It’s the first day of summer! I was going to go all coconut oil defensive this week, but I just couldn’t get the words out. So instead I’m going to talk about another hot topic, that has seen its efficacy come into question lately. We hear about this one all the time. Today I’m going to talk about vitamin D, and why I think it’s important.
I find that we hear a ton about vitamin D twice a year, at the beginning of summer, and at the beginning of winter. Why does this timing make sense? Well, at the beginning of the summer we are all getting ready to (or have already been) spend a ton of time outdoors in the sunshine. In the winter we hear a lot about it because we don’t spend a lot of time outside, so many of us fall to near deficiency levels.
So why is vitamin D important to us?
Vitamin D isn’t a vitamin at all; it’s a steroid hormone precursor. It serves many functions in the body, probably the most important of which is the maintenance and metabolism of calcium. As vitamin D levels rise, so too does the amount of calcium. As calcium levels skyrocket, vitamin D may be rendered ineffective. Why is this important? High levels of calcium can have some nasty side effects, particularly heart problems, and kidney stones. Calcium is one of those minerals whose levels need to be controlled in order to make sure things are running smoothly. Vitamin D, in the converted form of calcitrol helps your parathyroid glands to maintain calcium levels. So when you have a deficiency in vitamin D, you have a decrease in calcitrol. This causes the parathyroid gland to become overactive, and phosphorus levels in the body drop. Without phosphorus, your body cannot let calcium mineralize in bone. This can lead to issues in bone density. One of the best ways that I have heard it put, if calcium is the lumber then vitamin D is the carpenter.
Vitamin D is also useful in situations of low immunity. I personally tend to rely on it a lot when I have a cold or flu. Why is this? Your immune cells have vitamin D receptors. It is suggested that vitamin D seems to mitigate excessive inflammation responses, which are linked to autoimmune conditions. Randomized studies haven’t been able to absolutely back up these claims, but there is a lot of anecdotal evidence and case studies out there that support these claims.
Vitamin D has also been implicated in blocking excess estrogen, which can help to prevent estrogen dominant cancers such as breast, ovarian, and colon. These claims are seen in a couple studies, though certainly there is no consensus as to the validity of the results.
Some studies have suggested that low levels of vitamin D can lead to weight management issues as well. Some practitioners will suggest that you get your vitamin D levels checked if you have difficulty losing weight. I personally don’t see the need to check for vitamin D levels unless you have a condition that impairs your ability to absorb vitamin D or to make the conversion such as kidney, or liver problems. (My opinion.)
Vitamin D that we consume is biologically inactive. It has to be metabolized in order to become biologically active. There is a very specific pathway that it goes through in order to become activated. It will first be hydroxylated within the liver, and then will be metabolized within the kidney in order to reach its active form. Humans are one of the only species who are able to convert vitamin D though a sunlight mediated pathway. The sunlight-mediated pathway adds the absorption through the skin to the liver and kidney pathway noted above. So to recap, the vitamin D metabolism pathway is skin, liver, kidney.
Okay, so how exactly does one get vitamin D? Well the most obvious answer is sunlight. It also happens to be the best source of it out there. This is why people tend to approach near deficiency levels in the winter time. Due to our location, the sunrays during the winter are not strong enough to allow us to absorb vitamin D. This is when you will see people with seasonal affective disorder. This is why many people will supplement with vitamin D during the winter. It helps to avoid the winter blues. Interesting note: sunscreens with SPF higher than 8 will block the absorption of vitamin D from the skin. This would be more problematic but a lot of food in North America is enriched with vitamin D, which helps to keep us above deficiency levels.
Some dietary sources of vitamin D are:
It should be noted that it is near impossible to overdose on vitamin D when it is acquired from sunlight. The danger of overdosing comes when vitamin D is consumed, and supplemented excessively. When vitamin D is obtained from the sun, the skin has the ability to destroy levels above and beyond what is considered safe. The liver and kidney don’t have this ability.
I personally am a fan of vitamin D supplementation. Obviously it is ideal to get it from the sunlight, and from consuming foods that have naturally occurring high levels of vitamin D, but that isn’t always practical. We see this in the winter when the sunlight is so weak that we can’t properly absorb it. This is when I tend to encourage supplementation. Every individual has different needs, but I find that supplementation when required is definitely helpful. I have had the misfortune of experiencing seasonal affective disorder, and it isn’t fun. Since that time, I religiously supplement with vitamin D, both during the winter and during the summer. Obviously because of the sunlight during the summer I will back off on how much I am consuming via supplementation in order to avoid excessive consumption. I prefer using liquid Vitamin D3 as a supplement, it has been shown to absorb much better than using the tablet form.
I’m not telling you to take my word as gospel. I don’t pretend to know everything, and things are constantly evolving. I always encourage patients to do research. In my opinion, knowledge is power. So when patients ask me whether vitamin D is important, I will tell them my thoughts before I encourage them to do a little research of their own. There is so much conflicting information out there, and the only way to make an informed choice is to educate yourself.
We’ve waited what seems like ages for the sun to shine continuously. It was a long winter, and an even longer spring. In honour of the first day of summer, get outside. Go enjoy some fresh air, and absorb some of that free vitamin D. Your body will thank you!