Nutrition 331 Nutrition for Health

Study Guide

Unit 3: Dietary Reference Intakes and Diet‑Planning Guides

Introduction

How do you know if your diet is adequate in all the essential nutrients but is not too high in nutrients that cause health problems? What standards do health professionals and scientists use to evaluate a healthy diet? This unit summarizes the nutrition standards created for health professionals and scientists as well as the diet-planning guides created for the public.

Nutritional guidance has been provided to Canadians since 1942 with the publication of Canada’s Official Food Rules. Since then, many revisions of the nutrient requirements, dietary recommendations, and guidelines have been made. Revisions are necessary to ensure that current recommendations reflect advances in the knowledge of dietary requirements, changes in education techniques, and alterations in Canadian food supply and food consumption patterns. The present focus is not just freedom from nutrient deficiency, but also reduction of the risk of chronic, nutrition-related diseases and disorders such as cardiovascular disease, obesity, diabetes, and cancer.

To use or apply diet-planning guides correctly, you must understand their strengths and limitations. After completing this unit, you will begin to gain such an understanding by starting an assignment assessing the nutritional adequacy of your own diet using Canada’s Food Guide.

Objectives

After completing this unit, you should be able to

1. describe the goals of Dietary Reference Intakes (DRI).
2. describe and explain the basis for the Recommended Dietary Allowances (RDA) and Daily Values (DV), and describe the potential uses for each.
3. describe the purpose and content of Canada’s Food Guide (2019), focusing on adults.
4. discuss the reasons for including variety, moderation, calorie control, and balance in eating guidelines.
5. identify the key nutrients found in each food group.
6. interpret information included in food labels in the standard nutrition facts table.
7. understand what foods provide protein, carbohydrates, and fats.

Section 1: Dietary Reference Intakes

The first step in setting standards and guidelines is to determine the appropriate levels of required nutrients. Researchers and nutrition experts review the available scientific literature (as described in Unit 2) and create technical recommendations for use by nutrition professionals.

Dietary Reference Intakes (DRI) refers to five sets of standards described on page 33 of the eText (Table 2-1: Nutrient Standards).

Estimated Average Requirements (EAR) are used by nutrition and health professionals to plan group diets (e.g., daycares, seniors’ lodges) and for assessing the adequacy of a population’s diet.

Acceptable Macronutrient Distribution Ranges (AMDR) are established for the energy-giving nutrients (also called macronutrients). The ranges are designed to lower the risk of chronic disease. We will discuss this further in Units 5, 6, and 7.

The terms Recommended Dietary Allowance (RDA) and Acceptable Intake (AI) are used interchangeably in the eText and Study Guide and are the focus of this section. Factors considered in the establishment of the RDAs are outlined below.

• The recommended nutrient levels for protein, vitamins, and minerals are set sufficiently high to meet the body’s needs and to reduce the risk of chronic disease. The RDAs are designed to provide nutrients in recommended amounts for almost all healthy individuals, so as to cover the requirements of 97 or 98 percent of the population. Thus, the RDAs exceed the needs of almost all people. They are generous, yet safe and adequate.
• In the cases of some nutrients, there is not enough scientific knowledge to conclude specifically the amount of nutrient required for 97 or 98 percent of the population. The new DRIs address this problem by introducing a category called Adequate Intake (AI) for nutrients such as chromium and calcium.

When using the RDA or AI, you should recognize several of their limitations:

• They are established for healthy people with normal intestinal absorption of nutrients. People suffering from an acute or chronic illness may have different nutrient needs. Modifying diets for special needs is a job for a dietitian.
• They are set for only 38 nutrients. The body also needs other trace nutrients that must be provided through the consumption of a wide selection of foods.
• They are established without taking into account all nutrient interactions. For example, excess zinc will interfere with copper absorption, or excess protein may increase calcium excretion. Such nutrient interactions are of concern, especially when protein, mineral, or mega-vitamin supplements are used.
• In spite of increased interest in the physiological changes during the aging process, only limited data are available on the nutrient requirements of the elderly. The RDAs for both youth and the elderly are extrapolated mainly from those of young adults.
• Nutrient requirements vary with body size, growth rate, or both. The RDAs are based on the average growth rate or physiological changes according to age. For exceptional individuals who have different growth spurts, the RDAs may be inappropriate.

Finally, a common mistake is to interpret intakes that are less than the RDA as a “deficiency,” rather than an indication of a possible inadequacy, with the probability of deficiency increasing as the intakes fall. The RDAs are only “best guesses” of the nutrient levels people require. Consequently, adequate intakes are achieved when the diet has 95 percent of the RDAs or more. The further below 95 percent of the RDA a nutrient is, the more likely the person is to have low nutrient stores, which may lead to poor health and nutrient deficiency symptoms.

