Vitamin D Deficiency in Perimenopause: Signs and What to Do

Vitamin D deficiency is common across all ages, but the menopause transition introduces a convergence of risks that makes insufficiency particularly consequential. Oestrogen withdrawal accelerates bone turnover, and adequate vitamin D is a prerequisite for the calcium absorption that slows that process. At the same time, low vitamin D has been linked in observational research to low mood, muscle weakness, and disrupted sleep — symptoms that overlap substantially with perimenopause itself. Disentangling the two requires testing, not guessing.

Why perimenopause increases vitamin D risk

Vitamin D is synthesised in the skin on exposure to UVB radiation and absorbed in smaller amounts through food. Several factors common in midlife converge to reduce supply: spending more time indoors, using higher-SPF sun protection, living at higher latitudes, and having darker skin pigmentation. In addition, oestrogen appears to upregulate the enzyme that converts vitamin D to its active form (calcitriol) in the kidney — so as oestrogen declines, vitamin D metabolism may become less efficient even when intake is adequate.

Symptoms that may signal insufficiency

Vitamin D deficiency rarely presents with a single dramatic sign. Most people describe a cluster of vague complaints that are easily attributed to stress, ageing, or perimenopause itself.

• Persistent fatigue that is not explained by poor sleep alone.
• Diffuse muscle aches or generalised weakness, especially in the thighs and upper arms.
• Low mood or a sense of flatness that does not fully respond to lifestyle measures.
• Bone pain, particularly in the lower back, hips, or shins.
• Frequent respiratory infections or a sense that immunity has reduced.
• Difficulty concentrating, sometimes described as an extension of brain fog.

None of these symptoms are specific to vitamin D deficiency; all are also common in perimenopause and a range of other conditions. This is exactly why a serum 25-hydroxyvitamin D test is the only reliable way to know where you stand.

Who is at highest risk

Deficiency is not evenly distributed. Clinicians generally pay closer attention to individuals who fall into one or more of the following groups.

• Skin types IV–VI: Melanin reduces UVB-driven synthesis, requiring longer sun exposure to produce the same amount of vitamin D.
• Northern latitudes (above roughly 35°N): UVB angle is too low for cutaneous synthesis from October to April in many regions.
• Housebound individuals: Outdoor sun exposure is effectively zero.
• People with obesity (BMI >30): Vitamin D is fat-soluble and can be sequestered in adipose tissue, reducing circulating availability.
• Those on medications that affect vitamin D metabolism: anticonvulsants, glucocorticoids, and some antiretrovirals.
• Anyone with malabsorptive gastrointestinal conditions: Crohn's disease, coeliac disease, or prior gastric bypass.

Bone health: the most direct clinical concern

The link between vitamin D and bone health is the most established. Vitamin D is required for the intestinal absorption of dietary calcium; without adequate circulating calcitriol, the gut absorbs only around 10–15% of ingested calcium, compared with 30–40% when vitamin D is sufficient. During perimenopause, oestrogen-driven bone protection wanes and remodelling becomes net negative. Vitamin D insufficiency compounds this by reducing the calcium supply that bone formation requires and by triggering secondary hyperparathyroidism — a state in which parathyroid hormone draws calcium out of bone to maintain serum levels.

National guidelines — including NICE in the UK and the Endocrine Society in the US — recommend a serum 25-hydroxyvitamin D level of at least 50 nmol/L (20 ng/mL) for bone health, with many specialists preferring levels above 75 nmol/L (30 ng/mL) during the menopause transition.

Testing and practical next steps

A serum 25-hydroxyvitamin D test (25(OH)D) is the standard measure. It is widely available through primary care and straightforward to request at a routine check-up. A fuller picture may also include calcium and parathyroid hormone, and, where bone loss is a concern, a DEXA scan to quantify density directly.

• Ask your clinician for a 25(OH)D test at your next well-woman or general health check.
• Note your latitude, typical outdoor time, and sun protection habits — relevant context for interpreting the result.
• Review current medications and supplements with your clinician before adding vitamin D.
• If supplementation is recommended, discuss the dose and monitoring plan; toxicity is rare but possible at sustained high doses.
• Consider dietary sources alongside supplementation: oily fish (salmon, mackerel), egg yolks, and fortified foods.