Capsules · 100 capsules · 100 servings · $0.40/serving
Serving Size:
1 Capsule
Amount Per Serving:
Vitamin C (as calcium L-ascorbate) Ester-C®‡ ... 540 mg
Calcium (as calcium L-ascorbate) Ester-C®‡ ... 60 mg
Citrus Bioflavonoid Complex ... 50 mg
(Citrus aurantium) (peel and fruit)
Rutin (sophora japonica) ... 75 mg
(Japanese pagoda tree bud extract)
French Maritime Pine Extract ... 3 mg
(Pinus pinaster) (bark) Pycnogenol®‡‡
Other Ingredients:
Vegetarian capsule (hydroxypropyl methylcellulose, water), stearic acid, microcrystalline cellulose, and silicon dioxide.
Free of the following common allergens: milk/casein, eggs, fish, shellfish, tree nuts, peanuts, wheat, gluten, and soybeans. Contains no artificial colors, flavors, or preservatives.
Caution
If you are pregnant, nursing, have a medical condition, or taking prescription drugs, consult your physician before using this product. KEEP OUT OF REACH OF CHILDREN.
Take 1 capsule, 1 to 2 times daily with food or as directed by a healthcare professional.
Open original label
Source: Fullscript supplier catalog · September 06, 2026. Formulas and labels can change. Check the packaging you receive.
Ester-C® Bio from Klaire Labs/SFI Health delivers calcium ascorbate, a pH-neutral, non-acidic form of vitamin C that supports immune function, antioxidant activity, and collagen synthesis. Unlike standard ascorbic acid, Ester-C® is buffered and contains naturally occurring vitamin C metabolites that may support enhanced cellular uptake. It's well-suited for individuals with sensitive digestive systems who want daily vitamin C without GI discomfort.
Why It's Worth Considering: Klaire Labs applies practitioner-grade manufacturing standards, and the Ester-C® form is a clinically recognized, patented compound, not a generic buffered ascorbate, making it a deliberate choice over commodity vitamin C products.
Take 1 capsule, 1 to 2 times daily with food or as directed by a healthcare professional.
| Feature | Ascorbic Acid | Buffered (Ascorbate) | Liposomal | Ester-C |
|---|---|---|---|---|
| Bioavailability | Good (standard) | Good (gentler) | Excellent (2-3x) | Good |
| GI Tolerance | May cause acidity | Very gentle | Excellent | Gentle |
| Best For | Budget, general use | Sensitive stomachs | Maximum absorption | Sustained release |
| Price | $ | $ | $$$ | $$ |
For maintenance, 500-1000mg daily is sufficient. For immune support during illness, 2000-4000mg in divided doses. The body can only absorb ~200-500mg at once, so split large doses throughout the day. Liposomal forms bypass this limit with 2-3x better absorption.
For most people, standard ascorbic acid at 500-1000mg is sufficient. Liposomal vitamin C is worth the premium if you need higher therapeutic doses (2000mg+) without GI distress, or if you have absorption issues. Studies show liposomal C achieves 2-3x higher blood levels than standard forms.
Vitamin C is water-soluble and excess is excreted in urine. The main risk of high doses (3000mg+) is GI distress (diarrhea, cramping) and increased oxalate production, which may contribute to kidney stones in susceptible individuals. The 'bowel tolerance' test, increasing dose until loose stools, then backing off, is a common practitioner approach.
Meta-analyses show regular vitamin C supplementation reduces cold duration by 8% in adults and 14% in children, and reduces severity. It does NOT prevent colds in most people, but it does in those under physical stress (athletes, military). Taking vitamin C after cold symptoms start has minimal benefit, daily prevention is key.
Take with food to reduce potential stomach acidity. Morning dosing is common since vitamin C may mildly increase alertness. If taking large doses (1000mg+), split into 2-3 doses throughout the day for better absorption and sustained blood levels.
No significant interactions identified. Always consult your healthcare provider.
† These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
