by Marion Nestle

Currently browsing posts about: Vitamin D

May 27 2020

What’s the story on Vitamin D

Yesterday, I wrote about current research suggesting that higher levels of blood Vitamin D [actually, 25-hydroxycholecalciferol, or 25(OH)D] help to protect against Covid-19.

To understand concerns that this evidence may not be totally convincing, it’s useful to know the basics about this “vitamin,” which I put in quotes because its active form is a hormone that helps govern calcium balance.  Here’s how it works.

  • Sunlight acts on a form of cholesterol in skin (7-dehydrocholesterol) to covert it to cholecalciferol, the chemical name for vitamin D3.
  • Vitamin D3 goes to the liver where an enzyme converts it to 25 (OH)D.
  • 25(OH)D goes to the kidney where an enzyme converts it to 1,25-dihydroxycholecalciferol (a.k.a. 1,25-dihydroxyvitamin D), the active hormone.

If you eat foods containing vitamin D3 (fish and meat, which have it in very small amounts, or fortified milk) or vitamin D2 from plants, yeast, or supplements, these travel in the blood to the liver where they undergo the same metabolic steps.

This means that there are three sources.

  • Sunlight on skin—this produces thousands of IU (International Units)
  • Food—is low in this vitamin
  • Supplements—vary, but high doses are not recommended by most health authorities; they may induce hyper-immune responses (not a good idea)

The commonly recommended daily dose of vitamin D is 400-600 IU.

Sunlight on skin is by far the best way to get your vitamin D hormone.

Sensible sun exposure, especially between the hours of 10:00 am and 3:00 pm produces vitamin D in the skin that may last twice as long in the blood compared with ingested vitamin D.If sun exposure produces slight pinkness, the amount of vitamin D produced in response to exposure of the full body is equivalent to ingesting 10,000-25,000 IU.

 In the UK, a study showed that 13 minutes of midday sunlight exposure during summer, just three times per week, maintains healthy levels in white adults ; other studies have shown 30 minutes of midday summer sun exposure in Oslo to be equivalent to consuming 10,000–20,000 IU of vitamin D.

How does all this relate to Covid-19?

So far, we do not have studies of vitamin D supplements in patients with Covid-19 or longer term prospective trials.  These will undoubtedly come.

While waiting for those results, enjoy the sunshine!

May 26 2020

Vitamin D and Coronavirus? Will it help?

In the past few weeks, several studies have appeared linking low levels of the vitamin D intermediate, 25-hydroxycholecalciferol [25(OH)D] to Covid-19 severity.

Previous studies have noted that vitamin D deficiency may be a biomarker of sepsis risk, and giving supplements helps to protect people from acute respiratory infections.

Supplements?

The supplement marketer Wileys Finest says

Did you know there is a special role for vitamin D in our immune cells? Our immune cells use vitamin D to function normally. That’s why experts recommend supplementing with 2,000 IU per day (50 mcg) to support healthy immune function.1,2  P.S. Vitamin D3 is the better choice!

It cites two additional studies:

But wait!

COVID-19: Internet ‘rife with misinformation’ about Vitamin D, say scientists.  Reports arguing high dose Vitamin D supplementation could treat COVID-19 are based on speculation and are a risk to public health, warns a team of scientists from across the globe…. Read more.

This article refers to Vitamin D and SARS-CoV-2 virus/COVID-19 disease, by Martin Kohlmeier and colleagues.  These scientists summarize the situation succinctly (rearranged for readability).

(1) Vitamin D is essential for good health.

(2) Many people, particularly those living in northern latitudes (such as the UK, Ireland, Northern Europe, Canada and the northern parts of the USA, northern India and China), have poor vitamin D status, especially in winter or if confined indoors.

(3) Low vitamin D status may be exacerbated during this COVID-19 crisis (eg, due to indoor living and hence reduced sun exposure), and anyone who is self-isolating with limited access to sunlight is advised to take a vitamin D supplement according to their government’s recommendations for the general population (ie, 400 IU/day for the UK7 and 600 IU/day for the USA (800 IU for >70 years)) and the European Union (EU).

(4) There is no strong scientific evidence to show that very high intakes (ie, mega supplements) of vitamin D will be beneficial in preventing or treating COVID-19.

