Due in stock end of October 2026. Pre-order now and we'll dispatch as soon as it arrives.
Dual Vitamin C — ascorbic acid and calcium ascorbate, with zinc
Each capsule provides 500mg vitamin C (625% NRV), half as ascorbic acid and half as calcium ascorbate, with 10mg zinc (100% NRV) and 25mg citrus bioflavonoids. Take 1 or 2 capsules daily, depending on preference.
Key Benefits
- Vitamin C (500mg per capsule, 625% NRV) contributes to the normal function of the immune system, to normal collagen formation for the normal function of skin, gums, bones, cartilage and blood vessels, to normal energy-yielding metabolism, to the reduction of tiredness and fatigue and to the protection of cells from oxidative stress. Vitamin C increases iron absorption. Vitamin C contributes to maintaining the normal function of the immune system during and after intense physical exercise; the beneficial effect is obtained with a daily intake of 200mg in addition to the recommended daily intake of vitamin C, which 1 capsule provides.
- Per capsule: 250mg calcium ascorbate and 250mg ascorbic acid.
- Citrus Bioflavonoids (25mg per capsule; 50mg per 2 capsules) — naturally-occurring plant compounds included alongside the vitamin C, as they are found together in nature.
- Zinc 10mg per capsule (100% NRV) as zinc bisglycinate. Zinc contributes to the normal function of the immune system.
Why Dr Marks?
Formulated by practising UK GPs and formulated within UK EVM and European guidance levels when used as directed.
How to take it
Take 1 or 2 capsules daily, depending on preference, ideally with food and a glass of water. Do not take more than 2 capsules (1,000mg vitamin C) a day. 90 capsules per pouch.
Cautions & interactions
- If you take levothyroxine, take this product at least 4 hours apart.
- Leave at least 2 to 3 hours between this product and tetracycline or quinolone antibiotics or bisphosphonates.
- If you have a history of kidney stones or haemochromatosis (iron overload), please check with your GP before taking high-dose vitamin C, as it increases iron absorption.
- Contains citrus (bioflavonoids), so please avoid if you have a citrus allergy. Please check the pack for the final allergen statement.
Suitability
Suitable for vegetarians (vegetable HPMC capsule). Made in a factory that also handles milk, egg, fish and crustaceans. Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Do not exceed the stated dose. Keep out of reach of children.
Formulation Comparison
Dr Marks Dual Vitamin C with Zinc vs Typical High-Street Supplement
90 vegan capsules · 1–2 a day · 19p–38p/daySuitable for vegans & vegetarians
| What to look for | Dr Marks Dual Vitamin C with Zinc | Typical High-Street Supplement |
|---|---|---|
| Dual-form Vitamin C | Dr Marks500mg per capsule (1,000mg per 2 capsules), split 50/50 between buffered Calcium Ascorbate & Ascorbic Acid |
Typical High-Street100% acidic ascorbic acid alone |
| Added co-factors | Dr Marks10mg Zinc (as bisglycinate, 100% NRV) + 25mg Citrus Bioflavonoids per capsule |
Typical High-StreetPlain Vitamin C or effervescent tablets with sweeteners |
| Flexible daily dosing | Dr Marks1–2 vegan capsules daily (90-capsule pouch: 45–90 days' supply) |
Typical High-StreetFixed single-dose tablets or sugary gummies |
| Excipients & coatings | Dr MarksNo titanium dioxide, talc, tablet glazes or artificial colours |
Typical High-StreetBulking agents, tablet glazes and artificial colours |
| Format & packaging | Dr MarksFlat, letterbox-friendly resealable pouch |
Typical High-StreetBulky plastic tubs or blister packs |
| Formulated by | Dr MarksPractising UK GPs |
Typical High-StreetGeneric mass-market contract formulas |
Compared against common single-form or standard A–Z high-street tablet formulations. Formulated within UK EVM and European guidance levels when used as directed.Made in a UK factory that also handles milk, egg, fish and crustaceans.
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 or 2 capsules a day with a main meal and water. Taking capsules alongside food supports normal digestion and helps make a daily habit stick.
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.
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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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