Macronutrients

Macronutrients required for optimal human processes include protein, carbohydrates, and lipids. Current recommendations allow for more flexibility based upon individualized dietary needs and suggest that adults consume 45% to 65% of their total calories from carbohydrates, 20% to 35% from fat, and 10% to 35% from protein.^37,38 Protein is the most common non-water substance in the body, making up 50% of dry weight of humans.^31,32 In the periodontium, proteins are present as structural proteins, such as collagen, and enzymes.^31,32 When proteins are consumed, they are subsequently broken down into the component amino acids.^31,32 Overall, 22 amino acids are required for protein synthesis and nine are considered essential amino acids (i.e. histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine).^31,32 Major dietary sources for dietary protein are milk, meat, eggs, and legumes.^31,32 Carbohydrates are used primarily as a source of energy and also aid in fat metabolism.^31,32 In periodontal tissues, carbohydrates are found as glycoproteins and glycosaminoglycans, which are required for the synthesis of the ground substances of connective tissues such as chondroitin, keratin, dermatan sulfates.^31,32 Glucose is also required for erythrocyte and neurological functioning.^31,32 Lipids provide energy, energy storage, and thermal insulation.^31,32 Humans require two essential fatty acids: linoleic and linolenic acid.^31,32 Fats are also required for the absorption of fat-soluable vitamins (i.e. Vitamins A, D, E, and K).^31,32 When used for energy, 1 gram of protein or carbohydrates provide 4 kilocalories (kcal) of energy whereas 1 gram of lipid provides 9kcal of energy.^31,32

An overall excess in calorie consumption can result in several adverse outcomes, including insulin resistance, excess glucose production, and increased adiposity.^39,40 When caloric intake exceeds overall energy needs, metabolic pathways are activated to induce insulin metabolism and lipoprotein synthesis in the liver and, ultimately, increases in free fatty acids and a decrease in lipolysis, which—when sustained—can result in increased adiposity.⁴⁰ As adipose tissue deposits increase, a concomitant increase in pro-inflammatory cytokine production and, further, an increase in the production in reactive oxygen species (ROS) and markers of systemic inflammation, like C-reactive protein.⁴⁰

High levels of carbohydrate consumption (defined as > 45% of total caloric intake) have been associated with an increased periodontal disease prevalence and increased gingival inflammation.^41-43 Gingival inflammation and risk of periodontal disease progression was also reduced when carbohydrate consumption was restricted.⁴³ It is also important to note that refined carbohydrates (e.g. sugars) and other carbohydrates (fiber and sugar alcohols) have divergent effects on periodontal health. Excessive consumption of refined carbohydrates promote increased microbial dysbiosis and, thus, periodontal disease progression.^44,45 Free sugars also act on cells in the periodontal ligament inducing apoptosis and decreasing proliferation.⁴⁶ Conversely, fiber and sugar alcohols (e.g. xylitol) may have a protective effect on the periodontium.^42,47-49 Xylitol has been shown to demonstrate an antimicrobial effect on periodontal pathogens like Porphrymonas gingivalis (P.g.) and Aggregatibacter actinomycetemcomitans (A.a.).^47-49

Analysis of the National Health and Nutrition Examination Survey (NHANES) data demonstrated a positive association between low fat intake (<23.2% of total caloric intake) and periodontal disease progression.⁵⁰ However, the nature of the fat consumed is also a significant consideration for the impact on periodontal health.⁵¹ A diet high in anti-inflammatory omega-3 fatty acids and/or with a favorable omega-3 to omega-6 fatty acid ratio has been demonstrated to promote periodontal health.^43,44,52 Conversely, high dietary consumption of saturated fatty acids or an unfavorable omega-3 to omega-6 fatty acid ratios can promote increased inflammation and a progression of the inflammatory process in periodontal disease.^43,44,52,53