(5) There are evidenced health risks with excessive vitamin D intakes especially for those with other health issues such as a reduced kidney function.

This seems like sensible advice.

As readers of this blog know, I am not a fan of supplements, particularly in high doses, mainly because there is so little evidence that supplements do anything to make healthy people healthier.  There is also some evidence that they could be harmful, especially those that are fat-soluble, as is vitamin D.

I am particularly skeptical of the benefits of Vitamin D:

  • Its best source by far is from the action of sunlight on skin.
  • It is not a vitamin; it is a hormone (widespread hormone replacement therapy does not seem like a good idea).
  • It is unclear whether 25 (OH)D is the best measure of hormone status (it is just the easiest one to do).
  • More research on immune effects is needed.

In the meantime, what to do?

It’s summer in the Northern Hemisphere.  Get outside!

Tomorrow: I will explain more about why the effects of Vitamin D are so hard to figure out.

Apr 16 2020

Watch out for Coronavirus frauds and unproven promises

Frauds and fraudulent information are so prevalent that the FDA says what it’s doing about them on its Coronavirus web page.

My email inbox is deluged with marketers claiming that their products boost immune systems in general, and protect against Coronavirus in particular.  Often, they cite evidence but this is highly selective and sometimes based on studies paid for by their sponsors.

The bottom line on keeping immune systems healthy?  Eat a healthful diet, don’t gain excess weight, and get plenty of physical activity.  OK, good luck doing that while you are under lockdown, but you can give it a good try.

Here are some of the items that have ended up in my inbox.

Despite FDA pronouncements, industry coalition action, the coronavirus claims warning letters keep coming:  The US Food and Drug Administration has issued an additional six warning letters in recent days on coronavirus claims. The letters coincide with an industry coalition raising a red flag on the growing flood of such claims on dietary supplement-type products….Read more

Unproven COVID-19 health claims: China’s crackdown on ads for oral sprays, probiotics and anti-hangover tea: The Chinese authorities have named and shamed a string of fake advertisement, mostly surrounding unproven COVID-19 health claims.

Consumers warned of sports nutrition products making coronavirus claimsThe European Specialist Sports Nutrition Alliance (ESSNA) has warned consumers of the increase in companies and individuals making unfounded claims in light of the current coronavirus situation….Read more

Cocoa and the coronavirus: can it boost the immune system?  Cacao beans have been consumed by humans for over 3,000 years and the ingredient is well-known for its wide range of health benefits, recent research suggests it can provide stronger protection against influenza virus infection…. Watch now [but watch critically.  If you even give this a moment’s thought….]

 

CRN UK highlights why essential nutrients have never been more essential:  The ongoing threat of coronavirus could increase the potential for deficiencies in key micronutrients supporting the immune system, according to The Council for Responsible Nutrition UK (CRN UK). Read more  [How about eating a healthy diet and getting plenty of exercise?].

Could vitamin D play a role in coronavirus resistance? Research thinks so:  Vitamin D supplements may aid in the resistance of respiratory infections such as the coronavirus or limit the severity of the illness in those infected, according to researchers. Read more.  [And what kind of research are we talking about here?  Some of it is industry-funded, as this example demonstrates (thanks to Claudia Santos for sending)].

Aug 18 2014

Food Navigator on what’s happening with the nutrition label

Food Navigator—USA’s Elaine Watson just put together a special edition on the revamping of the Nutrition Facts label.  Her title: Radical overhaul or a missed opportunity?

To understand what’s happening with food labels, you can start with the FDA’s home page on its proposed revisions.  The comment period has ended.  You can read the comments that have been filed on the Nutrition and Supplement Facts panels, and those filed on the proposed changes to the standards for serving sizes.  These are fun to read; opinions, to say the least, vary.

But back to Food Navigator, which collects in various pieces on the topic in one place.  The “Radical overhaul” piece contains a summary of the major provisions.  Others in the series are also useful (I’m quoted in some of them):

Does vitamin D belong on the Nutrition Facts panel?

FDA proposals to list “added sugars” on the Nutrition Facts panel have already generated heated debate, so it’s perhaps unsurprising that its plan to include vitamin D is proving equally controversial…

Should ‘added sugars’ be listed on the Nutrition Facts panel?

