Transcript Getting Rich Can Kill You - Go-Med

Getting Rich Can Kill You!
A Warning to Developing Countries…
Learn from Our Mistakes!
Robin Carr, Ph.D.
3 Requirements of Science
1. Look for evidence! (Especially ‘peer-reviewed’.)
(And don’t accept just evidence that fits your theories.)
2. Don’t believe any one individual or any one scientific
finding. Assess the ‘weight’ of evidence.
3. While it’s sometimes necessary to focus on narrow
questions and specific details, always step back now
and then to see the broader picture.
Investigate the research yourself!
• PubMed Central (PMC) is the U.S. National
Institutes of Health (NIH) free digital archive of
biomedical and life sciences journal literature.
http://www.ncbi.nlm.nih.gov/pubmed/
http://www.ncbi.nlm.nih.gov/pmc/
• Abstracts are almost always provided along with the
references, and sometimes the entire article is
provided free on-line, from a provided link.
http://www.ncbi.nlm.nih.gov/pubmed/
http://www.ncbi.nlm.nih.gov/pmc/
Next…About Correlations
• A correlation is a measure of how closely
2 variables are related to each other.
• Correlations are the most frequently used tool in
epidemiological and human dietary research.
But they must be used with caution.
Example
• Did you know that a positive correlation
was found between eating ice cream
and getting divorced?
Which is the cause? Which is the effect?
Summer
Ice Cream
Divorce
Does eating more ice cream increase your risk of divorce?
Which is the cause? Which is the effect?
Ice Cream
Divorce
Or, do you eat more ice cream when you get divorced?
The answer…
Summer
Ice Cream
Divorce
Summer increases the chances of both!
When Cause & Effect is Assumed
Leg Length
Pant Length
Sometimes the context makes cause and effect obvious.
But assumptions can sometimes be wrong.
He who does not know food, how can he
understand the diseases of man?
Hippocrates, the “father of medicine” (460-357 BC)
A Story about Proteins
•
•
•
Protein is one of the basic components of food and makes all life
possible. All of the antibodies and enzymes, and many of the
hormones in the body are proteins. They provide for the transport of
nutrients, oxygen and waste throughout the body. They provide the
structure and contracting capability of muscles. They also provide
collagen to connective tissues of the body and to the tissues of the
skin, hair and nails. There are hundreds of thousands of different
kinds of protein.
20 amino acids make up protein.
1. essential amino acids (9/8) – must be included in the diet.
2. nonessential amino acids (11/12) – the body can manufacture.
For “normal” adults: 1.0 g protein / kg body mass per day.
For active athletes: 1.4 g protein / kg body mass per day.
The Amino Acids
Essential Amino Acids
(must be obtained through the diet)
Isoleucine
Leucine
Lysine
Methionine
Conditional Amino Acids
(can’t be made fast enough to
support rapid growth)
Arginine
Histidine
Nonessential Amino Acids
(can be made by the body)
Alanine
Asparagine
Aspartic Acid
Cysteine
Glutamic Acid
Phenylalanine
Threonine
Tryptophan
Valine
Glutamine
Glycine
Proline
Serine
Tyrosine
Protein in Cultural History
• In the 19th century, protein was synonymous with meat.
• Early scientists like the German Carl Voit (1831-1908) found that
“man” needed only 48.5 grams/day, but he recommended 118
grams/day. (If something is good, more is better!)
• Well-known nutrition researcher Max Rubner stated that
protein intake (meaning meat) was a symbol of civilization.
“A large protein allowance is the right of civilized man.”
• The cultural bias was set. If you were rich, you ate meat. If you
were poor, you ate staple plant foods like potatoes and bread.
The “Protein Gap”
• In the 1960’s and 1970’s, it was constantly asserted that there
was a “protein gap” in the developing world.
• M. Autret of the Food and Agriculture Organization (FAO) of the
United Nations reported a very strong association (correlation)
between the consumption of animal-based foods and annual
income, and he implied causation.
AnimalBased
Foods
?
Annual
Income
Increases
What else could explain the association (correlation)?
A More Realistic Explanation!
