Pre-order: one or more items in this bundle are on pre-order. We'll dispatch your bundle as soon as all items are in stock (due in stock end of October 2026).
Two winter staples, Vitamin D3 + K2 and Dual Vitamin C, together for less.
What's in the bundle
- Vitamin D3 4,000 IU + K2: vitamin D3 100µg (4,000 IU) with vitamin K2 (MK-7) 100µg per capsule.
- Dual Vitamin C: 500mg vitamin C (625% NRV) per capsule, as 250mg ascorbic acid and 250mg calcium ascorbate, plus 25mg citrus bioflavonoids and 10mg zinc (100% NRV) as bisglycinate. 1 or 2 capsules daily.
Key benefits
- Vitamin D contributes to the maintenance of normal bones, teeth and muscle function.
- Vitamin D contributes to the normal function of the immune system.
- Vitamin K contributes to the maintenance of normal bones and to normal blood clotting.
- Vitamin C contributes to the normal function of the immune system and the reduction of tiredness and fatigue.
- Vitamin C contributes to normal collagen formation for the normal function of skin.
- Vitamin C contributes to the protection of cells from oxidative stress and increases iron absorption.
- Zinc contributes to the normal function of the immune system.
Why Dr Marks?
Formulated by GPs, using active forms where it matters, and bundled so you can save compared with buying each product separately.
Directions
- Vitamin D3 4,000 IU + K2: One capsule daily with food.
- Dual Vitamin C: 1 or 2 capsules daily with food and water (no more than 2 capsules a day).
Do not exceed the recommended dose of any product.
Good to know
Contains citrus (bioflavonoids). Contains vitamin K. If you take anticoagulant medicine such as warfarin, speak to your GP or pharmacist before taking these products. If you take levothyroxine, take these products at least 4 hours apart. Leave at least 2 to 3 hours between Dual Vitamin C and tetracycline or quinolone antibiotics or bisphosphonates, and check with your GP or pharmacist if you take thiazide diuretics or digoxin. Check with your GP first if you take anticoagulants, have a history of kidney stones or haemochromatosis, or are pregnant or breastfeeding. Dual Vitamin C contains 10mg zinc per capsule (20mg in 2 capsules); keep total zinc from supplements at or below 25mg a day.
Do not take alongside other vitamin D supplements or multivitamins containing vitamin D. 100µg (4,000 IU) is the maximum daily amount of vitamin D for adults.
Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Keep out of reach of children.
A GP’s View on Supplement Timelines
Consistent Daily Use: What Happens in the Body
Many supplement brands print fixed charts promising you will “feel more energy in Week 2” or “see thicker hair in Month 2”. As practising UK GPs, we won’t do that. What happens when you take a supplement depends on whether you are topping up an everyday diet (where nutrients work quietly in the background and you may not “feel” a sudden change) or correcting a low level found on a GP blood test.
Days 1–7
Daily routine & digestive comfort
Take 1 capsule a day with a main meal and water. Taking your capsule with food is gentler on the stomach and helps fat-soluble vitamins absorb normally.
Weeks 2–6
Steady daily nutritional intake
Consistent daily intake helps top up your diet every day rather than in sporadic bursts. Water-soluble nutrients (such as B vitamins and vitamin C) are used daily and aren’t stored in large amounts, while fat-soluble nutrients (such as vitamin D) build up gradually with steady daily intake.
Weeks 8–12 (1–2 pouches)
Long-term maintenance & GP blood re-checks
Red blood cells turn over roughly every 90 to 120 days. When a GP treats a confirmed low level (such as vitamin B12 or vitamin D), NICE and NHS guidance typically schedules a clinical review or follow-up check around 3 months. For everyday dietary top-ups, steady ongoing habits matter most.
Not sure which one you need? Take the free nutrient quiz
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Dr Marc CrutchleyMBChB MRCGP MSc BSc (Hons), Co-founder
Dr Mark WilshereMBChB MRCGP DCH BSc (Hons), Co-founder
GP-Formulated in the UK✓ GMC-Registered Practising UK GPs · 40+ Years Combined Experience
Meet the GPs behind Dr Marks
Formulated by Dr Marc Crutchley and Dr Mark Wilshere, practising UK GPs.
With over 40 years of combined clinical experience as GMC-registered UK GPs, we formulate every Dr Marks supplement using bioavailable nutrient forms at meaningful daily doses — in clean plant-based capsules with zero synthetic fillers or binders.
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