Intakes, adequacy, food sources and biomarker status of iron, folate, and vitamin B₁₂ in Māori and non-Māori octogenarians : life and living in advanced age : a cohort study in New Zealand (LiLACS NZ) : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Nutrition and Dietetics, Massey University, Albany, New Zealand
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2017
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Massey University
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Abstract
Background: Iron, folate and vitamin B12 are the three key nutrients associated with the
development of anaemia and have also been associated with the dietary patterns linked to higher
malnutrition risk in older adults. Octogenarians may be at increased risk for iron, folate and vitamin
B12 deficiency due to reduced food intake. Dietary factors, cooking methods, medications, presence
of inflammation, and impaired gastrointestinal absorption may affect the availability and
bioavailability of these nutrients. There are currently no specific nutrient reference values (NRVs)
or biomarker cut-offs for adults in advanced age and little is known about the relationship between
dietary intake and biomarkers for older adults.
Aim: To investigate the intake, adequacy, food sources and biomarker status of iron, folate and
vitamin B12 and the relationship between dietary intake and biomarkers.
Methods: In the follow up assessment of LiLACS NZ, 216 Māori and 362 non-Māori participants
completed a detailed dietary assessment using 2x 24-hr multiple pass recalls. Adequacy of iron,
folate and vitamin B12 were determined by comparison to the Estimated Average Requirement
(EAR) for adults aged 71+ years. Serum ferritin, serum iron, total iron binding capacity, transferrin
saturation, red blood cell (RBC) folate, serum folate, serum vitamin B12 and haemoglobin were
compared to recognised cut-offs for adults. Generalised linear models and binary regression
estimated the association between dietary intake and biomarkers.
Results: Most participants had adequate dietary iron intakes (88% Māori; 95% non-Māori above
EAR) and biomarkers for iron (>94% above cut-offs). The EAR for vitamin B12 was met by 74% Māori;
78% non-Māori and folate met by 42% Māori; 49% non-Māori. Māori versus non-Māori had higher
intakes of vitamin B12 (p=0.038) and serum vitamin B12 (p=0.026). Increased dietary folate intake
was associated with increased RBC folate for Māori (p=0.001) and non-Māori (p=0.014) and with
increased serum folate for Māori (p<0.001). Folate intake >215μg/day was associated with reduced
risk of deficiency in RBC folate for Māori (p=0.001).
Conclusions: Dietary intake and stores of iron are largely adequate in this population. Strategies to
optimise the intake and bioavailability of foods rich in folate and vitamin B12 may be beneficial.
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Older people, Nutrition, New Zealand, Older Maori, Iron in human nutrition, Folic acid in human nutrition, Vitamin B12, New Zealand, Research Subject Categories::INTERDISCIPLINARY RESEARCH AREAS::Domestic science and nutrition