Transcript Chapter 4: The Human Body: From Food to Fuel

Complementary and Alternative Medicine
- Pages 73 - 104
Food Safety
- Chapter 18
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Functional Foods
Definition
• foods that contain physiologically active
compounds that provide health benefits
beyond basic nutrition
Examples
– Oat Bran Fiber
– Fish Oil Fatty Acids
– Phytochemicals*
– Plant Sterols and Stanols*
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Phytochemicals
Definition: non-nutrient compounds found in
plant derived foods
• may promote good health but are not
essential for life
• include thousands of complex chemicals
including pigments and antioxidants
• benefits may include reduced risk of
cardiovascular disease, hypertension,
cancer, type 2 diabetes, and others
• see Table SAN.1, pages 78 & 79 for selected
examples
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Benefits of phytochemical
supplements?
• information on how many phytochemical
work is still unclear
• phytochemical work together, not in
isolation
• the best way to add more
phytochemical to your diet is to
increase your consumption of fresh
fruits and vegetables
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Lycopene
• a carotenoid found in tomatoes and tomato
products
• has antioxidant and antiproliferative functions
• epidemiological studies have shown a
correlation between a high intake of lycopene
and reduced incidence of CVD, cancer, and
macular degeneration
• well-designed research examining the effect
of lycopene supplements has not yet been
conducted
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Soybeans
• epidemiological studies have linked a high
consumption of soy products to reduced risk
of cancers, including colon, prostate, uterine,
and breast
• contain isoflavones which acts as
phytoestrogens
• recent studies show increased bone density
with soy intake
• studies examining effects on cancer and CVD
risk have had mixed results
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Plant Sterols & Stanols
• similar chemical structure to cholesterol
• beneficial for lowering LDL
– competitively inhibit the absorption of
cholesterol in the small intestine
• naturally found in vegetable oils, legumes,
sunflower and sesame seeds, some fruits
and vegetables
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Health claims for functions foods
• must meet government guidelines in
order to make health claim
Examples
– foods high in b-glucan may highlight
benefits of reduced risk of CVD
– functional food created by addition of plant
sterols or stanols to margarine may claim
it helps lower cholesterol
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Vitamin & Mineral Supplements
• a billion dollar industry
• more than ½ of North Americans take
vitamin or mineral supplements, usually
self-prescribed
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Reasons to take
supplements…
• to correct overt deficiencies
– Rx at 2 - 10x the RDA (pharmacological dose)
• to improve nutrition status
– prevention of subclinical deficiencies
– habitual dieters, elderly, vegetarians
• reduce disease risks
• support increased nutrient needs (e.g.
pregnancy)
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Who needs supplements?
• taking supplements to “fix” a poor
diet is unwise
• foods provide not only nutrients but
also fiber & other health promoting
benefits
• whenever possible, nutritional
needs should be met with FOOD!
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Megadoses?
• appropriate for treatment of specific
conditions
Examples
– nicotinic acid to lower cholesterol
– Vitamin B12 to treat pernicious anemia
– folic acid & Vitamin B6 to counteract effects
of tuberculosis drugs
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Arguments against
supplements…
• health risks: toxicity
Examples
– high doses of Vitamin C  diarrhea
– megadoses of Vitamin B6  nerve damage
Nutrient
Upper
Limit
Daily Value
Multivitaminmineral
Single Nutrient
Supplement
Vitamin A
3000 mg
1500 mg
750 - 1500 mg
2400-3000 mg
Vitamin C
2000 mg
60 mg
10 - 90 mg
500-2000 mg
45 mg
18 mg
18 mg
15-18 mg
Iron
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Arguments against
supplements…
• interactions with other nutrients & medications
– Vitamin K interferes with medication to control blood
clotting
– antioxidant nutrients may counteract chemotherapy or
radiation treatment for cancer
• misinformation
• expensive
• supplements do not provide other compounds in
foods associated with health
• may lead to false sense of security about health
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Myths & Facts
• the soil contains inadequate nutrients
• supplements provide energy
• supplements improve athletic performance
and build muscle
• supplements reduce stress
• supplements can treat or cure illness and
disease
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Dietary Supplements in the Marketplace
• Claims allowed
– Health claims
(approved by FDA)
– Nutrient content claims
– Structure/function
claims
• Link substance and
effect on the body
• No approval required
• Must have “disclaimer”
statement on label
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Dietary Supplements in the
Marketplace
• Fraudulent products
– Secret cure—“breakthrough”
– Pseudomedical jargon—“detoxify”
– Can cure a wide range of diseases
– Has no side effects, only benefits
– Backed by “scientific research” but none is
listed
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Herbal Therapy
• the therapuetic use of herbs and plants to
promote health & treat disease
– e.g. ginseng, St. John’s wort, kava, milk thistle,
saw palmetto
• Bill C-51 - facts - See link on main web page
• remember: any herb that is strong enough to
help you may be strong enough to harm you!
