Birth of the modern diet

Question 1

16th Century – Food linked to health

Answer 1

Doctors monitored wealthy patients diet
 Court physicians schooled in digestion
 Majordomos (head chefs) dietary theory  practice
 Cooking central process of life
 4 fluids/humors
Blood – hot and moist
Phlegm – cold and moist
Yellow bile – hot and dry
Black bile – cold and dry
 Foods classified  - moist/dry, cold/hot
 Majordomo adjusted meal to temperment of eater

Question 2

17th Century – new physicians/scholars joined courts - ideas from Paracelcus

Answer 2

Technology of distillation developed
 Heat substances  3 parts
Volatile spiritous fluid (mercury - not actually mercury)
Oily substance (sulfur)
Solid residue (salt)
 Digestion = fermentation = putrefaction
 Green veggies/fruits fermented easily 
 gardens/cultivation
 sugar – hides goodness, blackens teeth
Moved to periphery of meal
Nutritive foods restorative
Restaurants (restores health

Question 3

18th – 19th Centuries

Answer 3

Focus on diets for factory workers, soldiers – spread diet to other classes
But centrality of meat & fats  modern problems?

Question 4

Canada’s Food Guides

Answer 4

Canada’s Official Food Rules – 1942
Canada’s Food Rules – 1944, 1949
Canada’s Food Guide – 1961, 1977, 1982
Canada’s Food Guide to Healthy Eating – 1992
Eating Well with Canada’s Food Guide - 2007

Question 5

Original Pyramid

But, major flaws:

Answer 5

1992, US Dept. of Agriculture
To help public make food choices for good health and to reduce risk of disease (typical diet had been 40% fat, 15% protein, 45% CHO calories)
Minimize fats and oils – 30% of calories or less
6-11 servings complex CHO (bread, cereals, rice, pasta)
Generous vegetables (including potatoes) and fruits
2-3 servings dairy products
2-3 servings meats or beans

Known some fats essential/beneficial (CHD risk)
No evidence for benefit of high CHO
Oversimplified
By promoting all complex CHO and eschewing all fats and oils  misleading guidance?
How went wrong? (desire to simplify for public)

Question 6

Fat

Answer 6

Saturated fat (meat, dairy)  cholesterol ( CHD)
But, PUFA, MUFA (veg. oils, fish)  cholesterol (except trans)
Also, omega 3’s beneficial
1960’s, 1970’s advice – replace sat’d fat with PUFA
Probably accounts for 50% CHD in 70’s & 80’s
Concept high fat  CHD stems from western diet
Crete (olive oil, fish) – fat 40% of calories, but CHD lower than Japan (fat 8-10% of calories)

1992 – simplify for public “fat is bad”
Didn’t want to suggest protein since red meats also high in sat’d fat
So “Fat is bad”  “CHO is good”
Am. Heart Assoc. and others:  50% CHO,  30% fat calories
But no studies showing direct health benefit of low fat diet
Food industry fat in products but sweeteners eg high-fructose syrups

LDL/HDL ratio strongest predictor for CHD
1990’s controlled feeding studies:
replace fat calories with CHO  LDL, also HDL
Also  triglycerides (risk of CHD)
replace PUFA, MUFA with CHO worse  LDL, HDL
replace sat’d fat with PUFA, MUFA  LDL, HDL
trans fats  LDL, HDL

Question 7

Carbohydrate

Answer 7

Sugars = empty calories, therefore complex CHO formed base of pyramid
But, refined CHO & starchy foods quickly  blood glucose (more so than whole grains)
Potatoes   blood glucose more quickly than table sugar
Sugar (sucrose) = glucose + fructose (more slowly  glucose)
Blood glucose, insulin  triglycerides, HDL
Epidemiology: high starch  type 2 diabetes, CHD
Epidemiology: high fibre  type 2 diabetes, CHD

Question 8

Veggies and Fruits

Answer 8

Least controversial
Retrospective studies suggest decrease cancer risk
Large prospective studies don’t support for overall fruits and veggies
But specific fruits and veggies decrease risks for certain cancers
Epidemiological studies support decreased risk for CHD, birth defects, cataract, macular degeneration
Potatoes not justified in veggies since mostly starch

Question 9

Protein Sources

Answer 9

Flaw in USDA pyramid in not recognizing differences
Red meat – high sat’d fat & cholesterol
risk of CHD, diabetes
colon cancer (probably from carcinogens)
Poultry, fish – more PUFA and omega-3
Replace for red meat  risk for CHD, colon cancer
Eggs – not much association with CHD
Nuts – often avoided because high fat – but PUFA, MUFA, omega-3
Controlled feeding studies show  blood cholesterol
Epidemiological studies show  CHD, diabetes, obesity

Question 10

Dairy Products

Answer 10

Concern USDA pyramid promotes over-consumption?
Usually justified by calcium content – to prevent osteoporosis and bone fractures
But highest bone fractures in countries with high dairy consumption
Large prospective studies don’t show fractures with dairy
Is high dairy consumption safe?
Some studies show  prostate cancer, ovarian cancer
Can usually get requirement from equivalent of one glass of milk
Calcium supplement in situations of requirement (eg. after menopause)

Question 11

harvard food guide

Answer 11

oil and grains at the bottom, counterinuitive.
moderation- unclear
seems like medeteranina food guide

Question 12

Much more research needed on:

Answer 12

Dairy products
Specific fruits and veggies
Risks/benefits of supplements
Childhood diets
Nutrigenomics