Many older persons find it difficult to maintain a diet that provides enough nutrients for optimal health. A recent study looked at whether it is possible for older persons to improve their diet quality by consuming walnuts on a daily basis.
The variety and quality of our diets tend to deteriorate as we age for many reasons that are usually related to financial, social, and health issues. Unfortunately, this also means that older persons do not consume enough key nutrients, which contributes to ill health and chronic disease. Small studies have shown that tree nuts may improve diet quality, as they contain key nutrients that can enhance health and wellbeing. A recent study in the British Journal of Nutrition looked at whether the nutrient profiles of older persons in the USA could be improved by incorporating walnuts into their diet.
Healthy elderly subjects (63-79 years old) were followed for two years in a prospective, dietary intervention trial. Participants were randomly assigned to a control or an experimental group. All were asked to continue their regular diets. However, those in the control group were asked to avoid all tree nuts and those in the experimental group were asked to consume walnuts on a daily basis (average 43 g), equating to 15% of their daily energy needs. Dietary intake was assessed using 24-hour diet recalls. Nutrient intake and displacement (the extent to which the intake of a nutrient was changed, or displaced, by consuming walnuts) was compared between the two groups at the end of the study.
Daily consumption of walnuts improved the nutrient profile and provided participants with a significantly higher mean daily energy intake (954 kJ higher). Intake of macronutrients including total protein from vegetables and total polyunsaturated fatty acids (PUFAs), and micronutrients such as magnesium, copper, and manganese were also significantly higher in the experimental group. In contrast, intake of macronutrients including total carbohydrates, animal proteins, saturated fatty acids (SFA), and micronutrients such as sodium, thiamin, riboflavin, and vitamin E were significantly lower in the experimental group. These changes correspond with guidelines for reducing cholesterol intake, which recommend decreasing SFA and increasing PUFA. This indicates that walnut consumption could have positive benefits for cardiovascular health. Displacement patterns also tended to improve nutrient profiles following walnut consumption.
Even though both the experimental and control diets met most of the criteria for the Acceptable Macronutrient Distribution Ranges (AMDR), both exceeded the recommended intakes for total fat, SFA, and sodium. The experimental diet also considerably exceeded the recommended intake for PUFA due to the PUFA content of walnuts. However, based on the results of clinical trials analyzing the factors involved in risk reduction of coronary heart disease, current PUFA recommendations may need to be increased. The authors also note that these results may not apply to other populations or age groups. Despite this, they recommend that clinicians and dieticians develop strategies to encourage older people to incorporate walnuts into their diet on a daily basis to improve diet quality.
Written by Natasha Tetlow, PhD
Bitok E, Jaceldo-Siegl K, Rajaram S, et al. Favourable nutrient intake and displacement with long-term walnut supplementation among elderly: results of a randomised trial. Br J Nutr. 2017;118:201-209. Available from: doi.10.1017/S0007114517001957.