Table 1.
Health and sociodemographic characteristics of the Newcastle 85+ Study participants with low and adequate protein intakes
| Low proteina (n = 199) | Adequate proteinb (n = 523) | p value* | |
|---|---|---|---|
| Women (%, n) | 67.3 (134) | 57.2 (299) | 0.013 |
| Education (≥ 12 y) (%, n) | 10.1 (20) | 13.5 (70) | 0.459 |
| Past occupation (routine and manual) (%, n) | 52.4 (100) | 49.5 (249) | 0.625 |
| Living alone (%, n) | 59.3 (118) | 57.3 (299) | 0.624 |
| Meal provision (%, n) | 4.6 (9) | 7.2 (36) | 0.209 |
| Luncheon club (%, n) | 7.5 (15) | 7.0 (37) | 0.818 |
| Unable to prepare hot meal (%, n) | 9.5 (19) | 9.6 (50) | 0.692 |
| Unable to go shopping alone (%, n) | 36.2 (72) | 34.4 (180) | 0.568 |
| Anthropometry | |||
| BMI (kg/m2) (mean, SD) | 25.9 (4.7) | 24.0 (4.1) | < 0.001 |
| Adjusted body weight (kg) | 65.7 (60.2–69.9) | 62.4 (56.6–68.8) | 0.001 |
| Weight loss (≥ 5% in 3 y) (%, n) | 47.0 (47) | 37.7 (112) | 0.101 |
| Fat mass (kg) (mean, SD) | 21.7 (8.1) | 17.9 (7.3) | < 0.001 |
| Fat-free mass (kg) | 43.7 (39.2–52.2) | 43.2 (37.5–51.4) | 0.136 |
| Lifestyle | |||
| Physical activity (high) (%, n) | 31.7 (63) | 39.5 (206) | 0.121 |
| Smokers (%, n) | 5.6 (11) | 6.1 (32) | 0.776 |
| Alcohol drinkers (%, n) | 71.8 (102) | 74.1 (269) | 0.603 |
| Dietary intake | |||
| Diet changed past year (%, n) | 7.6 (15) | 6.4 (33) | 0.564 |
| Total energy (MJ/day) | 5.3 (4.2–6.3) | 7.4 (6.3–8.8) | < 0.001 |
| Carbohydrates (g/day) | 151 (119–192) | 209 (172–253) | < 0.001 |
| Total energy from carbohydrates (%) | 50.2 (45.1–55.9) | 47.9 (43.3–53.4) | < 0.001 |
| Fat (g/day) | 48 (37–64) | 72 (57–91) | < 0.001 |
| Total energy from fat (%) | 35.7 (29.6–40.7) | 35.5 (31.2–41.1) | 0.084 |
| Total protein (g/day) | 42 (37–49) | 68 (58–82) | < 0.001 |
| Total energy from protein (%) | 13.0 (11.6–16.2) | 15.8 (13.8–18.2) | < 0.001 |
| Total protein (g/kg aBW/day) | 0.7 (0.6–0.7) | 1.1 (0.9–1.3) | < 0.001 |
| Protein distribution (CV) (mean, SD) | 0.18 (0.07) | 0.19 (0.06) | 0.024 |
| Biochemical | |||
| Albumin (g/L) | 40 (38–42) | 41 (39–42) | 0.059 |
| hs-CRP (mg/L) | 2.8 (1.4–6.2) | 2.4 (1.1–5.7) | 0.056 |
| Total cholesterol (mmol/L) | 4.8 (3.9–5.8) | 4.8 (4.0–5.7) | 0.399 |
| Health | |||
| Chronic disease count (≥ 3) (%, n) | 45.2 (90) | 37.7 (197) | 0.138 |
| Number of medications | 6 (4–9) | 6 (3–8) | 0.381 |
| Renal impairment (%, n) | 27.6 (53) | 22.1 (112) | 0.125 |
| Cognitive impairment (SMMSE < 26) (%, n) | 21.5 (53) | 26.6 (112) | 0.139 |
| Severe depression (%, n) | 7.1 (14) | 7.3 (37) | 0.907 |
| Swallowing problems (%, n) | 56.3 (112) | 58.2 (304) | 0.635 |
| Tooth count (mean, SD) | 5.3 (8.0) | 6.7 (8.5) | 0.013 |
| Self-rated health (fair or poor) (%, n) | 24.9 (49) | 20.2 (105) | 0.373 |
Values are medians and interquartile ranges unless stated otherwise. Meal provision included meals provided by the social services, voluntary services or other private help in the previous 4 weeks. Luncheon club comprises visits also in the previous 4 weeks. Swallowing problems included dry mouth and difficulty swallowing for other reasons. Protein intake distribution was calculated as SD/total protein intake with higher values reflecting more skewness of intakes across time intervals in the day
aBW adjusted body weight (kg), BMI body mass index, CV coefficient of variation, hs-CRP high sensitivity C-reactive protein, SMMSE standardised mini-mental state examination, y years
*Chi-squared test (χ 2) was used for categorical variables, independent t test for continuous normally distributed variables and Mann–Whitney U test for no protein intake difference for continuous non-normally distributed variables
aA protein intake < 0.8 g/kg aBW/day was considered low
b≥ 0.8 g/kg aBW/day was considered adequate. Body weight was adjusted to the nearest value to reflect a healthy BMI in older adults aged ≥ 71 years of 22–27 kg/m2 as described in Berner et al. [20]