Bio 108 Lecture 1:  How do people use plants?

                Think                                                           Pair                                    Share
 How do people use plants?
1. How many different ways do people use plants?  Here are a few categories and plants to get you started.  How many ways can you find?
 

2.  Plants as Food   

        Plants provide directly (eat the plant) or indirectly (eat the cow that ate the plant) all the food we eat.

        Does direct consumption of  plants provide most of the calories people eat?  How does the U.S. compare with developing nations which are poorer?  What about the amount of protein people get from plants?

        Answer these question based on the table below.
 

	Calories directly from plants	Protein directly from plants
US & Western Europe	65%	35%
Developing Nations (e.g., Mexico,India)	90%	80%

        What is the cause of the difference between the U.S. and Mexico?  The US eats far more __________.  This is because ________________.

 3.  Ten plants that feed the world (Chapters 12,13,14)
 
   Fig. 12.1  shows world crop production data from 2005.  Here are the top 10 plants farmers harvest.

Common Name	Amount produced per year (Millions of Metric tons)	Plant part	Grass, Legume  Starchy Staple, or Neither?	Comment
Corn (maize) .	711	fruit called grain		90% used for animal feed in U.S. Fig. 12.6
Wheat	630	fruit called grain		Fig. 12.4
Rice	621	fruit called grain		Fig. 12.11
White potato	324	tuber (enlarged tip of rhizome)		Fig. 14.4
Soybean	213	fruit called pod		Adds nitrogen to soil using root nodules (fig 13.2)
Cassava	213	tuberous roots		Fig. 14.6. Poisonous if incorrectly prepared
Palm fruit	172	fruit		Box 13.2  Unhealthy vegetable oil--saturated fat
Barley	139	fruit called grain		Beer!
Sugar producers listed below:
Sugar cane	1,285	stem		In Brazil, used for ethanol fuel
Sugar beet	251	root		I have put the sugar producing plants separately. Food???

"With the world's population growing by about 2 percent annually, there are 80 million more mouths to feed each year.  Just three crops--rice, wheat, and corn--provide 49% of the calories that people consume."   These plants are all in the grass family.

                                                                          Janet Raloff, Science News, August 16, 1997

• What 3 plants provide half the calories that feed the world?__________________
• What family are these 3 plants in? ________________
• Corn is the number one crop in the U.S.  What is 90% used for?______________

Look at the chart below.  How has the percent of people in the U.S. living on farms changed over the past 200 years?  ______

What technologies have made this possible? (p. 236-242)

____________________________________________________

Read about the Gulf of Mexico "dead zone" and how this is related to agricultural fertilizers.

On a more local level, high nitrogen levels can contaminate groundwater in shallow wells and are especially dangerous for babies.

4.  Vegetarian diet (p. 170-175)

    a.  Vegetarians have lower rates of
            Heart disease
            Colon cancer
            Breast cancer
            Obesity
            Osteoporosis (brittle bones)

            (and many more)

    b.  Vegetarians could be 2 types
        1) Lacto-ova vegetarians: Eat milk and eggs
        2) Vegans:  No animal products (this is VERY difficult!)

    c. Vegetarian diets are healthier because:

            1) lower in animal fats

            2) higher in the vitamins and nutrients contained in plants. 

CAUTION: Pregnant women and children should talk to a professional nutritionist before starting a vegetarian diet.

Many new compounds are being discovered each day.  Here are a few:

Food	Product	Prevents
tomatoes	lycopenes	prostate cancer
carrots	carotene	antioxidant that prevents cell damage linked to aging
broccoli            Box 10.2 p.174

5. USDA "My pyramid": Go the My Pyramid web site and see what you should be eating (fig. 10.5). 

   "My pyramid" above courtesy of USDA (United States Department of Agriculture)

                                                 
 
 6. The  healthy eating pyramid developed by the Harvard School of Public Health offers a negative critique of the USDA's food pyramid and suggests these guidelines:
 Summary of the Healthy Eating Pyramid from Harvard School of Public Health:

Food group	Servings
Red meat, butter	Use sparingly
White rice, white bread, potatoes, pasta and sweets	Use sparingly
Alcoholic drinks	In moderation (1 drink per day)
Dairy or calcium supplement	1-2 times per day
Fish, poultry, eggs	0-2 times per day
Nuts, legumes	1-3 times per day
Vegetables	in abundance
Fruits	2-3 times per day
Whole grain foods	at most meals
Plant oils (includes olive, canola, soy, corn, sunflower, peanut)	daily
Exercise (not a food!)	daily
Multiple vitamin (not a food!)	daily

Exercise:  Compare the USDA My pyramid to Harvard's healthy eating pyramid.

Compare	USDA My pyramid	Harvard School of Public Health Healthy Eating Pyramid
Red meat
Beans (legumes)
Grains (whole vs. refined)
Exercise (physical activity)
Dairy
Oils
Red wine and vitamins
Which pyramid do you think is healthier? (Or perhaps you have other ideas?)

 7.  Compare fast food to a healthy, vegetarian meal.  Which would fill you up more?  Explain your answer.

    

Burger King Meal	Vegetarian stir fry
Whopper 780 Cal	Brown rice (1 cup)  215 Calories
Fries (medium) 360 Cal	Kidney beans (1 cup) 250 Calories
Coke (medium) 230 Cal	Carrots (1 cup) 40 Cal
Total 1,370	Cabbage (1 cup) 17 Cal
Note: An average man, age 19-25, might use 2,900 Calories per day	Spinach (1 cup) 22 Cal
An average woman, age 19-25, might use 2,200 Calories per day	Cashews (1/2 cup)  280 Cal
	Apple (1) 50 Cal
	Tomato juice (1 cup) 41 Cal
	Total 915 Cal

 9. Tips on how to lose weight (see "Balanced Nutritional Requirements" p. 171)

• Consume fewer calories than expended. 
• Eat foods that have lots of bulk (fresh fruits, fresh vegetables, soups like pea & bean) but are low in calories (low in meat and fat). This idea comes from the book "Volumetrics" by Barbara Rolls. based on her research on human eating behavior. Dr. Rolls claims that people tend to eat the same amount of food each day by weight, so you should eat more foods that have low calorie-density (calories per weight of the food).
• Exercise to increase muscle mass.  Maintaining muscle tissue consumes calories

10. Glycemic index p. 173 or GI is the latest dietary idea that is gaining popularity. GI measures how fast a food is broken down into blood glucose.  Foods broken down more quickly like sugar and white bread are considered unhealthy while those broken down more slowly like fruits, vegetables and whole grains (for example, whole wheat bread) are considered healthier.

11. Other interesting books related to what we eat

    a. Omnivore's Dilemma by Michael Pollan.  What should we eat?  Pollan traces back food you buy in the grocery store to see how it is grown and raised.

    b. Coming Home to Eat by Gary Nabhan.  The Locovore Movement suggests that we eat locally grown food.  Nabhan spends a year eating food grown in a 200 mile radius of Tucson.

    c. Waistland by Deirdre Barrett.  Our ancestors were Hunter-Gatherers, not farmers.  Is wild meat, nuts and berries the optimal diet?  And has our reliance on cereal grains caused the obesity epidemic?

    d. The End of Overeating by David Kessler.  The former head of the FDA describes what restaurants do to sell food: Sugar, Fat, and Salt. A detailed account of what NOT to eat.

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