Vitamin D and weight loss

Last week I wrote an article about vitamin D deficiency and the positive effect of vitamin D on muscle strength and muscle mass. Today I will focus specifically on the effects of vitamin D on fat mass and fat burning. In this article I will also discuss recommended supplementation doses in concrete terms. Because in the previous article I also gave some general explanation about the different forms of vitamin D, it may be useful to read both for a complete picture.

Vitamin D and its relationship with weight loss

As so often, we see different studies on a particular topic with varying results. Vitamin D, especially vitamin D3, is growing in popularity. This is partly because of people who very selectively show only the positive results from studies, such as in relation to weight loss. Unfortunately, the same applies to the effect of vitamin D on fat mass and body weight: studies do not produce a clear picture.

I will discuss a few of them here.

"Vitamin D makes fattened pigs less fat and gives them more muscle mass": Purdue University study

In last week's article about vitamin D, I wrote, among other things, that the influence on muscle mass in humans is still unclear because of conflicting study results. Researchers from Purdue University, however, saw in their study with fattened rats that vitamin D not only led to more muscle mass, but also to less body fat [1]. These rats were also given extra calcium in addition to vitamin D. As I indicated in last week's article, however, a considerable part of the population has a vitamin D deficiency [2]. For calcium, this is not the case or is the case to a much lesser extent [3,4]. The question is therefore to what extent vitamin D, calcium, or specifically the combination of the two caused the fat-burning effect. Because of the difference in daily intake of vitamin D and calcium, for the average Dutch person the chance that extra vitamin D helps with this is greater than the chance that extra calcium does.

Now, this study was about fattened pigs, both through extra carbohydrates and extra fats, but you can imagine that someone who takes in a calorie surplus to gain muscle mass ("bulking") would of course be happy with even more muscle mass and less extra fat as a result.

"Vitamin D3 makes overweight women lose 3 kg in 12 weeks": University of Tehran study

In a study from Iran, middle-aged women with moderate overweight (BMI of 30) lost almost 3 kilos in 12 weeks through daily intake of 25 micrograms (1/1000 of a milligram) of vitamin D3 [5]. While the group of women who received a placebo lost on average almost half a kilo of body fat and gained half a kilo of muscle mass in the same period, the women who took vitamin D lost 2.7 kg of fat mass and gained almost 2 kilos of muscle mass.

"More vitamin D in the blood means more weight loss": University of Minnesota study

Because overweight is a fairly major concern in the Western world, many of the studies into possible aids for weight loss have logically been conducted among people with overweight.

In contrast to the rats that were fattened, participants in a study by the University of Minnesota were given an 11-week diet containing 750 kcal less than they burned daily [6]. So weight loss was already expected. The question was whether people with more vitamin D in their blood would also lose more weight. That turned out to be the case. For every increase of 1 ng/ml in calcidiol (the form in which vitamin D is measured in the blood), the people losing weight lost an additional 0.2 kilos.

They therefore saw a clear association between a decrease in weight and an increase in vitamin D concentration in the blood. However, the researchers state that it is unclear whether the participants lost more weight because of increased vitamin D levels or the reverse: that losing weight caused vitamin D to rise.

"More weight loss with vitamin D or more vitamin D by losing weight?": University of California study

Researchers from the University of California had the same problem [7]. They looked at data from a trial with 383 overweight women (BMI 25-40) who had to lose weight over 24 months with the help of a program designed for that purpose. All women had more vitamin D (calcidiol) in their blood after 24 months. In the women who had lost more than 10% of their weight, however, the increase in calcidiol was greater than in the women who had lost between 5 and 10 percent. The group that had lost 5 to 10 percent of body weight, in turn, saw calcidiol rise more than the group that had lost less than 5%.

These findings suggest that weight loss, presumably associated with a reduction in body fat, is associated with increased serum 25(OH)D concentration in overweight or obese women.*

C.L. Rock, University of California

_{*25(OH)D = calcidiol, the inactive form of vitamin D measured in the blood}

As far as they know, the women who lost the most weight did not receive extra vitamin D. The researchers point out, however, that they did not take into account the amount of vitamin D the women got from sunlight or diet. Given the fact that there are few natural dietary sources of vitamin D and the study was conducted in the months from November to January, the chance is small that one group received much more vitamin D than the other.

