NOW Foods C-500 ASCORBATE (100 Veg Capsules) — Buffered, Non-Acidic Vitamin C with Citrus Bioflavonoids
If standard vitamin C supplements give you heartburn, stomach cramps, or acid reflux, you are not alone. Traditional vitamin C is chemically pure ascorbic acid, which carries a sharp, sour pH of roughly 2.5 — nearly as acidic as lemon juice or vinegar. For millions of people with a sensitive digestive tract, taking high-potency ascorbic acid can trigger uncomfortable stomach irritation and digestive distress.
NOW® C-500 ASCORBATE solves this dilemma by using calcium ascorbate, a mineral-bound “buffered” form of vitamin C. By chemically binding ascorbic acid to gentle calcium, this formula neutralizes excess acidity into an easy-to-digest, almost pH-neutral compound (pH ~7.0) that is exceptionally kind to your stomach lining while delivering 500 mg of active, highly absorbable vitamin C per capsule.
Quick Product Snapshot:
Active Potency: 500 mg Vitamin C (from Calcium Ascorbate) + 55 mg Elemental Calcium per vegetarian capsule.
Synergistic Absorption: Fortified with 10 mg of natural Citrus Bioflavonoid Complex for cellular defense.
Stomach Friendly: Non-acidic, buffered delivery designed for empty-stomach tolerance and acid-sensitive systems.
Dietary Standards: Non-GMO, Vegan/Vegetarian, Soy-Free, Gluten-Free, Kosher, and Halal friendly.
Why Buffered Vitamin C Matters: Calcium Ascorbate vs. Ascorbic Acid Explained
To understand why calcium ascorbate works so well, it helps to look at how digestion works in everyday terms. When you swallow regular ascorbic acid, your stomach experiences an immediate spike in free acid concentration. In individuals prone to gastroesophageal reflux disease (GERD), gastritis, or ulcers, this acidic surge stimulates the production of digestive enzymes like pepsin and can irritate the delicate lining of your esophagus and stomach.
In contrast, calcium ascorbate acts like a built-in cushion. Because the ascorbic acid molecule is pre-combined with alkaline calcium, the compound enters the digestive system in a neutralized state. It breaks down gently in the intestines, delivering its active antioxidant payload directly into your bloodstream without sparking gastric flare-ups.
What Does Scientific Clinical Research Say?
Peer-reviewed medical trials have thoroughly investigated the real-world digestive benefits of buffered calcium ascorbate:
Reduced Stomach Acidity and Pepsin Irritation: A landmark pharmacological study published in the Korean Journal of Physiology & Pharmacology demonstrated that while standard ascorbic acid significantly elevated total gastric acid output and irritating pepsin activity, calcium ascorbate raised gastric fluid pH toward neutral without provoking excess gastric secretions, preventing stomach lining deterioration while matching the full antioxidant potency of pure vitamin C (Lee JK, Jung SH, Lee SE, et al. Korean J Physiol Pharmacol. 2018;22(1):35-42. PMID: 29302210).
Superior Human Tolerability & Cellular Uptake: A comprehensive systematic literature review published in Nutrients evaluated alternative vitamin C delivery mechanisms, finding that non-acidic calcium ascorbate formulations produced significantly fewer epigastric adverse events (such as heartburn, nausea, and cramping) and improved quality of life compared to conventional ascorbic acid, while successfully maintaining elevated vitamin C concentrations inside immune-protecting white blood cells (Calder PC, et al. Nutrients. 2025;17(2):279. doi:10.3390/nu17020279).
Nutritional Feature
Standard Ascorbic Acid
NOW C-500 Calcium Ascorbate
Acidity / pH Level
Highly Acidic (pH ~2.5)
Buffered / Near Neutral (pH ~7.0)
Stomach Comfort
Can cause burning, reflux, or cramping
Gentle on sensitive stomach linings
Empty Stomach Use
Generally discouraged
Well-tolerated with or between meals
Mineral Support
Zero mineral content
Supplies 55 mg elemental calcium per capsule
The Synergistic Formula: Citrus Bioflavonoids & Targeted Health Benefits
In nature, vitamin C never grows in isolation. Whenever you peel an orange or a grapefruit, the vitamin C inside the fruit pulp is naturally surrounded by plant pigments called bioflavonoids (specifically hesperidin and naringin). NOW Foods incorporates 10 mg of a concentrated Citrus Bioflavonoid Complex into every capsule to mirror this natural whole-food partnership.
