Unlike the name implies, vitamin D is not a vitamin – it’s a prohormone.
And a deficiency of this prohormone could be part of the reason you experience fatigue!
Way back in 1922 researchers didn’t have a clear idea of the difference between hormones and vitamins. Which is why vitamin D got labeled as a vitamin – it was the fourth vitamin discovered that prevented disease. But the modern understanding of the D vitamin shows this substance to be much more than a vitamin. Vitamin D has hormonal effects on your body.
Without it, you’d experience no shortage of adverse effects – including Ricketts. In today’s developed world, intense levels of vitamin D deficiencies like those found in Ricketts are rare. While Ricketts may be on the decline, sub-clinical vitamin D deficiencies are still very common in the first world.
It’s these sub-clinical levels of vitamin D deficiency that could be causing your fatigue. In today’s post, we’ll explore all the nuances to vitamin D. I’ll show you how to ensure you never experience any vitamin D related fatigue!
You can’t eat your way out of a vitamin D deficiency
In all honesty, you could eat yourself out of a vitamin D deficiency. But it would be a ton of work. And you’d be eating the same thing over and over.
You see, the overwhelming majority of vitamin D comes about through sun exposure. Not through your diet. To further complicate matters, depending on how far north or south of the equator you are, you can’t synthesize vitamin D from the sun year-round.
Here in Canada, I can start synthesizing vitamin D on March 1. But only for about an hour. The angle at which the sun hits your part of the globe determines whether or not vitamin D synthesis via sunlight is a go.
If all that is sounding far too complicated, just download a free app called D-minder. It will tell you how much vitamin D you can make from the sun based on where you live and the time of year.
Now, back to vitamin D from your food. Outside of cod liver oil and fatty fish like salmon and maceral, you’re not going to get much vitamin D from your food. Yes, food manufacturers are regulated to fortify foods like milk, margarine, and even breakfast cereals with vitamin D. But the amount of vitamin D found in these fortified foods is really low.
Adding vitamin D to foods is enough to prevent Ricketts. Which is an absolutely incredible advancement. But if you’re not eating fatty fish or cod liver oil on the regular, you’re still at high risk for developing a sub-clinical vitamin D deficiency.
Take a boo at the chart below. Cod liver oil has a whopping 1360 IU of vitamin D in just one tablespoon! Compared to breakfast cereal that has about 40IU of vitamin D. There’s a world of difference between the two.
|Food||IUs per serving*||Percent DV**|
|Cod liver oil, 1 tablespoon||1,360||340|
|Swordfish, cooked, 3 ounces||566||142|
|Salmon (sockeye), cooked, 3 ounces||447||112|
|Tuna fish, canned in water, drained, 3 ounces||154||39|
|Orange juice fortified with vitamin D, 1 cup (check product labels, as the amount of added vitamin D varies)||137||34|
|Milk, nonfat, reduced fat, and whole, vitamin D-fortified, 1 cup||115-124||29-31|
|Yogurt, fortified with 20% of the DV for vitamin D, 6 ounces (more heavily fortified yogurts provide more of the DV)||80||20|
|Margarine, fortified, 1 tablespoon||60||15|
|Sardines, canned in oil, drained, 2 sardines||46||12|
|Liver, beef, cooked, 3 ounces||42||11|
|Egg, 1 large (vitamin D is found in yolk)||41||10|
|Ready-to-eat cereal, fortified with 10% of the DV for vitamin D, 0.75-1 cup (more heavily fortified cereals might provide more of the DV)||40||10|
|Cheese, Swiss, 1 ounce||6||2|
Not all fish is going to get your vitamin D levels up
After reading the last section, you’re probably thinking to yourself:
Great. All I need to do is eat fatty fish like salmon and I don’t have to worry about my vitamin D levels.
Plus, I love salmon!
This is going to be so easy!
If only it were that simple. Alas, the fishing industry has complicated matters. You see, farmed salmon is not the same as wild salmon – at least so far as vitamin D is concerned.
Farmed salmon has about 25% the vitamin D that wild salmon has. (2)
This puts the vitamin D level of farmed salmon in the same league as milk – AKA not a great source of vitamin D. You’d have to eat 4x three-ounce servings of farmed salmon every day just to prevent vitamin D deficiency. Gross!
Remember, if you’re relying on fish for vitamin D, make sure your fish is wild-caught! The farmed stuff just won’t cut it!
This is why relying on food as your sole source of vitamin D is not the best strategy. Obtaining optimal vitamin D levels from food alone would require you to eat a lot of the same foods over and over.
Take a look at the above chart and see what foods would be required eating every day just to ensure you don’t experience a vitamin D deficiency! And this is just to prevent a deficiency – it doesn’t even take into account optimal levels!
That is unless you opt for a tablespoon of cod liver oil every morning – that alone would ensure you have optimal vitamin D levels! More on cod liver oil below!
Who’s at risk for vitamin D deficiency?
If you’ve got pale skin as I do and you live near the equator, you’re probably not at any risk for a vitamin D deficiency. But sunburns should be a legitimate fear. You see, the lighter your skin tone the more adept you are at synthesizing vitamin D from the sun.
Why do you think there are so many pale red heads in Ireland and the UK?