AnimalBased
Foods
Annual
Income
Increases
Philippine Connection
• In 1967, while on the faculty at Virginia Tech, Dr. T. Colin Campbell
began working on a ten-year project in the Philippines (funded by the
U.S. Agency for International Development) to improve childhood
nutrition among the poor.
• Ultimately, 110 nutrition “mothercraft” self-help education centers
were established around the country, focussed on educating mothers
of malnourished children about healthy “local” foods.
• The aim was to make sure that children of the poor were getting as
much protein as possible, since there was a perceived “protein gap”
in the developing world.
Protein and Cancer?
• Part of this project involved investigating the high prevalence of
liver cancer, usually an adult disease, in Filipino children. It was
thought to be caused by aflatoxin, a mould found in peanuts
and corn, which is one of the most potent carcinogens known.
• “Children who ate the highest-protein diets were the ones most
likely to get liver cancer. They were the children of the wealthiest
families.”
Campbell TC and Campbell TM (2006) The China Study. Dallas,
Texas: Benbella Books, p.5
The Indian Study
• One group of rats was given aflatoxin and then fed diets of 20%
protein. The other group was also given aflatoxin and then fed
diets of only 5% protein.
• Every single animal fed a 20% protein diet got liver cancer or its
precursor lesions.
• Not a single animal fed a 5% protein diet got liver cancer or its
precursor lesions.
• 100% versus 0%? This seldom occurs in biological sciences. It
was a very provocative finding!
Madhavan TV and Gopalan C (1968) The effect of dietary
protein on carcinogenesis of aflatoxin. Arch Path 85:133-7.
Three Stages of Cancer
• Initiation - A carcinogen enters a cell and is converted by cellular
enzymes to highly reactive products that bind to the cell’s DNA,
forming carcinogen-DNA complexes (adducts) that are often
repaired. If not repaired before the cell divides, the “daughter cells”
will have this new genetic defect (mutation). This occurs quickly and
is usually irreversible. It represents a potential for cancer.
• Promotion - Some factors (promoters) may act to increase the
growth and multiplication of these mutant cells over a longer period
of time, while other factors (anti-promoters) work against this.
• Progression - Large foci (clusters of mutant cells) progress in the
growth and may wander from their initial site (metastasize).
The Promotion Stage
• Many animal studies have shown that nutrition may be far more
important in controlling the cancer promotion stage than the dose of
the initiating carcinogen.
O’Connor TP, Roebuck BD and Campbell TC (1985) Dietary
intervention during the post-dosing phase of L-azaserine-induced
preneoplastic lesions. Journal of the National Cancer Institute
75:955-957 (cover article).
• Nutrients (esp. casein) from animal-based foods increased tumour
development while nutrients from plant-based foods decreased
tumour development.
Hawrylewicz EJ, Huang HH et al. (1982) Enhancement of the 7,12dimethylbenz(a) anthracene (DMBA)mammary tumorigenesis by
high dietary protein in rats.” Nutr. Reps. Int. 26:793-806.
What about the type of protein?
• What protein consistently and strongly promoted
cancer?
Casein (87% of cow’s milk protein) promoted all
stages of the cancer process.
• What type of protein did not promote cancer, even at
high levels of intake?
The safe proteins were from plants, including wheat
and soy.
Protein Excesses?
• Peer-reviewed biochemical research, funded by the National
Institutes of Health, the American Cancer Society and the American
Institute for Cancer Research, resulted in dozens of articles
published in some of the best scientific journals. The results were
shocking…
“Low protein diets inhibited the initiation of cancer by aflatoxin,
regardless of how much of this carcinogen was administered …In
fact, dietary protein proved to be so powerful in its effect that we
could turn on and turn off cancer growth simply by changing the level
consumed.”
The China Study, p.6
The Human Question
• So far, most of this research had involved laboratory
studies performed on animals: rats and mice.
• Would similar results be found with humans?
‘The China Study’ Scientific Team
• Dr. T. Colin Campbell was Project Director;
• Dr. Junshi Chen, deputy director of China’s premier diet & health
research laboratory;
• Dr. Junyao Li, one of the authors of the China Cancer Atlas Survey
and a key scientist in China’s Academy of Medical Sciences;
• Dr. Richard Peto of Oxford University, one of the leading
epidemiologists in the world, who has been knighted for his work.
