Presentation on theme: "Chapter 6 Thinking About Fruits and Vegetables in a Very Different Way."— Presentation transcript:
Chapter 6 Thinking About Fruits and Vegetables in a Very Different Way
In all things of nature there is something of the marvelous Aristotle
l As impressive as the benefits of whole grains are, the benefits of eating fruits and vegetables are even greater.
l Fruits and vegetables are the real phytochemical power houses. l One serving of vegetables or fruits can have 100s of different phytochemicals l Different fruits and vegetables have different phytochemicals. Eating a variety is the best way to get all of them.
Common Phytochemicals l Carotenoids l Beta-carotene l Lycopene l Lutein l Zeaxanthin l Organosulfurs l Flavinoids l Phytosterols l Alkaloids l Tannins l Saponins l And many, many others
l Here are some pictures of some phytochemicals
para-coumaric acid Copy right by Michael Davidson Optical microscopy techniques
Lung cancer and vegetable intake Vegetable intake grams/day Relative risk Am Inst for Cancer Research, 1997
Stomach cancer and vegetable intake Vegetable intake grams/day Relative risk Am Inst for Cancer Research, 1997
Stomach cancer and fruit intake Fruit intake grams/day Relative risk Am Inst for Cancer Research, 1997
l So why are fruits and vegetables so important?
Free Radicals are oxygen atoms that are missing an electron
Where do free radicals come from? l Most are produced by our own bodies l UV light l burned food l toxic chemicals l Industrial l automobile pollution l 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 MMWR 1997;46: yrs yrs
l If one free radical steals an electron from a strand of DNA, a mutation or cancer has started. l Most of these abnormal cells are destroyed by our own bodies. l It only takes one to slip through our defenses for a cancer to take over
l 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. Its kind of like having a spare electron.
The Typical American (Western) Diet: What most Americans Eat l Red meat l Processed meat l Butter l Potatoes l Refined grains l High fat dairy foods There are few phytochemicals here
What we should be eating if we want the health benefits
l 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
l 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
l 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
Normal cell Abnormal cell Spontaneous or inherited mutation Carcinogen Cell proliferation Tumor Metastasis Repair
Where fruits, vegetables, and whole grains can stop the cancer process
Normal cell Abnormal cell Spontaneous or inherited mutation Activated carcinogen Cell proliferation Tumor Metastasis Repair
An Apple a day (with the skin) peel +flesh flesh concentration Cancer cell spreading Sun, J Agric Food Chem 2002:50:7449
Why not just make a pill that contains phytochemicals? l The pill will never contain all the same phytochemicals because we still dont even know what they are l Phytochemicals dont work all by themselves. They need the other chemicals with them. l The phytochemicals only appear to work when they are in their natural food, not a pill l The dosages may be too high
Some of the pills are very dangerous l Randomized clinical trial with 18,000 smokers and former smokers l 30 mg of beta-carotene plus vitamin A l Followed for 4 years l Studied terminated 2 years early Omenn, N Engl J Med,1996, 334:(18)
Risk of Death
Lung Cancer Death
Cardiovascular Disease Death
l In this and in many other studies the supplements actually increased risk l Risk of many supplements are unknown l Supplement claims are unregulated. They can say what ever they want. l Consumers tend to believe the marketing hype of supplement makers. l No pill can compare with the benefits of eating whole foods.
In other studies: l Long term supplementation with beta- carotene had no effect on preventing cancers or cardiovascular disease
What about Vitamin C? l 500 mg of Vitamin C every day for 3 weeks caused more DNA damage than the placebo group l Vitamin C has no effect on cancer, cardiovascular disease
Vitamin E l 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? l Some experts say there is no harm in this, but neither is there any evidence that it improves health l If you are not going to eat a good diet, a one-a-day vitamin probably wouldnt do any harm
Points to Remember l Americans get suckered in to supplement makers claims. Dont get suckered in. l Our understanding of the functions of phytochemicals and free radicals is very limited. l Everyday the DNA in our cells gets attached 10,000 times by free radicals. Phytochemicals can neutralize free radicals and help prevent cancer.
Continued…. l 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. l Whole foods are incredibly complex. Scientists are just beginning to figure out how our bodies use everything that is in the food we eat. l Consuming individual phytochemicals in supplements is not recommended; eat whole foods.