Effects of Starch on Oral Health: Systematic Review to Inform WHO Guideline

A systematic review was conducted to update evidence on the effect of total dietary starch and of replacing rapidly digestible starches (RDSs) with slowly digestible starches (SDSs) on oral health outcomes to inform updating of World Health Organization guidance on carbohydrate intake. Data sources included MEDLINE, Embase, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, LILACS, and Wanfang. Eligible studies were comparative and reported any intervention with a different starch content of diets or foods and data on oral health outcomes relating to dental caries, periodontal disease, or oral cancer. Studies that reported total dietary starch intake or change in starch intake were included or where comparisons or exposure included diets and foods that compared RDSs and/or SDSs. The review was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-analyses) statement, and evidence was assessed with the GRADE Working Group guidelines. From 6,080 papers identified, 33 (28 studies) were included in the RDS versus SDS comparison: 15 (14 studies) assessed the relationship between SDS and/or RDS and dental caries; 16 (12 studies) considered oral cancer; and 2 studied periodontal disease. For total starch, 23 papers (22 studies) were included: 22 assessed the effects on dental caries, and 1 considered oral cancer. GRADE assessment indicated low-quality evidence, suggesting no association between total starch intake and caries risk but that RDS intake may significantly increase caries risk. Very low-quality evidence suggested no association between total starch and oral cancer risk, and low-quality evidence suggested that SDS decreases oral cancer risk. Data on RDS and oral cancer risk were inconclusive. Very low-quality data relating to periodontitis suggested a protective effect of whole grain starches (SDS). The best available evidence suggests that only RDS adversely affects oral health.