chapter 6 thinking about fruits and vegetables in a very different way

Chapter 6

Thinking About Fruits and Vegetables in a Very Different

Way

In all things of nature there is something of the marvelous

Aristotle

As impressive as the benefits of whole grains are, the benefits of eating fruits and vegetables are even greater.

Fruits and vegetables are the real phytochemical power houses.

One serving of vegetables or fruits can have 100’s of different phytochemicals

Different fruits and vegetables have different phytochemicals. Eating a variety is the best way to get all of them.

Common Phytochemicals

Carotenoids Beta-carotene Lycopene Lutein Zeaxanthin Organosulfurs Flavinoids

Phytosterols Alkaloids Tannins Saponins And many, many

others

Here are some pictures of some phytochemicals

para-coumaric acid

Copy right by Michael Davidsonhttp://micro.magnet.fsu.edu/index.htmlOptical microscopy techniques

para-coumaric acid

Saponin

Zeaxanthin

ajoene

Calcium Pectate

Lung cancer and vegetable intake

-0.3

0.2

0.7

1.2

1.7

2.2

2.7

0 100 200 300 400 500

Vegetable intake grams/day

Rel

ativ

e ri

sk

Am Inst for Cancer Research, 1997

Stomach cancer and vegetable intake

-0.3

0.2

0.7

1.2

1.7

2.2

2.7

0 100 200 300 400 500

Vegetable intake grams/day

Rel

ativ

e ri

sk

Am Inst for Cancer Research, 1997

Stomach cancer and fruit intake

0.4

0.6

0.8

1

1.2

1.4

0 100 200 300 400 500

Fruit intake grams/day

Rel

ativ

e ri

sk

Am Inst for Cancer Research, 1997

So why are fruits and vegetables so important?

Free Radicals are oxygen atoms that are missing an electron

Where do free radicals come from?

Most are produced by our own bodies UV light burned food toxic chemicals Industrial automobile pollution unknown sources

Cigarette Smoke

One puff of smoke contains:

100,000,000,000,000,000

free radical species

Tobacco is responsible for 31% of all cancers

If you are a smoker your life will be shortened by 13 years on

average

74.479.8

61.2

65.3

55

60

65

70

75

80

US Mean Smokers

Males FemalesMMWR 1997;46:444-51

-13.2 yrs

-14.5 yrs

If one free radical steals an electron from a strand of DNA, a mutation or cancer has started.

Most of these abnormal cells are destroyed by our own bodies.

It only takes one to slip through our defenses for a cancer to take over

Each cell gets 10,000 free radical attacks every day

How do we protect our selves?

Eat more fruits, vegetables, and whole grains.

Some phytochemicals are also anti-free radicals (anti–oxidants). They have the ability to donate an electron to a free radical with out harming itself. It’s kind of like having a spare electron.

The Typical American (Western) Diet: What most

Americans Eat

Red meat Processed meat Butter Potatoes Refined grains High fat dairy foods

There are few phytochemicals here

What we should be eating if we want the health

benefits

In 2001, 553,768 Americans died of cancer. Of these deaths, 387,637 (70%) could have been prevented with good nutrition, physical activity, and avoiding tobacco

Over 230 different studies have evaluated the impact of fruits and vegetables on cancer. Fruits and vegetables help prevent cancers of the stomach, esophagus, lung, oral cavity, pharynx, endometrium, pancreas, and colon

When the people who consumed the most fruits and vegetables were compared to those who ate the least, they had half the cancer risk.

The Cancer Process

Normalcell

Abnormalcell

Spontaneous or inherited mutation

Carcinogen

Cell proliferation

TumorMetastasis

Repair

Where fruits, vegetables, and whole grains can stop the cancer

process

Normalcell

Abnormalcell

Spontaneous or inherited mutation

Activatedcarcinogen

Cell proliferation

TumorMetastasis

Repair

An Apple a day (with the skin)

0.09

0.29

0.49

0.69

0.89

1.09

0 8 10 11 12 15 19 20 26 30 40 50 75 100

peel

peel+flesh

flesh

concentration

Can

cer

cell

spre

adin

g

Sun, J Agric Food Chem 2002:50:7449

Why not just make a pill that contains

phytochemicals?

The pill will never contain all the same phytochemicals because we still don’t even know what they are

Phytochemicals don’t work all by themselves. They need the other chemicals with them.

The phytochemicals only appear to work when they are in their natural food, not a pill

The dosages may be too high

Some of the pills are very dangerous

Randomized clinical trial with 18,000 smokers and former smokers

30 mg of beta-carotene plus vitamin A Followed for 4 years Studied terminated 2 years early

Omenn, N Engl J Med,1996, 334:(18)

Risk of Death

0.9

0.95

1

1.05

1.1

1.15

1.2

Risk of Death

Placebo

Vitamin A andbeta-carotenesupplement

Lung Cancer Death

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

Lung Cancer Death

Placebo

Vitamin A andbeta-carotenesupplement

Cardiovascular Disease Death

0.8

0.85

0.9

0.95

1

1.05

1.1

1.15

1.2

1.25

1.3

Cardiovascular Disease Death

Placebo

Vitamin A andbeta-carotenesupplement

In this and in many other studies the supplements actually increased risk

Risk of many supplements are unknown Supplement claims are unregulated. They

can say what ever they want. Consumers tend to believe the marketing

hype of supplement makers. No pill can compare with the benefits of eating

whole foods.

In other studies:

Long term supplementation with beta-carotene had no effect on preventing cancers or cardiovascular disease

What about Vitamin C?

500 mg of Vitamin C every day for 3 weeks caused more DNA damage than the placebo group

Vitamin C has no effect on cancer, cardiovascular disease

Vitamin E

Long-term supplementation with Vitamin E revealed no prevention of CVD, stroke, or cancers

Blot, 1993; Stephens, 1996

What about a one-a-day vitamin?

Some experts say there is no harm in this, but neither is there any evidence that it improves health

If you are not going to eat a good diet, a one-a-day vitamin probably wouldn’t do any harm

Points to Remember

Americans get suckered in to supplement makers claims. Don’t get suckered in.

Our understanding of the functions of phytochemicals and free radicals is very limited.

Everyday the DNA in our cells gets attached 10,000 times by free radicals. Phytochemicals can neutralize free radicals and help prevent cancer.

Continued….

Eating at least five or more servings of fruits and/or vegetables everyday provides significant protection against many cancers and other diseases; even more servings per day is better.

Whole foods are incredibly complex. Scientists are just beginning to figure out how our bodies use everything that is in the food we eat.

Consuming individual phytochemicals in supplements is not recommended; eat whole foods.