Vitamin D is Crucial to Overall Health

Are you getting enough vitamin D? It is vital you do! This super vitamin, which the skin produces in response to ultraviolet (UV) rays from the sun, is not only important for strong healthy bones, it is also necessary for your overall health. It’s an essential factor in making sure your muscles, heart, lungs and brain work well, and it helps your body fight cancer.

Low levels of vitamin D have been found to be very common in the United States and Canada, resulting in significant health problems.1  Vitamin D insufficiency is now recognized as a pandemic, affecting 30-50 percent of the population.1,2  Vitamin D insufficiency is a key contributor to many human diseases including several cancers, diabetes, cardiovascular disease, depression, cognitive decline, and autoimmune diseases.1, 3

It is estimated that over 50 million adults in the United States either have, or are at risk of developing, osteoporosis.4  Osteoporosis is a condition where you lose too much bone or don’t make enough bone to replace the bone that you normally lose. If you lose too much bone, your bones become less dense and are more likely to break. People with osteoporosis have low bone density. Maintaining vitamin D sufficiency is crucial for bone health, and a key feature in a strategy to prevent osteoporosis.

Vitamin D’s role in bone health

Vitanin D functions as a hormone because it sends a message to the intestines to increase the absorption of calcium and phosphorus. By promoting calcium absorption, vitamin D helps to form and maintain strong bones.Vitamin D also stimulates osteoblastic (bone-building cells) activity. Vitamin D deficiency results in diminished calcium absorption, and has been linked to a higher incidence of osteoporosis-related bone fractures seen in postmenopausal women and older Americans.3, 5 

There have been claims that vitamin D supplementation is unnecessary for bone health. A 2015 analysis pooled many studies and stated the conclusion that vitamin D supplementation does not reduce the risk of falls or other negative outcomes by 15 percent or more.6

However, there are details to be considered. This analysis did not take  into account D2 vs. D3, and also did not group studies by the dose of vitamin D. A previous pooled analysis, which analyzed studies based on the dose of vitamin D, established that dose matters. This analysis  considered the actual intake of vitamin D, not just whether or not the person had been assigned to the supplement group. In this analysis, there was a 30 percent reduction in hip fracture rate at the highest level of vitamin D intake (792-2000 IU) in the supplement groups compared to the control groups. 7, 8

An earlier meta-analysis supports this idea, recommending 800 IU as the minimum effective dose.9 However, another meta-analysis in 2018 disagreed; the authors did not find a reduction in risk even when examining only trials that used 800 IU/day or more.10, 11

We don’t know exactly why the results of these analyses have not been consistent. There are many factors that affect bone health, including weight-bearing physical activity. A combination of nutrients work together to keep bones strong, including vitamin D, calcium, magnesium, phosphorus, vitamin K, and polyphenols.

In many supplementation studies, the baseline blood vitamin D levels of the patients are not taken into account. Vitamin D is probably most effective when it moves someone from a level of deficiency or insufficiency to sufficiency. If the dose is too small to achieve that, or if many of the participants are already sufficient, we may not see an effect.

Regardless, vitamin D is an essential nutrient, and it is imperative to get adequate amounts to perform all of its vital functions in the body. For many people, supplementation is necessary to be vitamin D sufficient.

Vitamin D  fights  multiple diseases, including cancer  

Vitamin D is known to have protective effects on bone health, and, in addition, vitamin D has several other critical functions.

Scientists have found that vitamin D has biological actions in almost every cell and tissue in the human body. Keeping vitamin D levels in the favorable range is associated with a longer life. In the elderly and in middle-aged adults, in a variety of different populations from different countries, sufficient vitamin D levels were linked to a lower risk of death from cancer, cardiovascular disease, or all causes. 12-15 Vitamin D regulates several genes and cellular processes related to cancer progression. Some of the most groundbreaking findings in nutrition science in recent years have been evidence of the powerful protection provided by vitamin D against common cancers:

  • Breast cancer: Higher blood vitamin D levels are associated with a lower risk of being diagnosed with breast cancer and a higher rate of survival among women who have already been diagnosed.16
  • Colorectal cancer: A 2015 review of 15 studies found that sufficient vitamin D levels were consistently associated with reduced risk of colorectal cancer. 17 Even after diagnosis with colorectal cancer, higher vitamin D levels are associated with reduced mortality.18  
  • Cancers of the prostate, pancreas, lung, and endometrium are also associated with vitamin D insufficiency. 1, 19

Vitamin D has growth-inhibitory effects on cells derived from breast, colon, prostate, and skin cancers, and a 2014 meta-analysis concluded that supplementation with vitamin D3 was associated with a 12 percent lower risk of death from cancer. 20 D3 is the natural form of the vitamin, made by the body in response to sunlight. Because it is absorbed better and  is more effective, less D3 is needed than D2 21-25  In a review of 56 trials of vitamin D supplementation, vitamin D3 was found to decrease mortality risk, however D2 was not. 20 26 For comparison, the tolerable upper limit (the maximum recommended daily dose) is currently 4000 IU.

