The effects of a low-sodium base-producing diet including red meat compared with a high-carbohydrate, low-fat diet on bone turnover markers in women aged 45-75 years.

A randomised, parallel-design dietary intervention study was conducted in women (aged 45-75 years) with prehypertension or stage 1 hypertension. The aim was to compare the effects on bone turnover of a low-Na base-producing (LNAB) Dietary Approaches to Stop Hypertension (DASH)-type diet (including six serves lean red meat/week) with a high-carbohydrate low-fat (HCLF) diet with a higher acid load (both >800mg dietary Ca/d). Fasting serum bone markers (baseline and week 14) and 24 h urinary electrolyte excretion (baseline, weeks 4, 8, 12 and 14) were measured. After the intervention period, the LNAB group (n 46) had a fall of 26 (SEM 6) % (P<0.0001) in urinary Na, an increase in K excretion (6·8 (SEEM 3·6) mmol/d; P=0·07) and, compared with the HCLF group (n 49), a greater reduction in urinary Ca excretion by 0.7 (SEM 0·3) mmol/d. Serum 25-hydroxyvitamin D, intact parathyroid hormone and osteocalcin did not change, and both groups had a similar increase of 23 (SEM 5) % (P< 0.000 1) in C-terminal telopeptide of type I collagen. The HCLF group had an 11 (SEM 4) % increase (P=0.003) in N-terminal propeptide, type I procollagen, which could indicate an increased rate of bone turnover. The fall in urinary Ca with the lower-Na lower-acid load diet is likely to have long-term beneficial effects on bone. As bone resorption was not different between the two dietary patterns with relatively high Ca intake, the effect on bone health of a dietary pattern with a lower acid load warrants further study on a lower Ca intake.