Aging
Abstract & Commentary
Dietary Patterns at Midlife and Health in Aging
By Traci Pantuso, ND
Adjunct Faculty, Bastyr University, Seattle, WA
Dr. Pantuso reports no financial relationships relevant to this field of study.
Synopsis: In women surviving to older ages, diet quality at midlife appears to be strongly associated with a greater likelihood of not having mental and physical limitations.
Source: Samieri C, et al. The association between dietary patterns at midlife and health in aging. Ann Intern Med 2013;159:584-591.
Maintaining health and well being in aging populations is important for many reasons, and is particularly relevant with the increase in life expectancy and aging baby boomer population. Epidemiological research has demonstrated associations between better diet quality and decreased risk for developing cancer, major coronary artery disease, and type 2 diabetes.1 In the study being reviewed here, the authors investigated the relationship between midlife dietary patterns and the prevalence in women who were aging well and who were participating in the Nurses’ Health Study. The authors hypothesized that midlife factors, particularly dietary patterns at midlife, may contribute to the quality of the aging process.
To evaluate dietary patterns, the authors used the Alternative Healthy Eating Index-2010 (AHEI-2010) and the Alternate Mediterranean diet (A-MeDi) scores to evaluate the Food Frequency Questionnaires (FFQ) that the participants in the Nurses’ Health Study had completed in the past. The Healthy Eating Index is an index that was based on the Dietary Guidelines for Americans; the AHEI-2010 incorporates more recent knowledge regarding specific nutrients and the risk of disease in the assessment. Both of these diet evaluation tools are well validated.2 For example, in past studies the alternate healthy eating index was associated with a lower risk for metabolic syndrome and insulin resistance, slower atherosclerotic progression in women with cardiovascular disease, and 19% lower risk for major chronic disease. There is also evidence pointing to improved cognitive function and physical functioning and decreased depression with adherence to the Mediterranean diet and the healthy eating index.
The Nurse’s Health Study, which began in 1976, is a cross-sectional observational study with 121,700 female nurses who were aged 30-55 years old and in 11 states at baseline. In 1976, the female nurses completed a mailed baseline questionnaire. Follow-up questionnaires were sent every 2 years and are 90% complete for all person years.
In 1980, 1984, 1986, and every 4 years thereafter, participants completed a semi-quantitative food frequency questionnaire (FFQ). In 1992, 1996, and 2000, a 36-item questionnaire evaluating eight health parameters — the medical outcomes short form 36 health survey (SF-36) — including mental health and physical functioning was administered (see Table 1).
Table 1. Questionnaires, Timing, and Trial Participants
| Assessment | Time Period | Participants |
|---|---|---|
| FFQ | 1980, 1984, 1986 and every 4 years thereafter | All participants in the Nurses' Health Study |
| SF-36 | 1992, 1996, 2000 | All participants in the Nurses' Health Study |
| Cognitive Study | 1995-2001 | 21,202 participants > 70 years old were eligible |
A cognitive function study occurred in the 21,202 eligible female nurses who were ≥ 70 years of age between the years of 1995-2001. Ninety percent of the 21,202 eligible women participated in the cognitive assessment.
In this study of the 21,202 eligible participants, 19,415 participated. Of the 19,415, a number of participants were excluded, leaving a total of 10,670 participants (see Table 2).
Table 1. Questionnaires, Timing, and Trial Participants
| Excluded Participants |
Reason for Exclusion |
|---|---|
| 2585 | History of 11 chronic diseases as of 1986 |
| 2621 | Lack of dietary data in 1984 and 1986 |
| 44 | Did not complete the SF-36 |
| 289 | Lack of data on the mental health index or on the physical function scale |
| 637 | Education data missing |
| 1665 | Body mass index data missing |
| 904 | Missing physical activity data |
Healthy vs Usual Aging. The authors classified healthy aging as being free of 11 chronic diseases and having no impairment in cognition, no physical disabilities, and intact mental health. Chronic diseases that were evaluated on the biennial questionnaires and in the cognitive study included cancer, myocardial infarction, percutaneous transluminal coronary angioplasty, coronary artery bypass surgery, congestive heart failure, stroke, type 2 diabetes, kidney failure, chronic obstructive pulmonary disease, Parkinson disease, multiple sclerosis, and amyotrophic lateral sclerosis.
Dietary Patterns. To decrease the chance of reverse causation, the authors focused on the dietary reports of the women with an age range of 57-61 years (median age, 59). The authors wanted to create a lag time between the knowledge of dietary patterns and determination of healthy aging to reduce the possibility of a participant changing her diet due to a new disease condition.
Dietary quality at midlife was measured by averaging the information from the 1984 and 1986 FFQs where participants answered "how often, on average, they consumed a standard portion of each food." The intake of food was then converted into the actual nutrient intake by using the U.S. Department of Agriculture database. The authors then used the 1984 and 1986 FFQ scores to calculate the AHEI-2010 and A-MeDi scores.
AHEI-2010. The scoring of the AHEI-2010 is based on component-specific criteria supported by current dietary guidelines or research studies in the literature. Each component was scored from 0 (worst) to 10 (best). The range of the total AHEI-2010 scores are from 0 (non-adherence) to 110 (perfect adherence).
The components of the AHEI-2010 are:
- Intake of vegetables, excluding potatoes
- Fruits, excluding juices
- Whole grains
- Nuts, legumes, and vegetable proteins
- Long chain omega-3 polyunsaturated fatty acids (PUFAs)
- Lower intakes of sugar-sweetened beverages or fruit juices
- Lower intakes of red or processed meats, trans fats, and sodium
- Moderate intake of 0.5-1.5 alcoholic drinks per day
A-MeDi. Each component is scored from 0 to 1 with 0 being below the median and 1 being above the median. For components that are detrimental to health 0 is given to intake above the median and 1 is given for intake below the median. Total scores range from 0 (non-adherence) to 10 (perfect adherence).
