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Hey everyone, Mikki here. You're listening to Mini Mikkipedia. And today I want to chat about vitamin D, which is pretty topical because in New Zealand, we have pretty much just passed the time where you can spend a reasonable amount out in the sun from 11 till 3.30 and get exposure to those UVB rays that allow us to synthesize vitamin D from the sun. Those UVB rays aren't strong enough in winter and

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pretty much everywhere in New Zealand now, it's getting a little bit challenging to do that. Unless of course you are out there sunbathing and nothing for extended periods of time. Now, this doesn't mean you have to go and burn yourself in the sun, just FYI. But what it does mean is that sunlight is really important for our ability to produce vitamin D. And it extends way beyond bone health, which is often what we think about when we think about vitamin D. And the

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Reference range that we get for vitamin D in the blood from the laboratory pretty much refers to the amount of vitamin D required for optimal bone health, but vitamin D does so much more than that. And I want to talk about it today in the context of body composition. So first sort of backing up the track a little bit.

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Vitamin D plays a crucial role in fat metabolism and overall metabolic health. it affects fat storage and burning. Deficiencies can definitely impact weight gain. And there are things you can do to help optimize your levels for better health and weight management. Vitamin D is a fat soluble vitamin that acts more like a hormone than a typical vitamin. It plays a critical role in calcium metabolism, helping deliver that calcium into the bones, an immune function,

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and body fat regulation. And just FYI, this was one of the reasons why vitamin D status was a big talking point amongst health professionals when the whole pandemic, hoo-ha, sort of really was everything we were all talking about, you know, back in 2020, 2021, et cetera. Unlike other vitamins, your body can produce vitamin D when your skin is exposed to the UVB rays of the sunlight. However, modern environments

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Indoor work environments and excessive sunscreen use mean that people aren't necessarily getting enough. And top that with the fact that, as I mentioned, in certain countries, the position of the sun in the sky means that we don't get those UVB rays that we actually need. Adequate vitamin D levels are ideally above 100 nanomoles per liter.

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though this is controversial in some instances with some suggesting that above 50 nanomoles is also optimal. However, there are some issues with measuring vitamin D levels as a reliable marker of vitamin D status. So I do want to acknowledge that. And measuring parathyroid hormone or PTH has been suggested as an alternative or complementary approach. Some of the issues with measuring our vitamin D is the variability in our serum 25

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hydroxy vitamin D level, which is the most common method used to assess vitamin D status. Individual variations in metabolism, genetics, and storage in fat tissues can affect our vitamin D levels, making it less reliable as a universal indicator of vitamin D sufficiency. There are also bioavailability concerns. In people carrying excess body fat, vitamin D can be sequestered into adipose tissue.

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This leads to low serum levels despite adequate intake. So this complicates its interpretation of your serum 25 hydroxy vitamin D. And there are fluctuating levels. So it can fluctuate based on seasonal sun exposure, on supplementation and diet, which does make single point measurements potentially misleading. Having said that though, as a general person who has access to general blood tests,

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Getting that serum marker for vitamin D is still something to sort of look at and use as a bit of a baseline. However, parathyroid hormone is more stable, so it responds directly to calcium and vitamin D levels in the blood, offering a more stable long-term marker of vitamin D sufficiency. PTH does rise in deficiency, so if vitamin D levels are low,

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The body compensates by increasing PTH, which leads to bone resorption and calcium release to maintain balance. Elevated PTH levels can indicate vitamin D insufficiency, even if your serum 25-hydroxy vitamin D level appear borderline normal. Some studies also suggest that PTH is associated with metabolic syndrome markers, insulin resistance, and inflammation. Even when vitamin D levels are considered adequate,

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So just gives you signs that if you present with metabolic syndrome in the presence of PTH being elevated, it might indicate a deficiency in vitamin D. So potentially both for bone health and long-term vitamin D status, PTH may provide additional insight beyond measuring serum 25-hydroxy vitamin D alone. However,

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In of itself, PTH is not a perfect measure as it can be influenced by dietary calcium intake, kidney function, and individual variability. So probably a combined approach measuring both vitamin D and PTH levels may provide the most accurate picture of someone's vitamin D status. Alrighty then, so what does this have to do with weight loss? Let's talk about how vitamin D influences fat metabolism.