Campbell TC and Campbell TM (2006) The China Study.
Dallas, Texas: Benbella Books.
Findings of the China Study
•
The largest and most comprehensive study of human diet, lifestyle and
disease in the history of biomedical research was organized through
Cornell University, Oxford University and the Chinese Academy of
Preventive Medicine, and involved 367 variables taken from
questionnaires, blood tests, urine samples and 3-day diet inventories
taken from 6500 adults from 65 Chinese counties.
•
Called “the Grand Prix of epidemiology” by the New York Times, it
produced more than 8,000 statistically significant correlations between
various dietary factors and disease.
•
People who ate the most animal-based foods got the most chronic
disease.
•
People who ate the most plant-based foods were the healthiest.
Disease Groupings in the China Study
Diseases of Poverty
(Nutritional Inadequacy
& Poor Sanitation)
Pneumonia, intestinal obstruction,
peptic ulcer, digestive disease,
pulmonary tuberculosis, parasitic
disease, rheumatic heart disease,
metabolic and endocrine disease other
than diabetes, diseases of pregnancy
and many others
Diseases of Affluence
(Nutritional Extravagance)
Cancer (colon, lung, breast, leukemia,
childhood brain, stomach, liver),
diabetes, coronary heart disease
(from The China Study, p. 76)
Rural Chinese versus U.S. Diets
(normalized for a body mass of 65 kg)
NUTRIENT
RURAL CHINA
UNITED STATES
2641
1989
14.5
34-38
33
12
64
91
Animal Protein
(% of calories)
0.8
10-11
Total Iron
34
18
Calories
(kcal/day)
Total Fat
(% of calories)
Dietary fiber
(g/day)
Total Protein
(g/day)
(mg/day)
(age-standardized rates from The China Study, p. 74)
From Underfed to Overfed
• In the year 2000, for the first time in human history, the
number of overweight people in the world rivalled the
number of underweight people. (While the world's
underfed population had declined slightly since 1980 to
1.1 billion, the number of overweight people had surged
to 1.1 billion.) Both the overweight and the underweight
suffer from malnutrition.
• "Often, nations have simply traded hunger for obesity,
and diseases of poverty for diseases of excess.”
Worldwatch (2000) Underfed and Overfed: The Global Epidemic of
Malnutrition. Paper #150: Worldwatch Institute, Washington, DC.
Countries: “Developing” to “Developed”
Major trends usually occur during this shift:
• increased longevity (life expectancy at birth)
e.g. Canada 81.23, U.S. 78.11, Philippines 71.09
CIA World Fact Book
https://www.cia.gov/library/publications/the-world-factbook/
• improved sanitation and drinking water
• improved access to high quality medical care
• decrease in amount of daily physical activity
• shift from a plant-based diet to an animal-based diet
• increase in levels of obesity
• nutrient deficiencies & infectious diseases give way to
chronic sedentary and degenerative diseases of excess
Diseases of Affluence
•
•
•
•
•
•
•
hypoglycemia
hyperglycemia
type II diabetes
high blood pressure
coronary artery disease
strokes
autoimmune diseases
(e.g. rheumatoid arthritis, gout, bursitis, neuritis, and some sciatica)
• osteoporosis
• many cancers
Cancer in China
• Counties with the highest incidence of some cancers had rates more
than 100 times greater than counties with the lowest rates of those
cancers. (In the U.S., cancer rates in one area are never more than
about 3 times higher than in the lowest incidence areas.)
• Since 87% of China’s population is the same ethnic group (the Han),
why is there such a variation in the rates of cancer? It had to be due
to environmental factors like poor nutrition, lack of exercise and
unhealthy living environments.
• (Some U.S. scientists had already estimated that genetics only
determines about 2-3% of the total cancer risk.)
Doll R and Peto R (1981) The causes of cancer: quantitative
estimates of avoidable risks of cancer in the United States today.
J Natl Cancer Inst 66:1192-1265.
