October 8, 2021
by Larissa J. Rowdon, BHK, MSc Candidate; Wendy E. Ward, BAS, MSc, PhD
ERIODONTAL DISEASE AND A PLANT-BASED DIET
What is a ‘plant-based diet’? Essentially, this is an umbrella term that describes a diet characterized by a focus on food sources from plants with a lower, although not necessarily eliminated, consumption of animal and animal-derived products. Canadians are hearing and reading about this topic more and more, especially since the 2019 update of Canada’s Food Guide has a focus on fruits and vegetables, plant-based proteins such as nuts, seeds and legumes as well as whole grains.1 These recommendations can be seen visually on the Eat Well Plate, in which fruits and vegetables represent one half of the plate while the remaining half is divided equally with whole grains and protein – with plant-based sources of protein encouraged more often. These recommendations were guided by evidence that consuming plant-based foods containing low levels of saturated fat, high levels of polyunsaturated fat and/or high levels of fibre can improve health, in part, by lowering one’s risk of cancer, heart disease, and type 2 diabetes2 – of which the latter two chronic conditions are closely linked with periodontal disease.3,4 While there is limited research regarding the effects of plant-based diets on periodontal health, a plant-based diet is known to support improved health outcomes in patients with existing heart disease and type 2 diabetes – risk factors for periodontal disease.
PERIODONTAL HEALTH AND PLANT-BASED DIETS: WHAT DO WE KNOW?
Only a few studies5-8 have examined the implications of plant-based diets for periodontal health. (Table 1) These studies have included a range of designs and participants, including case-control studies of individuals consuming a vegetarian and raw vegan diet without pre-existing systemic diseases or prior treatment for periodontal disease who were risk-matched with individuals not following a plant-based diet.5,6 Other studies are interventions among individuals with gingivitis who were following a Western diet7 and individuals already diagnosed with but not yet treated for chronic periodontitis.8 Each of these four studies examined a slightly different plant-based diet: one considered lacto-ovo-vegetarians and vegans;5 another considered “wholesome nutrition” characterized by a “preference of food of plant origin”8 – meaning that meat, fish, and egg intake was limited to no more than two portions per week; the third considered the effects of an “anti-inflammatory” diet characterized by reducing the level of animal proteins as much as possible while ensuring a substantial daily consumption of omega-3 fatty acids, vitamins C and D, antioxidants, fiber, and nitrate-containing plants; and the fourth considered a raw vegan diet, in which at least 80% of the diet consisted of plant-based foods. These diets are defined in more detail in Table 2. The two intervention studies recruited participants who already had some degree of gingivitis or periodontal disease.7,8 In one intervention,7 patients were randomly allocated to either the anti-inflammatory diet or were instructed to continue following their usual diet (Western diet) as a control. In the other intervention,8 all participants worked with a nutritionist to adopt a ‘wholesome nutrition’ diet (Tables 1 & 2) for one year. Overall, positive results were observed between plant-based diets and outcomes of periodontal health in these studies. (Table 1) The most notable findings included a decreased probing depth,5,6,8 decreased bleeding on probing,5-7 decreased number of missing teeth,5,6 decreased inflammation,5-8 and decreased concentrations of salivary IL-1β and IL-6 – two sensitive markers of inflammation and periodontal tissue breakdown.8 Across these studies, both males and females were studied and there appeared to be no differences in response to plant-based diets between sexes.
With consuming a plant-based diet, it is important to remain vigilant with oral hygiene practices despite the primarily positive implications for periodontal outcomes.9 For example, a vegetarian intake has been associated with an increased risk of dental erosion10 and decay,5 as evidenced by a greater number of fillings.6 This may be due to the greater presence of acidic foods such as certain raw fruits and vegetables in plant-based diets. More frequent consumption of such foods results in a more acidic oral environment8 which encourages demineralization of the teeth.5 However, increased dental decay and erosion were not observed in all studies discussed and thus these potentially harmful effects to oral health may be specific to plant-based diets that eliminate animal
products completely. This could be because individuals who follow such plant-based diets may be consuming raw fruits and vegetables that produce higher levels of acid more frequently throughout the day. In turn, this could maintain a consistently acidic oral environment despite the better hygiene behaviours (i.e., higher frequency of brushing and flossing) associated with these diets compared to their omnivorous counterparts.