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Vitamin D plays a key role in hormone regulation, including hormones like leptin and insulin, which are critical for appetite control and fat storage. Leptin is a hormone that tells your brain that you're full and that you should stop eating. And when you're low on vitamin D, leptin signaling can become less effective, making it easier to overeat. At the same time, vitamin D helps regulate insulin levels, reducing the likelihood of insulin resistance. That's a condition

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clearly linked to increased fat storage. Research has shown that people with higher vitamin D levels tend to have a lower body fat percentage and improved weight loss outcomes compared to those who are deficient, albeit these are just associative studies. Some studies suggest that supplementing with vitamin D when combined with diet and exercise can enhance fat loss results, but I will say that these findings, while they're statistically significant in some studies,

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they may not really be clinically meaningful at this stage. So it's fair to say we do need more research in the area of vitamin D supplementation and body composition related outcomes, albeit there's a little bit of an association there. Studies have tested the hypothesis that adiposity can in fact attenuate our own vitamin D response to having that the collicul...

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Saffron supplementation or the supplementation you get from the doctor for vitamin D. So in the majority there is a significant inverse relationship between BMI and or fat mass and Vitamin D. So the higher the fat mass the lower the vitamin D status and this occurs irrespective of population group and across a wide range of supplemental doses that are given for varying durations of either one week to one year. So

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quite a long period of time. For example, there's a study by Forsyth and colleagues where they had a change in vitamin D among older adults, which decreased by approximately 6.5 nanomoles per liter with every additional five unit increase in BMI, which suggests that individuals may require a larger dose of vitamin D or a longer supplemental period

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achieve the desired vitamin D status compared with leaner people or even independent, and these were independent of baseline concentrations. Interestingly, this effect was only found in older adults. So it was a non-significant effect in younger adults who had a higher fat mass. So this might suggest that the effect of adiposity on vitamin D status might become more prominent with increasing age.

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really been no sort of interpretation or explanation for that. I'm wondering whether it's got anything to do with vitamin D receptors and whether these change as we get older. Additionally, vitamin D plays a direct role in insulin regulation. It influences insulin sensitivity and secretion by acting on the pancreatic beta cells which produce insulin.

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Studies have suggested that vitamin D helps regulate intracellular calcium in insulin-sensitive tissues, improving glucose uptake and metabolism. So these effects of vitamin D deficiency, either acting together or alone, all serve to increase insulin resistance. Although there is evidence to support a relationship between vitamin D status and insulin resistance, the underlying mechanisms do require further exploration. So there's that suggestion that

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If you are more deficient in vitamin D, you are more likely to be insulin resistant, given the impact on those beta cells of the pancreas. But we do need further research in that area. But of course, just taking vitamin D is not a magic pill. However, having optimal vitamin D levels can definitely help create the right conditions for fat loss. So let's look at what happens when you don't get enough vitamin D.

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Just so you know, approximately 24 % of the US population has a serum 25-hydroxy vitamin D status below 15 nmol per litre, which indicates vitamin D deficiency here in New Zealand using those New Zealand units. In Canada, about 37 % of Canadians have that vitamin D level under 15 nmol per litre, which reflects a significant prevalence of deficiency that's close to 40%. And interestingly,

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In New Zealand, we have around about 33 % of the population at the last Ministry of Health survey that have levels of vitamin D that are below that 50 nanomoles per litre. And in fact, 5 % of the population have a vitamin D deficiency lower than even 25 nanomoles per litre. So as I said to you, like it's pretty common in New Zealand in winter to be low in vitamin D.

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And this is only low in comparison to the cutoffs that I just mentioned, that 50 nanomoles per liter. Whereas some people say, as I said earlier, that optimal is about 100 to 120. So your doctor might sign you off as having adequate vitamin D at say 60 nanomoles per liter. Whereas that is still 40 units below where others would say is optimal. So do bear that in mind. Vitamin D deficiency is, as I've said, really common.

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And the number goes up, that prevalence number goes up in people with darker skin, those living in northern climates, and individuals with higher body fat. And when you're low in vitamin D, there have been these links established that there is increased fat storage. Vitamin D levels have been linked to higher body fat percentages, so your body might store more fat and struggle to burn it efficiently.

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And without enough vitamin D, as I mentioned, your cells can become less responsive to insulin, increasing fat storage and raising your risk for metabolic issues. And vitamin D does play an anti-inflammatory role in the body and deficiency can lead to chronic inflammation, which is associated with obesity and difficulty losing weight. There's an association with leptin, as I mentioned, vitamin D is low. Your brain may not receive proper signals from leptin leading to overeating and weight gain.

