Vitamin D for women who train
Vitamin D contributes to normal muscle function and the maintenance of normal bones, two foundations of consistent training. Those roles continue all year, even though the amount your skin can produce changes with season, location and lifestyle.
Vitamin D through the seasons
Your body can produce vitamin D3 when UVB radiation reaches the skin. The amount produced varies with latitude, season, time of day, cloud cover, clothing, skin pigmentation and how much time you spend outdoors.
This means that two women with similar training schedules can have very different opportunities to produce vitamin D. Indoor training, early sessions, covered skin and limited midday exposure can all reduce the contribution from sunlight, even during brighter months.
From sunlight to an active hormone
UVB radiation converts 7-dehydrocholesterol in the skin into previtamin D3, which then becomes vitamin D3, or cholecalciferol. The liver converts it into 25-hydroxyvitamin D, the form normally measured when vitamin D status is assessed.
The kidneys and other tissues can then produce calcitriol, the active hormone. Calcitriol binds to the vitamin D receptor inside cells and influences gene activity, including processes involved in calcium and phosphate balance.
Why vitamin D matters when you train
Vitamin D is not a quick performance ingredient. Its relevance is more fundamental and long-term. Normal muscle function supports every stride, pedal stroke and strength session.
Maintaining normal bones matters across years of training, particularly in sports that repeatedly load the skeleton.
Why it remains relevant all year
Vitamin D continues to perform the same biological roles when sunlight becomes stronger. What changes is how much the skin may contribute. Diet, daily routines and sun exposure also vary greatly between individuals.
The Daily Performance is designed as a year-round formula. Including vitamin D3 in the daily serving creates a consistent routine instead of requiring the formula to change with every season.
What vitamin D is officially allowed to claim
Under Regulation (EU) No 432/2012, these claims may be used for foods that meet the conditions for being a source of vitamin D. The Daily Performance provides 60 µg of vitamin D3 per daily scoop and meets that condition.
- Vitamin D contributes to normal absorption/utilisation of calcium and phosphorus.
- Vitamin D contributes to the maintenance of normal bones.
- Vitamin D contributes to the maintenance of normal muscle function.
- Vitamin D contributes to the normal function of the immune system.
The Daily Performance provides 60 µg of vitamin D3, equal to 2,400 IU and 1,200% of the EU NRV, per daily scoop.
How to interpret 60 micrograms
The Daily Performance provides 60 µg of vitamin D3 per daily scoop. This equals 2,400 IU and 1,200% of the EU nutrient reference value. The percentage may look high because the NRV is a labelling reference, not a maximum intake level.
EFSA has set the tolerable upper intake level for adults at 100 µg per day. This refers to total long-term intake from all dietary sources and is not a target.
Vitamin D3 in The Daily Performance
The formula uses vitamin D3 as cholecalciferol, the same form produced in the skin. Research comparing the two dietary forms generally finds that D3 raises and maintains circulating 25-hydroxyvitamin D more effectively than D2 under comparable conditions.
Vitamin D3 sits within a broader formula that also provides 75 µg of vitamin K2 as MK-7 and 193 mg of magnesium as magnesium bisglycinate.
- Commission Regulation (EU) No 432/2012: authorised health claims
- EFSA NDA Panel, 2023: Tolerable Upper Intake Level for vitamin D
- Kift and Webb, 2024: Globally estimated UVB exposure times required to maintain vitamin D status
- Tripkovic et al., 2012: Comparison of vitamin D2 and vitamin D3 supplementation
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