An excess of nutrients obtained from ordinary foods seldom poses a problem because the body can absorb less, or can store or excrete the excess, without harm. However, if nutrient intake is substantially too high (e.g., from the use of supplements), adverse effects may occur. The Tolerable Upper Intake Level (UL) serves as a guide for what intakes are considered excessive and hazardous to health.

Energy requirements are compiled slightly differently from RDAs. Estimated Energy Requirements (EER) are described on pages 36–37 of the eText. It’s important that estimated energy requirements are not too high, as they could encourage overeating and obesity. Therefore, energy recommendations are based on average needs rather than estimations for the highest needs.

In summary, the DRIs are designed for people of all ages—from infants to senior citizens. They are separated into eighteen age-gender categories, plus five categories for stages of pregnancy and lactation. They are technical guidelines describing nutrients that are used by scientists researching nutrition and by health professionals to assess diets and provide nutrition advice.

Section 2: Canada’s Food Guide

Canada’s Food Guide describes a healthy diet. Following the diet will help people

• get enough vitamins, minerals, and other nutrients.
• reduce the risk of obesity, type 2 diabetes, heart disease, certain types of cancer, and osteoporosis.
• achieve overall health and vitality.

The diet is based on extensive scientific evidence. It was developed by looking at different combinations of amounts and types of food to find an eating pattern that meets nutrient needs. The diet was also evaluated against evidence that links certain foods with reduced risk of chronic diseases. The diet meets the nutrient standards called Dietary Reference Intakes (DRI). The DRI summarizes 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. A diet based on Canada’s Food Guide falls within the DRI’s AMDR for carbohydrate, protein, and fat in the diet.

Diet-Planning Principles

The eText does not include the latest version of Canada’s Food Guide. Instead, the new food guide is available online at https://food-guide.canada.ca/en/. The specific sections you must read are highlighted below.

A Brief History of Canada’s Food Guide from 1942 to Present

The first food guide for Canadians appeared nearly 80 years ago. Wartime food rationing created a public health concern for preventing nutritional deficiencies and improving the health of the population. Canada’s Official Food Rules was launched in 1942 and identified six food groups (Milk; Fruit; Vegetables; Cereals and Breads; Meat, Fish, etc.; and Eggs) along with specified daily intakes.

Since then, the food guide has undergone many changes to name, messaging, and recommended foods. You may be most familiar with the seventh revision, Eating Well with Canada’s Food Guide, published in 2007. It is described in detail on pages 38–44 of the eText. This rainbow-themed six-page guide was based on four food groups (Vegetables and Fruits; Grains; Milk and Alternatives; and Meats and Alternatives). It provided recommended numbers of servings in each group and included guidance on types and amounts of added oils and fats to consume. A feature of this guide was the increased emphasis on reducing risk of chronic, nutrition-related diseases.

In January 2019, the latest edition of Canada’s Food Guide was released by Health Canada. This new guide will be discussed in greater detail and will be the resource you use in NUTR 331.

Although the food guide has undergone different looks, new names, and new messages, the general objective has always been guiding food selection and promoting the nutritional well-being of the Canadian population.

The new version of Canada’s Food Guide has undergone a substantial transformation from all previous versions. The previous guide placed meats and alternatives in one food group and milk and alternatives in another. The new food guide places these food into one food group, known as protein foods. Another major change is that the new food guide does not state the recommended amounts of foods. The new guide recognizes that healthy eating is more than the foods you eat. It is about where, when, and why you eat. Another significant change is its entirely digital, web-based format. Canada’s Food Guide can now be easily accessed from any mobile device and is highly interactive and colourful.

Canada’s Dietary Guidelines

These guidelines, based on best-available scientific evidence, are the starting point for Health Canada’s nutrition policies, programs, and educational resources. The underlying principles of Canada’s Food Guide are based on Canada’s Dietary Guidelines and are summarized as follows:

GUIDELINE 1

Nutritious foods are the foundation for healthy eating.

• Vegetables, fruit, whole grains, and protein foods should be consumed regularly. Among protein foods, consume plant-based more often.
  • Protein foods include legumes, nuts, seeds, tofu, fortified soy beverage, fish, shellfish, eggs, poultry, lean red meat including wild game, lower fat milk, lower fat yogurts, lower fat kefir, and cheeses lower in fat and sodium.
• Foods that contain mostly unsaturated fat should replace foods that contain mostly saturated fat.
• Water should be the beverage of choice.