Blood Cholesterol & Cancer
• Blood cholesterol levels in rural China were far lower than
expected (measured in mg/dL):
Av. Rural China
127
Av. U.S.
215
Minimal Safety (assumed)
150
• As levels dropped from 170 to 90, there were associated
decreases in cancers of the liver and colon (p<0.01), and
rectum, male lung, adult leukemia and adult brain (p<0.5).
•
NOTE:
This correlation even at very low levels is surprising, due to a
statistical phenomenon. Real relationships between 2 variables
sometimes cannot be seen when the range of data is limited!
Weight (lb.)
Weight versus Height
250
230
210
190
170
150
130
110
90
70
50
y = 6.1614x - 266.62
r = 0.82
50
55
60
65
70
Height (in.)
75
80
85
Weight (lb.)
Weight versus Height
250
230
210
190
170
150
130
110
90
70
50
y = 6.1614x - 266.62
r = 0.82
50
55
60
65
70
Height (in.)
75
80
85
Weight versus Height
180
160
Weight (lb.)
140
120
100
80
y = 2.2288x - 14.284
r = 0.24
60
40
20
0
60
61
62
63
64
Height (in.)
65
66
67
Breast Cancer
• The American death rate from breast cancer was 5 times higher
than the rural Chinese rate. In fact, from an international
perspective, breast cancer can clearly be seen as a disease of
affluence that is highly related to animal fat (and, possibly just by
association, animal protein).
Carroll KK, Braden LM et al. (1986) Fat and cancer. Cancer
58:1818-25
• This finding has been confirmed many times since then.
Carroll KK, Braden Lm et al. (1986)
Fat and cancer. Cancer 58:1818-25
Carroll KK, Braden Lm et al. (1986)
Fat and cancer. Cancer 58:1818-25
Carroll KK, Braden Lm et al. (1986)
Fat and cancer. Cancer 58:1818-25
Colorectal Cancer
• A major American Cancer Society study finds people who
reported the highest consumption of red and processed meat
had a significantly higher risk of colorectal cancer than those
who reported the least consumption. The study of nearly
150,000 Americans, the largest and most comprehensive to
date, adds substantially to previous evidence linking highest
consumption of red and processed meat to intestinal cancer.
Chao et al. (2005) Meat Consumption and Risk of Colorectal
Cancer. JAMA (Journal of the American Medical Association)
293: 172-182.
A Major Recent Study!
• “Red and processed meat intakes were associated with modest
increases in total mortality, cancer mortality, and cardiovascular
disease mortality.”
Sinha R, Cross AJ et al. (2009) Meat Intake and Mortality: A
Prospective Study of Over Half a Million People. Archives of
Internal Medicine 169(6), 562-571.
Nitrites and Nitrosamines
• Sodium nitrite:
A meat preservative used since the 1920’s, it kills
bacteria, colours meat pink and adds to the taste.
• Nitrosamines:
A family of chemicals of which at least 17 are
“reasonably anticipated to be human carcinogens.”
National Toxicology Program (2001) Ninth report on
carcinogens, revised January 2001. Washington, DC:
U.S Dept of Health and Human Services.
http://ntp.niehs.nih.gov/index.cfm?objectid=72016262-BDB7CEBA-FA60E922B18C2540
Value of a Plant-Based Diet
• “Recent scientific findings are suggesting that diets
largely based on plant foods, such as some vegetarian,
Mediterranean, or rural Asian diets, could best prevent
nutrient deficiencies as well as diet-related chronic
diseases. These diets contain no or very little meat.”
• Diets largely based on plant foods, such as wellbalanced vegetarian diets, could best prevent nutrient
deficiencies as well as diet-related chronic diseases.
Sabaté, Joan (2003) The contribution of vegetarian diets to health
and disease: a paradigm shift? American Journal of Clinical
Nutrition, Vol. 78, No. 3, 502S-507S.
1960’s Perspective
from Sabaté, Joan (2003)
Current Perspective
from Sabaté, Joan (2003)
Well-Planned Diets
from Sabaté, Joan (2003)
Plant Protein
• “Plant protein can meet requirements when a variety of plant foods
is consumed and energy needs are met. Research indicates that
an assortment of plant foods eaten over the course of a day can
provide all essential amino acids and ensure adequate nitrogen
retention and use in healthy adults, thus complementary proteins
do not need to be consumed at the same meal.”
