After reading articles and watching videos (Weston A Price, ..) heavily criticizing USDA's recommendations, I thought it would be interesting to directly ask Health Canada (which I believe recommends pretty much the same diet as the USDA) what evidence supports their recommendations.
I'm really interested in anything you have to say about their answer, the sources, what the reputation of the sources is, what led to these recommendations, etc. Do you think the evidence is real science, or fake aggregation of articles that nobody reads correctly anyways ?
I often hear people saying that X ou Y is bad science. How can I know whether the bad science is Health Canada's, or Paleo's science (FTR, I have been on a LowCarbHighFat diet for 8 months now, and it's worked wonderfully for me up to now, so I'm inclined to think that either my genetics are different from the 'general population', or that their science is bad science).
From what I read from their answer, their whole paradigm revolves around the following hypotheses :
- Saturated Fats are bad : all recommendations are consistent with this hypothesis (choose skim milk, avoid fatty meats, and so on)
- Mono/poly-unsaturated are less bad than Saturated fats
- They believe in the "calorie-in/calorie-out" hypothesis : so everything is about the number of calories for each maronutriment
Thank you for contacting Health Canada online.
Our sincere apologies for the delay in responding to you. We had to consult a number of experts in the office in order to provide a comprehensive response to your inquiry. We apologize for any inconvenience the delay may have caused.
1. The guide states that the food guide is "evidence-based", but I cannot find the complete list of references that you have been using to reach your conclusions. The process seems to be described, but where can I find the evidence itself ?
A range of evidence helped to shape the revised Canada???s Food Guide. Nutrient standards and the prevention of chronic disease were key scientific inputs.
When developing a policy such as Canada's Food Guide it is important to look at the totality of evidence (the total body of publicly available evidence) rather than individual scientific studies. Many of the references included below are themselves reviews of a body of evidence.
For example, the Dietary Reference Intakes reports each contain a comprehensive review of the literature on nutrients and various health outcomes as part of the determination of nutrient standards. The reports examined for evidence on the relationship between foods and chronic disease risk reduction were also comprehensive reviews of available scientific studies.
Nutrient standards and assessment methods were provided in the Dietary Reference Intakes (DRI) reports of the Institute of Medicine (References 1-7). The DRIs summarize research findings about the amount of each nutrient and calories needed for good health and the prevention of chronic disease, while avoiding the negative effects of consuming too much of any individual nutrient. See reference 8 for more on the use of the DRIs in developing Canada???s Food Guide.
The WHO/FAO Joint Report on Diet, Nutrition and the Prevention of Chronic Diseases (2003), including the background papers in the journal Public Health Nutrition (2004), and the 2005 Dietary Guidelines Advisory Committee Report (USA) were reviewed for convincing evidence on the association of foods and chronic disease risk (References 9-17).
Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Washington, DC: National Academies Press; 1997.
Institute of Medicine. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, DC: National Academies Press; 1998.
Institute of Medicine. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: National Academies Press; 2000.
Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academies Press; 2001.
Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: National Academies Press; 2002.
Institute of Medicine. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. Washington, DC: National Academies Press; 2004.
Institute of Medicine. Dietary Reference Intakes: Applications in Dietary Assessment. Washington, DC: National Academies Press; 2000.
Katamay, SW, Esslinger, KA, Vigneault, M, Johnston, JL, Junkins, BA, Robbins, LG, et al. (2007). Eating well with Canada???s food guide (2007): Development of the food intake pattern. Nutrition Reviews, 65(4), 155-166. Available on Health Canada???s website: http://www.hc-sc.gc.ca/fn-an/pubs/fd_int_pat-ela_mod_alim-eng.php
Joint WHO/FAO Expert Consultation on Diet, Nutrition and the Prevention of Chronic Diseases. Diet, nutrition and the prevention of chronic diseases: report of a joint WHO/FAO expert consultation (WHO technical report series; 916). Geneva: World Health Organization; 2003.
Darnton-Hill I, Nishida C, James WPT. A life course approach to diet, nutrition and the prevention of chronic diseases. Public Health Nutrition. 2004;7(1A):101-21.
Swinburn BA, Caterson I, Seidell JC, James WPT. Diet, nutrition and the prevention of excess weight gain and obesity. Public Health Nutrition. 2004;7(1A):123-146.
Steyn NP, Mann J, Temple N, et al. Diet, nutrition and the prevention of type 2 diabetes. Public Health Nutrition. 2004;(1A):147-165.
