October 18, 2016
by Wendy E. Ward, Professor & Canada Research Chair Faculty of Applied Health Sciences, Brock University
“Superfood” – a term we are increasingly exposed to in our daily life. From food packaging, trendy beverage vendors and cafes, books promising a way to lose weight or live longer, or in the broader media, the term is everywhere. But what does it mean? What is a “superfood”? It is “a nutrient-rich food considered to be especially beneficial for health and well-being”. 1 So, in reality, it is just a healthful food and not a mysterious creation from a food lab. Interestingly, a quick search of examples of superfoods on the internet or popular health and cookbooks suggest a long list of “superfoods”. Some we know well such as blueberries, kale, collard greens, quinoa, Greek yogurt and kale, and others are more exotic such as acai berries, chia seeds and seaweeds. Most of us are already consuming one or more servings of these so-called “superfoods” in our daily diet.
As a nutritional scientist I prefer to avoid using “superfood” but rather to focus on healthful foods, which together constitute a healthy diet. Fruits and vegetables, in their natural state with no processing, are among the best examples of healthful foods. And in discussing oral health, there is the long history of the importance of fruits containing vitamin C for maintenance of healthy gums. However, even with this long history, data showing higher oxidant stress in periodontal disease continues to stimulate interest in the levels of antioxidant nutrients including vitamin C and E, and bioactives that may help prevent periodontal disease and enhance periodontal therapy.
The term “bioactive” encompasses a wide range of different food components that can have a variety of biological effects, some of which may be related to antioxidant activity. Bioactives are present in a variety of foods with plant-based foods such as fruits and vegetables a particularly rich source. Examples from the literature on nutrition and periodontal disease include lycopene, beta-carotene and flavonoids. Bioactives differ from nutrients that are classified as essential as they are non-essential to sustain life but may influence health outcomes. Thus, while Health Canada has established dietary reference intakes (DRIs) for Canadians, these are for nutrients with no formal guidelines for bioactives. 2
Relationship Between Antioxidant Status and Periodontal Disease
Many studies have shown that higher antioxidant status is associated with reduced risk of periodontal disease. Within these studies, most have assessed the relationship of individual nutrients (vitamin C, vitamin E) and/or evaluated intake of whole foods (fruits and vegetables) using dietary questionnaires.
A study from our research group identified that higher intakes of fruits and vegetables, vitamin C, vitamin E and beta-carotene was associated with better healing–reduced probing depth–after periodontal therapy in 63 men and women. 3 Interestingly, the positive association was observed when five or more servings of fruits and vegetables were consumed. Canada’s Food Guide recommends that men and women over age 50 consume seven servings of fruits and vegetables per day for overall health 4 but Canadian survey data shows that more than 50% of Canadians do not consume this recommended level. 5 Of note is that this study did not elucidate which fruits and vegetables were most associated with a better periodontal treatment outcome. It is likely that some may be more beneficial than others; this aspect requires further study. Moreover, that this positive association was observed only in non-smokers and not smokers, combined with existing literature, suggests that smokers had lower antioxidant status and/or that continued smoking elevated oxidant stress. However, these hypotheses require further investigation, particularly as antioxidant status was not measured biochemically. Several other studies have shown similar relationships for these nutrients, and often one nutrient was studied in isolation of others. 6
It is generally accepted that evaluating nutrient or food intake from dietary questionnaires can be difficult and it is important to understand that while useful, data obtained using these tools is not as accurate as biochemical or serum measures of status. Thus, studies incorporating serum measures are particularly helpful to identify associations and potential areas for follow-up study. Two studies have used the large data set collected through the Nutritional Health and Nutrition Examination Survey (NHANES), “a program of studies designed to assess the health and nutritional status of adults and children in the United States”. 7 Using data from the NHANES III survey (1988-1994), including 11,895 individuals, Chapple et al. showed that individuals classified with mild or severe periodontal disease had lower serum concentrations of vitamin C and total antioxidant capacity (TAOC) with the strongest association among the group with severe periodontal disease. 8 TAOC was calculated as the sum of several known antioxidant nutrients (vitamins A,C,E and beta-carotene). Also using NHANES data, but from a newer survey (1999-2002), Zong et al. showed a non-linear inverse association between serum alpha-tocopherol (marker of vitamin E status in humans) and severity of periodontitis in a group of 4708 individuals. 9 The non-linear relationship refers to the finding that the lowest serum alpha-tocopherol quartile was associated with a greater risk of having periodontal disease compared to those in the highest quartile of serum levels. Studies investigating smaller sample sizes show similar findings when serum markers of antioxidant status are assessed. 10,11
While these studies have identified an association between higher intakes of specific nutrients (vitamins C & E) or overall higher intakes of fruit and vegetables with a lower risk of periodontal disease, it is important to acknowledge that these are not ‘cause and effect’ relationships. For examples, it is possible that individuals with periodontal disease have lower antioxidant status because the disease process results in a poor diet and/or may in itself lower antioxidant status. Findings from intervention trials, preferably randomized controlled trials, are needed to identify if lower antioxidant status is a risk factor for periodontal disease development.