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Low vitamin D is also associated with low mood and that can drive eating behaviors that promote overeating, increasing sugar intake and starting that sort of binge cycle of craving sugar, eating sugar, having energy crashes and then repeating. So it becomes a sort of cyclical thing. And there is definitely an association between that seasonal effect disorder in winter and low vitamin D as well.

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So if you struggle with weight gain despite exercising and eating right, it makes sense to do a lot of biomarker checking as I mentioned last week in that weight loss resistance episode. But of course, definitely check your vitamin D too. And in New Zealand, it's a user-pays test. It's not often just sort of covered by the public health system. And it might cost around 70 or $75. But I think if you're struggling with any of the things that I'm talking about,

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it would be well worth you getting a test, at least to see where you're at. So, you know, when it comes to boosting vitamin D, how do you do it? Well, first and foremost, sunlight exposure in summer. So the best natural source for us to synthesize vitamin D is through the sun, aiming for 10 to 30 minutes of sun exposure on your skin without sunscreen a few times a week.

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on your skin's tone. And it's often said that if you expose areas of your skin which don't often get exposed, like say underneath your arms or your torso, if you don't often show your torso sort of without having a t-shirt on or anything like that, then that's the kind of exposure that you want. But of course, please just make sure that you don't burn. Of course, dietary sources are often mentioned and

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Some of them really erroneously, I did see a reel the other day that said that dates were a really rich source of vitamin D. And I'm like, I don't think you know what you're talking about, because really dates are not a good source of vitamin D. And in fact, not a whole lot of foods have a lot of vitamin D, but you do get some through fatty fish, some through egg yolks, and also some dairy products are fortified with vitamin D. I'm not sure how bioavailable that is. Supplementation is really can be your best bet. If you live in a place

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with limited sunlight or struggle to get enough from food, then a vitamin D supplement that also has a vitamin K2 added that helps deliver that vitamin D to where it's required can be helpful in anything from one to 5,000 international units per day. And don't dismiss tanning beds either because a very short period of time in a tanning bed can help improve that vitamin D synthesis in your body. And again, I'm not suggesting

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doing tanning beds to those dangerous levels which promote like a burning or skin cancer, but it has been shown to improve vitamin D status. And of course, as I said, check your levels just so you know where you're at. And look, if you had the resources, this might be something you do a couple of times a year as you're headed into winter and as you're headed into spring or into summer can be a good idea every six months or so.

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You don't want too high a vitamin D. So high levels above 250 nanomoles or 100 nanograms per milliliter can lead to hypercalcemia, which causes nausea, potential kidney issues, and arterial calcification, which is clearly what you want to avoid. So I mentioned K2 as being really important to help deliver the vitamin D where it's required.

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Other co-factors of vitamin D metabolism that we need to ensure are adequate is magnesium, which helps convert vitamin D into its active form and prevent toxicity. I mentioned vitamin K, that is the thing that helps prevent arterial calcification. Vitamin A works with vitamin D for immune and bone health. And vitamin A is not the beta-carotene necessarily you get from vegetables, although that can count, but it's like what you find in liver, for example.

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and organ supplements. And as I mentioned, getting regular blood testing, even for both vitamin D and parathyroid hormone can help maintain balance and avoid unnecessary supplementation if you don't need it. What I would say, and this is bit of an add on, is that anyone with an autoimmune conditioner, it is worth getting your vitamin D tested because of the role that vitamin D plays in the immune system. So if it is low, it will be impacting on your

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overall health status in addition of course to weight gain and ability to lose fat. So vitamin D plays a crucial role in fat metabolism, insulin sensitivity and appetite regulation. And low levels are linked to increased fat storage, higher inflammation and metabolic imbalances, all of which can make fat loss more challenging. So if you're struggling with stubborn weight gain, it is worth looking into your vitamin D levels and also making sure that your

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optimizing exposure in the sun and potentially taking supplements and just keeping an eye on your overall metabolic health with regards to insulin resistance and glucose uptake. So hopefully that provides you a little bit of insight, things that you don't often hear talked about, vitamin D and its role in fat loss. If you've got any questions, concerns, you want me to help you sort of figure out your vitamin D status and what you need.

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Book a consult, you can do that over on my website mikkiwilliden.com or hit me up in the DMs on Instagram @mikkiwilliden which is where you'll also find me on Twitter and threads or Facebook wikkiwillidennutrition. Alright team, you have the best week. See you later.