A row is brewing over the merits of including ‘added sugars’ on the Nutrition Facts panel, with critics arguing that our bodies don’t distinguish between ‘naturally occurring’ and ‘added’ sugar – and neither should food labels – and supporters saying it will help consumers identify foods with more empty calories.

 Nutrition Facts overhaul is a missed opportunity for long chain omega-3s EPA and DHA, says GOED

The FDA’s overhaul of the Nutrition Facts panel misses a public health opportunity by prohibiting firms from even highlighting long chain omega-3 fatty acids EPA and DHA on the panel, says GOED.

What are the biggest contributors of added sugars to the US diet?

Check out this analysis of NHANES data to see where our added sugars are coming from plus read new comments about the ‘added sugars’ labeling proposal from Ocean Spray cranberries and others.

Former FDA commissioner: Nutrition Facts overhaul doesn’t go far enough

FDA proposals to overhaul the Nutrition Facts panel on food labels don’t got far enough, says former FDA commissioner David Kessler, M.D.

Behavioral scientists: Changing serving sizes on Nutrition Facts label could have unintended consequences

FDA proposals to change the way serving sizes are calculated to better reflect real-life eating behavior could encourage some people to eat even more unless the wording is changed, says one expert group.

Until phosphorus gets on the USDA’s radar, labeling policy won’t change: NKF

While phosphorus is an essential nutrient found naturally in some foods such as egg yolk and milk, it is increasingly added to packaged foods via a raft of phosphorus additives, and some experts believe it should be listed on the Nutrition Facts panel.

Canada’s proposed Nutrition Label changes emphasize calories, sugar

Health Canada is proposing changes to nutrition labels that would make them easier for consumers to read.

RD: There’s a health continuum for every food; what pillars do you want to stand on?

Rachel Cheatham, RD, founder of nutrition strategy consultancy FoodScape Group, talks food labeling at the IFT show.

Is your product ready for nutrition label changes?

“A 16-ounce drink and a two-ounce bag of potato chips are a single serving. If it’s bigger than that, from 200 to 400%, then you need to declare two columns of information—one for the serving size and one for the whole container.”

Proposed nutrition labels more effective than current labels: survey

Consumers find proposed labels easier to read in less time.

How much do consumers use (and understand) nutrition labels?

New research from the NPD Group is questioning how many US consumers even routinely check nutrition labels anymore.

 FDA’s proposed nutrition label changes emphasize calories, serving sizes

If approved, the new labels would place a bigger emphasis on total calories and update serving sizes, while also drawing attention to added sugars and nutrients such as Vitamin D and potassium.

CRN, NPA submit comments on FDA’s proposed changes to food, supplement labels

Both the Council for Responsible Nutrition and the Natural Products Association have submitted a comments on FDA’s proposed revisions for food and dietary supplement labels.

The FDA’s next step is to deal with the comments and issue final rules.  By when?

Eventually.  Stay tuned.

Jul 24 2014

FDA’s food label proposals: comments on Vitamin D

The FDA is taking comments on label proposals until August 1 (see info at end of post).  Here’s mine on voluntary vitamin D labeling.

July 17, 2014

TO:  FDA

FROM:  Marion Nestle, Professor, New York University

RE:  Proposed revision to Nutrition Facts Panel: VITAMIN D

This is to argue against permitting food companies to voluntarily label added “Vitamin” D on the Nutrition Facts panel.  Doing so will not promote—and may possibly harm–public health.

