4 Versus Vegetables (days/week) Fruit (days/week) Skimmed milk (mL/day) Whole milk (mL/day) Coconut milk (mL/day) Meat (days/week) Fish (days/week) Table 4: Simple correlation coeﬃcients between periodontitis and dietary intakes expressed by the frequency or the amount. Periodontitis r −0.232 −0.217 −0.304 −0.097 0.119 0.058 0.052 P value 0.031† 0.043† 0.004† 0.375 0.273 0.598 0.637 Values are correlation coeﬃcients (r), †P < 0.05. One possible pathway is that periodontal infection in- duces systemic inﬂammation contributing to the develop- ment of HT. Endothelial dysfunction through periodontal infection-inﬂammation pathway [3, 25] might be the link between periodontitis and HT. The emerging evidence on the positive association of other inﬂammatory disorders, such as systemic lupus erythematosus [26] and rheumatoid arthritis [27], with increased HT risk, supports this as a plausible mechanism. The second pathway is that periodontitis might be associated with HT-related nutrients and foods. In this study, the severity of periodontitis but not the number of teeth lost was signiﬁcantly and strongly associated only with daily potassium intake among the traditional risk factors related to HT, including nutrients, cholesterols, obesity, and diabetes. Moreover, we found that periodontitis was associated with less intake of potassium-containing foods, fruit, and vegetables. These results suggest that high con- sumption of potassium, possibly reducing the risk of HT, might decrease periodontitis severity and partially explain the association between periodontitis and HT. The mechanisms on the possible causative links of peri- odontitis with potassium intake could be speculated. Firstly, potassium intake checked by 24-hour urinary excretion is associated with the consumption of vegetables and fruit [22], which may beneﬁcially inﬂuence oral health [28]. Secondly, the tissue destruction in periodontitis is considered to be caused mainly by an aberrant inﬂammatory response involv- ing prolonged release of neutrophil enzymes and reactive oxygen species. Potassium is reported to inhibit reactive oxygen species formation by human white blood cells [29] as well as to protect against hypertensive vascular injury and cardiac dysfunction, though, reducing reactive oxygen species in salt-induced experimental hypertension [30]. Veg- etables and fruit are primary dietary sources of antioxidants, such as vitamins C and E. Intake of potassium-rich vegetables and fruit might help to prevent periodontitis by reducing free radicals and oxidative stress in periodontal tissue. Previously, we reported that the mean levels of 8-hydrox- ydeoxyguanosine (8-OHdG), a marker of oxidative DNA damage in 24-hour urine samples, were signiﬁcantly higher in hypertensive subjects than in normotensive subjects in Tanzania [31]. Our results suggested that a beneﬁcial eﬀect of the intake of potassium-rich vegetables and fruit on HT and periodontitis might be related to their roles in inﬂammation International Journal of Hypertension or oxidative stress, and that 24-hour urinary excretion of potassium might be a good biomarker for the risk evaluation of periodontitis as well as HT. The possibility that people with severe periodontitis who lose more teeth tend to eat less vegetables to absorb potassium, and therefore have higher BP, may be excluded because 24-hour urinary potassium excretion was signiﬁcantly inversely related only with peri- odontitis but not with tooth loss. Several limitations in the present study should be con- sidered. First, the cross-sectional design basically precludes any causal inferences about the role of potassium intake between periodontitis and HT. Second, our analysis was carried out only once. Nevertheless, this study has several strengths. First, we controlled other major traditional risk factors, including potential confounders such as age, gender, race, diabetes, hypercholesterolemia, BMI, smoking, and alcohol consumption. The age range was limited to 46– 58 years old to avoid the aging inﬂuence on HT and periodontitis. Second, the subjects were particularly suitable for the investigation of dietary inﬂuence on BP and oral health because they were on no medication and neither consumed alcohol nor smoked. Both of these are well-known confounders causing periodontitis as well as risk factors of HT. Third, to avoid examiner bias, oral examination was performed by a single examiner who was unaware of other health examination data. In addition, to provide an adequate assessment of the severity of periodontitis, CPITN was used as recommended by the WHO. CPITN score has become widely accepted as the method of choice for epidemiological and screening studies for periodontitis [19–21]. Fourth, nutritional assessments were carried out using not only a food frequency questionnaire but also biomarkers from 24- hour urine samples from African Muslim women whose dietary customs did not vary on a daily basis. 5. Conclusion The present study demonstrated the association among dietary potassium intake, periodontitis, and HT. Low-potas- sium intake in the diet mostly accompanied by low dietary ﬁber intake increases BP as well as periodontal inﬂammation. Moreover, periodontitis may raise BP through chronic inﬂammatory and oxidative stress mechanisms. Therefore, oral health is important in reducing the risk of HT, and traditional dietary customs of consuming more potassium from vegetables and fruit are expected to decrease the risk of HT and periodontitis, both presently deteriorating the quality of life in the elderly, although this expectation remains to be proven by long-term intervention trials. Acknowledgments The authors are grateful to all those who participated in the CARDIAC health survey and oral health examination and to volunteer workers from the study sites and from the former WHO collaborating Center for Research on Primary Preven- tion of Cardiovascular Disease. This study was supported in part by the CARDIAC Study fund donated to the WHO