GUIDELINE 2

Processed or prepared foods and beverages that contribute to excess sodium, free sugars, or saturated fat undermine healthy eating and should not be consumed regularly.

GUIDELINE 3

Food skills are needed to navigate the complex food environment and support healthy eating.

• Cooking and food preparation using nutritious foods should be promoted as a practical way to support healthy eating.
• Food labels should be promoted as a tool to help Canadians make informed food choices.

Source: Health Canada. (2019, January 22). Canada’s dietary guidelines, Government of Canada. https://food-guide.canada.ca/en/guidelines/

These guidelines are the result of an extensive systematic and consultative review of the current scientific evidence investigating the relationship between food and health. Input was sought from a long list of health professionals, academics, and national Indigenous organizations to name a few. Health Canada included much public consultation to gain insight into what is relevant and clear to Canadians. Dietary guidelines from other countries were also examined to gain a broader perspective on content and use. Of note is the deliberate prohibition of lobbying from the food industry, including agriculture. The full report is extensive and can be accessed from the Canada’s Food Guide home page. The key point to remember here is that Canada’s Food Guide is the practical application of Canada’s Dietary Guidelines for the general public.

Optional: For more information, visit the Canada’s Dietary Guidelines website.

Canada’s Food Guide, 2019

Go to the Canada’s Food Guide home page to open the guide and navigate through the site. Keep this link open as you read through the following sections.

The new Canada’s Food Guide is represented as one image—the Eat Well Plate. The actual recommendations fall into two main categories: healthy food choices and healthy eating habits.

• Healthy food choices describes the pattern of eating that provides for adequate nutrition while reducing risk of chronic diseases such as heart disease, type 2 diabetes, and some forms of cancer. This section is the focus for NUTR 331.
• Healthy eating is more than the foods you eat. It is also about healthy eating such as the where, when, why, and how you eat. Although this is an important part of healthy eating, the content is for your own interest and benefit.

Healthy Food Choices

Information about healthy food choices is available in Canada’s Food Guide. The following is a snapshot of the recommendations for a healthy diet. The key message is to make it a habit to eat a variety of healthy foods each day.

1. Eat plenty of vegetables and fruits, whole grains, and protein foods. Choose protein foods of plant origin, rather than animal origin, more often. Visit Healthy Food Choices for details about these foods, including examples, important nutrients, preparation tips, snacking ideas, and making healthy choices.
   • vegetables and fruits
     • Make half your plate vegetables and fruits.
     • Eat a wide variety of vegetables and fruits.
     • Vegetables and fruits are important sources of fibre, vitamins (especially vitamins A and C and folate), and minerals (especially magnesium and potassium).
     • Vegetables and fruits may lower risk of heart disease.
     • Fresh, frozen, and canned are all healthy options.
     • Choose whole or cut fruits and vegetables instead of their juices; replace juice with water.
     • Use healthy options for cooking and seasoning.
   • whole grains
     • Whole grains are higher in nutrients and fibre than refined grains.
     • Whole grains are important sources of fibre, vitamins, and minerals (especially thiamin, riboflavin, niacin, folate, iron, zinc, magnesium, and potassium).
     • A diet high in fibre may help to lower risk of stroke, colon cancer, heart disease, and type 2 diabetes.
     • Whole wheat and multigrain foods may not be whole grain; always choose foods with the words whole grain followed by the name of the grain; e.g., whole grain oats, whole grain wheat, or 100% whole wheat.
   • protein foods
     • Protein foods provide protein, most vitamins (except vitamin C and folate), and all minerals.
     • Plant-based proteins can provide more fibre and less saturated fat than other types of protein foods; for that reason, they are beneficial in preventing heart disease.
     • Protein foods include eggs, lean meats and poultry, nuts and seeds, fish and shellfish, lower fat dairy products, beans, peas, and lentils, fortified soy beverages, tofu, and soybeans and other soy products.
   • making healthy choices
     • Choose foods that have little or no added sodium, sugars, or saturated fat.
     • Compare the nutrition facts table on foods to choose products that are lower in sodium, sugars, or saturated fat.
2. Choose foods with healthy fats.
   • Healthy fats are unsaturated fats such as olive, canola, peanut, sesame, soybean, flaxseed, safflower, and sunflower.
   • Choosing foods containing unsaturated fats instead of saturated fats can lower risk of heart disease.
   • Foods containing unsaturated fats include nuts, seeds, avocado, fatty fish, vegetable oils, and soft margarine.
   • Foods containing saturated fats include fatty meats, high-fat dairy products, some highly processed foods, and some tropical oils such as palm oil and coconut oil.
   • Fatty fish, including trout, salmon, herring, and mackerel, are good sources of healthy fats.
   • Limit foods that contain saturated fats. (See the website for examples of foods that contain saturated fat.)
3. Limit highly processed foods. If you choose these foods, eat them less often and in small amounts.
   • Highly processed foods are processed or prepared foods and drinks that add excess sodium, free sugars, or saturated fat to the diet. Click on the link for examples.
   • High sodium intake may increase blood pressure that can increase risk of heart disease.
   • High intake of foods and beverages with added sugars is associated with increased risk of obesity and type 2 diabetes.
   • A high intake of sugary drinks, including 100% fruit juice, is associated with an increased risk of cavities in children.
   • Replacing foods that contain mostly saturated fats with unsaturated fats can reduce risk of heart disease.
   • Processed meats can be high in sodium and saturated fat that increases heart disease risk.
   • High intake of processed meats may be linked to an increased risk of colon cancer.
4. Make water your drink of choice.
   • Water hydrates without adding calories, sugar, sodium, or saturated fat.
   • Drinking water replaces water lost by breathing, sweating, and excreting waste.
   • Choose water over fruit juices, even unsweetened ones.
   • Other healthy drink choices include unsweetened lower fat milk, unsweetened plant-based beverages such as soy beverage or almond beverage, and unsweetened coffee and tea.
   • Limit drinks such as sugary drinks, colas, alcoholic drinks, vegetable juices, and hot chocolate or specialty teas and coffees made with higher fat dairy.
   • Limit caffeine-containing drinks such as colas, tea, coffee, and some energy drinks, especially in children.