Rationale

  • “Vitamin” D is not a vitamin; it is a hormone synthesized by the action of sunlight on skin.  For this reason alone, it does not belong on the food label.
  • Vitamin D fortification must be understood as a form of hormone replacement therapy.   As such, it raises questions about efficacy, dose, and side effects that should be asked about all such therapies.
  • Fortification and supplementation provide hormone Vitamin D by the oral route.  This is not physiological.  Active vitamin D is synthesized in the body through a series of reactions that begin with the action of sunlight on skin.  Sunlight on skin produces ample Vitamin D, is regulated to promote synthesis as needed and avoid toxicity, and may lead to synthesis of other useful biological components; the unphysiologic oral route does not produce the same benefits.[i]
  • As a hormone, Vitamin D is found naturally in very few foods (e.g., fish); in them, it is present in small amounts.  It is present in most foods as a result of fortification.
  • Permitting Vitamin D to be listed on food labels will encourage fortification, undoubtedly of foods that would not otherwise necessarily be recommended.  To cite just one example: Yum Bunny Caramel Milk Spread fortified with vitamin D at 10% of the DV.  This product is half sugars by weight, marketed as “a good source of calcium and vitamin D,” and clearly aimed at children. See: http://www.yumbunny.com/about-us.   Whether such products should be considered “good sources” also deserves scrutiny.
  • The U.S. Preventive Services Task Force concludes that evidence is insufficient to determine how Vitamin D supplementation (and, therefore, fortification) affects fracture incidence.[ii],[iii],[iv] 
  • Data from the Women’s Health Initiative also are consistent with largely inconclusive findings about hormone Vitamin D supplements and bone health.[v]
  • The Institute of Medicine (IOM) does not consider deficiency of Vitamin D to be a serious problem in the United States, except among certain population groups.  Instead, because of widespread fortification and supplementation, it is concerned about the possibility of adverse consequences from overconsumption through supplementation or fortification.[vi]
  • Many scientific debates about hormone Vitamin D are as yet unresolved.[vii],[viii]  
  • The lack of compelling research has permitted Vitamin D to become “trendy.”  It is advertised on boxes of fortified cereals, has its own pro-supplement advocacy group, and generates millions in annual supplement sales.[ix]

In the absence of stronger evidence for benefit from fortification, and some evidence for possible adverse consequences, the FDA should not contribute to further commercialization of this misnamed hormone by permitting it to be listed on food labels.

References

[i] Wacker M, Holick MF.  Sunlight and Vitamin D: A global perspective for health. Dermato-Endocrinology 2013;5(1):51–108.

[ii] Cranney A, Horsley T, O’Donnell S, Weiler H, Puil L, Ooi D, et al.  Effectiveness and safety of vitamin D in relation to bone health. Evidence Report/Technology Assessment No. 158. Rockville, MD: Agency for Healthcare Research and Quality. 2007.  http://www.ncbi.nlm.nih.gov/books/NBK38410. Accessed February 5, 2013.

[iii] Chung M, Balk EM, Brendel M, Ip S, Lau J, Lee J, et al  Vitamin D and calcium: a systematic review of health outcomes. Evidence Report/Technology Assessment No. 183. Rockville, MD: Agency for Healthcare Research and Quality. 2009.  http://www.ncbi.nlm.nih.gov/books/NBK32603/. Accessed February 5, 2013.

[iv] Chung M, Lee J, Terasawa T, Lau J, Trikalinos T. Vitamin D with or without calcium supplementation for prevention of cancer and fractures: an updated meta-analysis for the U.S. Preventive Services Task Force. Ann Intern Med. 2011;155(12):827-38.

[v] Prentice RL, Pettinger MB, Jackson RD, Wactawski-Wende J, LaCroix AZ, Anderson GL, et al.  Health risks and benefits from calcium and vitamin D supplementation: Women’s Health Initiative clinical trial and cohort study.  Osteoporosis Int.  2013;24(2):567-580.

[vi] Institute of Medicine.  Dietary Reference Intakes: Calcium, Vitamin D.  Washington, DC: National Academies Press, 2011.

[vii] Rosen, Clifford J,  Abrams, Steven A,  Aloia John F. et al.  IOM Committee members respond to endocrine society vitamin D guideline. J Clin Endocrinol Metab. 2012;97:1146-1152.

[viii] Holick, Michael F,  Brinkley Neil C, Heike, A et al  Guidelines for preventing and treating vitamin D deficiency and insufficiency revisited.  J Clin Endocrinol Metab. 2012;97:1153-1158.

[ix] Much growth in vitamin sales driven by vitamin D.  Nutr Business J. 2009;14(6/7):5.

Here’s how to file comments:

The proposed revisions are to:

The FDA makes it very easy to file comments. It provides:

File comments here

Feb 26 2013

Supplements? Advice about Calcium and Vitamin D vs. Osteoporosis

Malden Nesheim and I wrote an editorial for the Annals of Internal Medicine that has just gone online, and is likely to elicit plenty of discussion.  We comment on the highly conservative, evidence-based recommendations of the U.S. Preventive Services Task Force for taking supplements of calcium and vitamin D as a means to prevent osteoporosis.