In all likelihood, light skin tones resulted as an adaptation to living cloudy environments – like those environments found in the UK and Ireland. Synthesizing vitamin D through miles of cloud cover is a tricky endeavor. The lighter your skin tone, the easier time your body would have had in transforming what little rays of sun did make it through the clouds into vitamin D.
Thus, one massive group at risk of vitamin D deficiency are those with darker skin tones living in cloudy environments or far away from the equator.
Darker skin tones are the result of higher levels of melanin. In sunny environments, melanin acts as a natural protectant from the harmful rays of the sun. But it also inhibits your ability to synthesize vitamin D. (3, 4)
In the United States, those with Hispanic or African-American heritage more commonly experience vitamin D deficiency in the winter months. (5) During the winter months, it’s not possible to synthesize vitamin D from the sun. Remember, the darker your skin tone, the more time you need to spend in the sun in order to obtain adequate vitamin D levels!
Skin tone aside, there are other members of the population that are at high risk for vitamin D deficiency. These include: (6)
- Those with inflammatory bowel disease (Crohn’s or Ulcerative Colitis)
- In IBD conditions, the GI tract can struggle to digest dietary fat. Since vitamin D is fat-soluble, this lack of absorption can result in a deficiency.
- If you have a diagnosis of IBD, ensure you’re testing your vitamin D levels regularly.
- Older adults
- As we age, our skin struggles to synthesize vitamin D from sunlight as easily.
- If you’re overweight or obese, you will likely require more vitamin D than is recommended by the RDA.
- Those who have undergone a gastric bypass surgery
- In gastric bypass surgery, part of the small intestine is bypassed. This is the same part of the small intestine where vitamin D absorption occurs.
- If you’ve had this surgery, make sure you’re getting outdoors to make vitamin D via sunlight every day!
How do you know you’ve got a vitamin D deficiency?
I’d encourage you not to use symptoms as a reliable indicator of vitamin D status. The only true way to whether or not you’ve got a vitamin D deficiency is through laboratory testing. The early symptoms of vitamin D deficiency are just too vague and non-specific.
If your vitamin D deficiency is both severe and chronic, the following symptoms are probable:
- A bone-thinning disorder in adults that is accompanied with muscle weakness.
- A condition of reduced bone mineral density resulting in an increased risk of fracture.
- This results from severe vitamin D deficiency in childhood.
If your vitamin D deficiency is mild, the following symptoms are commonly listed in the literature:
- Muscle aches and weakness (7)
- Muscle twitching or fasciculation (8)
- Fatigue (9)
- Decrease immune system function (10, 11)
- You may experience this as getting sick often.
- Low mood (12, 13)
Notice how the above symptoms are ones each of us has experienced. These are what are known as non-specific symptoms. Meaning they don’t point directly to one illness/disease.
This is what makes diagnosing vitamin D deficiency so challenging. You cannot rely on symptoms. You have to rely on laboratory testing.
What are the ideal vitamin D levels?
Ok, now you know to avoid diagnosing vitamin D levels based on symptoms alone. So, you’ve gone ahead and tested your levels. Make sure the test is measuring the maker known as 25-hydroxyvitamin D3.
What are the ideal serum levels of vitamin D? (14)
Optimal levels = 80-200 nmol/L
Moderate deficiency = 25-80 nmol/L
Severe deficiency = <25 nmol/L
High levels = 200-250 nmol/L
Toxic levels = >250 nmol/L
I recommend testing your vitamin D levels twice per year. Once in the spring. And once in the fall.
Spring testing will reveal what your vitamin D levels are like after coming out of the winter darkness. Fall testing will ensure you have adequate vitamin D stores as you head into the winter months.
Ideally, you get your vitamin D from the sun. This way it is impossible to overdose. But when living at latitudes that are far from the equator, supplementation becomes necessary. Especially in the winter.
How much vitamin D should you take to prevent fatigue?
Well, that depends. Each of you reading this article is dealing with a rather unique set of health circumstances. Different doses are required for different conditions.
For those of you dealing with fatigue, I’d like to see your vitamin D levels above 100 nmol/L and below 200 nmol/L.
This is why I’m such a strong advocate for testing. By testing, you’ll know exactly where your vitamin D levels are at. This tells you how much vitamin D you should be taking.
Here’s a general guideline for vitamin D dosing I use in the clinic:
- Maintenance dose
- Used for those whose vitamin D levels are already in the optimal range.
- 1000-5000 IU per day
- This shall be sourced first from sunlight. Supplement only when necessary.
- Deficiency dose
- Used for those with low vitamin D levels.
- 5000-10,000 IU/day
- Sourced from sunlight and supplements.
Is vitamin D the root cause of your fatigue?
I’d wager that a vitamin D deficiency being the root cause of your fatigue is highly unlikely. I wrote about a recent study that showed those with CFS aren’t usually dealing with nutritional deficiencies. Including vitamin D.
But that’s not to say your vitamin D levels aren’t contributing to your fatigue. They absolutely could be. I recommend all of my fatigue patients strive to keep their vitamin D levels within the optimal range at all times.
To do this, you’re going to need to utilize laboratory testing. Remember, no guessing on your vitamin D levels!
Ok, now you know all there is to know about vitamin D and fatigue!
It’s time for me to hear from you!
How has vitamin D affected your energy levels?
Leave your answers in the comments section below!