Learn all about Vitamin D
What is Vitamin D?
Boost immunity & bone strength with essential vitamin D3. Important for mood, muscles & calcium use. Feel the sunshine inside!
Benefits of Vitamin D
- Improves the body's use of calcium and strengthens bones (increases bone density), reducing the risk of broken bones in older adults.[ref]
"Vitamin D deficiency is surprisingly common even in sunny countries, affecting muscle function, bone health and immunity. While sunlight remains our primary source, supplementation is often necessary due to modern indoor lifestyles and concerns about skin cancer risk from UV exposure."
- Dr. Michael F. Holick, Professor of Medicine, Physiology and Biophysics at Boston University Medical Center (source)
How to use Vitamin D
Dosage
600-4,000 IU (International Units) daily for adults is common. Higher amounts are often needed if you have low levels (deficiency).
Timing
Best absorbed with fatty meals; timing throughout day not critical
Notes
A blood test is the best way to know the right dose for you. The D3 form (cholecalciferol) is usually recommended over the D2 form for supplements.
Who should take Vitamin D?
- Older adults at risk for weak bones (osteoporosis).
- People who get little sun exposure or have darker skin tones.
- People living far from the equator (northern latitudes), especially in winter.
- Those with conditions making it hard to absorb nutrients (malabsorption) or with kidney/liver disease.
How does Vitamin D work?
Vitamin D from sun or food needs to be activated by the body in two steps (first in the liver, then kidneys) to become 'calcitriol'. This active form attaches to special spots (receptors) on cells throughout the body, influencing many bodily functions. In the gut, it boosts calcium absorption from food. In bones, it works with another hormone (parathyroid hormone) to keep calcium levels balanced, supporting bone building and maintenance.
Frequently asked questions
Natural sources of Vitamin D
Most Vitamin D (80-90%) is made by your skin when exposed to UVB rays from sunlight. Food sources include fatty fish (salmon, mackerel), cod liver oil, egg yolks, and mushrooms grown in sunlight. Many foods have Vitamin D added (fortified), like milk, plant-based milks, and cereals. How much Vitamin D your skin makes depends greatly on the season, where you live (latitude), time of day, and your skin colour.
Potential side effects & risks
Warnings
People with certain conditions (like sarcoidosis, tuberculosis, lymphoma, kidney disease, or overactive parathyroid glands) should only use vitamin D under a doctor's guidance, as their body might process it differently or be more sensitive.
Side effects
Rare at normal doses. Taking too much (over 10,000 IU daily for a long time) can cause high calcium levels (hypercalcaemia). Symptoms include kidney stones, confusion, muscle weakness, and stomach problems.
Interactions
May increase absorption of aluminium from some indigestion remedies (antacids). Can interfere with certain cholesterol drugs and reduce the effect of some blood pressure medications (antihypertensives).