Nutrient status, metabolic health and immune function in healthy and active older people

authored by

Felix Kerlikowsky

supervised by

Andreas Hahn

Abstract

Background and aim: Nutrition is not only primarily concerned to achieve energy and nutrient needs, but also contributes to long-term health and the prevention of chronic degenerative diseases. The older population is not clearly defined, but is characterised by a phase of life in which the heterogeneity of health status and thus the level of independence increases significantly compared to younger populations. Scientific recommendations on energy and nutrient requirements are not fundamentally different between older people and the general population. However, older people are at greater risk of nutrient deficiencies due to physical, social and cognitive changes. The micronutrients vitamin D, cobalamin, folate and long-chain omega-3 fatty acids (n3 FA) are considered particularly critical in older people. In addition, deficiencies of these micronutrients are thought to increase the incidence and progression of degenerative diseases and to be causal for chronic inflammation in old age. Previous studies investigate nutrient deficiencies in older people in nursing homes or with already impaired health. Limited knowledge exist about nutrient deficiencies in active, independent older people. Therefore, the overall aim of this thesis was to assess and to improve the status of critical micronutrients in physically active and independently living older people and to investigate their impact on a number of health-related biomarkers and inflammation. Methods: This study was conducted as a 12 week single-centre, two-armed, double-blinded, and randomised clinical trial (RCT). In total, 133 healthy subjects met all the inclusion criteria (≥ 70 years, living home dwelling, and independently) and were included in the study. Exclusion criteria were defined as intake of dietary supplements up to three months before the examination, BMI>35kg/m2, severe diseases, and intake of immunosuppressant’s. The multi-micronutrient supplement (MMN) contained several micronutrients in physiological doses (i.e. 400 µg folic acid, 100 µg cobalamin, 50 µg cholecalciferol, 18 mg tocopherol, 100 µg selenium, 1000 mg EPA/DHA). The status of the following micronutrients was measured: Omega-3 Index (O3I) for relative EPA+DHA levels of total fatty acids in red blood cells, serum 25-hydroxyvitamin D (25-(OH)D), red blood cell folate (RBC folate), and holotranscobalamin (holoTC). In addition, concentrations of methyl malonic acid (MMA) and homocystein (hcy) were measured. Inflammatory biomarkers (i.e. white blood cell count, granulocyte/lymphocyte ratio, platelet count, CRP) were included in an aggregated marker of low-grade inflammation, previously described as the INFLA score. Results: The prevalence of micronutrient deficiencies was low with 7% having serum concentrations of 25-(OH)D less than 50 nmol/L, 11% having RBC folate concentrations less than 570 nmol/L and 12% having serum concentrations of holoTC less than 50 pmol/L. Sex differences were found only in cobalamin status, where 22% of male and only 8% of female subjects were classified as having a low cobalamin status. A total of 88% failed to achieve a desirable O3I of >8%. However, 63.1% of the total cohort had elevated hcy concentrations. After the intervention, there was a significant increase in all biomarkers of micronutrient status compared to the placebo group, leading to a further improvement in vitamin D, folate, cobalamin and n3 FA status in the intervention group. Hcy concentrations were significantly reduced after 12 weeks of micronutrient supplementation. Depending on age and increase in the O3I, a reduction within the INFLA score was observed. However, the reduction were only significant in subjects aged 80 years and older. Conclusion: Our findings suggest that physically active and independently living older people with high levels of education, physical activity and health awareness are not necessarily at higher risk of vitamin D, folate and cobalamin deficiency. Specifically, gaps in micronutrient status are also prevalent in healthy and active older people. Regardless of folate and cobalamin status older people benefit from the intervention with a reduction in elevated hcy concentrations. Individual’s ≥80 years or with low O3I benefited from MMN supplementation by reducing inflammatory activity.

Organisation(s)

Nutrition Physiology and Human Nutrition Section

Type

Doctoral thesis

No. of pages

115

Publication date

2023

Publication status

Published

Electronic version(s)

https://doi.org/10.15488/15765 (Access: Open)