October 1, 2011
by Wendy E. Ward, B. Arts & Sci. (Hons), MSc, PhD and Peter C. Fritz, BSc, DDS, FRCD(C), PhD (Perio), C
This same time last year we provided a summary of literature suggesting that vitamin D – often referred to as the “sunshine vitamin” because we can endogenously synthesize it via stimulation of our skin by ultraviolet rays – may protect against periodontal disease. Since vitamin D and calcium are often studied together when assessing bone health there was also discussion of appropriate calcium intakes. Since this time, the new dietary recommendations, referred to as Dietary Reference Intakes, for both vitamin D and calcium intake was released by the Institute of Medicine in the United States (U.S.).1 The review of these two nutrients was jointly commissioned and funded by the U.S. and Canadian governments; Health Canada uses these recommendations for Canadians.
THIS REVIEW WILL EXAMINE TWO MAIN ASPECTS:
• How have the recommendations for daily vitamin D and calcium intake changed or not changed?
• How do the newly recommended dietary levels of vitamin D and calcium correspond to the levels in individual studies showing a benefit of vitamin D and calcium for periodontal health?
NEW RECOMMENDATIONS FOR VITAMIN D INTAKES
Of note from the updated review is the fact that vitamin D intakes for adults age 19 and older should be up to three times higher than the previous recommendation (Table 1).1 The recommended dietary allowance for an adult age 19 years to 50 years has tripled from 200 IU to 600 IU. Similar to the previous recommendation for adults over age 70, the Dietary Reference Intake (DRI) for vitamin D is higher than all other age groups as it is recognized vitamin D needs are higher due to less efficient synthesis of vitamin D and greater needs to help maintain bone health at this stage of life. Although the recommendations are now higher for some age groups, it cannot be assumed that all individuals need to increase their intake of vitamin D. Some individuals will have appropriate intakes of vitamin D through their diet and/or a combination of diet and sun exposure. Because sun exposure will vary dramatically among individuals for a variety of reasons, the recommended intakes for vitamin D are established without considering vitamin D synthesis by exposure of skin to the sun’s ultraviolet rays. Guidance for determining vitamin D intake from food is provided in Table 2.2
These recommended daily intakes for vitamin D are closer to those of other health organizations who prior to the release of the new report had released their guidelines regarding appropriate intakes for prevention or management of chronic diseases – the Canadian Cancer Society3 and Osteoporosis Canada4 had previously recommended intakes of 1000 IU (25 ug) per day or between 400 and 2000 IU depending on age and whether osteoporosis was present. The new report also included a higher upper level intake (4000 IU or 100 ug/day; Table 1), twice the level from the previous report. The upper tolerable limit is set as the highest level of daily consumption that should be consumed – based on current data, consuming up to 4000 IU/day of vitamin D has not resulted in side effects in individuals who are not receiving medical supervision.
ESTIMATING VITAMIN D INTAKE
By knowing the vitamin D content of the most commonly consumed foods that are among the richest sources of these nutrients, an individual can estimate their daily intake, and importantly, determine whether they are consuming vitamin D at the recommended level. It is generally accepted that consuming the recommended levels of vitamin D (i.e. 600 IU/day for individuals under age 70) will result in serum 25-hydroxyvitamin D levels – the most reliable marker of vitamin D status – of approximately 50 nmol/L.1 This level is generally considered adequate for bone and overall health in healthy individuals. Serum levels between 30 and 50 nmol/L are generally considered to be inadequate for bone and overall health in healthy individuals. Vitamin D deficiency, resulting in poor bone health, is determined as a serum 25-hydroxyvitamin D level less than 30 nmol/L. An excessive level of serum 25-hydroxyvitamin D, i.e. greater than 125 nmol/L, may have adverse effects. Such a high level of serum 25-hydroxyvitamin D can only be achieved with supplementation and could not be achieved through dietary sources alone.
