How much Vitamin D is optimal for health? To answer this question, today I’ll examine the association between a circulating marker of Vitamin D, 25-hydroxyvitamin D, with all-cause mortality risk. Then, I’ll examine the literature to estimate a dietary intake that can achieve an optimal circulating 25-hydroxyvitamin D concentration.
Circulating 25-hydroxyvitamin D is the most commonly measured vitamin D metabolite because of its greater half life (~3 weeks) and up to 1000-fold higher serum levels compared with the physiologically active metabolite of vitamin D, 1,25-dihydroxyvitamin D (Zerwekh 2008). So what’s the evidence for the association between circulating 25-hydroxyvitamin D with all-cause mortality risk?
In a meta-analysis of 95 studies including 880,201 subjects, circulating 25-hydroxyvitamin D levels greater than 30 ng/mL (75 nmol/L) are associated with significantly reduced risk of death from all causes when compared with values less than 30 (<10, 20-29; Chowdhury et al. 2014):
Does the meta-analysis data for 25-hydroxyvitamin D mean that any values higher than 30 ng/mL are optimal for health? Maybe not. As shown below, although data from 11,315 subjects in the NHANES III study suggests that values between 30-40 ng/mL (75-99 nmol/L) may be optimal for decreased all-cause mortality risk (Sempos et al. 2013), 25-hydroxyvitamin D values greater than 48 ng/mL (120+ nmol/L) were associated with an increased all-cause mortality risk. Interestingly, in agreement with the Chowdhury meta-analysis data, this graph shows also increased mortality risk at values less than 30-40 ng/mL (75-99 nmol/L):
However, whether increased circulating 25-hydroxyvitamin D is associated with increased all-cause mortality risk is debatable. In another meta-analysis (Garland et al. 2014), although circulating 25-hydroxyvitamin D values less than 30 ng/mL were again associated with increased risk, in contrast, values greater than 48 ng/mL were not. Interestingly, values as high as 70 ng/mL (175 nmoL) were not associated with increased risk, either:
Aside from our skin making Vitamin D from sunlight during the summer months, what dietary intake can achieve the seemingly optimal 30-40 ng/mL (75-99 nmol/L) concentration for 25-hydroxyvitamin D in the winter? The RDA for Vitamin D is 600 IU for everyone older than 1 but younger than 70 (Institute of Medicine, 2010). If you’re over 70, the RDA is 800 IU. My average dietary intake is only ~170 IU-how can I increase this to at least the RDA, to achieve circulating values between 75-99 nmol/L?
Decent dietary sources of vitamin D include fish: salmon, sardines, mackerel, and tuna. Based on the table below (Holick 2007), eating ~3.5 ounces of wild salmon every day would achieve the RDA for vitamin D intake. In contrast, my daily tin of sardines puts me ~300 IU away from the RDA value! I could double my fish intake to ~8 oz./day, but I’d like to limit my animal protein intake, and, the extra ~200 calories would limit other nutrients that I’d like to enrich in my diet, like fiber.
Are there other, less calorie dense dietary sources of vitamin D? It’s important to note that dietary vitamin D can be found in 2 forms, D3, which is shown above, and D2. Which foods are rich in vitamin D2? Shown below is a picture of the best plant-based source of vitamin D2, maitake mushrooms:
The Vitamin D2 content of maitake mushrooms is 36 IU/calorie, whereas wild salmon only has 3.2 IU of vitamin D per calorie! Other “exotic” mushrooms (anything other than white button mushrooms is exotic to me!) like Chanterelle and Morel contain decent amounts of vitamin D2:
Before adding maitake and other “exotic” mushrooms into my nutritional plan for their vitamin D content, it’s important to ask, “does D2 increase circulating 25-hydroxyvitamin D to an equal extent as D3”? Unfortunately, the answer is no: although D2 and D3 both increase circulating 25-hydroxyvitamin D levels, D2-based sources increase 25-hydroxyvitamin D level about half as effectively as D3 (Trang et al. 1998). So, instead of consuming ~35g of maitake mushrooms to add 400 IU of vitamin D into my diet (to achieve the RDA of 600 IU), I’ve added ~70g/day.
12/29/2015 Update: Because of Maitake’s relatively high cost, $5 for only 100g, and the burden of having to eat it every day, for the past ~3 months I switched to Vitamin D supplements to achieve a D intake of ~1100 IU/day. Blood testing showed that this intake yielded a circulating 25-hydroxyvitamin D winter concentration of 31 ng/mL, putting me at low risk for all cause mortality, based on the meta-analysis D data.
