AS340 - Evidence for establishing optimum protein intake in older adults (WHI-FI)

Investigator Names and Contact Information

Jeannette Beasley (Jeannette.Beasley@nyumc.org)

Introduction/Intent

The purpose of this three-year project is to determine how protein intake relates to physical function and mortality among older women. The Women's Health Initiative (WHI) Food Frequency Questionnaire (FFQ) will be used to characterize the amounts and sources of protein intake. We will apply a novel statistical approach for correcting for dietary measurement error using biomarkers of energy and protein intake. Within the In-person visit cohort of 8000 WHI participants aged 80 and older we will: 1) Characterize biomarker-calibrated* protein intake in later life, and assess how protein intake has changed from the baseline dietary assessment; 2) Determine the association of biomarker-calibrated protein intake with physical function, as measured by the Short Physical Performance Battery; 3) Determine the association of biomarker-calibrated protein intake with risk of mortality. To accomplish these aims, 8,000 In-person visits will be conducted nationwide among women aged 80 and older from the WHI who were originally enrolled from 1993-1997. Participants will be mailed the WHI FFQ and be followed through at least 2015 (3-4 years) to ascertain mortality. This evidence is crucial for formulating evidence-based dietary guidelines that pertain to the growing population of older women in the US and worldwide.

Specific Aims

Women aged 80 and older are emerging as a critically important demographic group for public health and public policy. The United States (US) Census estimates that 6.3 million women were aged 80 and older in 2009, 5% of the total female population and 2% of the entire US population. By 2040, fueled by the baby boomers that will begin to reach the age of 80 in 2026, this group will be one of the fastest growing segments of the US population representing 8% of the female population and 4% of the total population ¹. At age 65, a women's life expectancy is 20 years, but women who survive to age 85 still have a life expectancy of 7.2 years. Today, 58% of Medicare beneficiaries are women, while 70% of Medicare beneficiaries ages 85 and older are women ². In the future, America will be "a society dominated by older people, and many of them older women" ².

The 2010 Dietary Guidelines for Americans provides specific recommendations for older adults (defined as >65 years old) regarding body weight, sodium, and Vitamin B12 ³. Recent research by our group and others suggests higher protein intake may be associated with a reduced risk of frailty ⁴ and preservation of lean body mass ⁵. Characterizing mechanisms through which higher protein intake may be related to successful aging phenotypes could inform dietary guidelines.

The purpose of this study is to address several major gaps in the research on nutrition among older women. The National Health and Nutrition Examination Survey (NHANES) provides valuable surveillance data to monitor dietary intake within the United States ⁶, and these data are used to set nutrition priorities and inform the Dietary Guidelines 3. However, NHANES does not sample adults over 79 years of age, and longitudinal studies that do include adults over 80 years of age do typically not collect nutrition measures (i.e. Longitudinal Study of Aging, Cardiovascular Health Study's All-star Study). This leaves the research community with a gap in the understanding of dietary habits and intervention targets for a subset of the United States population that could benefit in a major way from improved nutrition.

The WHI is unique in having biomarkers of energy and protein intake to calibrate self-reported measures. By collecting an updated dietary assessment in a large cohort of older women already being followed for health outcomes such as CVD and cancer, this study can contribute crucial new evidence on how dietary patterns relate to aging outcomes.

The primary specific aims are addressed by combining the exposure data collected in this study with the outcome data collected by the WHI parent study:

Specific Aims:

Within the In-person visit cohort of 8000 WHI participants aged 80 and older we will administer the WHI FFQ to:*

1. Characterize biomarker-calibrated** protein intake in later life, and assess how protein intake has changed from the baseline dietary assessment.

2. Determine the association of biomarker-calibrated protein intake with physical function, as measured by the Short Physical Performance Battery.

3. Determine the association of biomarker-calibrated protein intake with risk of mortality.

*The AS340 population is based on the Long Life Study population. The Long Life Study originally planned to enroll women aged 80 years and older. However, consent and participation were lower than initially expected, so the eligible pool was expanded to include women as young as 63 years by 12/1/11.

**Calibrated using biomarkers of energy and protein intake as previously described ⁷

Although the focus of this application is specifically on protein intake, the new data collected to accomplish the above specific aims will also support future studies of associations between nutrition in later life and risks of other major health outcomes (breast cancer, colon cancer, type 2 diabetes, and dementia/Alzheimer's Disease), as well as levels and trajectories of cardiovascular and inflammatory biomarkers and cognitive function.

Results/Findings A total of 6,094 FFQs were returned by AS340 participants. In addition to computed nutrients, the data file includes the scores for the Healthy Eating Index 2010 and associated My Pyramid Equivalents Database components (MPEDs). The FFQ data are available for investigators with approved paper proposals.

References

1. Bureau UC. Census Bureau Home Page. 2011; http://www.census.gov/.

2. Rice R. Philosophical perspectives in home care: the ontology of aging. Geriatr Nurs. Mar-Apr 2000;21(2):110.

3. DGAC. Report of the Dietary Guidelines Advisory Committee (DGAC) on the Dietary Guidelines for Americans, 2010, to the Secretary of Agriculture and the Secretary of Health and Human Services. In: Agriculture USDo, ed: Agricultural Research Service; 2010:453.

4. Beasley JM, LaCroix AZ, Neuhouser ML, et al. Protein intake and incident frailty in the Women's Health Initiative observational study. J Am Geriatr Soc. Jun 2010;58(6):1063-1071.

5. Houston DK, Nicklas BJ, Ding J, et al. Dietary protein intake is associated with lean mass change in older, community-dwelling adults: the Health, Aging, and Body Composition (Health ABC) Study. The American Journal of Clinical Nutrition. Jan 2008;87(1):150-155.

6. National Center for Health S. National Health and Nutrition Survey Description. 2006; (http://www.cdc.gov/nchs/about/major/nhanes/intro_mec.htm).

7. Neuhouser ML, Tinker L, Shaw PA, et al. Use of recovery biomarkers to calibrate nutrient consumption self-reports in the Women's Health Initiative. Am J Epidemiol. May 15 2008;167(10):1247-1259.