By: Wendy E. Ward, BArts & Sci (hons), MSc, PhD & Peter C. Fritz, BSc, DDS, FRCD(C), PhD
Serum 25-hydroxyvitamin D is the clinically useful marker of vitamin D status, and it is this form of vitamin D that is measured when a physician requests a “vitamin D test” for a patient. To achieve serum 25-hydroxyvitamin D levels of greater than 75 nmol/L, a vitamin D intake of at least 1,000 IU (25 ug) vitamin D per day would be required. Before we discuss the specifics of the relationship of vitamin D with periodontal health, it is prudent to provide some background about the current dietary recommendations for vitamin D.
Current recommendations for Vitamin D
For Canada and the United States, the current Dietary Reference Intake for vitamin D was released in 1997. The recommended level of vitamin D intake for men and women over age 30 are the following (6):
31-50 years 200 IU (5 ug)
51-70 years 400 IU (10 ug)
>70 years 600 IU (15 ug)
Not surprisingly, much new and important data have been published in the ensuing years since the release of these recommendations. Of note is the fact that much research includes diseases other than those where there is a well-established role of vitamin D in bone health. This demonstrates the potential wide-ranging biological effects of vitamin D. As a result, current dietary reference intakes for vitamin D are under review and it is anticipated that an updated recommendation will be released later this year. In the meantime, several health organizations have created specific recommendations for vitamin D intakes. The Canadian Cancer Society recommends 1,000 IU (25 ug) vitamin D per day for adults – especially during the winter months when endogenous production of vitamin D is negligible – for potential protection against cancer development.
Most recently, Osteoporosis Canada has developed guidelines that recommend daily vitamin D supplements of 400 IU (10 ug) to 1,000 IU (25 ug) for adults under age 50 without osteoporosis or conditions affecting vitamin D absorption.10 Osteoporosis Canada also recommends vitamin D supplements of between 800 IU (20 ug) to 2,000 IU (50 ug) vitamin D for men and women over age 5010. Notably, these are approximately 2 to 5 times higher than current dietary reference intakes for vitamin D.
Vitamin D and Periodontal Health
Vitamin D has been studied with respect to periodontal health because of known benefits to bone metabolism as well as anti-inflammatory activity involving T-cell homeostasis. Review of studies investigating the relationship between vitamin D intakes and periodontal health in adults suggest that vitamin D promotes periodontal health.
Using cross-sectional data from over 11,000 subjects that was collected as part of the National Health and Nutrition Examination Survey (known as NHANES III), investigators showed an inverse relationship between attachment loss and serum 25-hydroxyvitamin D (25(OH)D3) in men and women over age 50 but not among those under age 50. As noted by the authors, this finding may be explained by the fact that periodontal disease is more prevalent at older ages. Study subjects over 50 years of age had a fairly wide range of serum 25-hydroxyvitamin D levels, ranging from less than 40.2 nmol/L (n=554) through to individuals with levels greater than 85.6 nmol/L (n=449). Serum 25-hydroxyvitamin D levels of subjects were divided into quintiles, and thus individuals in the two highest quintiles had levels at approximately the level often advocated as having potential health benefits (i.e., serum 25-hydroxyvitamin D levels of 75 nmol/L). The authors also reported there was no relationship between bone mineral density (BMD) and attachment loss. This was a somewhat surprising finding as loss of BMD at the wrist, spine and hip are associated with a greater number of lost teeth due to loss of alveolar bone in the jaw. This finding also suggests that the potential immunomodulatory effects of vitamin D may be the predominant mechanism linking vitamin D with attachment loss.
Another study using the NHANES III data showed that subjects with the highest intakes of vitamin D were less likely to bleed on probing.
Male and female subjects ranged in age from 13 to over 90 years of age. Of note is the fact that all subjects in this analysis had never smoked, and this perhaps strengthens the findings as it could be postulated that higher serum 25-hydroxyvitamin D may have greater benefits among smokers due to compromised periodontium. The relationship was such that for every 30 nmol/L increase in serum 25-hydroxyvitamin D, there was a 10% lower odds for bleeding upon probing. Moreover, the association was linear over the range of serum vitamin D levels. The lowest and highest median quintile were 32.4 nmol/L and 99.6 nmol/L, respectively, with the highest mean quintile being even higher than the target vitamin D level of 75 nmol/L.
