Hello. This is Dr JoAnn Manson, professor of medicine at Harvard Medical School and Brigham and Women's Hospital. I'd like to talk with you about the Endocrine Society's recent clinical practice guidelines on vitamin D for disease prevention, rolled out at the Endocrine Society meetings in June 2024.
The bottom line of these guidelines is that there is a very limited role for vitamin D supplementation and for screening for vitamin D deficiency in the general population. The guidelines generally endorse the recommended dietary allowances (RDA) that were set forth by the Institute of Medicine (now known as the National Academy of Medicine) in 2011, which include an RDA of 600 IU daily for adults until age 70 and 800 IU daily after age 70.
Several groups were identified in these guidelines who may benefit from intakes above the RDA. These include older adults (aged 75 or older) who may benefit in terms of reducing mortality. Older adults have decreased intestinal absorption and skin synthesis of vitamin D and may benefit. Also, children and adolescents have potential benefits for preventing rickets as well as reducing risks for respiratory tract infections in those age groups. During pregnancy, vitamin D has a potential role in reducing preeclampsia and other pregnancy-related complications. And in the setting of prediabetes, vitamin D may reduce progression to type 2 diabetes.
The guidelines from the Endocrine Society did not recommend specific intakes of vitamin D for these clinical scenarios but did say that these groups may benefit from intakes above the RDA. Most of the population seems to do well with RDA levels that provide small to moderate amounts of vitamin D. This may be because the metabolism and physiology of vitamin D are very tightly regulated in the body, so most of us can get by with smaller amounts. However, several other groups may need higher intakes, including people with malabsorption conditions (such as Crohn's disease, ulcerative colitis, inflammatory bowel disease ,or post–gastric bypass surgery) and people taking medications for osteoporosis. Also, nursing home residents who may have low intake as well as those spending very little time outdoors may benefit from higher intakes than the RDA.
What else have we learned from randomized trials about who may benefit from vitamin D? The daily dose of vitamin D may be safer and more effective than the intermittent bolus dosing with very high doses of vitamin D. Also, randomized trials (such as the vitamin D omega-3 trial VITAL) and other trials suggest benefits of vitamin D supplementation for reducing risk for advanced cancer. Cancer death meta-analyses are now bearing that out, with half a dozen meta-analyses suggesting benefits for reducing autoimmune diseases, so people who have special risk factors for these conditions or strong family histories of these conditions may want to consider supplementation.
It appears from these randomized trials that doses of at least 2000 IUs, if not higher, are quite safe for many years. A dose of 2000 IU per day was found to be safe for 5.3 years in in the VITAL trial. It has also been found that in these randomized trials, body mass index and adiposity may modify the efficacy of vitamin D supplementation such that there were benefits in those with BMI below 25 for many health conditions, including cancer, autoimmune diseases, and others, with quite substantial risks reductions. But reductions were absent or minimal in those with higher BMIs. We definitely need more research to identify ways in which vitamin D supplementation may be of benefit across all categories of BMI, and this may include using metabolized forms of vitamin D, such as calcidiol or other formulations, the efficacy of which would not vary according to adiposity and BMI.
COMMENTARY
Vitamin D: Who Benefits From Supplements Now?
JoAnn E. Manson, MD, DrPH
DISCLOSURES
| July 16, 2024Hello. This is Dr JoAnn Manson, professor of medicine at Harvard Medical School and Brigham and Women's Hospital. I'd like to talk with you about the Endocrine Society's recent clinical practice guidelines on vitamin D for disease prevention, rolled out at the Endocrine Society meetings in June 2024.
The bottom line of these guidelines is that there is a very limited role for vitamin D supplementation and for screening for vitamin D deficiency in the general population. The guidelines generally endorse the recommended dietary allowances (RDA) that were set forth by the Institute of Medicine (now known as the National Academy of Medicine) in 2011, which include an RDA of 600 IU daily for adults until age 70 and 800 IU daily after age 70.
Several groups were identified in these guidelines who may benefit from intakes above the RDA. These include older adults (aged 75 or older) who may benefit in terms of reducing mortality. Older adults have decreased intestinal absorption and skin synthesis of vitamin D and may benefit. Also, children and adolescents have potential benefits for preventing rickets as well as reducing risks for respiratory tract infections in those age groups. During pregnancy, vitamin D has a potential role in reducing preeclampsia and other pregnancy-related complications. And in the setting of prediabetes, vitamin D may reduce progression to type 2 diabetes.
The guidelines from the Endocrine Society did not recommend specific intakes of vitamin D for these clinical scenarios but did say that these groups may benefit from intakes above the RDA. Most of the population seems to do well with RDA levels that provide small to moderate amounts of vitamin D. This may be because the metabolism and physiology of vitamin D are very tightly regulated in the body, so most of us can get by with smaller amounts. However, several other groups may need higher intakes, including people with malabsorption conditions (such as Crohn's disease, ulcerative colitis, inflammatory bowel disease ,or post–gastric bypass surgery) and people taking medications for osteoporosis. Also, nursing home residents who may have low intake as well as those spending very little time outdoors may benefit from higher intakes than the RDA.
What else have we learned from randomized trials about who may benefit from vitamin D? The daily dose of vitamin D may be safer and more effective than the intermittent bolus dosing with very high doses of vitamin D. Also, randomized trials (such as the vitamin D omega-3 trial VITAL) and other trials suggest benefits of vitamin D supplementation for reducing risk for advanced cancer. Cancer death meta-analyses are now bearing that out, with half a dozen meta-analyses suggesting benefits for reducing autoimmune diseases, so people who have special risk factors for these conditions or strong family histories of these conditions may want to consider supplementation.
It appears from these randomized trials that doses of at least 2000 IUs, if not higher, are quite safe for many years. A dose of 2000 IU per day was found to be safe for 5.3 years in in the VITAL trial. It has also been found that in these randomized trials, body mass index and adiposity may modify the efficacy of vitamin D supplementation such that there were benefits in those with BMI below 25 for many health conditions, including cancer, autoimmune diseases, and others, with quite substantial risks reductions. But reductions were absent or minimal in those with higher BMIs. We definitely need more research to identify ways in which vitamin D supplementation may be of benefit across all categories of BMI, and this may include using metabolized forms of vitamin D, such as calcidiol or other formulations, the efficacy of which would not vary according to adiposity and BMI.
Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.
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