Shopping Cart

0 item $0.00

My Cart -

0 item

Ester-C 24-Hour Immune Support

Availability: In stock

$23.99 $28.99

Quick overview

* Required Fields

$23.99 $28.99
Read More: Chart
Read More: 24 Hour Immune Support


Why Ester-C®?

You need your immune system working at its best all the time. That's why there's Ester-C®, The Better Vitamin C®. Ester-C® is a unique, exclusive form of Vitamin C designed to stay in your white blood cells for 24-hours, providing you with around-the-clock immune system support.* After all, you don't want your immune system unsupported when you need it most. Take Ester-C® every day, just once a day, and your immune system will "C" the difference!*


What Are The Full Benefits Of Using Ester-C®?

  • 24-Hour Immune system support*
  • Non-Acidic, stomach-friendly for people who have problems taking regular vitamin C formulas
  • Exclusive form of Vitamin C - Unlike any other
  • Enhanced with C-SorbTM to get Ester-C® into your white blood cells fast
  • Provides antioxidant support to help neutralize cell-damaging free radicals*
  • Supports heart health*
  • Helps maintain healthy skin and gums*

Ester-C® is Calcium Ascorbate, a unique, exclusive form of vitamin C. It is made using a proprietary, water-based manufacturing process that results in a pH neutral product containing naturally occurring vitamin C metabolites. These metabolites activate the vitamin C molecules, making it easier for the body to transport them from cell to cell for numerous health benefits.**

One clinical study showed that Ester-C® increased vitamin C levels in the body.¹ White blood cell levels of Vitamin C were elevated in subjects receiving Ester-C® when measured after initial dose. The presence of key metabolites such as threonate may contribute to this increased level and retention of vitamin C by the cells.


Is Ester-C® Gentle on My Stomach?

Some people find that their stomach becomes irritated when taking regular forms of vitamin C. But Ester-C's® unique metabolite is non-acidic and stomach-friendly.*

In one published study, individuals sensitive to acidic foods were given one gram of vitamin C as ascorbic acid or as Ester-C.® Subjects rated Ester-C® as tolerated "very good" significantly more than ascorbic acid.² So for anyone who has difficulty tolerating vitamin C, it's comforting to know that Ester-C® is non-acidic and gentle on the stomach.*

The Science Behind Ester-C

“24-hour immune support”

Ester-C is an absorbable, non-acidic form of vitamin C and is created through a unique water based production process which neutralizes ascorbic acid with calcium carbonate to create calcium ascorbate and the metabolites of vitamin C, such as calcium threonate. The Ester-C mechanism of action has been investigated in various models. Laboratory studies have shown that exposing animal or human cells to calcium threonate increases the uptake of vitamin C by these cells [1, 2]. This improved cellular uptake may further facilitate the retention of vitamin C in the body. In preclinical models, Ester-C exhibited a higher plasma concentrations and less rapid excretion of vitamin C than ascorbic acid [3].

The White blood cells (WBCs), as an important component of the body’s immune system, are vital in the maintenance of overall health. Phagocytes consume extracellular vitamin C when the immune system is activated, causing plasma and WBC vitamin C concentrations to decline rapidly during activated stress to the body[4]. Furthermore, certain populations, including those with heart[5], blood sugar [6,7] and lung [8] health concerns have been reported to have reduced WBC vitamin C concentrations compared to the general population. Repletion of vitamin C has been shown to help assist with the health of these important functions [9]. An increased retention of vitamin C in WBCs is conducive to providing maximum cellular concentrations of vitamin C for optimum biochemical activity, including immune function.

A series of human randomized controlled trials have shown that vitamin C from Ester-C can be retained in WBCs longer than ascorbic acid [10] [11, 12](data on file). Furthermore, the supplementation of Ester-C has demonstrated significant benefits to immune health in men and women compared to placebo over a 60-day period from November to February [13]. This study has also been cited in the 2007 and 2013 Cochrane reviews describing the role of vitamin C in support of immune system health [14, 15]

“Gentle on the stomach”

Large doses of vitamin C behave differently in the body and bring profound biological effects. The acidic nature of ascorbic acid can be associated with adverse gastrointestinal effects, particularly in people who are sensitive to acidic foods. A higher prevalence of epigastric adverse effects were observed when ascorbic acid was consumed compared to Ester-C (62.5% vs. 37.5%) in healthy volunteers with acid sensitivity and statistically more participants rated “very good” tolerability of Ester-C compared to ascorbic acid (72% vs. 54%) [16]. Additionally, a significant worsening of abdominal pain and diarrhea was observed when given ascorbic acid, while no significant changes were seen when given Ester-C [17]. These results support that Ester-C, as a non-acidic form of vitamin C, is gentler on the stomach than ascorbic acid.


