Vitamin D deficiency is one of the most common — and most easily missed — nutrient gaps out there. The symptoms are quiet and easy to blame on something else, and a meaningful share of people with low levels have no obvious symptoms at all. Here's what to actually watch for, who's most at risk, and what to do about it.

Written by Vita Globe Editorial Team | Reviewed against peer-reviewed research and federal health guidance

Common Signs of Vitamin D Deficiency in Adults

• Fatigue. Persistent tiredness that doesn't improve with sleep is one of the most frequently reported symptoms of low vitamin D^[3].
• Bone pain. Vitamin D helps your body absorb calcium, so low levels can show up as a dull, aching bone pain — often in the lower back, hips, or legs.
• Muscle weakness, aches, or cramps. Because vitamin D also plays a role in muscle function, deficiency can leave muscles feeling weak or sore for no clear reason.
• Mood changes. Low vitamin D has been associated with low mood and depressive symptoms, particularly in the darker winter months.
• No symptoms at all. This is the tricky part — a significant number of people with low vitamin D feel completely fine, which is why risk factors matter as much as symptoms^[1].

Signs in Children

In children, vitamin D deficiency can look like general muscle soreness or weakness in mild cases. Left untreated, more severe deficiency can lead to rickets — a condition that causes bowed or bent bones, joint deformities, and growth problems^[4]. It's rare in developed countries today, but it's part of why pediatricians often recommend vitamin D supplementation for breastfed infants specifically^[4].

Who's Most at Risk

Some people are far more likely to run low on vitamin D, regardless of symptoms^[1]:

• Adults over 65 — skin naturally becomes less efficient at producing vitamin D from sunlight with age.
• People with darker skin tones — higher melanin levels make it harder for skin to synthesize vitamin D from sun exposure.
• Anyone with limited sun exposure — people who work indoors, live in northern climates, or cover most of their skin for cultural or medical reasons.
• Breastfed infants, since breast milk alone typically doesn't provide enough vitamin D.
• People with certain health conditions, including Crohn's disease, celiac disease, cystic fibrosis, kidney or liver disease, and obesity — all of which can affect how the body absorbs or processes vitamin D.

How Vitamin D Deficiency Is Diagnosed

If you recognize a few of these signs — or fall into a higher-risk group — the only way to know for sure is a simple blood test that measures 25-hydroxyvitamin D (25(OH)D), the storage form of vitamin D in your blood^[1]. It's a standard test most doctors can order during a routine visit.

What to Do About Low Vitamin D

Sun exposure. Your body produces vitamin D when skin is exposed to UVB rays, but this needs to be balanced carefully against skin cancer risk — it's not a blank-check recommendation to skip sunscreen.

Food sources. Fatty fish like salmon, tuna, and mackerel are among the richest natural sources, along with egg yolks, beef liver, and mushrooms. Fortified foods — milk, cereal, orange juice, and some yogurts — are also common sources, especially for people who don't eat much fish.

Supplementation. Vitamin D3 (cholecalciferol) is the form most commonly recommended, as it's absorbed more efficiently than D2^[1]. General daily guidance is:

• Infants: 400 IU
• Adults ages 1–70: 600 IU
• Adults 71+: 800 IU

(These are general population guidelines, not a diagnosis — if a blood test shows you're significantly deficient, your doctor may recommend a higher, supervised dose to correct it.) A 2024 Endocrine Society guideline update goes a step further for a few specific groups: it recommends higher-dose vitamin D for adults over 75, people who are pregnant, and people with prediabetes, while stopping short of recommending routine high-dose supplementation above the standard guidance for other healthy adults^[2].

For a lot of people, a daily vitamin D gummy is simply the easiest way to stay consistent, especially through the winter months when sun exposure naturally drops.

FAQ: Signs of Vitamin D Deficiency

Can low vitamin D make you tired all the time?

Yes — fatigue is one of the most commonly reported symptoms of vitamin D deficiency, though it's also a symptom of many other things, which is why a blood test is the only way to confirm it^[1].

What does vitamin D deficiency pain feel like?

It's typically described as a dull, aching bone pain (often in the back, hips, or legs) rather than a sharp or localized pain, along with general muscle soreness or weakness^[3].

How long does it take to fix a vitamin D deficiency?

With consistent supplementation at the right dose, blood levels typically start improving within 8–12 weeks, though your doctor may recheck levels to confirm^[1].

Can you have vitamin D deficiency with no symptoms?

Yes, and it's actually common. This is exactly why risk factors — age, skin tone, sun exposure, certain health conditions — matter even if you feel fine^[1].

Sources

1. National Institutes of Health, Office of Dietary Supplements. Vitamin D — Health Professional Fact Sheet.
2. Demay MB, et al. Vitamin D for the Prevention of Disease: An Endocrine Society Clinical Practice Guideline. 2024.
3. Cleveland Clinic. Vitamin D Deficiency: Causes, Symptoms & Treatment.
4. American Academy of Pediatrics. Prevention of Rickets and Vitamin D Deficiency in Infants, Children, and Adolescents. Pediatrics, 2008.
5. Vita Globe. Vitamin D3 2,000 IU Gummies — product formulation and Supplement Facts panel.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and isn't a substitute for medical advice. If you suspect a vitamin D deficiency, talk to your doctor and ask about a 25(OH)D blood test before starting a high-dose supplement.