New Canada-US Dietary Reference Intakes on Macronutrients (Carbohydrate, Protein, Fat) Released

On September 5, 2002, a joint Canada-US expert report was released providing a comprehensive set of reference values for nutrient intakes for healthy US and Canadian individuals and populations. The report, "Dietary Reference Intakes (DRIs) for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein and Amino Acids", was released by the US Food and Nutrition Board, Institute of Medicine of the National Academies in collaboration with Health Canada. Full report: National Academies Press DRI Macronutrient Report.

The report provides an independent and critical review of the evidence relating macronutrient intake to risk reduction of chronic diseases and to amounts needed to maintain health. It establishes a set of reference values to expand and update previously published US Recommended Dietary Allowances (RDAs) and Canadian Recommended Nutrient Intakes (RNIs). The report also provides a substantial review of the role of daily physical activity in achieving and sustaining optimal health.

Health Canada has not yet determined how these recommendations will specifically affect Canadian nutrition guidelines and policies.

DRI Terminology

The DRIs for macronutrients are comprised of a set a reference values, that are defined as follows:

Acceptable Macronutrient Distribution Ranges (AMDR): a range of intakes (represented as percent of energy intake) for a particular energy source that is associated with reduced risk of chronic disease while providing adequate intakes of essential nutrients.

Recommended Dietary Allowance (RDA): the average daily dietary nutrient intake level sufficient to meet the nutrient requirement of nearly all (97-98%) healthy individuals in a particular life stage and gender group.

Adequate Intake (AI): the recommended average daily intake level based on observed or experimentally determined approximations or estimates of nutrient intake by a group (or groups) of apparently healthy people that are assumed to be adequate – used when an RDA cannot be determined.

Tolerable Upper Intake Level (UL): the highest average daily nutrient intake level that is likely to pose no risk of adverse health effects to almost all individuals in the general population. As intake increases above the UL, the potential risk of adverse effects may increase.

Estimated Average Requirement (EAR): the average daily nutrient intake level estimated to meet the requirement of half the healthy individuals in a particular life stage and gender group.

Estimated Energy Requirement (EER): the average dietary energy intake that is predicted to maintain energy balance in a healthy adult of a defined age, gender, weight, height and level of physical activity, consistent with good health.

Summary of Recommendations for Carbohydrates (Sugars and Starches)

Total Carbohydrate

The AMDR for carbohydrate is 45-65% of energy intake for all adults and children. This range is "based on evidence indicating a risk for coronary heart disease (CHD) at low intakes of fat and high intakes of carbohydrate and based on evidence for increased risk for obesity and its complications, including CHD, with high intakes of fat."

The RDA for carbohydrate is 130 g/day for adults and children "based on the average minimum amount of glucose utilized by the brain. This level of intake, however, is typically exceeded to meet energy needs while consuming acceptable intake levels of fat and protein." Median intakes are 200-330 g/day for men and 180-230 g/day for women.

Sugars

The conclusion of the report was that, "based on the data available on dental caries, behaviour, cancer, risk of obesity and risk of hyperlipidemia, there is insufficient evidence to set a UL for total or added sugars." This means that based on current scientific evidence, there is no level of total or added sugars intake that increases the risk of adverse effects related to these conditions.

Added sugars were defined as "sugars and syrups that are added to foods during processing or preparation", including "white sugar, brown sugar, raw sugar, corn syrup, corn-syrup solids, high-fructose corn syrup, malt syrup, maple syrup, pancake syrup, fructose sweetener, liquid fructose, honey, molasses, anhydrous dextrose, and crystal dextrose. Added sugars do not include naturally occurring sugars such as lactose in milk or fructose in fruits." Although this report distinguishes between added and naturally occurring sugars, the report noted that "added sugars are not chemically different from naturally occurring sugars."

Although no UL was set for added or total sugars, "a maximal intake level of 25 percent or less of energy from added sugars" was suggested for adults and children "based on the decreased intake of some micronutrients of American subpopulations exceeding this level." However, this level of intake far exceeds current average intakes, which are estimated to be 15.8 percent of total energy intake (calories) in the U.S. and less in Canada. Thus, this report does not recommend a decrease in intake of total or added sugars.

Summary of Other Recommendations

Energy (calories)

EERs for moderately active males and females 18 years of age and older are 3067 kcal/d and 2403 kcal/d respectively. EERs are lower for those younger than 18 years of age. 10 kcal/d for males and 7 kcal/d for females are to be subtracted for each year of age above 19 years.

Fat

The AMDR for fat is 20-35% of energy intake for all adults. This range is "based on evidence indicating a risk for coronary heart disease (CHD) at low intakes of fat and high intakes of carbohydrate and based on evidence for increased risk for obesity and its complications, including CHD, with high intakes of fat."

The AMDR for fat intake is 30-40% of energy for children 1-3 years and 25-35% of energy for children 4-18 years.

No AI, RDA or UL was set for adults. AI for infants: 0-6 months: 31 g/day; 7-12 months: 30 g/day.

Fatty Acids and Cholesterol

The AMDR for linoleic acid and alpha-linolenic acid is 5-10% and 0.6-1.2% of energy intake for children and adults based on current intakes and a lack of evidence indicating safety above this level. No AMDR is set for monounsaturated fatty acids because they are not essential in the diet and evidence linking them to chronic disease is limited.

It is recommended that diets be as low as possible in saturated and trans fatty acids and cholesterol because intake of these nutrients is associated with increased risk of coronary heart disease.

AI for linoleic acid for adults 19-50 years of age: 17 g/day for men; 12 g/day for women; alpha-linolenic acid: 1.6 g/day for men; 1.1 g/day for women. AIs are lower for younger and older individuals.

Protein and Amino Acids

The AMDR for protein is 10-35% of energy intake for adults, 5-20% for young children and 10-30% for older children to complement the AMDRs for fat and carbohydrate.

The RDA for men and women over 18 years of age is 0.8 g of good quality protein/kg body weight/day. Levels are higher for younger individuals. Protein quality was defined based on content of indispensable amino acids and digestibility.

Fiber

"Dietary Fiber" is defined as nondigestible carbohydrates and lignin that are intrinsic and intact in plants. "Functional Fiber" is defined as isolated, nondigestible carbohydrates that have beneficial physiological effects in humans. "Total Fiber" is the sum of "Dietary Fiber" and "Functional Fiber".

"There is no lower limit of intake and no known adverse effects with chronic consumption of Dietary Fiber or Functional Fiber. Therefore, an AMDR is not set for Dietary, Functional, or Total Fiber."

AI for Total Fiber: 38 g/day for men and 25 g/day for women ages 19-50 years. AIs are lower for younger and older individuals. Median intakes: 16.5-17.9 g/day for men; 12.1-13.8 g/day for women. Insufficient evidence to set a UL.

Physical Activity

For children and adults: "to prevent weight gain as well as to accrue additional, weight-independent health benefits of physical activity, 60 minutes of daily moderate intensity physical activity (e.g., walking/jogging at 4 to 5 mph) is recommended, in addition to the activities required by a sedentary lifestyle."