Reddy KS, Katan MB. Diet, nutrition and the prevention of hypertension and cardiovascular diseases. Public Health Nutrition. 2004;7(1A):167-186.
Key T, Schatzkin A, Willett WC, Allen NE, Spencer EA, Travis RC. Diet, nutrition and the prevention of cancer. Public Health Nutrition. 2004;7(1A):187-200.
Prentice A. Diet, nutrition and the prevention of osteoporosis. Public Health Nutrition. 2004;7(1A):227-243.
Nishida C, Uauy R, Kumanyika S, Shetty P. The joint WHO/FAO Expert Consultation on diet, nutrition and the prevention of chronic diseases: process, product and policy implications. Public Health Nutrition. 2004;7(1A): 245-50.
2005 Dietary Guidelines Advisory Committee. Report of the Dietary Guidelines Advisory Committee on the Dietary Guidelines for Americans, 2005. Available at: http://www.health.gov/dietaryguidelines/dga2005/report/. Accessed February 1, 2007.
2. What is the evidence backing the intake of 8 portions of grains/carbs per day ? In particular, what is the evidence that carbs/grains contribute to cardiovascular health ?
The food intake pattern (amount and type of food) recommended in Canada???s Food Guide was developed to meet nutrient needs and be consistent with reducing the risk of nutrition-related chronic diseases. While there are other dietary patterns that are consistent with health, this food intake pattern was developed in the Canadian context (using Canadian databases of the nutrient composition of foods as well as the foods available and typically consumed in Canada). The recommended number of Food Guide Servings represent an average amount that people should try to eat each day. They are not minimums or maximums.
The eating pattern in Canada's Food Guide falls within the DRIs' Acceptable Macronutrient Distribution Ranges (AMDRs) for carbohydrates in the diet. The AMDR for carbohydrates for people 19 years and older is 45-65% of total calories (Ref 5). Intakes below or above the AMDR may increase the risk of chronic diseases (including coronary heart disease), as well as increase the risk of insufficient intakes of essential nutrients (Ref 5).
The carbohydrates emphasized in Canada???s Food Guide are vegetables, fruits, and whole and enriched grains. Canada???s Food Guide also advises limiting the intake of processed foods where the carbohydrate is mostly added sugar or where added sugar is the main source of calories.
Canada's Food Guide recommends making at least half your grain servings whole grain each day. Whole grain products have been consistently and convincingly reported beneficial against coronary heart disease (References 13 & 17). In addition, Health Canada has approved the use of the claim "a healthy diet rich in a variety of vegetables, fruit and whole grain products may reduce the risk of heart disease" since the totality of available evidence supports this relationship.
3. What is the evidence behind recommending the use of unsaturated fats (both monounsaturated and polyunsaturated), and limiting the intake of saturated fats ? In particular, what is the evidence that high-saturated-fat diets contribute to cardiovascular disease? And what is the evidence that reducing the consumption of fats leads to better cardiovascular health?
Canada???s Food Guide recommends including a small amount (30-45 mL) of unsaturated fat as part of the healthy eating pattern that includes mostly lower fat foods. This will ensure people have enough essential fatty acids (linoleic and alpha-linolenic fatty acids).
A substantial body of evidence suggests that saturated fatty acids raise total and LDL blood cholesterol levels, which in turn increases risk of cardiovascular disease (Ref 5). There is a positive linear trend between intake of saturated fatty acids and risk of cardiovascular disease (Ref 5 & 17). Intakes should therefore remain as low as possible, while a nutritionally adequate diet is consumed (Ref 5). Health Canada also has an approved health claim stating that "a healthy diet low in saturated and trans fats may reduce the risk of heart disease."
High intakes of total fat (>35% of total energy) have been reported to increase the risk of cardiovascular disease, because at such levels, saturated fatty acid intakes increase (Ref 5). Saturated fats are present in all fats; therefore higher intakes of total fat will consequently result in higher intakes of saturated fats (Ref 17).
4. What is the evidence behind limiting the intake of salt? What is the exact recommendation of salt per day? What is the evidence backing the fact that salt intake contributes to cardiovascular disease?
