Feeling Low-Energy & Blah? You Might Be Lacking This Vitamin
Are you getting enough sleep, eating well, and exercising regularly, yet you still feel tired? Well, it could be a sign that your vitamin D levels are low. Feeling low energy (like you're physically and mentally dragging) is a frequently cited complaint among those with a poor vitamin D status. About 29% of U.S. adults1 are deficient in vitamin D (aka have blood levels less than 20 ng/mL, and 41% of adults1 have insufficient vitamin D levels (less than 30 ng/mL). So there's a decent chance you fall into one of these categories.
Here's what you need to know about vitamin D and energy, and how to raise your levels (to get your energy back!).
Vitamin D & low energy
Vitamin D helps support mitochondria (what we all have internalized as the powerhouse of the cell). Mitochondria are responsible for generating energy, and vitamin D is part of the process that helps these structures convert nutrients and oxygen into energy the body can actually use.
Research has consistently found a connection between vitamin D status and feeling tired. In studies, people who report occasional fatigue (which can involve more than just low energy, including changes in muscle strength and cognition) tend to have lower vitamin D levels than those who don't experience fatigue.*
For example, a 2016 study of female nurses in Iran found that low vitamin D levels accounted for 13 to 18% of reported prolonged tiredness. And in a 2019 study published in Nutrients, older adults with occasional fatigue had significantly worse vitamin D status than those without fatigue.
While low vitamin D isn't necessarily the only reason you may feel tired, it could absolutely be a contributing factor (especially if you also notice changes in your physical strength or ability to focus).
Other ways low vitamin D can leave you feeling “blah”
Vitamin D has far-reaching effects throughout the body, so low levels may affect how you feel in ways that go beyond simply feeling tired.
- Your sleep may suffer: Vitamin D receptors are found in areas of the brain involved in sleep regulation, and research has linked low vitamin D status with poorer sleep quality and shorter sleep duration. That can create a frustrating cycle: You sleep poorly, feel more tired, and still don't feel restored the next day.
- Your mood may feel off: Vitamin D receptors are widespread throughout the nervous system, and the nutrient is involved in brain function. Observational research has linked low vitamin D levels with low (and irritated) moods.
- Your muscles may feel weaker: Vitamin D plays an important role in normal muscle function. Severe deficiency can contribute to muscle weakness, which may make everyday activities feel more physically taxing.
- Your immune system may need more support: Vitamin D helps regulate both innate and adaptive immune responses, meaning it plays a role in helping immune cells respond appropriately.*
How to find out if vitamin D is part of the problem
The only way to know your vitamin D status is with a blood test measuring 25-hydroxyvitamin D, the main marker of vitamin D status. Vitamin D sufficiency is considered to be greater than 30 mg/mL, and optimal levels are even higher at 50ng/mL.
Safe sun exposure and consuming vitamin D-containing foods like dairy and some fatty fish and UV-treated mushrooms can help, supplements are the most efficient way to increase vitamin D intake (especially if your levels are low to begin with) . Vitamin D3 is generally more effective at raising blood levels than D2, and taking it with a meal containing fat may improve absorption.
This one is a great option for raising stubbornly low vitamin D levels. It provides 5,000 IU of vitamin D3 from an algal source, along with avocado, extra-virgin olive, and flaxseed oils to support absorption.* Here's a full list of our expert-vetted list for vitamin D supplements.
The takeaway
Feeling tired all the time (even when you're getting enough sleep) isn't something you have to simply accept. Low energy can have many causes, and it's worth looking into your vitamin D levels and integrating a quality supplement into your daily routine.