Global Health Through Oral Health: Global Nutrition Transition Challenges Oral Health

Although residing on separate continents an ocean apart, both are malnourished. Malnutrition (deviant nutritional status) includes both undernutrition (short stature) and malnutrition of affluence (overweight and obesity).¹ Malnutrition is as much about what we eat as it is about what we do not—either a lack of food or an overabundance of the wrong kinds of food, impacting both oral and systemic health. Malnutrition impairs immune function, elicits heightened susceptibility to infections, promotes poor development of organs, and constitutes a starting point and stimulus for failure in most biologic systems.

At least 300 million adults in the world are clinically obese (body mass index equal to or greater than 30 kg/m²), with widespread global childhood obesity.² In the US alone, about 39% of adults and 16% of children and adolescents are obese. Driving the global obesity epidemic is overconsumption of energy with decreased energy expenditure. Even in many resource-poor developing countries, severe obesity is prevalent among relatively affluent urban dwellers exposed to nutrition transition (readily available, calorie-sufficient diet and abandonment of traditional foods) with increased consumption of animal fat, protein, and refined sugars.^2-4 Tumor necrosis factor-a, a proinflammatory cytokine that is overexpressed in adipose tissue, activates several signal transduction cascades.² Thus, inflammation is a key feature of obesity, and the latter is a major risk factor for several nutrition-related chronic diseases (NRCDs), such as type 2 diabetes mellitus, hypertension, cardiovascular disease (CVD), and some cancers.^4,5 The link between prolonged inflammation and NRCDs is strong.^2,5 Like the undernourished, obese individuals may also be micronutrient deficient, readily susceptible to infections, and may be at increased risk of bacteremia and prolonged wound healing time.¹

With the rapid global shift toward diets linked with noncommunicable diseases notwithstanding, African villages are still characterized by infectious diseases, often complicated by malnutrition (particularly micronutrient deficiencies), which constitute the major causes of mortality and morbidity.^1,4,5 Malnutrition in these communities usually commences in utero as a consequence of maternal malnutrition and poor health, resulting in intrauterine growth retardation and low birth weight. About 90% of the 25 million babies born annually weighing less than 2.5 kg are in developing countries. The legacy of intrauterine stress includes poor development of some organs/systems (eg, tooth enamel, cell-mediated immune function, brain, and kidneys) and a higher risk of obesity and NRCDs in later adult life.^4,6,7 Recent studies indicate that an isocaloric but protein-restricted diet fed to pregnant rats causes changes in vascular endothelial function of offspring.⁸ This suggests endothelial dysfunction that underlies CVD in humans may start in utero. The scope of complex interactions between nutrition, infection, and immunity is now extended to include roles of specific nutrients (eg, resolvins and protectins derived from essential lipids) in modulating inflammation.⁹

The global burden of oral diseases is now fairly well characterized.¹⁰ These diseases include dental caries, periodontal inflammation, enamel dysplasia in the primary dentition, oral mucosal lesions (including noma), oropharyngeal cancers, and oral lesions associated with human immunodeficiency virus and autoimmune deficiency syndrome. Underprivileged populations are affected disproportionately by oral diseases,^7,10-12 with most of these conditions sharing common risk factors with nutrition-related chronic systemic diseases.^2,9,13 Inflammatory mediators play a key role in the pathogeneses. Chronic marginal protein malnutrition in children, for example, elicits changes in serum cytokines characteristic of a low-grade systemic inflammation.^14,15 This is consistent with the author’s reported observations 40 years ago that malnourished “Osegere children, in comparison with the (well-fed) optimal community from the same ethnic group in Nigeria, suffer more severe periodontal disease than can be attributed solely to poor oral hygiene.”¹⁶ At that time, it was virtually sacrilegious to ascribe the genesis of inflammatory periodontal disease to factors other than oral plaque. What was not widely appreciated then was the close, complex interaction of nutrition-related inflammatory effects on both oral and systemic health.¹⁷

Poverty and malnutrition are key global factors impacting various parameters of human health, including growth and development, host resistance to infections, and general lifestyles. To solve the global nutrition challenges related to human health, we must adopt a broad approach that recognizes malnutrition in its various forms.⁵ While pockets of undernutrition still exist, particularly in the developing world, there is an urgent need to appreciate the concept of nutrition transition, which relates to large, rapid global shifts in dietary habits and physical activity patterns.¹⁸ The latter is exemplified by the high prevalence of worldwide adult and pediatric obesity rates.¹⁸ The growth of multinational food companies has saturated both urban and rural communities in every country with junk food, increasing the high prevalence of noncommunicable chronic oral and systemic diseases.

The author would like to thank Dionne Dougall-Bass and Carol Schadelbauer of Burness Communications in the development of this report.

Cyril O. Enwonwu, ScD, PhD, MDS, BDS
Paul G. Rogers Ambassador for Global Health Research

Professor
Microbial Pathogenesis and Oncology and Diagnostic Sciences
School of Dentistry
University of Maryland

Adjunct Professor of Biochemistry and Molecular Biology
School of Medicine
University of Maryland
Baltimore, Maryland