A direct and progressive relationship between sodium intake and blood pressure, with no apparent threshold has been shown, based on a review of evidence from observational studies as well as large rigorous trials (Ref 17). For more information about sodium and cardiovascular health, please see Sodium in Canada on Health Canada???s web site: http://www.hc-sc.gc.ca/fn-an/nutrition/sodium/index-eng.php
The recommended intake level for sodium for adults 19-50 years old is 1500 mg. This level is expected to meet or exceed the sodium requirements of most individuals in that particular age group. The tolerable upper intake level (UL) of sodium was set at 2,300 mg/d for individuals aged 14 years and older (Ref 6). One teaspoon of salt contains approximately 2,400 mg of sodium. The UL is the highest average daily level of intake likely to pose no risk of adverse health effects, and reflects an intake level that should not be exceeded. Guidance to choose foods lower in salt and sodium is included on Canada???s Food Guide because sodium is ubiquitous in the Canadian food supply.
5. What is the evidence backing the intake of skim milk, instead of full-fat milk?
Drinking low fat milk is an effective way to consume protein, calcium, magnesium, riboflavin, vitamin A, vitamin B12, vitamin D and zinc while minimizing the amount of saturated fat and calories. See response to Question 3 for evidence on saturated fat and cardiovascular health.
6. What is the evidence backing the intake of soy beverages for those who do not drink milk?
Fortified soy beverage can be used as an alternative to milk. When fortified, soy beverages must contain added vitamins and minerals in amounts that make them a nutritionally adequate alternative.
7. What is the evidence backing the consumption of lean meats, as opposed to fatty meats?
To minimize the amount of saturated fat in the diet, Canada's Food Guide emphasizes lean cuts of meat and skinless poultry. See response to Question 3 for evidence on saturated fat and cardiovascular health.
8. What is the evidence backing the recommended cooking methods such as roasting and baking?
Lean meat, poultry and fish become higher fat choices once they are fried or served with gravy or other high fat sauces. Instead of frying or deep-frying meats, Canada's Food Guide recommends baking, broiling, poaching or roasting them and allowing the fat to drip off. See response to Question 3 for evidence on total fat intake and cardiovascular health.
*The reason I'm asking is because I cannot find any high-quality scientific evidence backing your claims. All I can find is evidence that claims the exact opposite of what you're saying: - Low-Carb, or Very-Low-Carb consumption (0-20% of daily calories max) - High-saturated fats (both animal based, and from tropical oils) and High monounsaturated fats (65% of daily calories) - Moderate protein intake (15-35% of daily calories)
There are a number of variants of these Low-Carb-High-Fat diets, but all of them tend to promote saturated fats from grass-fed, pasturized animals, full-fat raw milk, and tend to severely limit the consumption of grains/carbs. Most of these diets are in sync with your recommendations regarding fiber/vegetables consumption.
Also, I strongly believe that it would be a huge win for the whole canadian society if you could have an official public statement regarding these alternative diets. What is your expert advice on those? Is the scientific evidence they provide solid?*
The dietary guidance provided by Health Canada describes a pattern of eating that promotes health over a lifetime.
It is true that many different diets provide weight loss results in the shorter term. However, the most recent Report of the U.S. Dietary Guidelines Advisory Committee (2010) reiterates that weight maintenance depends on a balance of energy (Calorie) intake and energy expenditure, regardless of the proportions of fat, carbohydrate, and protein. It is also stated that "Diets that are less than 45% carbohydrate or more than 35% protein are difficult to adhere to, are not more effective than other calorie-controlled diets for weight loss and weight maintenance, and may pose health risk, and are therefore not recommended for weight loss or maintenance." (http://www.cnpp.usda.gov/dgas2010-dgacreport.htm)
The Office of Nutrition Policy and Promotion Health Canada
asked bysam_4 (110)
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on April 27, 2012
at 07:47 AM
Please read this and then send them the issues raised here. This is a fantastic article
PS Sorry, I didnt have time to read the whole post (in a rush to leave work), but I am sure that my answer will cover all of the points.
on April 27, 2012
at 07:31 AM
Wow that was pathetic. Every response was in the form of "there is substantial amounts of evidence that can't be falsified by any individual study indicating our recommendations are the right ones".
Nevermind that observational studies mean shit for nothing.
on April 27, 2012
at 08:17 AM
The worse is that your tax dollars are paying for this! The public servant that answered your questions probably spend a whole week replying to your email, receiving a very good salary...
on April 27, 2012
at 01:01 PM
Ahhh... Health Canada. I always laugh when I see their cheery little rainbow poster telling us to eat our grains.
But you know what bureau is even a bigger crock of shit? The CFIA. My father (who was a CFIA/DFO inspector for 30 years on farms, potato, and fish processing plants -we live in the East- plus has a PhD in Food Chemistry) believes the biggest bunch of crap about farming practices. (i.e. "grass-fed cows don't grow as well as grain-finished cows"). We have some very interesting arguments.