We would be remiss not to at least discuss briefly that dietary calcium levels may also be an important consideration when examining the relationship of vitamin D with periodontal health. The studies discussed so far measured calcium intakes, and unless calcium supplements were taken, most individuals had calcium intakes that were below recommended levels. For both men and women, calcium intakes should be 1,000 mg for age 31-50 years and 1200 mg for over age 50 years. One randomized controlled trial and a few cross-sectional studies have investigated both nutrients together in the context of periodontal health. The randomized controlled trial in healthy older individuals (over age 65 years) who received daily supplementation of calcium (500 mg) in combination with vitamin D (700 IU or 17.5 ug) showed a lower risk of tooth loss with no differences in probing depths at the end of 3 years.
This finding, combined with the studies investigating vitamin D alone, emphasize the importance of subjects meeting the recommended intake of calcium. A cross-sectional study showed that among patients with at least two interproximal sites with ≥3 mm clinical attachment loss, subjects who took vitamin D (≥400 IU or ≥10 ug per day) and calcium (≥1000 mg per day) supplements had better clinical status including shallower probing depths, fewer bleeding sites, lower gingival index values, fewer furcation involvements, less attachment loss, and less alveolar crest height loss. While a clinical benefit of supplementation was observed, the differences between groups were not statistically significant. It will be important to further study this relationship with a larger sample size and in randomized controlled trials.
The NHANES III data has also been used to examine if intake of dairy products relates to periodontal health as dairy foods represent a major dietary source of vitamin D as well as calcium.1 Over 12,000 individuals were included in this analysis and the prevalence of periodontitis was markedly lower for subject with the highest quintile of dairy intake compared to those consuming low amounts of dairy foods. Individuals were classified as having periodontitis if they had at least one site with an attachment loss of ≥3 mm and a probing depth of ≥4 mm. While findings to date suggest a positive role for vitamin D in periodontal health, randomized controlled trials, with a primary objective of determining optimal vitamin D levels for prevention of or attenuation of periodontal disease, are needed.
Improving Vitamin D Status: Food or Supplements?
As discussed earlier, it is believed that for optimal health, in general, serum 25-hydroxyvitamin levels should be 75 nmol/L or higher and that likely a diet containing a minimum of 1,000 IU (25 ug) vitamin D per day is required to achieve this level. Vitamin D is naturally present in only a few foods, namely fatty fish (1 serving contains approximately 350 IU or 8.75 ug) and eggs (1 egg contains approximately 30 IU or 0.75 ug vitamin D). Milk can be a major source as it is fortified with vitamin D. One glass of milk, regardless of fat content, contains 100 IU (2.5 ug) of vitamin D. Moreover, chocolate flavored milk beverage also contains 100 IU (2.5 ug) of vitamin D. So, if aiming for 1000 IU (25 ug) of vitamin D through dietary sources, many glasses of milk and multiple servings of fish need to be consumed each day. Thus, supplements are warranted to help achieve these levels of vitamin D.
Higher serum 25-hydroxyvitamin D is associated with better periodontal health:
- Inverse relationship between serum 25-hydroxyvitamin D and attachment loss in men and women over age 50.
- Calcium may also facilitate better periodontal health – a combination of daily supplements of calcium (500 mg) and vitamin D (700 IU) is associated with lower risk of tooth loss.
- Higher intake of dairy products is associated with a lower risk of periodontitis.
Serum 25-hydroxyvitamin D, the accepted marked of vitamin D status, should be at least 75 nmol/L to promote optimal health, including periodontal health. To achieve such serum levels, vitamin D intakes of at least 1,000 IU (25 ug) are likely required.
Few foods contain significant quantities of vitamin D either naturally or through food fortification and thus vitamin D supplements are likely needed to achieve appropriate serum levels of 25-hydroxyvitamin D.
Although the evidence regarding the important role of vitamin D in prevention of a wide range of diseases is increasing, it is important to recognize that vitamin D is unlikely a panacea for health, and that you can get “too much of a good thing”. It is advised that individuals do not consume in excess of 2,000 IU (50 ug) of vitamin D per day.
Published by Oral Health & Dental Practice Management, October 2010