Superfoods for Type 2 Diabetes: A Narrative Review and Proposal for New International Recommendations

Background and Objectives: Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease affecting an estimated 537 million individuals worldwide. 'Superfoods' can be integrated into the diet of T2DM patients due to their health benefits. Study Objectives: (i) To carry out a narrative review of 'superfoods' with the potential to reduce glycaemic levels in T2DM patients (2019 to 2022), (ii) to identify 'superfoods' with the potential to reduce HbA1c and (iii) to propose new guidance on the use of 'superfoods'. Materials and Methods: A narrative review was carried out using the databases PubMed, SciELO, DOAJ and Google Scholar. The keywords were ["type 2 diabetes" and ("food" or "diet" or "nutrition") and ("glycaemia" or "glycemia")]. Only review studies were included. Results: Thirty reviews were selected. The 'superfoods' identified as having a potential impact on glycaemic control were foods with polyphenols (e.g., berries), fermented dairy products, whole cereals/grains, nuts and proteins, among others. The possibility of an extensive reduction in Hb1Ac was reported for fermented dairy products, especially yoghurts enriched with vitamin D or probiotics (HbA1c reduction of around 1%) or by increasing the fibre intake by 15 g (or up to 35 g) (HbA1c reduction of around 2%). Conclusion: It is recommended that the identified 'superfoods' are included in the diet of T2DM patients, although this should not substitute an appropriate diet and exercise plan. In particular, yoghurts and an increased fibre intake (by 15 g or up to 35 g) can be used as nutraceuticals. New recommendations on the introduction of 'superfoods' in the diet of T2DM patients have been proposed.