Abstract
There is growing evidence that consumption of a Western diet is a risk factor for osteoporosis through excess acid supply; fruits and vegetables balance the excess acidity, mostly by providing K-rich, bicarbonate-rich foods. Western diets consumed by adults generate ~50-100 mEq acid/d; therefore, healthy adults consuming such a diet are at risk of chronic, low-grade metabolic acidosis, which worsens with age due to kidney function decline. Bone buffers the excess acid by delivering cations and it is considered that with time, an over-stimulation of this process will lead to the dissolution of the bone mineral content and, hence, to reduced bone mass. Intakes of K, Mg, fruit and vegetables have been associated with a higher alkaline status and a subsequent beneficial effect on bone health. Few studies have been undertaken in very elderly women (>75 years), whose osteoporosis risk is very pertinent. Our EVANIBUS (EVAluation of Nutrient Intake and Bone UltraSound) group developed and validated (n=51) a Food Frequency Questionnaire (FFQ) for use in a frail, elderly, Swiss population (mean age 80.4yrs SD 2.99), which showed intakes of key nutrients (energy, fat, carbohydrate, Ca, Mg, vitamin C, D and E) to be low in 401 subjects. A study was then conducted to assess the Net Endogenous Acid Production (NEAP) estimates and bone ultra-sound results in 256 women aged 75 y+). Lower NEAP (P= 0.023) and higher K intake (P=0.033) were significantly correlated to higher bone ultra-sound results. High acid load may be an important, additional risk factor, which may in turn, be particularly relevant in frail patients who already have a high risk of fracture. Our study contributes to knowledge by confirming a positive link between dietary alkalinity and bone health indices in the very elderly In a further study to compliment these findings, it has also been shown that in Ca sufficiency, an acid, Ca-rich water had no effect on bone resorption in a group of 30 young women, whilst an alkaline, bicarbonate-rich water led to a significant decrease in both PTH and of serum c-telopeptide excretion. Further investigations need to be undertaken to study whether these positive effects on bone loss are maintained over long-term treatment. Mineral water consumption could be an easy and inexpensive way of helping to prevent osteoporosis and therefore be of major interest for long term prevention of bone loss.