Large doses of hundreds of thousands of IUs may be problematic even when using vitamin D3. For example, a study testing a dose of 500,000 IU vitamin D3 in elderly women found an increased the rate of falls, and a trend toward an increase in fracture risk compared to placebo.27

One possible explanation of these negative effects is that the excessively large dose of vitamin D could have stimulated rapid bone turnover, resulting in the breakdown of existing bone.28 Not all studies on high dose vitamin D showed negative effects. 29

However, a recent meta-analysis pooled all the conflicting data, and concluded that high dose vitamin D supplementation had no effect on fracture risk but slightly increased the risk of falls. 30

A moderate, consistent daily dose of D3 is a safe and conservative method to keep vitamin D levels in a healthy range, not too high and not too low.
There is significant scientific agreement that a blood level of 25(OH)D (twenty-five-hydroxyvitamin D) should be at least 30 ng/ml for several aspects of health.14, 31, 32 It is reasonable, therefore, to supplement if one’s levels fall below this optimal range.

But again, more is not always better; the research suggests that increasing one’s 25(OH)D above approximately 45 ng/ml confers no further benefit and may even be detrimental.14, 33-36

Getting the right amount of vitamin D
For most people, the principal source of vitamin D is  produced by the skin in response to sunlight. Very few foods naturally contain vitamin D, and achieving adequate vitamin D levels via sunlight can be difficult depending on your geographical location, skin color, and opportunities for sun exposure, especially in the winter months.

Also, sun exposure to assure optimal Vitamin D status may damage and age the skin increasing wrinkling, mottling and the risk of skin cancer. A smart option is a moderate daily dose of vitamin D3, not too much or too little.

We should aim for the sweet spot of blood 25(OH)D to be between 30 to 45 ng/ml, as suggested by the scientific evidence14, 32, 37 

We should choose D3, the natural form of the vitamin, the form the body produces in response to sunlight. There is overwhelming evidence of benefit, and no risks noted in a reasonable dose. Ingest a moderate daily dose of supplemental vitamin D3 (approximately 50 mcg or 2000 IU/day) to reach the 30-45 ng/ml window. If you do not supplement, it makes sense to have your 25(OH)D levels tested and be proactive about your health because a long-standing deficiency can be harmful. If 25(OH)D is between 25 and 30 while taking 2000 IU (50 mcg), instead of increasing the dose, I recommend making sure the supplement is taken with a meal with fat (nuts and seeds) for better absorption. Only for those whose 25(OH)D is below 25 do I recommend moving the daily dose up to 3000 IU.