8/23/2016 Update: I stopped supplementing with 1000 IU of Vitamin D in June 2016, to explore the effect of 3-4 hours of weekly sun exposure on my circulating Vitamin D levels. My unsupplemented, circulating 25-hydroxyvitamin D level was 41 ng/mL in my 8/2016 blood test. Accordingly, I intend on increasing my Vitamin D intake to 1600 IU (1400 supplemental, ~200 dietary)/day to achieve a circulating winter 25-hydroxyvitamin D level that is similar my the summer value.
11/12/2017 Update: I’ve been supplementing with 2000 IU of D3/day, bringing my average daily total to ~2200 IU/day. Based on that, my latest circulating 25-hydroxyvitamin D level (tested in October, 2017) was 39 ng/mL .
If you’re interested, please have a look at my book!
Chowdhury R, Kunutsor S, Vitezova A, Oliver-Williams C, Chowdhury S, Kiefte-de-Jong JC, Khan H, Baena CP, Prabhakaran D, Hoshen MB, Feldman BS, Pan A, Johnson L, Crowe F, Hu FB, Franco OH. Vitamin D and risk of cause specific death: systematic review and meta-analysis of observational cohort and randomised intervention studies. BMJ. 2014 Apr 1;348:g1903.
Garland CF, Kim JJ, Mohr SB, Gorham ED, Grant WB, Giovannucci EL, Baggerly L, Hofflich H, Ramsdell JW, Zeng K, Heaney RP. Meta-analysis of all-cause mortality according to serum 25-hydroxyvitamin D. Am J Public Health. 2014 Aug;104(8):e43-50.
Holick MF. Vitamin D deficiency. N Engl J Med. 2007 Jul 19;357(3):266-81.
Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: National Academy Press, 2010.
Sempos CT, Durazo-Arvizu RA, Dawson-Hughes B, Yetley EA, Looker AC, Schleicher RL, Cao G, Burt V, Kramer H, Bailey RL, Dwyer JT, Zhang X, Gahche J, Coates PM, Picciano MF. 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 Jul;98(7):3001-9.
Trang HM, Cole DE, Rubin LA, Pierratos A, Siu S, Vieth R. Evidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does vitamin D2. Am J Clin Nutr. 1998 Oct;68(4):854-8.
Zerwekh JE. Blood biomarkers of vitamin D status. Am J Clin Nutr 2008;87:1087S-91S.
Fascinating article. You advocate blood testing here and in 3 other articles, as does Dr. Peter Attia. Where do you recommend one can get such detailed tests? And where can we find an expert to analyze the results and make educated recommendations? Caloric restriction and the science behind extended longevity are way beyond the average doctor.
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The vitamin D test can be purchased at lef.org. There may be other places that can measure it, but their price is decent. For the other blood measurements (anion gap, bicarbonate, etc.), in the US these tests are usually covered on a standard chemistry screen, which costs the price of your copay (~$30). If you need help interpreting your results, send me a message!
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I was researching for Vitamin D Sources when I first came to this blog for Vitamin D. I am really happy to read your blog.Thanks to the detailed information available on this blog, I now have trusted source for information and knowledge.
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Is bathing using soap a problem to absorption of vitamin D? I think vitamin D takes 48 hours to be produced or absorbed after you are exposed to sunlight. Soap “wash” the vitamin on the skin and the abortion is compromised.
By the way, isn’t easier and cheap to obtain vitamin D through supplements capsules?
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Maybe it’s cheaper to buy it in a pill, but we evolved to get it from the sun, just like we evolved to get our micronutrients from food, rather than from pills.
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I guess you mean “absorption” 😉
The international unit is such an ambigous and idiotic measure, as it is different for different substances. Why not use grams?
Thank you for the article!
Do you recommend a particular brand of Vit D3?
Nope, any D3 brand should be fine.
Great Blog!!! I would like to say thanks for share this great post. Vitamin D is one of the most necessary nutrients which is required by the body, the best and way to get it is to add some of the food items which have it in abundance. Mushrooms are the best when it comes to boosting your Vitamin D intake.
1 ng/mL corresponds to how many IU of vitamin D ? In other words, how many supplements of 1000 IU should I take daily to go from my latest blood test of 45 ng/mL to the optimal 75 ng/mL ?
Based on the meta-analysis, above 30 ng/mL is associated with maximally reduced risk of all-cause mortality. 30 ng/mL equates to 75 nMol (not mg/dL). So whatever you’re doing to get to 45 ng/ml in terms of supplementation is probably close to optimal.