Spotlight on: Vitamin D3 (Cholecalciferol)

Essential for:

• Absorption of calcium and phosphorus
• Helps maintain optimum calcium levels
• Development and maintenance of bones and teeth
• Maintenance of muscle function
• Immune function
• Helps reduce inflammation
• Involved in cell division process


• The sun (around 90%), when sunlight (UV rays) hits our skin and triggers D3 synthesis
• Diet (around 10%), high sources include oily fish, red meat, egg yolks, fortified foods

At risk of deficiency:

• Body’s ability to manufacture D3 tends to decline with age
• Reduced exposure to sunlight e.g. can’t get out of the house, winter months,  Northern hemisphere
• Tend to cover skin when outdoors
• Darker skin tones

Signs and Symptoms of deficiency:

• Ricketts (used to be seen in children, relatively uncommon nowadays)
• Osteopenia (lower bone density)
• Increased susceptibility to infections, colds, flu etc
• Tiredness, fatigue and feeling ‘down’
• Back, ‘bone’ and muscle pain

Can I take too much D3 supplement?:

• Recommended maximum dose 4000 IU per day for adults (NHS, England)
• High dose over long period may cause hypercalcaemia (calcium builds up affecting kidneys, heart and bones)
• You can’t overdose on vitamin D3 from sunlight, however, remember to protect your skin against sunburn

Potential interactions:

• Digoxin, may increase toxicity
• May increase risks of hypercalcaemia with several prescription medications
• Speak to healthcare practitioner if thinking of taking a vitamin D3 supplement alongside prescription medication

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