  1. Holick MF, Chen TC. Vitamin D deficiency: a worldwide problem with health consequences. Am J Clin Nutr 2008, 87:1080S-1086S.
  2. Lee JH, O'Keefe JH, Bell D, et al. Vitamin D deficiency an important, common, and easily treatable cardiovascular risk factor? J Am Coll Cardiol 2008, 52:1949-1956.
  3. Holick MF. Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease. Am J Clin Nutr 2004, 80:1678S-1688S.
  4. National Osteoporosis Foundation: What is Osteoporosis? []
  5. Brincat M, Gambin J, Brincat M, Calleja-Agius J. The role of vitamin D in osteoporosis. Maturitas 2015, 80:329-332.
  6. Bolland MJ, Grey A, Gamble GD, Reid IR. Vitamin D supplementation and falls: a trial sequential meta-analysis. Lancet Diabetes Endocrinol 2014, 2:573-580.
  7. Bischoff-Ferrari HA, Willett WC, Wong JB, et al. Fracture prevention with vitamin D supplementation: a meta-analysis of randomized controlled trials. JAMA 2005, 293:2257-2264.
  8. Bischoff-Ferrari HA, Willett WC, Orav EJ, et al. A pooled analysis of vitamin D dose requirements for fracture prevention. N Engl J Med 2012, 367:40-49.
  9. Tang BM, Eslick GD, Nowson C, et al. Use of calcium or calcium in combination with vitamin D supplementation to prevent fractures and bone loss in people aged 50 years and older: a meta-analysis. Lancet 2007, 370:657-666.
  10. Bolland MJ, Grey A, Avenell A. Effects of vitamin D supplementation on musculoskeletal health: a systematic review, meta-analysis, and trial sequential analysis. Lancet Diabetes Endocrinol 2018, 6:847-858.
  11. Daniells S. Vitamin D & bone health: The flawed logic of RCTs for vitamins. In Nutra-ingredients USA, 2018 []Chen P, Hu P, Xie D, et al. Meta-analysis of vitamin D, calcium and the prevention of breast cancer. Breast Cancer Res Treat 2010, 121:469-477.
  12. Gaksch M, Jorde R, Grimnes G, et al. Vitamin D and mortality: Individual participant data meta-analysis of standardized 25-hydroxyvitamin D in 26916 individuals from a European consortium. PLoS One 2017, 12:e0170791.
  13. Pilz S, Grubler M, Gaksch M, et al. Vitamin D and Mortality. Anticancer Res 2016, 36:1379-1387.
  14. ittermann A, Iodice S, Pilz S, et al. Vitamin D deficiency and mortality risk in the general population: a meta-analysis of prospective cohort studies. Am J Clin Nutr 2012, 95:91-100.
  15. Srinonprasert V, Chalermsri C, Chailurkit LO, et al. Vitamin D insufficiency predicts mortality among older men, but not women: A nationwide retrospective cohort from Thailand. Geriatr Gerontol Int 2018.
  16. Kim Y, Je Y. Vitamin D intake, blood 25(OH)D levels, and breast cancer risk or mortality: a meta-analysis. Br J Cancer 2014, 110:2772-2784.
  17. Choi YJ, Kim YH, Cho CH, et al. Circulating levels of vitamin D and colorectal adenoma: A case-control study and a meta-analysis. World J Gastroenterol 2015, 21:8868-8877.
  18. Ng K, Wolpin BM, Meyerhardt JA, et al. Prospective study of predictors of vitamin D status and survival in patients with colorectal cancer. Br J Cancer 2009, 101:916-923.
  19. Peterlik M, Grant WB, Cross HS. Calcium, vitamin D and cancer. Anticancer Res 2009, 29:3687-3698.
  20. Bjelakovic G, Gluud LL, Nikolova D, et al. Vitamin D supplementation for prevention of mortality in adults. Cochrane Database Syst Rev 2014, 1:CD007470.
  21. Tripkovic L, Lambert H, Hart K, et al. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. Am J Clin Nutr 2012.
  22. Logan VF, Gray AR, Peddie MC, et al. Long-term vitamin D3 supplementation is more effective than vitamin D2 in maintaining serum 25-hydroxyvitamin D status over the winter months. Br J Nutr 2013, 109:1082-1088.
  23. Lehmann U, Hirche F, Stangl GI, et al. Bioavailability of vitamin D(2) and D(3) in healthy volunteers, a randomized placebo-controlled trial. J Clin Endocrinol Metab 2013, 98:4339-4345.
  24. Holmberg I, Berlin T, Ewerth S, Bjorkhem I. 25-Hydroxylase activity in subcellular fractions from human liver. Evidence for different rates of mitochondrial hydroxylation of vitamin D2 and D3. Scand J Clin Lab Invest 1986, 46:785-790.
  25. Houghton LA, Vieth R. The case against ergocalciferol (vitamin D2) as a vitamin supplement. Am J Clin Nutr 2006, 84:694-697.
  26. Smith H, Anderson F, Raphael H, et al. Effect of annual intramuscular vitamin D on fracture risk in elderly men and women--a population-based, randomized, double-blind, placebo-controlled trial. Rheumatology (Oxford) 2007, 46:1852-1857.
  27. Sanders KM, Stuart AL, Williamson EJ, et al. Annual high-dose oral vitamin D and falls and fractures in older women: a randomized controlled trial. JAMA 2010, 303:1815-1822.
  28. Rossini M, Gatti D, Viapiana O, et al. Short-term effects on bone turnover markers of a single high dose of oral vitamin D(3). J Clin Endocrinol Metab 2012, 97:E622-626.
  29. Rossini M, Alberti V, Flor L, et al. Effect of oral vitamin D2 yearly bolus on hip fracture risk in elderly women: a community primary prevention study. Aging Clin Exp Res 2004, 16:432-436.
  30. Zheng YT, Cui QQ, Hong YM, Yao WG. A meta-analysis of high dose, intermittent vitamin D supplementation among older adults. PLoS One 2015, 10:e0115850.
  31. Schottker B, Ball D, Gellert C, Brenner H. Serum 25-hydroxyvitamin D levels and overall mortality. A systematic review and meta-analysis of prospective cohort studies. Ageing Res Rev 2013, 12:708-718.
  32. Bischoff-Ferrari HA. Vitamin D and fracture prevention. Rheum Dis Clin North Am 2012, 38:107-113.
  33. Melamed ML, Michos ED, Post W, Astor B. 25-Hydroxyvitamin D Levels and the Risk of Mortality in the General Population. Arch Intern Med 2008, 168:1629-1637.
  34. Durup D, Jorgensen HL, Christensen J, et al. A reverse J-shaped association of all-cause mortality with serum 25-hydroxyvitamin D in general practice: the CopD study. J Clin Endocrinol Metab 2012, 97:2644-2652.
  35. Sempos CT, Durazo-Arvizu RA, Dawson-Hughes B, et al. Is there a reverse J-shaped association between 25-hydroxyvitamin D and all-cause mortality? Results from the U.S. nationally representative NHANES. J Clin Endocrinol Metab 2013, 98:3001-3009.
  36. Durup D, Jorgensen HL, Christensen J, et al. A reverse J-shaped association between serum 25-hydroxyvitamin D and cardiovascular disease mortality - the CopD-study. J Clin Endocrinol Metab 2015:jc20144551.
  37. Schottker B, Haug U, Schomburg L, et al. Strong associations of 25-hydroxyvitamin D concentrations with all-cause, cardiovascular, cancer, and respiratory disease mortality in a large cohort study. Am J Clin Nutr 2013.