ADA Reports: Position of the American Dietetic Association and
Dietitians of Canada: Vegetarian diets Journal of the American
Dietetic Association Online June 2003, Volume 103, Number 6.
Young VR, Pellett PL. Plant proteins in relation to human protein
and amino acid nutrition. Am J Clin Nutr 1994;59:1203S-1212S.
• Beans & rice together provide plenty of all the essential amino
acids.
Nutritional adequacy of plant-based diets
• “Energy and protein intakes are similar for plant-based diets
compared with those containing meat. Fe and vitamin B12 are
the nutrients most likely to be found lacking in such diets.
Bioactive substances present in foods of plant origin significantly
influence the bioavailability of minerals and requirements for
vitamins. Well-balanced vegetarian diets are able to support
normal growth and development. It is concluded that meat is an
optional rather than an essential constituent of human diets.”
Sanders TA (1999) Nutritional adequacy of plant-based diets.
Proc Nutr Soc. May;58(2):265-9.
Phytochemicals
• Phytochemicals (there are thousands) are found naturally in plants,
helping them to protect themselves from bacteria and disease.
Some act as antioxidants, limiting and repairing cell damage
caused by free radicals. Others act as hormone-like substances to
prevent cancer or block the enzymes that promote the development
of cancer and other diseases.
• Flavonoids, found in apples, strawberries, grapes, onions, green
and black tea and red wine, may decrease atherosclerotic plaque
and DNA damage related to cancer development.
• Carotenoids (beta-carotene, lutein, zeaxanthin, crytoxanthin and
lycopene) protect the eye from harmful oxidation reactions.
• Lignans, found in flaxseed, seaweed, soybeans, bran and dried
beans, are “phytoestrogens” that interfere with the action of the sex
hormone estrogen and may help prevent hormone-related cancers,
slow the growth of cancer cells, and lower the risk for heart disease.
Position of the American Dietetic Association and
Dietitians of Canada: Vegetarian diets
• “It is the position of the American Dietetic Association
and Dietitians of Canada that appropriately planned
vegetarian diets are healthful, nutritionally adequate,
and provide health benefits in the prevention and
treatment of certain diseases.”
ADA Reports: Position of the American Dietetic Association and
Dietitians of Canada: Vegetarian diets Journal of the American
Dietetic Association Online June 2003, Volume 103, Number 6.
256 mostly peer-reviewed references
The Mediterranean Diet
• The weight of evidence suggests that a Mediterranean style of
eating may be the healthiest approach.
• In “a population-based, prospective investigation involving
22,043 adults in Greece who completed an extensive, validated,
food-frequency questionnaire…
• CONCLUSIONS: Greater adherence to the traditional
Mediterranean diet is associated with a significant reduction in
total mortality.”
Trichopoulou A et al. (2003) Adherence to a Mediterranean diet
and survival in a Greek population. N Engl J Med. 26;348(26):
2599-608.
Mediterranean Diet and Longevity
• First, there appears to exist sufficient evidence that diet does
indeed influence longevity.
• Second, an optimal diet for the prevention of both coronary heart
disease and cancer is likely to extensively overlap with the
traditional Mediterranean diet. It is not yet clear which
components in the Mediterranean diet are more important for its
apparent health effects, but olive oil, plant foods and moderate
wine consumption are likely candidates.
Trichopoulou A, Critselis E (2004) Mediterranean diet and
longevity. Eur J Cancer Prev. 2004 Oct;13(5):453-6.
Mediterranean Diet Leads To Longer Life
• The Mediterranean diet has been associated with longer life
expectancy among elderly Europeans. The diet typically involves a
high intake of vegetables, legumes, fruits, and cereals; a moderate
to high intake of fish; a low intake of saturated fats; a high intake of
unsaturated fats (especially olive oil); a low intake of dairy products
and meat; and a modest intake of alcohol, mostly wine. Current
evidence suggests that such a diet may be beneficial to health.