5. Use food labels.

   The information on food labels falls into several categories: Nutrition Facts Table; Ingredient List; Nutrition Claims; Food Allergen Labelling; and Date Labelling.

   • The nutrition facts table provides information about serving size, calories, other nutrients such as fats and sugar, and percent daily values (% DV). The % DV can be used as a guide to compare nutrients in a product. For example, 5% DV or less is a little and 15% DV or more is a lot.
   • The ingredient list lists all ingredients by weight starting with the ingredient weighing the most.
   • Nutrition claims include nutrient content claims and health claims. Go to Nutrition Claims to read about the permitted nutrient content and health claims on foods in Canada.
   • Food allergen labelling provides information to help avoid specific food allergens or sensitivities. See Allergens and Gluten Sources Labelling for a list of common food allergens that may appear on labels. Gluten and sulphites are other compounds that may be identified on food labels.
   • Date labelling provides date information such as best before, packaged on, and expiration.
6. Be aware of food marketing that can influence food choices. Go to Marketing Can Influence Your Food Choices to learn more about the many forms of food marketing and how food marketing can affect your food choices.

Source: Health Canada. (2019, December 17). Healthy food choices, Government of Canada. https://food-guide.canada.ca/en/healthy-food-choices/

Healthy Eating Habits

This section on healthy eating habits in Canada’s Food Guide focuses on the environment within which we eat. The messaging may seem like common sense, but there is an increasing awareness and concern over the erosion of traditional mealtime patterns. Meals are eaten almost anywhere except the home and time to prepare meals is often limited. Health Canada has made an effort to reinforce the principle that healthy eating is more than just the foods we eat.

Here’s a snapshot of the key recommendations:

• Be mindful of your eating habits.
• Cook more often.
• Enjoy your food.
• Eat meals with others.

We recommend that you explore this section of Canada’s Food Guide for your own benefit.

Source: Health Canada. (2019, December 17). Healthy eating habits. Government of Canada. https://food-guide.canada.ca/en/healthy-eating-habits/

Canada’s Food Guide: Strengths and Limitations

Strengths:

• It is based on the most current evidence investigating the relationship between food and health.
• The Eat Well Plate is colourful and simple; half the plate is vegetables and fruit, one quarter is grains; and the other quarter is foods rich in protein.
• The digital format is highly portable and appealing to the new generation of tech-minded Canadians.
• The website is limitless in capacity to provide as little or as much information a consumer wishes, and practical tips and recipes are embedded throughout the guide.
• The recommended diet is based on a pattern of eating instead of a prescription for specific types and amounts of foods and thus flexible in terms of caloric needs.
• The recommendations are applicable to a wide variety of ethnic and plant-based eating patterns.
• Information on how to use food labels is clearly provided.
• The recommendations extend beyond food itself. The positive behaviours of selecting, preparing, and consuming meals are included as part of healthy eating.