Joel Fuhrman, M.D. is a board-certified family physician, seven-time New York Times bestselling author and internationally recognized expert on nutrition and natural healing, who specializes in preventing and reversing disease through nutritional methods. Dr. Fuhrman coined the term “Nutritarian” to describe his longevity-promoting, nutrient dense, plant-rich eating style.
For over 30 years, Dr. Fuhrman has shown that it is possible to achieve sustainable weight loss and reverse heart disease, diabetes and many other illnesses using smart nutrition. In his medical practice, and through his books and PBS television specials, he continues to bring this life-saving message to hundreds of thousands of people around the world.


Comments (0):



05/09/2019 10:04 AM

Dear Friends:  I am asking as many of us as possible rally together to combat the harmful campaign of bad information being promoted by VegSource, and it’s front man Jeff Nelson.


There are two main reasons why we need to reply to the unscientific claims Nelson and the VegSource camp are making.  Most important is the fact that the misleading advice poses a significant health risk to the public.  To advise those of us consuming a nutratarian diet we don’t need a source of DHA/EPA and the majority of vegans don’t need supplementation of essential fats put us at risk for the development of serious diseases.  The second reason is because of the disgusting personal attacks levied against Dr. Fuhrman.  Nelson and VegSource continue to ramp up the ad hominem vitriol.  They can’t support their position with credible science and good data so they attempt to personally deride Dr. Fuhrman, a practicing physician, researcher and thought leader that proves them wrong.  This is beyond bad form and is unacceptable.


Below are some links to YouTube videos.  I strongly encourage all of us that have a few minutes to post a comment(s) in opposition to both their message and their tact please do so.  We are the torchbearers of good science, truth and civility.


Thanks everyone.

This comment was last edited on 05/09/2019 09:45 PM


05/24/2019 10:24 AM

Won't accessing all the above links draw even more attention to the misleading info?  I think so! 

matthewbader replies:

05/24/2019 01:08 PM

I don't get it.  Seems completely off topic and spam(y).


05/24/2019 10:36 AM

For optimal absorption of Vitamin D3 into the bones you have to take it with Vitamin K2.


matthewbader replies:

05/24/2019 01:09 PM

How much Vitamin D3 do you take a day and what are you D3 levels?


05/24/2019 01:07 PM

I am a D3 / K2 junkie.  I have done a lot of reaserch on D3.  30-45 ng/ml is far too low for disease prevention.  Dr. Mercola (and others) recommend between 60-80 ng/ml for optimal health year round.  With testing your levels 2-3 times per year so you know you are in the healthy range.  Here is a link to his artilce with sources at the bottom:

Dr. Ferreri replies:

05/28/2019 11:04 AM

Several physicians do recommend higher levels, however, as cited in the post, the epidemiology suggests that above 45 ng/ml, there is either a plateau in risk reduction or an increase in risk of mortality. 


05/03/2021 12:04 PM

I've heard that vitamin D needs to be taken with magnesium. Is this true? If so, any recommendations on dosage and type?


Dr. Ferreri replies:

05/06/2021 04:45 PM

Magnesium is essential for synthesis and function of vitamin D, so it is important to get adequate amounts of both, but it is not necessary to take them together. That being said, since magnesium is abundant in plant foods, if you take vitamin D with a meal, there will be magnesium present also.