What deficiency causes bowed legs? Understanding rickets and bone health

October 16, 2025 •

4 min read

According to the National Organization for Rare Disorders, vitamin D deficiency rickets is a treatable disorder of bone mineral metabolism that can lead to bowed legs. This condition, which softens and weakens a child’s bones, is primarily what deficiency causes bowed legs due to insufficient vitamin D, calcium, or phosphorus.

Quick Summary

This article explores nutritional causes of bowed legs, focusing on rickets due to vitamin D, calcium, or phosphorus deficiency. It covers symptoms, nutritional requirements, and dietary strategies for prevention and treatment, distinguishing it from non-nutritional causes.

Key Points

Primary Cause of Nutritional Bowed Legs: The most common nutritional deficiency causing bowed legs is Vitamin D deficiency, which leads to rickets in children.
Crucial Role of Vitamin D: Vitamin D is vital for the body's absorption of calcium and phosphorus, the minerals necessary for strong, mineralized bones.
Other Deficiencies: Insufficient intake of calcium or phosphorus, or malabsorption issues related to these nutrients, can also cause rickets.
Prevention Through Diet: A balanced diet rich in fatty fish, fortified dairy, eggs, and leafy greens, combined with adequate sun exposure, is key to preventing nutritional rickets.
Supplementation for High-Risk Groups: Exclusively breastfed infants, individuals with darker skin, or those with certain medical conditions may require vitamin D supplementation to meet their needs.
Treatment Success: Early intervention with diet correction and supplements can effectively reverse bowed legs caused by nutritional deficiencies in children.
Non-Nutritional Causes: Bowed legs can also result from other conditions like Blount's disease or genetic disorders, which do not respond to dietary changes.

The Primary Nutritional Cause: Rickets

Rickets is a condition affecting bone development in children, causing the bones to become soft, weak, and susceptible to deformities. A deficiency in vitamin D is the most common cause, as this vital nutrient is essential for the body to properly absorb calcium and phosphorus from food. Without adequate vitamin D, a child's bones cannot properly mineralize and harden, leading to skeletal issues such as bowed legs (genu varum).

Historically, rickets was more common in industrialized areas with poor sun exposure. While less prevalent in developed nations today due to food fortification, it can still affect at-risk groups, including exclusively breastfed infants without supplementation, children with darker skin, or those with underlying medical conditions that affect nutrient absorption.

The Role of Essential Nutrients in Bone Health

Several key nutrients work together to ensure healthy bone growth. A deficit in any of these can lead to complications. Here is how they function:

Vitamin D: Facilitates the body's absorption of calcium and phosphorus from the intestines. This is a crucial step for bone mineralization. The body produces vitamin D when the skin is exposed to sunlight, but it is also available from food sources and supplements.
Calcium: The primary mineral component of bone tissue, providing strength and structure. When calcium intake is too low, the body pulls calcium from the bones to support other functions, weakening the skeletal structure.
Phosphorus: Works in concert with calcium to build and maintain strong bones and teeth. Deficiencies are rare with a balanced diet but can occur with certain health conditions.

Symptoms and Diagnosis of Rickets

Beyond the hallmark sign of bowed legs, rickets can manifest in other ways that signal a problem with bone mineralization. If you notice any of these signs, it's important to consult a healthcare professional.

Skeletal Deformities: Thickened wrists and ankles, a protruding breastbone, and an unusually shaped skull are all potential signs.
Bone Pain and Weakness: Tenderness in the arms, legs, spine, or pelvis, along with decreased muscle tone.
Growth Issues: Delayed growth and motor skills.
Dental Problems: Weak tooth enamel, delayed tooth formation, and increased cavities.
Seizures: In severe cases, very low blood calcium levels can cause seizures.

Diagnosis typically involves a physical exam, blood tests to check vitamin D, calcium, and phosphorus levels, and X-rays to visualize bone abnormalities.

Nutritional vs. Other Causes of Bowed Legs

While nutritional deficiencies are a common cause of bowed legs, other factors can also lead to similar deformities. The following table compares the characteristics of nutritional and non-nutritional causes.


