In our study, both energy and protein intake were lower than reported in the Tromsø study  and Norkost 3 study . However, the participants in those studies were younger than the participants in the current study. The mean age in the Tromsø study was 57 years for women and 58 years for men, while the oldest age group reported in the Norkost 3 study was 60–70-year-olds. Protein intake tends to decline with age , despite increased need and higher recommendations. Nevertheless, protein intake in our study was in accordance with the Nordic recommendations for older adults .
Previous analyses of protein distribution in the current study sample revealed that protein was distributed well . However, an even protein distribution during the day may not be beneficial if each meal does not contain enough protein to fully stimulate muscle protein synthesis. In our study, 28% of the participants did not eat 30 g of protein at any meal eaten during the day. In a Mexican study addressing the number of meals including at least 30 g of protein and risk of disability, 61% of participants reported eating zero meals with that amount of protein . By comparison, Hone et al.  found that the mean number of meals with at least 30 g of protein per day among people 65 years and older was 0.96, and that the number of meals with ≥ 30 g of protein significantly declined with age.
In our study, protein intake was skewed towards dinner, and very few participants ate the suggested threshold of 30 g of protein at meals other than dinner. A special feature of Norwegian dietary habits is that dinner is the only warm meal, whereas bread with some sort of spread is common for breakfast, lunch and the evening meal. Because dinnertime in Norway is quite early, normally between 4:00 and 6:00 p.m., many Norwegians also eat an evening meal. Skewed protein eating patterns have been identified by others [11, 25, 26]. However, compared with those studies, which revealed a pattern of low-protein breakfasts, medium-protein lunches and high-protein dinners, the pattern in our sample seemed to comprise one high-protein meal (i.e. dinner) and three low-protein ones. As a consequence, protein enhancement of the diet in Norway should focus on the low protein bread-based meals. Increased use of dairy products and protein-rich spreads could be potential targets for protein enrichment.
In our cross-sectional study of older adults in Norway, we could not determine associations between biomarkers of protein and protein intake, number of meals with more than 30 g of protein or frequency of consumption of bread, yoghurt or cheese. Contrary to our expectations, we identified a negative association between RBP and consuming milk and eggs. However, because RBP has a short half-life (i.e. <1 d), it reflects only acute changes in protein intake. Data concerning protein sources represented the past 6 months; thus, any associations with RBP may be random despite their significance.
The lack of associations between biomarkers and nutrition may relate to the fact that participants were healthy and had a sufficient food intake. Their mean BMI was 26.3, which is fairly less than the study sample of the Tromsø study including 3286 participants . In the general population, a BMI exceeding 25.0 would be regarded as overweight. However, due to age-related changes in lean body mass, a BMI between 22.0 and 27.0 is recommended for older adults (i.e. ≥65 years old) in Norway’s national guidelines for the treatment and prevention of malnutrition . BMIs less than 22.0 are associated with higher mortality in older adults, whereas overweight is not [28, 29]. Kvamme et al.  also found that health-related quality of life was significantly higher in moderately overweight individuals.
Risk of malnutrition, as measured with MNA, was not associated with energy intake, protein intake or biomarkers in our study. In the study of Zhang et al. , albumin and prealbumin were significantly lower among individuals evaluated to be at risk of malnutrition by the Mini Nutritional Assessment (MNA) than among those not at risk. In a cross-sectional study conducted in Italy in 2006, albumin, prealbumin and RBP were all shown to correlate with fat-free body mass in healthy underweight, normal weight and overweight older adults . Low serum values for those visceral proteins, even within the reference range, could suggest poor nutritional status . However, the number of participants at risk of malnutrition in our study was low (n = 7), and we emphasize that they were categorised as being at risk of malnutrition, not as having malnutrition. This MNA score is an opportunity to prevent malnutrition, even before the subjects show clinical signs. Preventing malnutrition can imply major cost savings for communities—in Norway, some 800 million NOK annually, or approximately 1.0% of all costs at hospitals .
Our protein intake data came from a single 24-h recall, which was a prominent weakness of our study. However, because the recall was performed in the participants’ homes, it was possible to gain accurate measures, as participants could present actual foods or their packaging, measure amounts in the plates and/or cups used and/or compare portion sizes with images in the portion sizes booklet. Thus, we believe that the recall data represent the actual daily intake quite well.