Our commentary: “To Supplement or Not to Supplement: U.S. Preventive Services Task Force Recommendations on Calcium and Vitamin D.”  Here’s what we said:

In this issue, the U.S. Preventive Services Task Force (USPSTF) plunges headlong into ongoing debates about whether healthy adults—those who show no signs of vitamin D deficiency or osteoporosis—should be advised to take combined supplements of calcium and vitamin D to prevent bone fractures and, if so, at what level (1).

In terse statements unlikely to settle the debates, the Task Force states first that insufficient evidence makes it impossible to determine how supplementation affects fracture incidence in men or premenopausal women. Next, it deals with postmenopausal women. For this group, the Task Force says that evidence is insufficient to assess the effects of daily supplementation with greater than 400 IU of vitamin D3 and greater than 1000 mg of calcium. The Task Force’s unambiguous conclusion: Supplementation at or below those levels does not prevent fractures. Because supplementation at or below 400 IU of vitamin D3 and 1000 mg of calcium seems to convey a slightly increased risk for renal stones, the USPSTF recommendation for postmenopausal women is also unambiguous: “do not supplement.”

The Task Force based these decisions on 2 commissioned evidence reviews and a meta-analysis  (2 – 4). More recent data from the Women’s Health Initiative also are consistent with inconclusive findings, except among a subgroup of long-adherent supplement recipients who experienced a reduced risk for hip—but not total—fractures (5).

The Task Force’s recommendations must be interpreted in the light of ongoing disputes about the most effective method for assessing vitamin D deficiency, whether calcium and vitamin D supplements are needed by a large portion of the population, and what level of supplementation might best maximize benefits and minimize risks.

In 2011, after reviewing more than 1000 studies, the Institute of Medicine (IOM) concluded that vitamin D and calcium are indeed critical to bone health but their role in other diseases—cancer, heart disease, diabetes, immune function, and reproductive health, for example—remains uncertain. The IOM did not consider deficiencies of either calcium or vitamin D to be serious problems in the United States, except among certain population groups. Instead, because of widespread fortification and supplementation, the IOM was concerned about the possibility of adverse consequences from oversupplementation (6).

With risks as well as benefits in mind, the IOM established the average adult daily requirement for calcium at 800 to 1000 mg depending on age, the Recommended Dietary Allowance (the amount needed to meet the needs of about 97% of the population) at 1000 to 1200 mg, and the safe upper level of intake at 2000 to 2500 mg. Its corresponding recommendations for vitamin D were 400 IU, 600 IU (800 IU for older adults), and 4000 IU, respectively. The IOM viewed these levels as sufficient to maintain blood levels of 25-hydroxyvitamin D at or above 20 ng/mL, a level it considered adequate to meet population-based needs regardless of amounts synthesized as a result of sun exposure.

Vitamin D, of course, is not a vitamin in the usual sense. It is a hormone produced in response to the action of sunlight on skin. Like other hormones, vitamin D has multiple roles in the body, not all of them well-understood. Vitamin D supplementation, therefore, must be considered a form of hormone replacement therapy. As such, it raises all of the questions about efficacy, dose, and side effects currently asked of such therapies.

In that light, the 2011 recommendations of the Endocrine Society deserve special scrutiny (7). The Society approaches questions about vitamin D from a standpoint quite different from that of the IOM. It appointed its own task force to make recommendations based on the premise that vitamin D deficiencies are common among all age groups. The Society prefers 30 ng/mL of 25-hydroxyvitamin D as the target level for maximum benefits. By that criterion, virtually all U.S., Canadian, and European adults are deficient in hormone vitamin D and require daily supplements of 1500 to 2000 IU. For adults with demonstrated deficiency, the Society recommends treatment with 50 000 IU of the hormone once a week or daily supplementation of 6000 IU for 8 weeks, followed by 1500 to 2000 IU for maintenance.

