Insuf cient data on the risks or bene ts of these interventions on BP in CKD populations per se precluded speci c recommendations in this guideline. Research recommendations  Conduct clinical trials evaluating different dietary sodium reduction strategies for prevention of clinical endpoints of critical importance for CKD populations, including kidney failure, CV disease, and mortality.  There are inconsistencies among the studies examining the relationship of dietary sodium intake with health outcomes in persons with diabetes.45,46,85 Additional research is required to investigate the consistency of effects of dietary sodium changes on health bene ts and harms across different causes and severities of CKD.  It is unknown if there is a minimum dietary sodium level in CKD below which health risks are increased. Most of these www.kidney-international.org chapter 2 data derive from studies evaluating sodium intake using spot urine sodium measurements. There is current con- troversy about the accuracy of assessing sodium intake us- ing random spot urine specimens, and potential increased risk of adverse health outcomes at the low- sodium intake range when assessed by this method.86 Additional research is required in both sodium-intake assessment methodology in CKD, and to evaluate the health impacts of very low-sodium intakes in CKD populations.  Recent small, single-center clinical trials evaluating chronic oral sodium bicarbonate supplementation versus placebo have not found changes in BP.87 89 These ndings raise the possibility that the anion associated with sodium intake may in uence the BP response. Future research is required to determine if relationships of sodium intake with BP are in uenced by the accompanying anion.  In the general population, potassium-containing salt sub- stitutes have been demonstrated to lower BP. 