• This study involved over 74,000 healthy men and women, aged 60
or more, living in nine European countries. When dietary exposures
were calibrated across countries, the reduction in mortality averaged
7% (1% to 12%).
Trichopoulou A, Orfanos P et al. (2005) Modified Mediterranean diet
and survival: EPIC-elderly prospective cohort study. British Med J
330 (7498): 991.
http://www.bmj.com/cgi/content/full/330/7498/991
Mediterranean Diet & CHD
• “Epidemiological studies as well as randomised dietary trials
suggest that Mediterranean diet may be important in relation to
the pathogenesis and prevention of coronary heart disease
(CHD). A striking protective effect of a Mediterranean diet rich in
alpha-linolenic acid (ALA) was reported in the Lyon Diet Heart
Study with a 50 to 70% reduction of the risk of recurrence after
four years of follow-up in CHD patients.”
de Lorgeril M, Salen P (2006) The Mediterranean diet in
secondary prevention of coronary heart disease.
Clin Invest Med. June 29(3): 154-8.
Mediterranean Diet & Obesity
• “The sample included 17,238 women and 10,589 men not
obese and aged 29-65 y at baseline (1992-96)…High MD
adherence was associated with significantly lower likelihood of
becoming obese among overweight subjects…MD adherence
was not associated with incidence of overweight in initially
normal-weight subjects…results suggest that promoting eating
habits consistent with MD patterns may be a useful part of
efforts to combat obesity.”
Mendez MA, Popkin BM (2006) Adherence to a Mediterranean
diet is associated with reduced 3-year incidence of obesity.
J Nutr. Nov. 136(11): 2934-8.
Organizations Supporting Vegetarianism
•
•
•
•
•
The American Institute for Cancer Research and the World Cancer
Research Fund call for choosing predominantly plant-based diets rich
in a variety of vegetables and fruits, legumes, and minimally processed
starchy staple foods and limiting red meat consumption, if at all.
The American Cancer Society recommends choosing most food from
plant sources.
The American Heart Association recommends choosing a balanced
diet with an emphasis on vegetables, grains, and fruits.
The Heart and Stroke Foundation of Canada recommends using
grains and vegetables instead of meat as the centerpiece of meals.
The Unified Dietary Guidelines developed by the American Cancer
Society, the American Heart Association, the National Institutes of
Health, and the American Academy of Pediatrics call for a diet based
on a variety of plant foods, including grain products, vegetables, and
fruits to reduce risk of major chronic diseases.
What is stopping the change?
• “Most evidence suggests that a shift to largely plant-based diets
would reduce chronic disease risks among industrialized and
rapidly-industrializing populations. The accomplish this shift, it will
be necessary to overcome market-place barriers and to develop
new policies that will encourage greater consumption of fruits,
vegetables and grains as a means to promote public health.”
Nestle M. (1999) Animal versus plant foods in human diets and
health: is the historical record unequivocal? Proc Nutr Soc
1999;58:211–8.
The Broader Picture
• Rearing cattle produces more greenhouse gases than driving cars.
Steinfeld H et al. (2006) Livestock’s Long Shadow: Environmental
Issues and Options. FAO (Food and Agriculture Organization) of the
United Nations.
• On average, land requirements for meat-protein production are 10 times
greater than for plant-protein production.
Leitzmann C (2003). Nutrition ecology: the contribution of vegetarian
diets. American Journal of Clinical Nutrition 78 (Suppl), 658S.
• Producing one kilogram of animal protein generally requires nearly 100
times more water than producing one kilogram of grain protein.
Pimentel D, Piemental M (2003). Sustainability of meat-based and plant
based diets and the environment. Am J Clin Nutrition 78(Suppl), 662S.
• Less than half the harvested acreage in the U.S. is used to grow food
for people. For every sixteen pounds of grain and soybeans fed to beef
cattle, we get back only one pound of meat on our plates.
Gussow JD (1994). Ecology and vegetarian considerations: does
environmental responsibility demand the elimination of livestock?
American Journal of Clinical Nutrition 59 (Suppl), 1111S.
For your health…
for your environment…
for compassion to animals…
Please…eat less meat!