Limitations:

• The digital format may not appeal to some individuals and may not be accessible to people without Internet access or digital devices. Even fairly tech-savvy people may get lost in this fairly complex tool. Despite the adoption of a totally digital format, as yet, there is no app for Canada’s Food Guide.
• Without specific recommendations for some foods, some nutrients may be difficult to consume in amounts that meet the DRI. For example, removal of the Milk and Alternatives food group (which was present in previous versions of the food guide) may result in suboptimal intakes of calcium and vitamin D.
• Without suggested numbers of servings, some individuals may over- or under-consume some foods. For example, nuts and seeds are healthy but are also high in calories. With no serving size, one could easily consume an excess of calories unintentionally.
• Not all foods that are grouped together are created equal. For example, different vegetables have major differences in their content of vitamins A and C and folate. The food guide provides no emphasis on different types of vegetables.
• The colourful picture is very appealing, but the foods may not be accessible to a lot of Canadians. Strawberries, blueberries, and even tomatoes are expensive even when in season.
• The Eat Well Plate may not be as culturally diverse as intended; it is still to a large extent Eurocentric.
• There is no recommendation for a healthy amount of physical activity.

These are only some of the advantages and limitations. You may come up with others and will have a chance to discuss them later when you do your assignment. But the consensus among nutrition professionals is that this new guide is a step in the right direction. As history has shown, the guide will be continually revised as the science and food supply evolves.

Section 3: Nutrition Facts and Claims on Food Labels

Food labels list the ingredients of a product in descending order, by weight. This list is invariably written in small print. Often, a food label will have words in much larger print that imply something that is not quite accurate. For example, a fruit juice package may have “made with blueberries” (in large letters), but the list of ingredients (in small print) reveals that berries are the second or third ingredient, behind cheaper fruit juices such as apple juice. As the label does not state the actual amount of each ingredient, it is impossible to determine whether blueberry juice is a major ingredient (say, 30%) or a minor ingredient (say, 3%). To make it even more confusing, the label may have a large image of blueberries, not apples!

It is important to carefully read the serving size on a nutrition facts table. A quick glance at a nutrition facts label might give a misleading impression. For example, the label on a bag of potato chips may indicate that a single serving has 150 kilocalories. However, a “serving” may be defined as only one-quarter of a bag. Serving sizes often vary between similar products. For example, the serving size on one can of sardines may be 58 grams (half a can), but for another can it may be 106 grams (the whole can). Accordingly, if you wish to compare two brands of a particular food (e.g., breakfast cereals), you must compare them using the same serving sizes.

Consumers can also use percent daily value (% DV) as a guide for comparing foods (p. 58 of the eText). The % DV indicates, at a glance, whether there is a lot or a little of a nutrient per serving of food (relative to the daily amount required). Percent daily value is discussed in more detail on the Health Canada website.

Percent DV for fat and carbohydrate cannot be interpreted as percent of calories or percent of the weight of the food. For example, a nutrition facts table with 20% DV for fat means the food is high in fat. Some interpret this to mean that the food is 20% by weight, but that is not correct.

Nutrition and diet-related health claims usually highlight one nutrient of a food and are optional. Some evidence suggests that food products with nutrition and diet-related health claims may cost more than products of comparable nutritional value that do not include a claim (Riciutto & Tarasuk, 2005). To assess the overall value of a food, read the nutrition facts and the ingredient list, and check comparable foods. For example, a product that is low in sodium or high in fibre may still be high in fat and calories.

Section 4: Looking at the Whole Diet

How can we best assess a person’s daily diet? Figure 2-12: Two Days’ Meals displays the meals eaten by a student over two days (Monday’s Meals on p. 61 and Tuesday’s Meals on p. 62). A quick comparison reveals that the student made healthier food choices on Monday than on Tuesday. But how do we quantify this? A quick and simple method is to compare the diet eaten each day with Canada’s Food Guide. This shows that the meals eaten on Monday (compared with Tuesday) had a higher content of fruit, vegetables, and whole grains. Clearly, Monday’s meals come much closer to the Eat Well Plate.

A second method is to tabulate how much of each nutrient is in each food. The total intake for each day can then be compared with the DRI values. This has been partly done for each day in the table. We see that Monday’s meals had a higher content of fibre, vitamin C, and calcium but less saturated fat.

Assignment

After taking the Unit Quiz, begin Assignment 1: Diet Analysis. Continue working on the course as you conduct your assessment of your nutrient intakes using Canada’s Food Guide (Part II of the assignment).

Review Questions

See eText Chapter 1, Self-Check:

• question 4 (p. 28)

See eText Chapter 2, Self-Check:

• questions 1, 2, 4, 5, 6, and 7 (p. 73)