Bioflavonoids act like microscopic “bodyguards” for vitamin C: they protect the fragile ascorbate molecule from degrading or oxidizing before your cells have a chance to absorb it (Vinson JA, Bose P. Am J Clin Nutr. 1988;48(3):601-604. PMID: 3414575). Together, this buffered duo delivers broad-spectrum daily wellness:
✓ 1. Robust Immune System Defense
Your white blood cells (such as phagocytes and lymphocytes) actively accumulate up to 80 times higher concentrations of vitamin C than the surrounding bloodstream. When seasonal pathogens strike, these immune cells consume their internal vitamin C reserves at a rapid rate to generate protective antibodies and fight off oxidative damage. Replenishing with 500 mg of non-acidic ascorbate helps ensure your frontline defenses stay charged and ready.
✓ 2. Youthful Collagen Production for Skin, Hair, Nails & Joints
Collagen is the biological glue that gives your skin its bounce, your hair its strength, your nails their durability, and your joints their flexible cushioning. Your body cannot physically assemble collagen without vitamin C; it serves as the essential catalytic cofactor for two critical enzymes (prolyl hydroxylase and lysyl hydroxylase) that knit amino acids into strong collagen fibers. Regular supplementation helps support natural skin elasticity and protects structural tissue against premature aging.
✓ 3. Broad-Spectrum Free Radical Scavenging
Every single day, your body encounters free radicals — unstable molecules generated by air pollution, ultraviolet sunlight, psychological stress, and normal metabolic activity. Vitamin C is one of the body’s most powerful water-soluble antioxidants, actively donating electrons to stabilize these rogue molecules before they can damage cell membranes or vital DNA structures. Furthermore, vitamin C helps recharge spent vitamin E, recycling it back into an active lipid antioxidant.
✓ 4. Gentle Non-Heme Iron Absorption
Non-heme iron found in plant foods (such as spinach, beans, and grains) can be difficult for the human digestive tract to absorb. Vitamin C chemically converts dietary iron into a soluble ferrous state, significantly enhancing intestinal absorption without necessitating stomach-churning acidic pills.
Dietary supplements sold across third-party internet marketplaces frequently suffer from unverified potency claims, cheap synthetic fillers, and dangerous heavy metal adulteration. NOW Foods stands as an industry benchmark in analytical rigor, investing millions into private, state-of-the-art testing laboratories located in Bloomingdale, Illinois, and Sparks, Nevada.
NOW conducts over 31,000 analytical tests every single month across raw materials, in-process production, and finished products. Their testing protocols follow exacting standards to ensure uncompromising purity:
Advanced Analytical Testing Methods Used by NOW:
Trace Heavy Metal Screening (ICP-MS): Utilizing Inductively Coupled Plasma Mass Spectrometry, NOW chemists screen for toxic heavy metals — including lead, arsenic, cadmium, and mercury — down to parts-per-billion (ppb) detection levels. This ensures finished lots strictly satisfy California Proposition 65 thresholds and exceed United States Pharmacopeia (USP) safety limits.
Potency & Identity Verification (HPLC / UHPLC): High-Performance Liquid Chromatography is utilized to verify the exact molecular fingerprint and concentration of calcium ascorbate, ensuring that each capsule delivers 100% of the 500 mg active vitamin C stated on the label throughout its entire shelf life.
Multi-Residue Pesticide & Solvent Screening (GC-MS/MS & LC-MS/MS): Gas Chromatography and Liquid Chromatography tandem mass spectrometers screen raw botanicals and extracts for over 200 agricultural chemicals, synthetic residues, and extraction solvents down to trace thresholds.
