Ester-C Bio is a vitamin C supplement that helps capillary strength, connective tissue health, and immune function, thanks to calcium L-ascorbate Ester-C paired with citrus bioflavonoids. Active ingredients include Ester-C calcium L-ascorbate, Citrus bioflavonoid complex, rutin, and Pycnogenol, all picked to support immune health and vascular function. Klaire Labs is recognised for professional-grade, hypoallergenic formulations and GMP-compliant manufacturing that healthcare professionals trust. Not a quick fix, but reliable daily support.

Available Sizes & Variants:

100 capsules Ester-C Bio – allergen-free, professional-grade immune support

Benefits & Features:

• Supports capillary strength and connective tissue health.
• Star ingredient Ester-C calcium L-ascorbate minimises stomach upset while delivering potent vitamin C for immune support.
• Citrus bioflavonoids and rutin support absorption and antioxidant protection, helping keep capillaries resilient.
• Pycnogenol from pine bark supports microcirculation and may reduce oxidative stress.
• Pairs well with a multivitamin or probiotics routine for a balanced daily wellness plan, promoting overall resilience and ensuring you don't miss essential micronutrient coverage.

Drawing on Klaire Labs' heritage of purity and accuracy, Ester-C Bio combines non-acidic calcium L-ascorbate with plant bioflavonoids to aid capillaries and immune health. The blend leverages a patented Ester-C base with Pycnogenol® to support microcirculation and antioxidant protection, while being free from dairy, gluten, soy and major allergens. Manufactured in GMP-certified facilities, this professional-grade formula embodies Klaire Labs' commitment to high quality and transparency. Purity matters. Trusted by clinicians. It also pairs well with a vitamin d supplement for a balanced wellness routine.

(other) Vegetarian capsule (hydroxypropyl methylcellulose, water), stearic acid, microcrystalline cellulose, and silicon dioxide.

• GTIN: 828054002159
• Manufacturer: Klaire Labs
• Categories: Klaire LabsNew ArrivalsOut of stockPopular Supplement Brands
• Best buy: 6 - 24 months+

United Kingdom Shipping:

Orders placed by 2pm (Monday to Friday) are dispatched the same day. Orders placed after 2pm will be dispatched the next working day.

Free shipping on orders over £50 to the UK.

Returns: Our products are meant to make you feel healthy and at your best. If you need to return your item, you can do so free of charge within 30 days in the same original and unopened packaging. Subject to T&C's.

Take one capsule once or twice daily with food, or follow your healthcare professional's advice. Take 1 lozenge daily or as directed by your healthcare professional\, lozenge may be broken into smaller pieces if lower dosage is desired.
Do not take within 5 hours of bedtime as it may interfere with sleep.

Please consult the product packaging for accurate instructions on how to use the product.

The Active Ingredient Is: Vitamin C (Calcium L-ascorbate Ester-C)

Vitamin C, in the Ester-C form as calcium L-ascorbate, is a water-soluble nutrient essential for normal connective tissue health and immune function. This non-acidic, buffered form is designed to minimise gastrointestinal discomfort while delivering antioxidant support alongside plant-derived bioflavonoids.

This formulation combines Ester-C calcium L-ascorbate with a Citrus bioflavonoid complex, rutin and Pycnogenol®, which together help stabilise capillaries and support antioxidant activity and recycling of vitamin C.

What Does Vitamin C Do?

Vitamin C participates in normal collagen synthesis and supports capillary strength, connective tissue structure and immune system function. The accompanying bioflavonoids contribute to antioxidant protection and may enhance vitamin C absorption and recycling. The NHS and EFSA recognise vitamin C as supporting these normal physiological functions.

This supplement is not intended to diagnose, treat, cure, or prevent any disease.

Klaire Labs is our chosen brand for Ester-C Bio because this professional‑grade maker brings a long-standing reputation for purity, rigorous quality standards, and transparent sourcing. This brand is widely recognised in the healthcare community for its focus on hypoallergenic formulations and strict quality control, making Klaire Labs a trusted partner for sensitive and choosy consumers. The brand’s commitment to high‑grade ingredients and clear labelling aligns with Welzo’s standards for safety and reliability. For us, Klaire Labs’ well‑established practice of operating with strict purity and potency protocols underpins why we stock this brand in our UK catalogue, supported by Welzo's medical team for compliance with our ingredient quality and purity standards. Welzo's healthcare professionals and our ingredient quality and purity standards inform our evaluation, reinforcing Klaire Labs as a trusted supplier.

In terms of product fit, Ester-C Bio leans on branded ingredients such as Ester-C® and Pycnogenol®, with a formulation built to support capillary strength and immune function as described in the brand materials. This makes Klaire Labs especially suited to delivering a well‑characterised, specialist vitamin C supplement for the British market, where clarity of ingredients and manufacturing transparency are highly valued. Our product selection process emphasises thorough vetting by Welzo's expert team to ensure we maintain high standards for both brand and formulation.