They therefore turn it around and state that weight loss is the way to increase vitamin D:

In summary, low serum 25(OH)D concentration in overweight or obese individuals can be favorably modified by a behavioral weight loss intervention. Weight loss and maintenance of that loss in overweight or obese women improves vitamin D status

C.L. Rock, University of California

So that would not help you if your goal is weight loss. However, vitamin D has several functions, such as its role in calcium metabolism and the immune system. The question is, however, whether that really helps you here.

An overweight woman goes to the doctor:

Woman: "I have a calcium deficiency"

Doctor: "You actually have a vitamin D deficiency that is causing a calcium deficiency. As a solution, you can take extra vitamin D daily or diet and train strictly for a year and lose 30 kilos"

I think I know which solution she will choose. After all, losing weight is difficult for many people, at least more difficult than taking vitamin D.

Studies with negative results

Okay, so it may be unclear whether you lose weight because of more vitamin D or whether you get more vitamin D by losing weight. In any case, there is a positive association. Or is there? Unfortunately, several studies do not see this association at all. It could never be simple!

"People with severe overweight do not lose weight with 500 micrograms to 1 milligram of vitamin D per week": Norway study

The positive results above are very different from those of a Norwegian study from 2008 [8]. In that study, people with severe overweight (average BMI 35) received 500 micrograms or 1000 micrograms (= 0.001 gram) for one year. That is almost three to six times as much per week as in the Iranian study. Yet this produced no different results compared with the group that received a placebo during that period.

Significant weight reduction in overweight and obese subjects is unlikely to occur with cholecalciferol* supplementation.

M. Sneve, University Hospital of North Norway

_{*cholecalciferol is the inactive form of vitamin D (see the previous article for more information).}

The Norwegians took into account the possibility that the participants' high body weight caused the increase in vitamin D levels to be disappointing. They therefore think the results might be different in a lean population. To lose weight with the help of vitamin D, you would then have to not be overweight to begin with. A bit unfortunate for people with overweight, but still useful for relatively lean people who want to gain muscle mass without seeing their body fat percentage rise too much.

The present study has several limitations.We included subjects with BMIO28 kg/m2 and, therefore, our results do not necessarily apply to a slimmer population. In particular, the resulting serum25(OH)Dlevelsmight have been higher, and possible side-effectsmore pronounced, in subjects with lower weight.

M. Sneve, University Hospital of North Norway

"Vitamin D helps heavy people lose weight only if vitamin D deficiency is sufficiently corrected": Seattle study

Researchers from the Fred Hutchinson Cancer Research Center in Seattle recently published the results of their study into vitamin D3 and weight loss [9]. They too conducted this study with overweight women who also had a vitamin D deficiency (age 50-75 years). 218 women were divided into two groups. One group received a placebo daily, the other group 50 micrograms of vitamin D3. Both groups followed a weight-loss program for one year. After a year, the researchers saw that both groups had lost the same amount of weight.

With one important caveat: as mentioned, the women had a vitamin D deficiency when they started the study. This deficiency ranged from 27 nmol/L to the deficiency threshold, 80 nmol/L. The researchers saw no difference unless vitamin D3 intake caused the women to rise above 80 nmol/L. In other words: if the threshold for vitamin D deficiency was crossed and there was no longer a deficiency, the women did benefit from the vitamin D3.

Vitamin D₃ supplementation during weight loss did not increase weight loss or associated factors compared with placebo; however, women who became replete experienced greater improvements.

C. Mason, Fred Hutchinson Cancer Research Center

"Vitamin D does not help heavy people lose weight, even if deficiency is corrected": Denmark study

When reading the Seattle study, we might still think that vitamin D helps with weight loss if you take enough to correct any deficiency. Researchers from Aarhus University in Denmark, however, concluded that even then vitamin D supplementation does not help with weight loss [10].

