Location: Jean Mayer Human Nutrition Research Center On Aging
2021 Annual Report
Objectives
Objective 1: Characterize diet to determine patterns that associate with healthy aging, and construct models of the various components of these dietary patterns to determine the contribution that each component of the pattern provides to overall associations, while concurrently considering the joint associations of different dietary components.
Subobjective 1.A: Form a new cohort composed of participants adhering to more plant-based dietary patterns to identify factors associated with long-term adherence to healthier dietary patterns and to examine the health benefits of adherence to these dietary patterns.
Subobjective 1.B: Describe the relationship between water intake, hydration and age, and examine the relationships between water intake and hydration and healthy aging.
Objective 2: Determine the relationships between specific foods, nutrients, and other bioactive dietary components of dietary patterns and healthy aging and key elements of healthy aging, such as physical, metabolic, musculoskeletal, vision, and cognitive function.
Subobjective 2.A: Examine the relationship between inadequate vitamin B12 status and accelerated brain aging and explore potential exacerbation of this relationship by high folate status.
Objective 3: Examine the potential genetic modification of the relationships between dietary patterns and their constituents associated with healthy aging, and employ metabolomic and transcriptomic “signatures” of optimal dietary patterns and of healthy aging to detect pathways that may link diet and healthy aging.
Subobjective 3.A: Examine the association between sugar-sweetened beverage (SSB) consumption and dyslipidemia and determine if single nucleotide polymorphisms (SNPs) in the CHREBP locus affect this association.
Approach
Diet plays a critical role in maintaining health across the lifespan, but questions remain about the relationship between nutrition and healthy aging, including physical, cardiometabolic, and cognitive health. Using an epidemiological approach applied to community-based, aging populations, we will study diet patterns and provide the evidence needed to create interventions to foster healthy aging. Most of our research will focus on the impact of the entire diet and dietary behaviors, a departure from the more traditional approach of isolating single nutrients. This approach, broadly referred to as dietary pattern analysis, is more predictive of health outcomes and more reflective of the way people eat.
We will link this approach with genetics, metabolomics, and transcriptomics in the context of large community-based aging cohorts so we can characterize not just healthy aging phenomena, but make an impact by identifying optimal dietary and behavior patterns at both the individual and population levels. The dietary pattern methodology allows us to capture the complexity of diet and the interactions of different dietary components. In addition to conventional diets, we will include alternative diets such as whole food and plant-based (e.g., vegan diets). We will identify factors associated with adherence to such diets; examine potential mechanisms by which bioactive dietary components affect health outcomes (e.g., B vitamins and dementia); and identify factors, such as genetic variation, responsible for differences in response to dietary patterns and food components (such as sugar intake). Results of this research will allow us to translate the science of nutrition and healthy aging into guidance for the public.
Progress Report
For the online Adhering to Dietary Approaches for Personal Taste (ADAPT) project, a longitudinal study of healthy dietary patterns and psychobiological, cultural, social, and environmental predictors of long-term dietary adherence to certain dietary patterns in adults (subobjective 1.A), progress was seen in many areas. In March 2021, we initiated ADAPT Exam 2, which collects follow-up data on demographics, lifestyle, dietary patterns and adherence, quality of life, and health history among Exam 1 participants; we have follow-up data on over 700 participants to date. In a sub-group of 250 participants, a newly developed electronic 3-day food record is being administered to capture dietary patterns in greater detail and determine feasibility for use in the larger cohort. Using ADAPT data on more than 9,000 popular diet followers, we showed that BMI is lower among individuals who made active decisions to adhere to a specific diet, particularly more plant-based diets and/or diets limiting highly processed foods (such as vegan, vegetarian, whole food plant-based, Paleo and Mediterranean diet patterns) compared with those who simply "try to eat healthy" but do not adhere to a defined dietary pattern. One of the dietary patterns we are studying is the Paleo diet. We worked to clarify discrepancies in the overall nutritional composition of historic vs. modern day Paleo diets to help better understand the evolution of this dietary pattern and its nutritional composition.
As part of Subobjective 1.B, we examined beverage consumption patterns and hydration status in older adults and identified five unique consumption patterns characterized by consumption of alcoholic beverages, sweetened beverages, skim/low-fat milk, plain water, and tea. Greater adherence to the plain water pattern was associated with better hydration as measured by 24-hour urinary creatinine levels whereas greater adherence to the sweetened beverage pattern was inversely associated with hydration status. We published a paper examining the relationship between water intake, hydration and cardiometabolic risk in older adults. Our findings show that low water intake and under-hydration can increase risk of dyslipidemia in older adults. We did not observe higher glucose and elevated hemoglobin A1c levels with low water and under-hydration in our older sample as has been previously reported in younger adults. This may be a consequence of the higher prevalence of insulin resistance and impaired fasting glucose in our older study participants.
We also examined the benefits of healthy dietary patterns for development of metabolic syndrome in older adults. In a longitudinal analysis examining adherence to the 2015 Dietary Guidelines for Americans and the 2018 Physical Activity Guidelines for Americans, the study team demonstrated that adherence to either guideline was associated with an approximately 45% lower risk of developing metabolic syndrome, and adherence to both was associated with a 52% lower risk of developing metabolic syndrome. This indicates that both regular physical activity and a healthy diet in midlife may be required for optimal cardiometabolic health in later life.
As part of Objective 1, we examined the relationship between adherence to different healthy diet patterns and circulating levels of ceramides, a type of lipid found in high concentrations within cell membranes and critical to membrane function. We observed that a higher overall diet quality was associated with ceramide levels and attenuated the association between ceramides and cancer mortality, suggesting that there may be shared biological mechanisms in the relations among ceramides, diet, and cancer mortality.