PERIODONTAL HEALTH AND NEW RECOMMENDATIONS FIR VITAMIN D INTAKE
Before we compare the current recommendations with the intakes included in studies investigating the link between vitamin D status and periodontal health it is prudent to state that the current recommendations are based solely on the benefit of vitamin D and calcium to bone health. As stated in the Report Brief, “The Committee provided an exhaustive review of studies on potential health outcomes and found that the evidence supported a role for these nutrients in bone health but not in other health conditions.”1,5 As such, the data to date linking higher serum 25-hydroxyvitamin D with better periodontal health was not sufficient, particularly from clinical trials, to be considered in setting the new recommendations. This is important to keep in mind as we move forward and discuss what has been shown in regarding an individuals’ vitamin D status and their periodontal health. While it may seem discouraging that these recommendations cannot be directly extrapolated to achieve improved periodontal health, the newly released levels of vitamin D are closer to those associated with improved periodontal health in individual studies.
VITAMIN D AND PERIODONTAL HEALTH
A few studies have shown that, in general, higher serum 25-hydroxyvitamin D and/or higher consumption of dairy products is associated with better periodontal health.6-9 In these studies, periodontal health was evaluated by measuring one or more of the following outcomes: attachment loss, probing depths, number of bleeding sites, gingival index, furcation involvement, and alveolar crest height loss.
A study using data collected as part of the National Health and Nutrition Examination Survey (known as NHANES III) reported that individuals with serum 25-hydroxyvitamin D in the highest quintile (106 nmol/L) versus the lowest quintile (31 nmol/L) were less likely to bleed on probing.6 Moreover, there was an overall trend across the quintiles (median serum 25-hydroxyvitamin D levels of 31, 47, 60, 75, 106 nmol/L) that higher serum 25-hydroxyvitamin D was associated with better periodontal health.6 Another study using data from NHANES III reported that there was a similar significant trend across quintiles for serum 25-hydroxyvitamin D and periodontal attachment loss for men and women over age 50. Quintiles for serum 25-hydroxyvitamin D were <40, 40-53, 53-67, 68-85 and >85 nmol/L.7 Together, the cross-sectional data suggest that levels of serum 25-hydroxyvitamin D that are greater than the 50 nmol/L achieved by consuming vitamin D at recommended intakes (i.e. 600 or 800 IU/day) may benefit periodontal health.6,7
Another study showed that patients receiving periodontal maintenance therapy who took vitamin D and calcium supplements tended to have shallower probing depths, fewer bleeding sites, lower gingival index values, fewer furcation involvements, less attachment loss, and less alveolar crest height loss.8 The findings did not reach statistical significance but suggest a potential benefit of vitamin D intakes of 1049 IU compared to 156 IU in patients who did not use vitamin D and calcium supplements. Of note is the lower than recommended levels of vitamin D in the “non-takers” group. Calcium intakes were also lower than recommended in the non-takers (1769 versus 642 mg). Without a group of individuals taking vitamin D and calcium at recommended intake levels it is unknown if the suggested beneficial trend would exist if “non-takers” had higher vitamin D intakes that were similar to recommended intake levels. There is some data to suggest that vitamin D deficiency does com
promise recovery after surgery for periodontitis; less gain in clinical attachment loss and probing depth reduction was observed in patients with vitamin D deficiency at time of surgery.10
In summary, it is likely that the new recommendations for vitamin D, which are based on bone health, likely benefit periodontal health too. The continuum of the positive association between serum-25 hydroxyvitamin D and better periodontal health (less bleeding on probing; less periodontal attachment loss) from the two cross-sectional studies require further study. Studies to date provide a scientific basis for further study, particularly randomized controlled trials, that are needed to more definitively elucidate the levels of vitamin D that will optimize periodontal health.