Feature	Nutritional Rickets	Other Causes (e.g., Blount's Disease)
Underlying Cause	Lack of vitamin D, calcium, or phosphorus.	Abnormal growth in the growth plates, genetic conditions, or trauma.
Onset	Occurs during periods of rapid growth, most commonly between 6 and 24 months of age.	Can present at similar ages but does not necessarily correlate with dietary factors.
Associated Symptoms	Bone pain, muscle weakness, dental issues, skeletal deformities.	Primarily affects the knees and lower legs, potentially causing uneven bowing.
Primary Treatment	Correcting nutritional deficiencies with supplements and dietary changes.	May require bracing or surgery to correct the bone alignment.
Response to Treatment	Often reversible, especially when treated early with proper nutrition.	Non-nutritional causes do not respond to dietary changes and require specific medical interventions.

A Nutrition Diet for Preventing Rickets

Preventing nutritional rickets focuses on ensuring adequate intake of bone-building nutrients from infancy through a balanced and nutrient-rich diet.

Sunlight: Safe, moderate sun exposure allows the skin to produce vitamin D. The amount needed varies by skin tone, geographic location, and season.
Vitamin D-Rich Foods: Include fatty fish like salmon and mackerel, egg yolks, and fortified foods such as milk, cereal, and orange juice.
Calcium-Rich Foods: Consume dairy products like milk, yogurt, and cheese, as well as leafy greens (kale, collard greens), almonds, and fortified plant-based milks.
Supplements: For breastfed infants or individuals with dietary restrictions or absorption issues, vitamin D and calcium supplements are often necessary under medical guidance.
Balanced Diet: A diet rich in whole foods, including vegetables, fruits, whole grains, and lean protein, supports overall bone health.

Treatment and Outcome

If nutritional rickets is diagnosed, treatment typically involves high doses of vitamin D and calcium, administered under a doctor's supervision. For mild cases in young children, correcting the nutritional deficiency can often reverse the bowing over several months to a year as the child grows. However, severe or persistent deformities may require corrective surgery or the use of braces. For cases of rickets caused by non-nutritional factors, treating the underlying medical condition is necessary.

Conclusion

Bowed legs can have a number of causes, but one of the most significant and treatable forms is nutritional rickets, caused by a deficiency in vitamin D and related minerals like calcium and phosphorus. Through a proper nutrition diet that includes sun exposure and fortified or naturally rich foods, coupled with supplementation when needed, this condition is largely preventable and curable in its early stages. Early diagnosis and intervention are critical for a positive outcome, ensuring healthy bone development for a child. For personalized guidance on bone health, consult with a healthcare provider or a registered dietitian.

One of the great medical successes of the 20th century was the use of vitamin D-fortified foods to help prevent rickets, as noted in a review of vitamin D deficiency rickets.

When to Seek Medical Help

It is crucial to consult a pediatrician if you notice persistent bowing of your child's legs after age two, significant bone pain, or other symptoms of rickets. While physiological bowing is normal in infants and typically resolves, ongoing issues warrant a medical evaluation to rule out underlying conditions and begin treatment if necessary. For more information on pediatric bone health, visit the Children's Hospital of Philadelphia website.

Frequently Asked Questions

Yes, a severe and prolonged Vitamin D deficiency can cause bowed legs. It leads to a condition called rickets in children, which softens the bones and causes them to bend under the body's weight.

The primary role of Vitamin D is to help the body absorb calcium and phosphorus from the food you eat. Without enough vitamin D, these minerals cannot be properly utilized to build and maintain hard, healthy bones.

Treatment for nutritional rickets involves increasing the child's intake of vitamin D and calcium through diet and supplementation, under a doctor's supervision. In mild cases, the bone deformity may correct itself over time with proper nutrition.

A severe vitamin D deficiency in adults leads to a similar condition called osteomalacia, or soft bones. While adult bones do not typically bow, they can become weak, soft, and prone to fractures.

Good sources of vitamin D include fatty fish (salmon, tuna), egg yolks, and fortified foods like milk, cereal, and orange juice. Calcium is found in dairy products, leafy greens (kale, broccoli), and fortified foods.

While sunlight is the body's natural way of producing Vitamin D, relying solely on it can be unreliable due to factors like geography, skin pigmentation, and sunscreen use. Therefore, a combination of sun exposure, diet, and sometimes supplements is recommended.

A medical professional will need to diagnose the cause using blood tests and X-rays. While most cases of infant bowing resolve naturally (physiological genu varum), persistent bowing or other symptoms like bone pain point toward an underlying issue that requires medical evaluation.