As part of Objective 2, we continued to maintain our long-running program on carbohydrates and healthy aging. One recently completed study showed that participants with higher whole grain consumption were better at maintaining healthier waist circumference, glucose, blood pressure, cholesterol, and triglycerides helping to promote cardiometabolic health. Another study found that participants who ate a diet with a higher ratio of total carbohydrate to fiber, a marker of poor carbohydrate quality, experienced a greater increase in waist circumference, on average, compared to those who ate a diet with a lower ratio. We also observed that participants who ate a diet higher in total fiber, cereal fiber, or fruit fiber experienced a smaller increase in waist circumference, on average, compared to those who ate less fiber. However, this relationship was attenuated among participants who consumed a higher carbohydrate diet.
We recently initiated a new project examining the cardiometabolic effects of low carbohydrate diets, with a focus on the large variety of possible low carbohydrate diet patterns based on the quality of the carbohydrate foods removed from the diet and the types/sources of fats substituted for the carbohydrate foods.
We continue to maintain and update a publicly available, comprehensive dietary fiber database linking fiber to health outcomes. We also have worked to improve the web-interface for user-friendly, online searching. This tool is updated annually and contains population, intervention, comparator, and outcome (PICO) data extracted from published human intervention studies. Dietary fiber research remains active as demonstrated by a 41% increase in publications from the first release of the database (containing data from 868 studies) to the most current version 6 (1,227 studies). The database, a rich resource aimed at assisting policymakers and researchers, is housed on the Institute for the Advancement of Food and Nutrition Sciences (IAFNS) website.
In another project under Objective 2, we modeled various units of protein intake in relation to markers of cardiometabolic health to demonstrate the impact of using different protein intake units. Our results showed that the relationship between protein intake expressed as g/kg of actual body weight and cardiometabolic outcomes was confounded by body weight. We concluded that authors should use g or % energy to assess protein intake in observational studies.
The last project falling under Objective 2 for which we demonstrated significant progress was a study of dietary antioxidants and sarcopenia. Our study showed that antioxidant intake may protect against loss of grip strength and gait speed (a measure of walking ability), both of which are markers of sarcopenia.
As part of Objective 3, we previously observed that increased consumption of sugar-sweetened beverages (SSB), contribute to development of dyslipidemia. To examine the role of genetics in this association, we conducted a meta-analysis of data from 11 Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) and showed that genetic variants within or near the Carbohydrate-responsive Element-binding Protein (CHREBP) locus may modify the associations between SSB consumption and high-density lipoprotein cholesterol and triglyceride concentrations (N=63,599). We replicated these findings in an independent cohort of 57,794 adults of European ancestry in the U.K. Biobank, which yielded results consistent with our earlier analysis. Together these studies suggest that adults with a specific genetic variation may be protected against SSB-inducted low High-Density Lipoprotein (HDL) concentrations. These results highlight the importance of understanding the complex role of dietary intake patterns and genetics in disease risk.
Accomplishments
1. Drinking plenty of water is good for heart health in older adults. The role of water and hydration in physical performance has been well-described in young adults and, on the other end of the age spectrum, it is well-known that rates of dehydration in older adults are high and frequently lead to hospitalization. In contrast, there is little evidence about the possible consequences of chronic underhydration in community-dwelling older adults. ARS-funded researchers in Boston, Massachusetts, examined the relationship between water intake and markers of hydration status and cardiometabolic health in 2238 community-dwelling older adults, on average age 70-years-old, and showed a consistent pattern between low water consumption and urinary markers of underhydration and dyslipidemia. This adds to the growing evidence from younger individuals that inadequate water intake and underhydration may lead to higher cardiometabolic risk in older adults.
Review Publications
Hruby, A., Jacques, P.F. 2020. Protein intake and human health: Implications of units of protein intake. Advances in Nutrition. https://doi.org/10.1093/advances/nmaa097.
Walker, M.E., Xanthakis, V., Peterson, L.R., Duncan, M.S., Lee, J., Ma, J., Bigornia, S., Moore, L.L., Quatromoni, P.A., Vasan, R.S., Jacques, P.F. 2020. Dietary patterns, ceramide ratios, and risk of all-cause and cause-specific mortality: the Framingham offspring study. Journal of Nutrition. 150(11):2994-3004. https://doi.org/10.1093/jn/nxaa269.
Liu, J., Rehm, C.D., Shi, P., McKeown, N.M., Mozaffarian, D., Micha, R. 2020. A comparison of different practical indices for assessing carbohydrate quality among carbohydrate-rich processed products in the US. PLoS ONE. 15(5):e0231572. https://doi.org/10.1371/journal.pone.0231572.
Sawicki, C., Lichtenstein, A.H., Rogers, G., Jacques, P.F., Ma, J., Saltzman, E., McKeown, N.M. 2021. Comparison of indices of carbohydrate quality and food sources of dietary fiber on longitudinal changes in waist circumference in the Framingham offspring cohort. Nutrients. 13(3):997. https://doi.org/10.3390/nu13030997.
Karlsen, M.C., Lichtenstein, A.H., Economos, C., Folta, S., Chang, R., Rogers, G., Jacques, P.F., Livingston, K., McKeown, N.M. 2020. Participant characteristics and self-reported weight status in a cross-sectional pilot survey of self-identified followers of popular diets: Adhering to dietary approaches for personal taste (ADAPT) feasibility survey. Public Health Nutrition. 23(15):2717-2727. https://doi.org/10.1017/S1368980020001330.
Agoulnik, D.S., Pascal Lalonde, M., Ellmore, G.S., McKeown, N.M. 2021. Part 1: The origin and evolution of the Paleo Diet. Nutrition Today. 56(3):94-104. https://doi.org/10.1097/NT.0000000000000482.