– e.g. gingko biloba may cause hemorrhage,
licorice, hawthorn & senna may interfere with
cardiac drugs such as digoxin, kava may increase
sedative effects of narcotics & alcohol
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Food Safety
• History
– Major killers in society used to be outbreaks of
devastating human diseases
– typhoid, scarlet fever, diphtheria
• Now microbes are of concern
– bacteria, fungi and viruses can all cause foodborne illness
– major concern for daily health
• food additives and contaminants are also of
significant concern to many
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Food-Borne Illness (F-BI)
•
•
•
•
•
cause up to half the cases of diarrhea
considerable cost and death rate
loss of productivity
“travelers diarrhea”
GI tract environment (bacteria)
significantly altered with change of
outside environment and food choices
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Microbes - Table 17-1
• Bacteria - salmonella, e coli
– single celled organisms
– some produce toxins - illness
– others produce enzymes that digest substances around
them
• Fungi
– simple parasitic life form
– molds, mildews, yeast
• Virus - hepatitis, norwalk
– smallest, use host to reproduce
• Parasites - giardia
• Microbes either
– directly infect intestinal wall
– produce toxins in the food
• tablespoon of dirt ~ 2 billion microbes
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Mad Cow Disease
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Prions and Mad Cow Disease
• Bovine spongiform encephalopathy (BSE), known as
“mad cow disease,” is a chronic degenerative
disease that affects the central nervous system of
cattle. Once thought to infect only cows, scientists
have found that BSE can cause a rare, but fatal,
brain-wasting disease in humans.
• Researchers believe that prions—proteins found in
the cells of humans and other mammals—are
responsible. When mammals eat tissues
contaminated with abnormal prions, they can develop
BSE. Cooking and irradiation do not kill or deactivate
abnormal prions.
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Impact of F-BI
• Can be more severe and prolonged reaction
in some who are more susceptible
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–
–
–
–
infants, children and elderly
liver disease, diabetes, HIV
cancer patients
pregnant women
condition can become lengthy and lead to food
allergies, seizures, blood poisoning
• F-BI often results from unsafe food handling
– World Health Organization rules
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Why so Common?
• Increase in central processing
– large scale impact when microbe growth
does occur
• increased consumption of raw animal
products
• goal of increased shelf life
• science becoming more aware of its
prevalence
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Food Preservation
• Historical preservatives
– salt, sugar, smoke, fermentation, drying
• alter composition of food, to be
unsuitable as host for microbes
• decrease free water
• fermentation, pickling
– highly acidic and alcoholic environment, no
microbe growth
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Preservation
• Also pasteurization, sterilization, refrigeration,
freezing, irradiation, canning, chemical
preservation, aseptic processing
• aseptic processing
– sterilization of food and packaging - boxed juice,
milk
• irradiation
– alters composition of food
– does not become radioactive
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Food Technology: Irradiation
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Food Safety: Consumer’s
Role
• Keeping food safe
– Clean
– Separate
– Cook
– Chill
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General Rules
• Purchasing
– select perishables last, keep separate, store
quickly
– don’t by or use food from broken or bulging
containers
– purchase only pasteurized milk and cheese
• Preparation (* raw meat *)
– wash hands with soapy hot water
– use clean equipment (counters, cutting boards)
– thaw in fridge, cold water or microwave
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General Rules
• Cooking Food
– cook food thoroughly (*meat*)
– consume cooked food immediately
– serve animal products on clean plate, not on the
one used for preparation.
