|Dawson-hughes, Bess - Jean Mayer Human Nutrition Research Center On Aging At Tufts University|
|Mitchell, Paul - University Of Notre Dame|
|Cooper, Cyrus - University Of Oxford|
|Gordon, Catherine - Cincinnati Children'S Research Hospital|
|Rizzoli, Rene - Geneva University Hospital|
Submitted to: Osteoporosis International
Publication Type: Other
Publication Acceptance Date: 1/21/2016
Publication Date: 2/8/2016
Citation: Dawson-Hughes, B., Mitchell, P.J., Cooper, C., Gordon, C., Rizzoli, R. 2016. Response to Fenton and Fenton: evidence does not support the alkaline diet. Osteoporosis International. doi: 10.1007/s00198-016-3505-y.
Technical Abstract: In the space available in this broad review, we focused on large trials published since the 2011 Fenton meta-analysis. This included two trials published in 2013 and one in 2015. These trials found favorable effects of supplementation with alkaline salts of potassium, in amounts of 60 mmol/day and higher, on bone turnover, calciumbalance, and calciumexcretion. The one recent study that evaluated BMD reported significantly reduced rates of bone loss in the alkali group compared with placebo. Our conclusion was that the effect of alkaline salts of potassium on rates of bone loss is not adequately established and that "long-term trials are needed to assess the effect of supplementation on BMD and fracture risk." We agree that one cannot equate diet modification and alkaline salts of potassium. Unfortunately, no large long-term dietary acid-reducing intervention trials have been reported since 2011. However, a couple of recent prospective observational studies have linked fruit intake and serum bicarbonate levels to BMD in older adults. For example, in MrOS and MsOS (Hong Kong), higher fruit (but not vegetable) intake was associated with higher BMD. In Health ABC, higher serum bicarbonate levels were associated with higher total hip BMD. In addition to their alkaline load, fruits and vegetables contain several components that may favor bone health, including vitamins, minerals, and phytochemicals. In contrast, we are not aware of any components of fruit that are thought to be harmful to the bone. It is possible that fruits and vegetables are more favorable to bone health than alkaline salts of potassium. This is a challenging but important research question to address through long-term dietary intervention trials. The magnitude of the fruit and vegetable intervention would need to be substantial. If the recent potassium bicarbonate dose finding trial is informative, many older adults would need considerably more alkali than that provided by three servings of fruit and vegetables per day to achieve the neutral net acid excretion level associated with maximal suppression of bone reabsorption. We do not share the correspondent's concern that alkali-producing diets are B-restrictive; rather, they are the kinds of diets that are widely recommended. For example, the US Dietary Guidelines 2015-2020 recommend ten servings of fruits and vegetables per day for adults. The mean fruit and vegetable intake of the adult US population is half that amount, whereas mean intake of grains, considered to be acid-producing based on their sulfur content, is twice the amount recommended. Diets that meet these guidelines are therefore far more alkali-producing than current average US diets.