This systematic review and meta-analysis evaluated the effects of reduced sodium intake on blood pressure, cardiovascular disease, and potential adverse effects in adults and children. The review included 14 cohort studies and five randomised controlled trials (RCTs) in adults, and 37 RCTs in adults and nine controlled trials and one cohort study in children. The results showed that reduced sodium intake significantly lowered resting systolic and diastolic blood pressure in adults by 3.39 mm Hg and 1.54 mm Hg, respectively. In children, reduced sodium intake significantly reduced systolic and diastolic blood pressure by 0.84 mm Hg and 0.87 mm Hg, respectively. No significant adverse effects on blood lipids, catecholamine levels, or renal function were found in adults. In children, no effects on blood lipids, catecholamine levels, or side effects were reported. The review also found that higher sodium intake was associated with an increased risk of stroke, stroke mortality, and coronary heart disease mortality. The overall quality of evidence for reduced sodium intake reducing blood pressure in adults was high, while in children it was moderate for systolic and low for diastolic blood pressure. The review concluded that reduced sodium intake is beneficial for lowering blood pressure and reducing the risk of stroke and fatal coronary heart disease in adults. The evidence suggests that most people will likely benefit from reducing sodium intake.This systematic review and meta-analysis evaluated the effects of reduced sodium intake on blood pressure, cardiovascular disease, and potential adverse effects in adults and children. The review included 14 cohort studies and five randomised controlled trials (RCTs) in adults, and 37 RCTs in adults and nine controlled trials and one cohort study in children. The results showed that reduced sodium intake significantly lowered resting systolic and diastolic blood pressure in adults by 3.39 mm Hg and 1.54 mm Hg, respectively. In children, reduced sodium intake significantly reduced systolic and diastolic blood pressure by 0.84 mm Hg and 0.87 mm Hg, respectively. No significant adverse effects on blood lipids, catecholamine levels, or renal function were found in adults. In children, no effects on blood lipids, catecholamine levels, or side effects were reported. The review also found that higher sodium intake was associated with an increased risk of stroke, stroke mortality, and coronary heart disease mortality. The overall quality of evidence for reduced sodium intake reducing blood pressure in adults was high, while in children it was moderate for systolic and low for diastolic blood pressure. The review concluded that reduced sodium intake is beneficial for lowering blood pressure and reducing the risk of stroke and fatal coronary heart disease in adults. The evidence suggests that most people will likely benefit from reducing sodium intake.