• Storing and Re-heating
– keep hot / keep cold
– intermediate temperatures facilitates growth - fig
17.7
– reheat leftovers to cooking temperature (not just
warm)
– Cover and seal stored foods
– Leftovers in fridge for 2-4 days maximum
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Temperature Guide
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Treatment
•
•
•
•
•
Drink lots of fluids
bed rest
wash hands frequently
consult physician if severe for 2-3 days
Report to authorities if :
– food eaten at large gathering
– food from restaurant,…..
– food was a commercial product
• ie. high potential for large # of infections
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Food Additives
• intentional added to improve :
– palatability, nutrient content, shelf life, ease of
processing
– the three most common additives are sugar, salt,
& corn syrup
• incidental (contaminants)
– find there way into our food
• GRAS
– Generally Recognized As Safe
– list of compounds, used and considered safe in
1958
– FDA must now prove these substances are
harmful to get them removed from safe list
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Testing Food Additives
• Must use two animal species
• NOEL
– no observable effect limit
– highest dose that produces no effect
– short term/high dose ????
• Delaney Clause
– prevents addition of products that cause cancer
• Incidental food additives
– industrial chemicals, pesticides ...
– Canadian Food Inspection Agency (FDA in US) cancer safety margin
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New Food Additives
• Canadian Food Inspection Agency (FDA
in US) testing for approval
• Manufacturer must provide
– identity, composition, source, method of
content analysis and description of use,
applicability and necessity
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Additives
• Most used in processing, enhancement
of consumer appeal, and to prevent
spoiling
• recall - problems with F-BI increased
with central food production
– become largely unnecessary if buy fresh,
locally produced food and prepare at home
• variety and moderation can prevent
negative impact on health
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Natural Substances
• Many natural produced compounds are
potentially harmful
• many cultures traditionally avoid these
(differences)
• safrole - cancer - mace, nutmeg
• solanine - green potatoes
• mushroom toxins
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Food Safety
• Harmful substances in food
– Chemical contamination
• Pesticides
– Organic alternatives
• Animal drugs
• Pollutants
Photo © Photodisc
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Environmental Toxins
• Lead
– anemia, kidney disease, and nervous system
damage
– changes in last 25 years
– lead paint, gasoline, canning soldering, (let taps
run)
• Dioxins
– chlorine and benzene
– created by incinerating plastic an paper together cancer
– also accumulate in bottom feeding fish - great
lakes
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Environmental Toxins
• Mercury
– birth defects, acute toxicity
– large predatory fish
• Urethane
– forms during fermentation
– cancer causing
– fruit brandies, saki
• PCB’s
– liver tumors, reproductive problems
– fish (freshwater, industrial )
• BPA ?
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Toxins in the Food Chain
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Organic Foods
• Choosing organic can reduce overall use of
pesticides
– Pesticide contamination is low in all foods - its use is
damaging to environment however
• Organic produce has higher content of
phytochemicals - natural defenders against foreign
agents
• Choosing local produce reduces shipping costs, use
of green house fuels and the need for preservatives
• Genetically modified organisms (GMO)
– Prevalence is quite high, labeling now required in Europe
– Unknown long term consequences
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Genetically Modified Foods: Plant
Genetics
• Traditional breeding
– Cross two plants, develop
hybrids, takes time
• Genetic engineering
– Transform specific
genes
– Less time to get desired
effects
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