This clinical endocrinology perspective differs from the nutrition science perspective of the IOM committee, whose members tend to interpret studies of single nutrients within the context of the diet as a whole. From this standpoint, the amount of hormone generated by the action of sunlight on skin (which ought to be more than adequate for people who spend time outdoors in latitudes as far north as Boston) is crucial to decisions about supplementation. The IOM and Endocrine Society debated their conflicting perspectives in an exchange published in 2012 (8 – 9). The insufficiency of research to resolve such arguments has permitted vitamin D to become “trendy.” It is advertised on boxes of fortified cereals, has its own prosupplement advocacy group, and generates millions in annual supplement sales (10).

The USPSTF’s recommendations can be understood as an attempt to clarify the present situation with respect to one specific outcome of supplementation. In doing so, its recommendations have a substantial advantage. They depend on hard end points—fractures—rather than on blood levels of 25-hydroxyvitamin D, at best an indirect measure of vitamin D adequacy. The USPSTF uses the same precautionary approach as did the IOM. In the absence of compelling evidence for benefit, taking supplements is not worth any risk, however small.

A previous attempt to sort through the various claims for vitamin D noted an urgent need for further research to answer fundamental questions about the risks and benefits of sun exposure, fortification, and supplements, and the hormone’s role in body functions beyond bone mineralization (11). The USPSTF plans to publish further recommendations on the role of vitamin D in cancer prevention. When it does, we hope it will keep in mind the value of making a single recommendation about vitamin D and calcium supplementation that will encompass all potential benefits and risks. Multiple recommendations by condition confuse practitioners and the public. While we wait for the results of further research, the USPSTF’s cautious, evidence-based advice should encourage clinicians to think carefully before advising calcium and vitamin D supplementation for healthy individuals.

References

1  Moyer VA; U.S. Preventive Services Task Force.  Vitamin D and calcium supplementation to prevent fractures in adults: U.S. Preventive Services Task Force Recommendation Statement. Ann Intern Med. 2013. [Epub ahead of print]

2  Cranney A, Horsley T, O’Donnell S, Weiler H, Puil L, Ooi D, et al.  Effectiveness and safety of vitamin D in relation to bone health. Evid Rep Technol Assess (Full Rep). 2007:1-235. [PMID: 18088161]

Chung M, Balk EM, Brendel M, Ip S, Lau J, Lee J, et al.  Vitamin D and calcium: a systematic review of health outcomes. Evid Rep Technol Assess (Full Rep). 2009:1-420. [PMID: 20629479]

Chung M, Lee J, Terasawa T, Lau J, Trikalinos TA.  Vitamin D with or without calcium supplementation for prevention of cancer and fractures: an updated meta-analysis for the U.S. Preventive Services Task Force. Ann Intern Med. 2011;155:827-38. [PMID: 22184690]

Prentice RL, Pettinger MB, Jackson RD, Wactawski-Wende J, Lacroix AZ, Anderson GL, et al.  Health risks and benefits from calcium and vitamin D supplementation: Women’s Health Initiative clinical trial and cohort study. Osteoporos Int. 2013;24:567-80. [PMID: 23208074]

Institute of Medicine.  Dietary Reference Intakes: Calcium, Vitamin D. Washington, DC: National Academies Pr; 2011.

Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, et al; Endocrine Society.  Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011;96:1911-30. [PMID: 21646368]

Rosen CJ, Abrams SA, Aloia JF, Brannon PM, Clinton SK, Durazo-Arvizu RA, et al.  IOM committee members respond to Endocrine Society vitamin D guideline. J Clin Endocrinol Metab. 2012;97:1146-52. [PMID: 22442278]

Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, et al.  Guidelines for preventing and treating vitamin D deficiency and insufficiency revisited. J Clin Endocrinol Metab. 2012;97:1153-8. [PMID: 22442274]

10 Supplements stand out as 2008 sales bright spot for U.S. nutrition industry. Vitamins: D still shines. Nutrition Business Journal. 2009;14(6/7):5. Accessed athttp://newhope360.com/research-and-insights/supplements-stand-out-2008-sales-bright-spot-us-nutrition-industry on 15 February 2013.

11 Brannon PM, Yetley EA, Bailey RL, Picciano MF.  Overview of the conference “Vitamin D and Health in the 21st Century: an Update”. Am J Clin Nutr. 2008;88:483S-490S. [PMID: 18689388]  

Here’s the first objection: