Please note: In 2003, the CTF updated its Grades of Recommendations to include an "I Recommendation" for situations where insufficient evidence exists to allow a recommendation to be made. (Formerly, these situations were captured under a "C Recommendation".) This change is not retroactive, and all "C Recommendations" made prior to 2003 have not been reevaluated in light of the new "I" recommendation grade. For a discussion of these recommendation grades, please link to the 2003 article in the Canadian Medical Association Journal here.
Deficiency Disorders
Nutritional factor deficiencies have been linked to osteoporosis, diverticular
disease, constipation, and iron deficiency anemia. An estimated 40% of
North American women will suffer from osteoporosis-related fractures by
the time they reach age 70. Deficiency of dietary fibre has been implicated
in constipation and other gastrointestinal disorders such as diverticulosis.
Iron deficiency is common in menstruating women whose diet is deficient
in foods containing available iron, especially meats. Pregnant women, and
those who nurse for a prolonged period of time are also at risk for iron
deficiency. Up to 63% of people over age 60 have been documented to have
deficient iron intakes. Chronic alcoholics and strict vegetarians are also
at risk for deficiency disorders. An additional concern is malnutrition,
which is associated with an increased prevalence of complications and high
mortality among hospitalized patients. While those living alone are at
risk, institutional care is associated with malnutrition in as many as
52-85%.
Options
Screening measures included nutrient history-taking (self-administered
questionnaires, seven-day weighted dietary record, Food Frequency Questionnaire);
physical examination including anthropometric measures; and laboratory
measurement (albumin, serum transferrin, absolute lymphocyte count, specific
vitamins).
Outcomes
Change in dietary habits (e.g., reduced fat or cholesterol intake,
increased fibre intake); serum cholesterol levels. Other health outcomes
varied by specific dietary nutrient: main outcomes for fat intake were
myocardial infarction, sudden death, all-cause mortality and cancer incidence;
for fibre intake was colon cancer incidence; for sodium intake were hypertension
and blood pressure; and for calcium intake was rate of bone loss.
Evidence
MEDLINE was searched for the years1988 to 1992 using the MeSH headings
"deficiency diseases" or "malnutrition" or "nutrition disorders" or "nutrition
assessment" or "nutrition"; and "adults" or "aged". Materials prepared
for the 1989 U.S. Preventive Services Task Force were also used. Study results
were synthesized in table or graphic format only.
Values
The 13-member Task Force of experts in family medicine, geriatric medicine,
pediatrics, psychiatry and epidemiology used an evidence-based method for
evaluating the effectiveness of preventive health care interventions. Recommendations
were not based on cost-effectiveness of options. Patient preferences were
not discussed.
Background papers providing critical appraisal of the evidence and tentative
recommendations prepared by the chapter author were pre-circulated to the
members. Evidence for this topic was presented and deliberated upon in
1- to 2-day meetings, 2 to 3 times per year from January 1993 to June 1993.
Consensus was reached on final recommendations.
Benefits, Harms, and Costs
Usefulness of various detection measures was described in qualitative
terms only.
No evidence shows a screening benefit for elderly persons or alcoholics. Controversy exists regarding the benefit of supplementation for individuals who have an inadequate dietary intake of specific nutrients, have serum levels below accepted normal levels and no characteristics of classic deficiency syndromes.
The results of RCTs support that counselling by non-physicians can lead to changes in dietary habits. A study of adults with hypercholesterolemia found that those who received counselling and printed materials decreased their cholesterol and increased their fibre intakes. Another study found that middle-aged women who received individual and group nutritional counselling reduced the percentage of energy derived from dietary fat from 39% to 21%; no change occurred in the control group. In a study of men recovering from myocardial infarction, those who received individual and group counselling reported changes in fat intake which persisted for up to 24 months. A study of an intervention comprised of a 5-minute interview with a nurse, generic self-help materials and a follow-up phone call reported small but significant improvements in dietary fat and fibre intakes, but only for those with responsibility for meal production.
Controlled trials have shown decreases in the incidence of myocardial
infarction and sudden death, but not all-cause mortality in asymptomatic
middle-aged men with selected cardiac risk factors who were given diets
low in saturated fat. No evidence exists that changes in fat intake reduce
the incidence of various malignancies. Case-control studies report inconsistent
results about the association between fibre intake and colon cancer, but
meta-analyses of these studies suggest an overall benefit. Adverse effects
associated with changes in dietary intake of specific nutrients were identified
but not quantified.
Recommendations
Recommendation grade [A, B, C, D, E] and level of evidence
[I, II-1, II-2, II-3, III] are indicated after each recommendation. Citations
in support of individual recommendations are identified in the guideline
text.
The Canada Food Guide recommends eating a variety of foods and choosing
lower fat foods, and makes recommendations on daily adult intakes for specific
food groups. The 1989 U.S. Preventive Services Task Force recommended consumption
of foods high in complex carbohydrates and fibre, and periodic counselling
regarding dietary intakes of calories, fat, cholesterol, complex carbohydrates,
fibre and sodium. The American Medical Association, American College of
Physicians and American Heart Association make specific recommendations
about nutritional counselling.
Sponsors
The Canadian Task Force on Preventive Health
Care developed this guideline with funding from Health Canada.
Source Document
Patterson C. Nutritional counselling for undesirable dietary patterns
and screening for protein/calorie malnutrition disorders in adults. In:
Canadian Task Force on the Periodic Health Examination. Canadian
Guide to Clinical Preventive Health Care. Ottawa: Health Canada,
1994; 586-99.
Other
Canadian Task Force on the Periodic Health Examination. The periodic
health examination. Can Med Assoc J. 1979;121:1193-254.