Vitamin D Deficiency: Best Foods, Normal Blood Levels, Benefits and Warning Signs

Updated October 9, 2026 — Written by Dr. Shabbir Hussain, BPT, Registered Physiotherapist | Clinical Rehabilitation Specialist

Vitamin D Deficiency

Vitamin D helps your body absorb calcium and maintain healthy bones and muscles. Fatty fish, egg yolks, UV-exposed mushrooms and fortified foods can help supply this nutrient. A blood test measuring 25-hydroxyvitamin D can help assess your vitamin D status, but the result should be interpreted in context.

Vitamin D deficiency can go unnoticed because some people have no clear symptoms. When deficiency is significant, it may contribute to bone pain, muscle weakness and osteomalacia in adults. Understanding your food choices, blood test results and risk factors can help you decide when professional advice is needed.

Which foods are rich in vitamin D?

Few foods naturally contain substantial amounts of vitamin D. Useful sources include:

• Fatty fish: Salmon, trout, sardines and tuna.
• Egg yolks: A modest source of vitamin D.
• Fortified foods: Milk, plant-based milk alternatives, breakfast cereals and some yogurts, depending on the product.
• UV-exposed mushrooms: Some varieties provide vitamin D2.
• Other animal foods: Beef liver and cheese contain smaller amounts.

If you follow a vegetarian diet, look for vitamin D-fortified foods and check the nutrition label. Ordinary fruits, vegetables, rice and lentils generally provide little or no vitamin D.

What is the normal range for vitamin D levels?

The most useful routine blood test for assessing vitamin D status measures 25-hydroxyvitamin D [25(OH)D].

The US National Academies’ reference categories are:

Blood vitamin D level	General interpretation
Below 12 ng/mL	Risk of deficiency
12 to below 20 ng/mL	May be inadequate
20 ng/mL or higher	Adequate for most people
Above 50 ng/mL	Potential for adverse effects

These are general reference categories, not universal treatment targets. Clinical interpretation varies with individual health circumstances, and different medical organizations do not use identical thresholds. Your clinician should interpret your result rather than relying on a number alone.

What is vitamin D important for?

Vitamin D helps your body absorb calcium and maintain the calcium and phosphate levels needed for healthy bones. It also contributes to normal muscle function.

Adequate vitamin D is important for:

• Bone strength: Helps maintain normal bone mineralization.
• Muscle function: Supports normal muscle activity.
• Growing children: Helps prevent nutritional rickets.
• Adults: Helps prevent osteomalacia, a condition in which bones become insufficiently mineralized.

Vitamin D also participates in immune and other cellular processes. However, evidence does not establish that taking extra vitamin D prevents or treats every condition associated with it, including cancer, depression or cardiovascular disease.

What happens when your vitamin D is low?

Some people with low vitamin D have no obvious symptoms. When deficiency becomes significant, possible effects include:

• Bone pain or tenderness.
• Muscle weakness.
• Difficulty climbing stairs or rising from a chair.
• Bone discomfort that affects walking and everyday activities.
• Increased risk of osteomalacia in adults.

Severe deficiency can contribute to bone deformities in children and impaired bone mineralization in adults. These symptoms are not specific to vitamin D deficiency, so other causes—including anemia, thyroid disorders and musculoskeletal conditions—may need consideration.

People with limited sun exposure, darker skin, conditions that impair fat absorption, or certain kidney disorders may be more likely to develop inadequate vitamin D levels.

Can Physiotherapy Help with Vitamin D–Related Muscle Weakness?

Physiotherapy does not correct vitamin D deficiency itself, but it can help address associated muscle weakness, reduced mobility and difficulty performing daily activities.

Depending on the individual’s assessment, a physiotherapist may recommend:

• Gradually progressed strengthening exercises.
• Balance and functional mobility training.
• Safe walking and movement strategies.
• A tailored exercise programme for rebuilding strength and confidence.

If you have severe bone pain, suspected fractures, or marked muscle weakness, seek medical assessment before starting strenuous exercise. People with osteomalacia or fragile bones may require modified activities to reduce injury risk.

How can you maintain healthy vitamin D levels?

Include vitamin D-containing foods in a balanced diet, check whether commonly consumed foods are fortified, and discuss supplementation with a healthcare professional if you are at risk of deficiency.

Sunlight can contribute to vitamin D production, but the amount produced varies with skin pigmentation, season, location, clothing and other factors. Avoid sunburn and do not rely on unprotected sun exposure as your only strategy.

Supplements may be necessary for some people, particularly when deficiency is confirmed. High-dose vitamin D should not be taken without appropriate guidance: excessive supplementation can raise blood calcium and, in severe cases, damage the kidneys or cause abnormal heart rhythms.

The key takeaway: Vitamin D supports healthy bones and muscles, but the right approach is to combine appropriate nutrition, individual risk assessment and medically guided treatment when needed.

Medical Sources

1. NIH Office of Dietary Supplements — Vitamin D: Health Professional Fact Sheet Link: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/

2. NIH Office of Dietary Supplements — Vitamin D: Consumer Fact Sheet Link: https://ods.od.nih.gov/factsheets/VitaminD-Consumer/

3. Endocrine Society — Vitamin D for the Prevention of Disease: Clinical Practice Guideline Link: https://doi.org/10.1210/clinem/dgae290

Medical Disclaimer

This article is for general educational and informational purposes only. It is not a substitute for professional medical diagnosis, treatment, or individualized medical advice. If you have persistent, severe, worsening, or concerning symptoms, consult a qualified healthcare professional. Seek urgent medical care for emergency symptoms.