Automated Pathogen Screening: Automated Polymerase Chain Reaction (PCR) and microbiological culture plating rigorously inspect every single production lot for harmful bacteria and pathogens, including Salmonella, Escherichia coli, Staphylococcus aureus, total yeast, and molds.
Accredited Facility Certifications: NOW Foods’ analytical and microbiological laboratories maintain formal ISO/IEC 17025:2017 accreditation through the American Association for Laboratory Accreditation (A2LA). Their production facilities hold an “A” Good Manufacturing Practices (cGMP) rating from the Natural Products Association (NPA) and are audited under UL Solutions cGMP certification (21 CFR Part 111).
Full ingredient transparency is the bedrock of consumer safety. Below are the verified supplement facts and complete ingredient details for NOW C-500 ASCORBATE (Product Code: N0676 | UPC: 733739006769):
Supplement Facts
Serving Size: 1 Veg Capsule | Servings Per Container: 100
Active Ingredients
Amount Per Serving
% Daily Value
Vitamin C (from Calcium Ascorbate)
500 mg
556%
Calcium (from Calcium Ascorbate)
55 mg
4%
Citrus Bioflavonoid Complex
10 mg
† Daily Value not established
Other Ingredients: Hypromellose (cellulose capsule), Microcrystalline Cellulose, and Stearic Acid (vegetable source).
Allergen Free From: Not manufactured with wheat, gluten, soy, milk, egg, fish, shellfish, or tree nut ingredients. Produced in a cGMP facility that processes other ingredients containing these allergens.
Storage & Physical Appearance: Store in a cool, dry place after opening. Natural color variation may occur in this product over time without affecting potency or quality.
How to Take: Suggested Usage, Optimal Timing & Split Dosing
Manufacturer Directions: Take 1 capsule 1 to 3 times daily, preferably with meals or a tall glass of water, or as recommended by your physician.
Why We Recommend the “Split Dosing” Method
Vitamin C is water-soluble, which means your body does not store it in long-term bodily fat reservoirs. Research from the National Institutes of Health (NIH) indicates that intestinal vitamin C transporters (SVCT1) operate most efficiently at doses of 200 mg to 500 mg at a time.
If you take a massive 1,500 mg megadose all at once, your body absorbs a lower percentage and excretes the rest through urine within a few hours. By taking one 500 mg capsule in the morning and one capsule in the late afternoon, you maintain steady, saturated antioxidant blood levels throughout the entire 24-hour cycle.
Gentle on an Empty Stomach: While conventional ascorbic acid should almost always be taken with food to reduce irritation, calcium ascorbate’s buffered pH means it can safely be taken on an empty stomach if your schedule demands it.
Important Safety Guidelines, Constraints & Drug Interactions
True health authority requires addressing who a supplement is not suitable for. While vitamin C is widely regarded as one of the safest dietary supplements available, high-potency supplementation requires sensible precautions:
Kidney Stones & Hyperoxaluria: In the human body, a fraction of metabolized vitamin C naturally converts into oxalic acid (oxalate). If you have a personal medical history of calcium oxalate kidney stones, or suffer from severe renal impairment, you should consult your urologist or nephrologist before taking supplemental vitamin C doses exceeding 500 mg per day, and always ensure adequate daily water intake.
Iron Overload Conditions (Hemochromatosis): Because vitamin C substantially enhances non-heme iron absorption in the gastrointestinal tract, individuals diagnosed with hemochromatosis, thalassemia, or other iron-storage disorders should avoid high-dose vitamin C unless specifically directed by their treating physician.
Tolerable Upper Intake Level (UL): The Institute of Medicine (IOM) Dietary Reference Intake sets the Tolerable Upper Intake Level for adult vitamin C supplementation at 2,000 mg per day. Exceeding this threshold can draw water into the large intestine, causing osmotic diarrhea or loose stools (Johnston CS. Nutr Rev. 1999;57(3):71-77).
Calcium Considerations: Each capsule supplies 55 mg of elemental calcium (4% Daily Value). While this is a modest amount, individuals on strictly medically monitored low-calcium diets should factor this into their daily dietary calculations.