Only a few controlled trials have investigated if dietary intervention or nutritional supplementation can enhance the effectiveness of periodontal therapy. The strategy in these approaches is to increase intake of antioxidant nutrients and/or bioactives that are naturally present in fruits and vegetables. An often-cited study is one in which patients were randomized to placebo capsules or capsules containing fruit and vegetable juice powder alone or combined with berry powder. 12 While a greater reduction in probing depth was observed at two months post-therapy in the group receiving fruit and vegetable containing capsules compared to placebo, there was no difference with the capsule that also contained berry powder. As noted by the authors, effects may depend on whether antioxidants such as beta-carotene, are sufficiently elevated. 12 The authors identify that availability of beta-carotene may vary among individuals. For example, polymorphisms in the gene involved with conversion of beta-carotene to its active form can modulate its serum levels. While benefits beyond two months post-periodontal therapy were not observed with the intervention of fruit and vegetable capsules, further investigation is required before concluding that there is no long-term benefit.
The effect of dietary interventions in which intakes of whole foods are altered and thus behavioural change is required, is very challenging to study in a randomized controlled trial. In general, dietary habits of an individual that receives individualized support for diet modification will eat more healthfully. Thus, antioxidant status of individuals, as measured through serum measures of specific nutrients such as vitamins and beta-carotene will increase along with corresponding reductions in markers of oxidant stress. Patients randomized to customized dietary advice increased their intakes of fruits and vegetables at three and six months after periodontal therapy compared to individuals not receiving such advice. 13 However, clinical benefits were not observed. A higher increase of fruit and vegetable intake may be required as opposed to the increase of 2.3 (at three months) and 1.4 servings (at six months) per day that was observed. Studies that evaluate long-term benefits of dietary change, such as reduced recurrence of periodontal disease should be determined. Findings from cross-sectional studies, discussed earlier in this article, suggest potential benefits to periodontal health. The paucity of data regarding diet and supplements for periodontal health highlights this field as an important area for future study.
Further research is needed to determine if outcomes after periodontal therapy are further improved by a dietary intervention and/or supplementation with individual nutrients and/or bioactives.
By consuming a healthy diet that meets the recommended servings of fruits and vegetables, and selecting a variety of these, you will naturally be consuming “superfoods” to support overall health.
Given that most Canadians do not eat the recommended servings of fruits and vegetables per day, encourage higher intakes. Keep in mind the following aspects:
Wendy Ward is a Canada Research Chair in the Bone and Muscle Development in the Faculty of Applied Health Sciences at Brock University. Her research program investigates how early diet can set a trajectory for healthier bone at adulthood, and reduce the risk of developing osteoporosis during aging. Within this research program, a variety of novel foods and food components are studied: vitamin D, soy and its isoflavones, omega-3 fatty acids in flaxseed and fish oil, and flavonoids from tea.
Oral Health welcomes this original article.
1. Oxford Dictionary, Oxford University Press. Superfood. http://www.oxforddictionaries.com/definition/english/superfood Accessed August 15, 2016.
2. Health Canada. Dietary Reference Intakes. http://www.hc-sc.gc.ca/fn-an/nutrition/reference/table/ref_vitam_tbl-eng.php Accessed August 15, 2016
3. Dodington DW, Fritz PC, Sullivan PJ, Ward WE. Higher intakes of fruits and vegetables, beta-carotene, vitamin C, alpha-tocopherol, EPA, and DHA are positively associated with periodontal healing after nonsurgical periodontal therapy in nonsmokers but not in smokers. Journal of Nutrition. 2015;145(11):2512-2519.
4. Health Canada. How Many Food Guide Servings of Vegetables and Fruit Do I Need? http://www.hc-sc.gc.ca/fn-an/food-guide-aliment/choose-choix/fruit/need-besoin-eng.php Accessed August 15, 2016
5. Statistics Canada. Fruit and Vegetable Consumption, 2014. http://www.statcan.gc.ca/pub/82-625-x/2015001/article/14182-eng.htm Accessed August 15, 2016
6. Lau BY, Johnston BD, Fritz PC, Ward WE. Dietary strategies to optimize wound healing after periodontal and dental implant surgery: an evidence-based review. Open Dentistry Journal. 2013;7:36-46.
7. Centers for Disease Control and Prevention. National Health and Nutrition Examination Survey. http://www.cdc.gov/nchs/nhanes/ Accessed August 15, 2016
8. Chapple IL, Milward MR, Dietrich T. The prevalence of inflammatory periodontitis is negatively associated with serum antioxidant concentrations. Journal of Nutrition. 2007;137:657-664.
9. Zong G, Scott AE, Griffiths HR, Zock PL, Dietrich T, Newson RS.
Serum alpha-tocopherol has a nonlinear inverse association with periodontitis among US adults. Journal of Nutrition. 2015;145:893-899.
10. Iwasaki M, Manz MC, Taylor GW, Yoshihara A, Miyazaki H. Relations of serum ascorbic acid and alpha-tocopherol to periodontal disease. Journal of Dental Research. 2012;91(2):167-172.
11. Amarasena N, Ogawa H, Yoshihara A, Hanada N, Miyazaki H. Serum vitamin C-periodontal relationship in community-dwelling elderly Japanese. Journal of Clinical Peridontology. 2005;32:93-97.
12. Chapple ILC, Milward MR, Ling-Mountford N, Weston P, Carter K, Askey K, Dallal GE, DeSpirt S, Sies H, Patel D, Matthews JB. Adjunctive daily supplementation with encapsulated fruit, vegetable and berry juice powder concentrates and clinical periodontal outcomes: a double-blind RCT. Journal of Clinical Periodontology. 2012;39:62-72.
13. Javid AZ, Seal CJ, Heasman P, Moynihan PJ. Impact of a customized dietary intervention on antioxidant status, dietary intakes and periodontal indices in patients with adult periodontitis. Journal of Human Nutrition and Dietetics. 2014;27:523-532.