The A-MeDi included the following nine components:
- Vegetables, excluding potatoes
- Fruits
- Nuts
- Whole grains
- Legumes
- Fish
- Red or processed meats
- Moderate alcohol
- Monounsaturated fatty acid-saturated fatty acid ratio
Secondary Analysis. The authors performed secondary analysis between AHEI-2010 and A-MeDi scores and each of the four healthy aging components. The authors also investigated whether an association of AHEI-2010 or A-MeDi may be due to individual components of either measurement with healthy aging.
Results. Out of 10,670 subjects, 9599 (90%) had no cognitive impairment, 7234 (67.8%) had none of the conditions listed, 4606 (43.2%) had no mental health limitations, and 2905 (27.2%) had no physical function impairment. In addition, 1171 (11%) were healthy and 9499 (89%) were considered to be in the usual aging category. Of the 9499 (89%) persons in the usual aging category, 63.8% had limitations in physical, mental, or cognitive health; and 32.8% had both chronic diseases and limitations in physical, mental, or cognitive health. Only 3.4% had one or more chronic diseases, the most common of which were myocardial infarction/coronary bypass surgery (12%), diabetes (8.2%), and breast cancer (6.0%).
The women in the healthy aging group exercised more during midlife, had lower rates of hypertension and hypercholesterolemia, had lower prevalence of smoking, and lower obesity compared to the women in the usual aging group. At midlife, the women in the healthy aging group had higher baseline and age standardized A-MeDi and AHEI-2010 scores (4.5 and 53.2 points, respectively) compared to the usual agers (4.3 and 50.6, respectively). Higher scores on the AHEI-2010 and A-MeDi were strongly associated with healthy aging (P < 0.001 for AHEI-2010; P = 0.002 for A-MeDi).
Women in the highest quintile of diet scores assessed by the AHEI-2010 had a 34% (95% confidence interval [CI], 9-66%) greater odds of healthy aging. This trend was also demonstrated with the A-MeDi diet scores, which demonstrated a 46% (CI, 17-83%) greater odds of healthy aging compared to the usual agers.
Secondary Analysis. The authors also demonstrated that both the AHEI-2010 and A-MeDi scores were significantly associated with an increased likelihood of not developing limitations in mental health as measured by the SF-36 and impairments in physical function (P ≤ 0.005). The highest quintiles of both the AHEI-2010 and A-MeDi scores had an increased likelihood of not developing limitations in mental health or physical function compared to the lowest quintile of scores (see Table 3).
Table 3. Secondary Analysis
| AHEI-2010 | A-MeDi | |
|---|---|---|
| No Physical Function Impairment | 23% (CI, 11-36%) | 14% (CI, 3-26%) |
| No Mental Health Limitations | 13% (CI, 5-22%) |
Commentary
This study demonstrated that a better quality of diet at midlife was associated with good health and well being in individuals who survived to older ages. Adherence to the Mediterranean dietary patterns at midlife and beyond appears to be strongly associated with healthy aging and decreased impairment in multiple domains. Although this is a cross-sectional observational study (as opposed to the more methodologically sound controlled trial) that used newer though validated tools (A-MeDi and AHEI-2010) to interpret FFQs, the data are convincing and further supported by the literature that the Mediterranean dietary pattern is a healthy diet to recommend to most, if not all, patients.
A Mediterranean dietary pattern or a diet that scores high on the AHEI-2010 emphasizes a higher intake of vegetables (excluding potatoes), whole fruits, legumes, whole grains, fish, and other long chain omega-3 polyunsaturated fatty acids with a moderate intake of alcoholic beverages (red wine) and a low intake of red/processed meats, sodium, trans-fats/saturated fats and sugar sweetened or fruit juices. The strengths of this study are the large sample size and evaluation of healthy aging with multiple domains using validated methods. This study also was able to identify midlife dietary habits repeatedly with validated FFQs.
One drawback of this study is its limited generalizability, partly due to a study population consisting solely of female nurses. Also, this population is a health-educated population, possibly atypical from the aging U.S. population as a whole, and its reliance on self-reported questionnaires is not always the most accurate method of assessing diet. Finally, there were a large number of participants that were excluded due to missing data on the questionnaires; which may have influenced the results (see Table 2).
Recommending a diet similar to the Mediterranean diet pattern is a safe and realistic approach to increasing survival and leading to decreased cognitive and physical impairments and chronic disease.
Summary Points
- This study investigated dietary patterns at midlife and the association with health in aging in female nurses in the Nurses' Health Study, a large cross-sectional observation study in the United States that began in 1976.
- Higher scores on the AHEI-2010 and A-MeDi, two dietary scales, were strongly associated with healthy aging and a greater likelihood of not having physical and or mental limitations.
- Compared to controls, people with healthy diets exercised more during midlife, had lower rates of hypertension and hypercholesterolemia, and had a lower prevalence of obesity and smoking.
References
1. Sofi F, et al. Accruing evidence on benefits of adherence to the Mediterranean diet on health: An updated systematic review and meta-analysis. Am J Clin Nutr 2010;92:1189-1196.
2. Hoffman R, Gerber M. Evaluating and adapting the Mediterranean diet for non-Mediterranean populations: A critical appraisal. Nutr Rev 2013;71:573-584.
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