A weighty

Busting the myths of vitamin D toxicity

Are you vitamin D deficient? Experts estimate that nearly 70% of Canadians are. Does it matter? It sure does!

Benefits of vitamin D for weight loss

Recent research has shown that increasing your vitamin D levels can improve weight loss.

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Researchers reporting in the American Journal of Clinical Nutrition in 2014 found that women whose vitamin D blood serum reached healthy levels through supplementation during a diet and exercise program lost more weight than those whose blood serum levels did not reach that level.

Source: American Journal of Clinical Nutrition

An earlier study conducted in 2009 showed that many of the benefits of weight loss, such as lower blood pressure, blood sugar, and insulin levels, were better in participants who took calcium and vitamin D during their weight-loss program.

Those healthy outcomes are reason alone to consider vitamin D supplementation.

Vitamin D is an unusual vitamin. While we generally obtain vitamins from foods, there are no foods high enough in vitamin D to meet our needs. The sun is our most important source, but with the limited time we spend outdoors, use of sunscreen, and the long Canadian winters, many Canadians don’t get enough sun to make adequate vitamin D.

Like vitamins A and E, vitamin D is fat soluble. This means that it is absorbed by fat cells and stored in the body.

Heavier people need more

Some people think that vitamin D can build up in our body fat. If true, overweight and obese individuals would be at risk of too much vitamin D, particularly if they lose a large amount of weight in a short period of time.

Yet, this is simply not true. The opposite is true: overweight and obese individuals are at increased risk for vitamin D deficiency and the associated health problems. In fact, they need 2 to 3 times the amount of vitamin D supplements as do people of normal weight. Rather than worrying about toxicity, they should be worried about deficiency.

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That’s because only a fraction of the vitamin D that enters the body is stored in fat. More than 75% of the vitamin D ingested is broken down and eliminated without ever being stored or even converted to blood serum.

Source: The distribution and storage of vitamin D and its metabolites in human tissues Clinical Science

Vitamin D build-up in body fat does not continue indefinitely. When there is a continuous supply of vitamin D, a balance is reached between the vitamin D stored within our body fat and its removal for use.

Dr. Robert Heaney and colleagues from Creighton University discovered that groups with blood serum levels near 90 nanomoles per liter (nmol/L) use up their vitamin D just as fast as they are getting it.5 In fact, participants who regularly took over 2,000 International Units each day (IU/d), only stored a 7 to 12 day supply of vitamin D in their body. This means that they are using the vitamin D as they get it, with no excess storage.

False flood alarm

The myth that rapid fat loss could result in a sudden flood of vitamin D – or any other fat soluble vitamin for that matter – are also unsupported.

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A 2013 study centered on overweight participants in a weight-loss program found no change in vitamin D blood levels after an average total fat loss of 13%.

Source: Nutrients

Studies on weight loss surgery also show that vitamin D is not rapidly released. A 2011 study by members of Boston University School of Medicine followed 17 subjects for an entire year after undergoing a weight loss procedure, and there was no increase in blood serum levels despite an average fat loss of 90 lbs.

“Normal” vitamin D levels are those that you can attain naturally through sun exposure. The best evidence for normal levels comes from natives living at the equator (they make vitamin D all year) living a traditional lifestyle (they don’t wear sunscreen). Their blood levels of vitamin D are around 115 nmol/L.

Current guidelines from the U.S. National Academy of Medicine suggest up to 4,000 IU/d, with a goal of blood serum near 50 nmol/L. However, this recommendation is only for bone health, and is a one-size-fits-all for “most people”.

Yet there is enormous variability in required daily doses between people. Equally important, the risk of getting too much is very low. The greater risk is getting not enough. Comprehensive studies suggest that the minimal blood serum level necessary to prevent cancer and battle chronic diseases is above 100 nmol/L, twice the recommendations of the U.S. National Academy of Medicine.

A 2017 study reported in the journal Dermato-Endocrinology showed that the average adult needs between 6,000 and 8,000 IU/d to reach a blood serum level above 100 nmol/L. There was no risk of excess vitamin D at that level, and at even higher intakes.

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Vitamin D and Pure North

It’s important to separate fact from fiction, especially when the topic is your health. Knowing how to take care of our bodies today is the first step to preventing health concerns in the future.

Pure North S’Energy Foundation encourages everyone to consider the facts on vitamin D. We give you the knowledge you need to make your own choices. We also measure your blood levels of vitamin D. It’s the only way to know how much you need!

Research and References

Mason C, Xiao L, Imayama I, Duggan C, Wang C-Y, Korde L, McTiernan A. 2014. Vitamin D3 supplementation during weight loss: a double blind randomized controlled trial. The American Journal of Clinical Nutrition, 99:1015-1025.

Major GC, Alarie F, Doré J, Phouttama S, Tremblay A. 2007 Supplementation with calcium + vitamin D enhances the beneficial effect of weight loss on plasma lipid and lipoprotein concentrations. The American Journal of Clinical Nutrition, 85:54-59.

Referred to in Vieth 2009.

Mawer EB, Backhouse J, Holman CA, Lumb GA, Stanbury SW. 1972. The distribution and storage of vitamin D and its metabolites in human tissues Clinical Science, 43:413-431.

Heaney RP, Horst RL, Cullen DM, Armas LA. 2009. Vitamin D3 distribution and status in the body. Journal of the American College of Nutrition, 28:252-256.

Piccolo BD, Dolnikowski G, Seyoum E, Thomas AP, Gertz ER, Souza EC, Woodhouse LR, Newman JW, Keim NL, Adams SH, Van Loan MD. 2013. Association between subcutaneous white adipose tissue and serum 25-hydroxyvitamin D in overweight and obese adults. Nutrients, 5:3352-3366.

Pramyothin P, Biancuzzo RM, Lu Z, Hess DT, Apovian CM, Holick MF. 2011. Vitamin D in adipose tissue and serum 25-hydoxyvitamin D after Roux-en-Y gastric bypass. Obesity, 19:2228-2234.

Bischoff-Ferrari HA. 2014. Optimal serum 25-hydroxyvitamin D levels for multiple heath outcomes. Advances in Experimental Medicine and Biology, 810:500-525.

Kimball SM, Mirhosseini N, Holick MF. 2017. Evaluation of vitamin D3 intakes up to 15,000 internationals units/day and serum 25-hydroxyvitamin D concentrations up to 300 nmol/L on calcium metabolism in a community setting. Dermato-Endocrinology, 9: e1300213.

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