Proteins and Amino Acids: Function Follows Form

BIOL 103, Chapter 7-2

Today’s Topics

• Proteins in the Diet• The Pros and Cons of Vegetarian Eating• The Health Effects of Eating Too Little or Too

Much Protein

Proteins in the Diet• Recommended protein intake– Adult RDA = _________________________– __________ have highest needs relative to body

weight• Why? ___________________________________

• Physical stress ___________ your body’s needs for proteins– Infection, burns, fevers, surgery, intensive weight

training• Consumption in the US– Generally within or higher than recommended range

Problem Set 7, Question 1:

• How is it that our bodies are able to synthesize so many proteins in our body when our dietary protein requirement is relatively low?

Protein Quality

• Protein Quality– Complete proteins: supply _____ essential amino

acids• ________________________• Examples: animal proteins, soy proteins

– Incomplete proteins: _______________ essential amino acids• ________________________• Examples: most plant proteins

Protein Quality

• Incomplete and Complementary Proteins– Except soy, proteins in other plant foods is

incomplete (lacks 1 or more essential AA).– _________ incomplete complementary proteins =

___________________• Examples: rice and beans, peanut butter and bread,

pea soup with crackers, corn and tortilla.

Evaluating Protein Quality

• A high-quality protein:1. Provides ______________________ at amounts the

body needs2. Provides __________________________

________________________for making non-essential amino acids

3. Easy to ____________4. Protein digestibility-corrected amino acid score

(PDCASS): measure of protein quality that takes account the AA composition of the food and the digestibility of the protein.

Proteins and Amino Acids as Additives and Supplements

• Protein and AA additives– Contribute to

• Protein and AA supplements– Used for a variety of

reasons: dieters, athletes, certain diseases.

– Risks are unknown

Vegetarian vs. Vegan

Vegetarian• ___________________• Don’t Eat: • Types:

– Ovo-vegetarian: – Lacto-vegetarian:

• Products: Don’t mind using animal-derived products.

Vegan• ______________________• Don’t Eat: • Products: Avoids using

______________________ ________ including clothing, cosmetics, household, foods.

Pros and Cons of Vegetarian EatingProblem Set 7, Question 4

Health Benefits• Less ___________________• More magnesium, folate• More _________________• More _________________

______________________• Reduces risk for heart

disease, hypertension, and cancer.

Health Risks• Vegans may be low in:

calcium, iron, zinc, vitamin D, vitamin B12

• Higher intake of _________• More restrictive food

choices = _______________

The Pros and Cons of Vegetarian Eating

• Diet recommendations (pg. 258):1. Choose a variety of foods2. Choose whole, unrefined foods3. Choose a variety of fruits and vegetables4. Choose lower-fat dairy products and eggs in

moderation5. Consume a regular source of vitamins B12 and D• Fortified foods or supplements

The Health Effects of Too Little Protein

• Dietary protein = essential amino acids• Protein deficiency: ______________________

________________________• ________________________________– Kwashiorkor: _______________________• Symptoms: _____________, poor growth, bloated belly• Affects those between age of 18-24 months old• Associated with extreme poverty

The Health Effects of Too Little Protein

• PEM, cont.– Marasmus: _____________________________• Chronic PEM; “withering”• Affects Infants and 6-18 months old children• Usually the children are _____________ for their age

• How to treat?– Nutritional rehabilitation• Gradual and careful refeeding• Must start with fluid and electrolyte balance, then

introduce nutrients

The Health Effects of Too Much Proteins

The Health Effects of Too Much Proteins

1. Strains kidney function– Too much protein overwhelms kidneys, which

need to excrete products of protein breakdown

2. Obesity– Too much protein, becomes fat.– May alter ________________

______________ ______________________

The Health Effects of Too Much Proteins

4. Heart disease– If you eat too much ________________

increased saturated fat and cholesterol intake

5. Cancer– Increased risk for certain types of cancer if you

eat red meat• Example: animal protein/pork/beef and colon cancer

Problem Set 7, Q5

• Name two health effects related to consuming a very high protein diet.