Potential Medication Interactions: High-dose vitamin C can interact with certain prescription pharmaceuticals, including blood thinners (Warfarin), statin cholesterol therapies, and aluminum-based antacids (vitamin C can increase aluminum absorption). Always consult your primary healthcare physician before starting a new supplement regimen if you take prescription medications, are pregnant, or are nursing.
*Disclaimer: 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.
Why Choose VitaNet®, LLC for Your Nutritional Supplements?
In an era where anonymous third-party online vendors ship questionable bottles stored in unconditioned warehouses, VitaNet®, LLC provides authentic, family-owned reliability:
Serving Online Customers Since 1995: VitaNet®, LLC was founded in 1995 as an independent, family-owned discount retailer bringing over 31 years of hands-on industry experience and a deep understanding of natural health products to our shoppers[cite: 1].
Unconditional 100% Money-Back Guarantee: We stand entirely behind our curated catalog. VitaNet offers a comprehensive money-back guarantee that even pays return shipping costs on returned products, whether the bottle is opened or unopened[cite: 1].
Verified BBB A+ Accredited Business: We maintain an accredited A+ rating with the Better Business Bureau, reflecting over three decades of straightforward business integrity[cite: 1].
Direct Brick-and-Mortar Storefront & Telephone Support: Our physical storefront is located at 887 Edison Street Northwest, Hartville, Ohio 44632[cite: 1]. Real, knowledgeable customer service representatives are available by phone Monday through Friday to answer your order inquiries at (330) 877-8786 or toll-free at 1-800-877-8702[cite: 1].
Direct Inquiries: VitaNet, LLC • 887 Edison St NW, Hartville, OH 44632 • Phone: (330) 877-8786[cite: 1] • Email: Support@vitanetonline.com
Frequently Asked Questions (FAQ)
What is the main difference between calcium ascorbate and ascorbic acid?
Ascorbic acid is the pure, unbuffered form of vitamin C with an acidic pH of about 2.5, which can irritate sensitive stomach linings. Calcium ascorbate is chemically bound to calcium, creating a buffered, non-acidic compound (pH ~7.0) that is much gentler on digestion while delivering identical antioxidant benefits.
Will NOW C-500 Ascorbate trigger acid reflux or heartburn?
Unlike acidic supplements, buffered calcium ascorbate does not increase gastric acid production or provoke esophageal irritation. Clinical studies demonstrate that it raises stomach fluid pH toward neutral and significantly cuts down on epigastric distress, making it an ideal choice for people with GERD or acid sensitivity.
Why are citrus bioflavonoids included in this formula?
Citrus bioflavonoids are natural plant antioxidants found in fresh fruit. They work synergistically with vitamin C to protect it from premature oxidation and degradation in the body, enhancing its cellular effectiveness for immune and capillary support.
Does the calcium in this supplement replace my daily calcium pill?
No. Each capsule provides 55 mg of elemental calcium, which is roughly 4% of your recommended daily value. It serves primarily as a gentle chemical buffer for the vitamin C, though it does offer a small bonus toward your daily calcium intake.
How does NOW Foods test this product for heavy metal contaminants?
NOW Foods utilizes Inductively Coupled Plasma Mass Spectrometry (ICP-MS) in its ISO/IEC 17025 accredited in-house testing labs. This sensitive equipment screens every batch for trace heavy metals (lead, arsenic, cadmium, mercury) down to parts-per-billion levels to meet strict California Proposition 65 standards.
Can I take this supplement if I have a history of kidney stones?
If you have a history of calcium oxalate kidney stones, you should consult your doctor before taking high supplemental doses of vitamin C, as excess amounts can metabolize into oxalate. It is also recommended to drink plenty of fluids daily to support kidney filtration.
What if this product does not agree with my digestion?
VitaNet offers a 100% money-back guarantee on all products, and we even pay the return shipping costs for a full refund whether the bottle has been opened or not[cite: 1]. You can reach out directly to our store team in Hartville, Ohio at (330) 877-8786 for assistance[cite: 1].