NEW RECOMMENDATIONS FOR CALCIUM INTAKES
Because a major role of vitamin D is to facilitate calcium utilization in the body, it is important to consider the new recommendations for calcium. The recommended dietary intakes for calcium remained relatively unchanged from previous recommendations for adults over age 19 years (1). For men and women age 19 through 50 years, recommended calcium intake is 1000 mg/day – the same as the previous report. A difference is that the recommendation for men age 51-70 years is 1000 mg compared with 1200 mg calcium per day in the previous report. 1200 mg calcium per day continues to be recommended for women age 51 or older and for men age 70 years or older. While the release of the new guidelines regarding calcium intake may have appeared uneventful, there has been considerable attention in the health media regarding the safety of using calcium supplements regarding a report that calcium supplementation was associated with increased risk of cardiovascular disease events in healthy older adults. Due to the extensive media coverage, several reputable organizations such as Osteoporosis Canada and the American Society for Bone and Mineral Research have released guidance documents on this topic that recommend individuals do not exceed the recommended intakes for calcium, and that calcium supplements should only be used to help an individual to reach the recommended level of intake if they cannot reach it through diet alone.11,12 The website of Osteoporosis Canada can serve as a useful resource for individuals to estimate their calcium intake using the “calcium calculator” feature.13 Moreover, Osteoporosis Canada has provided practical guidance for estimating an individuals calcium intake: approximately 300 mg of calcium is consumed simply through eating a varied diet and 1 serving of milk (regardless of fat content), calcium fortified soy milk or orange juice, yogurt or cheese contain approximately 300 mg of calcium.11 An individual will not consume an unsafe level of calcium through consumption of foods.
A study that examined the relationship between consumption of dairy products and periodontal health showed that individuals consuming more than 4 servings of dairy a dairy versus those consuming less than 1 serving per day were 20% less likely to have periodontitis (periodontitis was defined in the study as 1 site with an attachment loss of ≥ 3 mm and a probing depth of ≥ 4 mm).9 Although milk is the only dairy product that contains substantial quantities of vitamin D, and the analysis considered other dairy products that are much lower in vitamin D, it is likely that at least several of the servings of dairy products were milk. Moreover, calcium intake from dietary sources was also likely higher in individuals consuming the most dairy products. A randomized controlled trial in healthy Americans over age 65 reported that supplementation with 500 mg of calcium and 700 IU vitamin D resulted in a lower of tooth loss and no differences in probing depths.14 This study was a considerable length, a 3-year supplementation study. Notably, the level of vitamin D supplementation was close to the 600 IU recommended for adults up to age 70 and 800 IU recommended for adults over age 70.
• New recommendations for vitamin D and calcium were based on bone health and not other health outcomes such as periodontal health.
• Adults up to age 70 years should consume 600 IU of vitamin D per day. Adults over age 70 should consume 800 IU of vitamin D per day. This level of vitamin D intake should result in serum levels of 25-hydroxyvitamin D of approximately 50 nmol/L.
• Too much vitamin D can have adverse effects. Consumption of vitamin D should not exceed 4000 IU vitamin D/day and serum 25-hydroxyvitamin D should be at least 50 nmol/L but not higher than 125 nmol/L to be adequate for bone health.
• Milk and fish provide more vitamin D compared to the most commonly consumed foods that contain vitamin D. If not consuming such foods it can be difficult to consume recommended intakes of vitamin D without use of vitamin D supplements.
• Calcium intake should be 1000 or 1200 mg, depending on age and gender, and, if possible, be obtained through consumption of foods rather than supplements.
• Calcium intake can be estimated by assuming an individual consumes 300 mg of calcium through eating a varied diet and approximately 300 mg by consuming 1 serving of milk, yogurt, cheese, or calcium-fortified soy milk or orange juice.
• Too much calcium may have adverse effects. Calcium supplementation is only recommended if an individual does not get sufficient calcium in their diet.
• Well-controlled clinical trials are needed to elucidate the optimal level of vitamin D and calcium for periodontal health.OH
Wendy Ward is a Canada Research Chair in Bone and Muscle Development in the Faculty of Applied Health Sciences at Brock University. Her research program investigates how early diet programs adult bone health and may attenuate the risk of developing osteoporosis. Within this program her research group studies the mechanisms by which phytoestrogens (i.e. isoflavones in soy, lignans in flaxseed), vitamin D and fatty acids regulate bone metabolism.
Peter Fritz is a certified specialist in Periodontics and is in full-time private practice in Fonthill, Ontario. The focus of his periodontal practice is dental implant therapy, bone and soft tissue reconstruction, and oral medicine. Dr. Fritz is an Adjunct Professor in the Faculty of Applied Health Sciences at Brock University.
Oral Health welcomes this original article.
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2. U.S Department of Agriculture, Agricultural Research Service. 2010. USDA National Nutrient Database Standard Reference. Release 23.
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