The Danes also used people with overweight and a vitamin D deficiency. This time 52 men and women aged 18 to 50 years with a BMI above 30 and a current vitamin D level below 50 nmol/L. For 26 weeks they received 75 micrograms of vitamin D per day or a placebo.

During that period, the average vitamin D level in the blood was increased from 33 to 110. So this was higher than in the women in the Seattle study. That is striking in itself, because in the Norwegian study almost twice as much was needed (140 micrograms per day) to raise levels in a year from about 50 nmol/L to 110 nmol/L, with the largest increase also reached in six months. For some reason, Denmark was more successful at raising the levels.

It did not make much difference, however. The researchers saw no difference in body fat between the group that received a placebo and the group that had successfully increased its vitamin D levels. What may matter is that the Danish participants had less time to lose weight with high vitamin D levels. That study lasted half a year, while at least three months seem to be needed for a large increase in vitamin D. So there was less time to benefit from the higher vitamin D levels.

Increasing 25OHD levels by VD treatment for 26 weeks have no effects on obesity complications in obese adults with low baseline plasma 25OHD.

L. Wamberg, Aarhus University

Conclusion: lose weight with vitamin D or not?

It therefore remains unclear to me what effect you can expect from vitamin D if you want to lose weight. Most studies have been done among people with significant overweight. The study in fattened rats seems most representative for someone who, for example, wants to gain muscle mass with as little increase in fat mass as possible.

The studies among people with overweight show large differences. This may possibly have to do with the overweight itself. In the Norwegian study, participants had an average BMI of 35 and vitamin D did not lead to greater weight loss. In the Tehran study, in which vitamin D did lead to this, the participants had an average BMI of 30. For someone of 1.83 meters, that is a difference of about 20 kilos. It would be nice if more research were done among lean people, but most researchers probably see no reason for it. They are often not concerned with lowering your body fat percentage by a few percent so that you can see that six-pack.

Finally, not all studies looked at the increase in vitamin D in the blood. So it is not clear how high their levels were, only how much they took. In the Seattle study, the effect of intake depended on the extent to which it increased levels in the blood.

It is a standard sentence that researchers like to use to cover themselves, but in this case it is more than justified:

More research should be done into the effect of vitamin D on fat burning.

Supplementing vitamin D?

You need vitamin D for much more than possible fat burning. In the previous part, I discussed risk groups of people who have an increased chance of vitamin D deficiency. However, this also showed that others can quickly have a deficiency as well, depending on which reference values you use.

You will probably not have your vitamin D levels measured daily. So the question is: does it make sense in your case to supplement your diet with extra vitamin D? Here it is useful to know that the recommendations for daily intake are mainly based on preventing complaints caused by deficiencies. To benefit optimally from the advantages of vitamin D, however, you need larger doses to build up sufficient reserves.

Risk of vitamin D overdose is much smaller than risk of deficiency

First of all, you can start from the principle: if it does not help, it will not harm. A vitamin D overdose appears to be barely possible.

The European labeling guideline for recommended daily vitamin D intake for people outside risk groups is 2.5 µg (micrograms) per day for people up to 50 years old

For an excess, you would have to take one hundred times that amount. Even then, this proved not to be enough for a toxic effect [11]. In older people with a severe vitamin D deficiency, a single injection of no less than 15 mg (6000 times the recommended daily amount) caused no dangerous side effects [12]. Here it should be noted that their calcidiol levels were already very low, so supplementation did not immediately lead to high levels.

In people with less extremely low levels, toxic effects occur only when more than 1000 micrograms per day are taken, 400 times the recommended amount [11].

The Vitamin D3 from Bodyenfitshop, for example, contains the maximum permitted 5 micrograms per capsule. They very cautiously indicate that you should take one capsule every other day. This is because Bodyenfitshop does not know your current levels and follows the recommended daily amount of 2.5 micrograms.

If we look at the recommendations of American researchers based on a possible deficiency, you see that in those cases you need much more (image top right, "table 1").

Reaching optimal vitamin D values

And then we are only talking about correcting a deficiency. The earlier-mentioned 75-80 nmol/L (amount of inactive vitamin D in your blood) is only the threshold for deficiency. Optimal values, comparable to those of people who live in sunny countries, lie between 135 and 225 nmol/L. An excess would only be present above 250 nmol/L.