Individuals who adhere to a plant-based diet may also have an overall healthier lifestyle than those who do not. For example, they may be more likely to be a non-smoker,5,11,12 to consume less alcohol,5,13 and be more physically active.5,13,14 These are all factors that can contribute to better periodontal health. A recent cohort study examining the oral health of individuals who had been vegetarian for at least two years also supported this.15 Results of this study showed that the vegetarians had overall good oral health – however, some of this was attributed to certain lifestyle factors that may contribute indirectly to positive oral health outcomes, such as greater consideration of food choices and being less likely to smoke or drink alcohol.15 Two case-control studies5,6 have also shown that following a plant-based diet was associated with better oral hygiene behaviours – more frequent brushing and flossing that were also reflected in a lesser accumulation of bacterial plaque – that were linked to better oral and periodontal health, likely stemming from the fact that individuals who follow plant-based diets tend to exemplify healthier lifestyle behaviours in many other aspects of their lives.
PLANT-BASED EATING FOR PERIODONTAL DISEASE PREVENTION?
While plant-based diets have been associated with an overall lower risk of chronic diseases closely related to periodontal disease such as type 2 diabetes and cardiovascular disease,16 these diets may also help prevent periodontal disease. But how? Consuming an anti-inflammatory diet significantly decreased the gingival inflammation that can progress to periodontal disease. Diet along with lifestyle behaviours may be helpful modulators of periodontal health. (Fig. 1)
Individuals who follow a plant-based diet consume greater amounts of certain macronutrients and micronutrients that contribute to preventing periodontal disease. (Table 3) This includes antioxidant micronutrients such as vitamins A (e.g., from carrots or broccoli), B (e.g., from legumes and leafy greens), C (e.g., from citrus fruits or brussels sprouts) and E (e.g., sunflower seeds and leafy greens) – these vitamins have been linked to periodontal disease prevention by reducing periodontal tissue inflammation.7,17,18 Additionally, polyphenols from tea or spices also demonstrate antioxidant and anti-inflammatory properties which can prevent the initiation and slow down the progression of periodontal disease.19 The consumption of antioxidants in general can contribute to periodontal disease prevention by improving the immune response and can result in less oxidative stress and inflammation that precedes periodontal disease.5,7
Consumption of polyols (e.g., from mushrooms) and polyunsaturated fatty acids such as omega-3 fatty acids (e.g., from nuts, seeds, plant oils, or tofu) have also been associated with a decreased risk of periodontal disease.17,20 Adequate fiber consumption has also been linked to a reduced risk of periodontal disease21,22 as well as slowed progression when the disease is already present.22 An inverse relationship between fiber consumption and inflammatory biomarkers has been shown.21
As previously mentioned, individuals who consume a plant-based diet may have other healthy habits, including ideal oral hygiene, a higher level of physical activity as well as not smoking and minimal to no alcohol consumption.5,11-13 Evidence suggests that vegetarians, in particular, are more health conscious than non-vegetarians.23 A cohort study of nearly 10,000 non-vegetarian, semi-vegetarian, and vegetarian women also found that vegetarians were more likely to be physically active14 – an important lifestyle factor for reducing chronic disease risk including periodontal disease.24 As such, by contributing to the presence of a strong foundation of healthy behaviours, plant-based diets may both directly and indirectly improve certain key modifiable risk factors of periodontal disease such as obesity, type 2 diabetes, and/or smoking habits.
A plant-based diet does not mean that meat or animal-derived products must be eliminated to potentially benefit periodontal health. As per Canada’s Food Guide, a healthy diet is one that emphasizes the intake of whole foods – fruits, vegetables, whole grains and plant-based proteins – while decreasing the consumption of animal and animal-derived products – and has been linked to many health benefits including periodontal health. Practical, actionable advice is provided in Table 4.
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About the Authors
Larissa Rowdon is a MSc Candidate in Applied Health Sciences at Brock University and holds a BHK from the University of Windsor. Larissa’s research focuses on periodontal health and healing with a goal of mobilizing this knowledge to researchers, practitioners, and patients.
Wendy Ward is a Professor and Canada Research Chair in the Department of Kinesiology in the Faculty of Applied Health Sciences at Brock University. Her team’s overall research goal within the Nutrition, Bone and Oral Health Research Group is to develop dietary strategies that help protect against osteoporosis and related fractures while also understanding the complex relationships with other health conditions such as periodontal disease.