protein determines its function in the body.

Potential Benefits and Risks of Vegetarian Diets

Benefits: 1. May reduce risk of heart disease, high blood pressure, diabetes, cancer, stroke, and obesity 2. Vegetarian diet food staples are rich in fiber, low in saturated fat and cholesterol

Here's an example menu for a balanced day. You just want a small amount of protein with each meal and you're covered:

Breakfast:2 egg omelet with 2 tablespoons shredded cheese1 slice whole grain toast Morning Snack:Apple with 1 tablespoon peanut butter Lunch:3 ounces grilled chicken breast on 2 slices whole-wheat bread with lettuce, tomato and 2 tablespoons hummus Afternoon Snack:6 ounces non-fat yogurt1 granola bar Dinner:Tofu and Broccoli Stir Fry with 1 cup cooked brown rice Daily Total: 1,650 calories; 87 grams protein (21% of calories)

Reasons for Choosing a Vegetarian Diet

Environmental concerns: 1. Fertilizers used on feed crops, transportation of animal feed, and the energy required to maintain, process, and transport animals and animal products contribute a significant amount of carbon dioxide emissions. 2. Farm animal production contributes nearly a fifth of the world's greenhouse gases.

Reasons for Choosing a Vegetarian Diet

Health concerns: 1. Helps you maintain a healthy weight and reduce risk for certain chronic diseases 2. Concern that hormones and antibiotics fed to animals may cause health risks

How Much Protein Do You Need?

Healthy adults should be in nitrogen balance, the state in which an individual is consuming the same amount of nitrogen from protein in the diet as he or she is excreting in the urine

Essential, Nonessential, and Conditional Amino Acids

Nine essential amino acids: 1. Cannot be made by the body 2. It is "essential" to obtain them from the diet Eleven nonessential amino acids: 1. Can be synthesized in the body from other amino acids Conditionally essential amino acid: 1. Under certain conditions, some nonessential amino acids cannot be made in body

Eating too little protein: Low-protein diets associated with loss of bone mass

Protein Energy Malnutrition (PEM): 1. Inadequate calories and/or protein 2. More common in children, because they are growing 3. Factors: poverty, poor food quality, insufficient food, unsanitary living conditions, ignorance, stopping lactation (nursing) too early

You Can Determine Your Personal Protein Needs

Protein requirements determined by nitrogen balance studies Nitrogen Balance: Amount of protein consumed = amount of protein used (nitrogen excreted) 1. Nitrogen Imbalances: Positive Nitrogen Balance = more nitrogen is retained (for protein synthesis) than is excreted 2. Negative Nitrogen Balance: more nitrogen is excreted than consumed (body proteins broken down) Examples: starvation, serious injury, or illness

Your Body Degrades and Synthesizes Proteins

Protein turnover: the process of continually degrading and synthesizing protein within the body: 1. 200 grams of protein are turned over daily 2. The intestines and liver account for as much as 50 percent of turnover. *Proteins and amino acids are lost daily through sloughed-off skin, hair, nails, and intestinal cells. *Amino acid pools provide the building materials to synthesize replacement proteins and nonprotein substances such as thyroid hormones and melanin.

Potential Benefits and Risks of Vegetarian Diets

Risks: 1. Potential deficiencies of nutrients found in animal foods 2. Protein, iron, zinc, calcium, vitamin D, riboflavin, vitamins B12 and A, omega-3 fatty acids

How Do Vegetarians Meet Protein Needs?

Vegetarians can meet protein needs by consuming: 1. Variety of plant foods 2. Protein-rich meat alternatives: Soy, Dried beans and other legumes, Nuts, Eggs, dairy (lacto-ovo-vegetarians)

Your Body Degrades and Synthesizes Proteins

When amino acids are broken down, the component parts meet different fates: 1. The nitrogen forms ammonia (NH3), which is converted to urea by the liver and excreted in urine via the kidneys 2. The carbon-containing remnants are converted to glucose and used as energy or stored as fat. *Surplus amino acids from excess dietary protein can't be stored as protein, so they are stored as fat.