Calcium – a scoping review for Nordic Nutrition Recommendations 2023

The aim of this scoping review was to conduct evidence-based documentations between calcium (Ca) intake and health outcomes for updating dietary reference values (DRVs) and food-based dietary guidelines (FBDGs) in the sixth edition of Nordic Nutrient Recommendations (NNR2023). The systematic literature search was limited to reviews on human data published between 2011 and June 2021. Systematic reviews (SRs) and original publications of relevance for this scoping review were included. A common practice of designing studies on health outcomes related to Ca supplement intake is to examine combined Ca and vitamin D, and therefore, a combination of Ca with vitamin D (CaD) was included in this review. In total, 27 studies addressing the association between dietary or supplemental Ca on bone health, bone mineral density (BMD), pregnancy-related outcomes, cardiovascular diseases (CVD), cancers, obesity, and mortality were reviewed. SRs showed that both dietary and supplemental Ca intakes were positively associated with BMD, but evidence did not support the benefit in fracture prevention. Current evidence did not support that Ca or CaD supplementation increases risk of coronary heart disease or all-cause mortality in older adults, but that Ca may be beneficial for hypertension, especially in young people. Increasing Ca intake may be beneficial during pregnancy, especially for those at high risk of pre-eclampsia due to ethnicity, age, high BMI, and those with low baseline Ca intake. The associations between high Ca intake and cancers were varied, with strong evidence that high consumption of dairy products is protective against colorectal cancer and limited-suggestive evidence that dairy products and diets high in Ca might also be protective against breast cancer. Moreover, there is limited-suggestive evidence that dairy products and diets high in Ca increase the risk of prostate cancer. Based on current evidence, Ca intake is beneficial or neutral in relation to most of the outcomes evaluated in this review. Data from the Nordic countries show that average Ca intake is around the same as previously recommended by NNR. However, the average Ca intake in the Baltic countries is below the recommendations.