In the Norwegian study in which participants in some cases received no less than 1000 micrograms per week (so more than 140 mcg per day), this was only enough to raise their values from a deficiency of about 50 nmol/L to about 110 nmol/L. Six months of substantial intake therefore still did not lead to ideal values (image on the right).

Because the chance of deficiency is much greater than the chance of overdose [13,14], I myself would be inclined to risk taking too much rather than too little. Especially in winter, when 90% of the vitamin D your body uses comes from previously built-up reserves [15], particularly if you are in a risk group. In any case, 5 micrograms per day applies as the recommended amount if you are over 50, but in winter that also seems too little to me even for younger people.

Advice: risk groups for vitamin D deficiency

The Nutrition Centre advises extra intake for the following groups [source: voedingscentrum]:

Supplementation advice Vitamin D
Group	Age group	Who	Extra vitamin D in micrograms (mcg)
Children	0 to 3 years	Everyone	10
Women	4 to 49 years	Dark (tinted) skin and/or not going outside enough	10
	50 to 69 years	Everyone	10
	70 years and older	Everyone	20
Pregnant women		Everyone	10
Men	4 to 69 years	Dark (tinted) skin and/or not going outside enough	10
	70 years and older

Given the above about optimal values, I would also see these recommendations as a minimum to prevent deficiency. If you want to reach optimal values, higher intakes are probably needed.

Measuring is knowing, blood test

To really know how much you need, you would therefore have to have it measured. Your current levels can provide good insight into how large your doses should or could be. It is even better, of course, if you can have the results measured after a few months. This can be done with a regular blood values test.

References

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   reduced fat mass and increased lean mass in rats. Nutr Res. 2008 Nov;28(11):783-90. doi: 10.1016/j.nutres.2008.08.004.
2. Fitsociety.nl/supplementen/vitamine-d/
3. Nordin, B.E.C. & Marshall, D.H. 1988. Dietary requirements for calcium. In B.E.C. Nordin, ed. Calcium in human biology, p. 447-471. Berlin, Germany, Springer-Verlag.
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5. Salehpour A, Hosseinpanah F, Shidfar F, Vafa M, Razaghi M, Dehghani S,Hoshiarrad A, Gohari M. A 12-week double-blind randomized clinical trial of vitamin D₃ supplementation on body fat mass in healthy overweight and obese women. Nutr J. 2012 Sep 22;11:78.
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8. Sneve M, Figenschau Y, Jorde R. Supplementation with cholecalciferol does not result in weight reduction in overweight and obese subjects. Eur J Endocrinol.2008 Dec;159(6):675-84.
9. Mason C, Xiao L, Imayama I, Duggan C, Wang CY, Korde L, McTiernan A. Vitamin D3 supplementation during weight loss: a double-blind randomized controlled trial. Am J Clin Nutr. 2014 May;99(5):1015-25.
10. Wamberg L, Kampmann U, Stodkilde-Jorgensen H, Rejnmark L, Pedersen SB, Richelsen B. Effects of vitamin D supplementation on body fat accumulation, inflammation, and metabolic risk factors in obese adults with low vitamin D levels-results from a randomized trial. Eur J Intern Med 2013;24:644–9.
11. Hathcock JN, Shao A, Vieth R, et al. Risk assessment for vitamin D. (2007) Am J Clin Nutr 85:6-18.
12. Burns J, Paterson CR. Single dose vitamin D treatment for osteomalacia in the elderly. (1985) Br Med J (Clin Res Ed) 290:281-282.
13. Vieth R. Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety. (1999) Am J Clin Nutr 69:842-856.
14. Muskiet F.A.J., van der Veer E.. Vitamine D: waar liggen de grenzen van deficiëntie, adequate status en toxiciteit? (2007) Ned Tijdschr Klin Chem Labgeneesk 32:150-158.
15. Heaney RP. The Vitamin D requirement in health and disease. (2005) J Steroid Biochem Mol Biol 97:13-19
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