Seattle is a hot spot for vitamin D deficiency. It isn't just that we're well-known for our cloud cover, many days of the year. Some summers, the sun doesn't make its appearance until early July, no joke. But, also, we are way up here, in the far northern corner of PNW USA. Hello, down there, can anybody hear me? The sunlight that we do receive in winter isn't strong enough for our skin's production of vitamin D. Vitamin D screening/testing is becoming commonplace, here, as a result.
The best source of vitamin D is prudent sun exposure. That was the original design. Some of us don't live where adequate sun abounds. For others, use of sunblock is a health necessity. And still for others, skin pigmentation prevents adequate production of vitamin D in the body. Finally, (something I don't relish thinking about), but as we age, our bodies become less efficient at using sun exposure for our vitamin D supply.
So, for those of us needing supplementation, this is what I've learned. (And if you don't know whether you need more vitamin D or not, your medical professional can run a blood test, to check your serum vitamin D levels.)
D2 & D3
There are different types/sources of vitamin D for supplementation. I don't know where D1 comes from, if it still exists, or what it is. But commonly in supplement form, you'll see labels on packages or vitamin bottles with D2 and D3.
D2 is vitamin D made from ergosterol, from fungi and protozoa. Vitamin D3 is made from cholecalciferol, which comes from an animal source (from sheep's wool, I believe). From what I've read, vitamin D3 is more like what our bodies form from sun exposure than vitamin D2. There is some evidence that suggests D3 is taken up by the body more easily than D2. That doesn't mean that D2 is completely useless, though.
There's also a D4 and a D5, but I've never seen either listed on any package label, or referred to as needed for health, in a medical article.
When reading food packages or vitamin bottle labels, check for ergocalciferol and/or cholecalciferol. Vitamin D without a subscript can refer to either D2 or D3, or even both. Together, they are known as calciferol.
While most commercial milk (and many brands of yogurt) is fortified with vitamin D, many other dairy products, such as cheese and ice cream, are not fortified with vitamin D.
Supplement forms of vitamin D Vitamin D as a supplement comes in liquid, gel caps (filled with liquid) and tablet (compressed solids, as in a stand alone vitamin D, or a daily multi-vitamin tablet, containing vitamin D).
There is also some evidence that vitamin D3 may be taken up via transdermal application (which is very helpful for elderly, who may not receive adequate sun exposure or supplements by mouth). This form is available as a patch, and as a cream.
The digestive system absorbs vitamin D as a liquid or gel cap, more easily than a solid/tablet. Some people have reported, anecdotally, that they feel better on the liquid drops than either gel caps or tablet. My own doctor didn't feel there was any efficacy benefit from the drops vs the gel caps, however.
Vitamin D is fat soluble. That means, it needs fat in the digestive system to absorb it's nutrient value.
Vitamin D in liquid form is also sold in a preparation of a liquid fat, to be taken regardless of whether you've just eaten some fat or not. This is very beneficial for those individuals who for one reason or another have an extremely limited diet, or can't take much by mouth.
I've read the advice to take vitamin D supplements with your heaviest meal meal of the day.
The human body benefits from adding Vitamin K, when supplementing vitamin D and calcium. Vitamin K is also a fat-soluble vitamin. There are a few forms of vitamin K. K1 and K2 are the natural sources. K1 is what is found in leafy green vegetables. The human body converts K1 to K2, with, but not limited to, the help of gut flora. Deficiency of vitamin K has been found in individuals with malabsorption issues, due to disease of the digestive system or extensive use of broad spectrum antibiotics.
Vitamin K2 is thought to be the main storage form of vitamin K, in animals. Food source-wise, K2 is found in animal livers and bacteria-fermented foods, including hard cheeses.
It is recommended to get both sources of vitamin K in your diet on a daily basis. Although vitamin K is fat-soluble, it doesn't appear to be stored long-term (like vitamin D), in the body.
Most of us have heard that vitamin K helps in blood coagulation. It also plays a key role in the body when paired with vitamin D. In a nutshell, if I recall correctly, vitamin D helps the body absorbs calcium, and vitamin K2 helps direct that calcium away from soft tissue (like arteries) and into the bones.
What I've observed with D2.
Alternative milks, like soy milk and almond milk, are mostly supplemented with vitamin D2, not D3. My guess is that alternative milks are not only market-targeted to those with dietary issues regarding lactose, but also to the vegetarian/vegan share of the market. D2 being from a non-animal source fits with that marketing model. Just something to be aware of, as some experts say that D2 is not taken up as easily by the body as D3.
Vitamin D toxicity from excess supplementation is rare and primarily happens in individuals with specific other medical conditions, such as hyperparathyroidism. But it can still happen. So mega-dosing isn't advised. (Just because a little is good doesn't mean that a lot is better.)
***None of this is to be read as medical advice. These are all things I didn't know about vitamin D until recently. Some of this information may be new to you, and I encourage you to do your own research and consult with your doctor/medical care professional about your nutritional needs. You already know this, but I have to say it -- I am not a medical professional, and I've never played one on TV.
Now, this is what I have chosen to do.
- I had vitamin D2 in my cabinet when I began this research. Although it is not as available to the body as D3, it's not useless. I didn't want throw it out, of course. But I also didn't want to rely on it as my only source of vitamin D supplementation. So, to use it up (and not have wasted money on something), I alternated the D2 with D3, every other day. I don't get any vitamin D from animal milk. Even if I tried drinking more milk, with lactose intolerance, it's been suggested that my body wouldn't be able to absorb all the nutrients, anyways, due to a compromised digestive system when I consume milk.
- I don't eat much fish, either. So, most of my vitamin D needs to come from supplements for most of the year.
- After finishing my D2, I settled on a liquid form of vitamin D3, in drops, to be taken on my tongue. The drops may be taken up by my body better than other forms. But also, I like them because they're very easy to take, with no extra pills to swallow.
- I take my vitamin D, twice each day, immediately after eating a spoonful of natural-style peanut butter. or handful of nuts with my breakfast., and right after lunch. I would take vitamin D with dinner (as that's my heaviest meal of the day), but I get so busy and tired at that hour that I forget.
- I don't count the vitamin D2 that is in the soy milk that I use, daily, towards my RDA for vitamin D.
- I've added a vitamin K2 supplement to my diet, as I don't eat enough sources of K2 on a regular basis. I do eat plenty of leafy greens, but I also have some nutrient absorption issues, and have taken more than my share of broad spectrum antibiotics, unfortunately.
If you think you need extra vitamin D, this is a good discussion to have with your doctor. Many doctors now routinely test for serum vitamin D levels.
(This is a lot of information. Sorry to have gone on so long.)
(This is a lot of information. Sorry to have gone on so long.)