1. Fay, M.J. and A.J. Verlangieri. Life Sci, 1991. 49(19): p. 1377-81.
2. Fay, M.J., M.J. Bush, and A.J. Verlangieri,. Gen Pharmacol, 1994. 25(7): p. 1465-9.
3. Bush, M.J. and A.J. Verlangieri. Res Commun Chem Pathol Pharmacol, 1987. 57(1): p. 137-40.
4. Stankova, L., et al. Infect Immun, 1975. 12(2): p. 252-6.
5. Wintergerst, E.S., S. Maggini, and D.H. Hornig. Ann Nutr Metab, 2006. 50(2): p. 85-94.
6. Ramirez, J. and N.C. Flowers. Am J Clin Nutr, 1980. 33(10): p. 2079-87.
7. Akkus, I., et al.. Clin Chim Acta, 1996. 244(2): p. 221-7.
8. Shidfar, F., et al.. East Mediterr Health J, 2005. 11(1-2): p. 87-95.
9. Jayachandran, M., et al. . Journal of Anti-Aging Medicine, 2000. 3(1): p. 37-42.
10. Moyad, M.A., et al. Adv Ther, 2008. 25(10): p. 995-1009.
11. Mitmesser, S., M. Combs, and M. Evans. The FASEB Journal, 2014. 28(1 Supplement).
12. Wright JV, S.R., Kirk FR. International Clinical Nutrition Review, 1990. 10(1): p. 7-10.
13. Van Straten, M. and P. Josling. Adv Ther, 2002. 19(3): p. 151-9.
14. Hemila, H., E. Chalker, and B. Douglas Cochrane Database Syst Rev, 2007(3): p. CD000980.
15. Hemila, H. and E. Chalker. Cochrane Database Syst Rev, 2013. 1: p. Cd000980.
16. Gruenwald, J., et al.. Adv Ther, 2006. 23(1): p. 171-8.
17. Ye, Q., M. Combs, and S. Mitmesser. The FASEB Journal, 2015. 29(1 Supplement).

Ester-C® 500mg Tablets

Ester-C® 500mg Tablets provide the support you can count on all day, every day.* A daily dose of Ester-C® gets into your white blood cells, and stays there - for up to 24 hours, which is longer than regular Vitamin C.† Plus, Ester-C® is manufactured without chemicals to neutralize pH, which means it's non-acidic and gentle on your stomach.* 

Available in 500mg (60ct, 90ct, 120ct and 180ct sizes).

Supplement Facts

Serving Size: 2 Tablets

Amount Per Serving % DV
Vitamin C (as Ester-C Calcium Ascorbate) 1000 mg (1 g) 1667%
Calcium (as Ester-C Calcium Ascorbate) 110 mg 11%
C-SorbTM Citrus Bioflavonoids Complex Citrus Bioflavonoids (Citrus sinensis) (fruit) Sweet Orange, Tangerine, Lime, Lemon, Acerola Rutin, Hesperidin Complex (Citrus spp.) (fruit) Naturally Occurring Vitamin C Metabolites 204 mg **

** Daily Value Not Established

Cellulose (Plant Origin), Croscarmellose, Calcium Silicate, Vegetable Magnesium Stearate, Cellulose Coating

FREE OF: yeast, wheat, milk derivatives, lactose, sugar, preservatives, soy, artificial color, artificial flavor, sodium (less than 5 mg per serving)

SUGGESTED USE: For adults, take one (1) 1000 mg daily or one(1) 500 mg tablet two times daily, preferably with a meal. As a reminder, discuss the supplements and medications you take with your health care providers.

If you are pregnant, nursing or taking any medications, consult your doctor before use. Discontinue use and consult your doctor if any adverse reactions occur.


Product Tags

Use spaces to separate tags. Use single quotes (') for phrases.

Write your own review