Food Sources ¹

Vitamin C is highly reactive and can be destroyed when exposed to light, oxygen, and heat, especially for prolonged periods of time. Steaming vegetables has been shown to be the best way to cook vegetables without significantly reducing the vitamin C content.² Under normal storage conditions, commercial vitamin C tablets are very stable, with nearly 95% potency retention over 5 years.³

Vitamin C is absorbed from the intestines directly into the blood, where it circulates freely. The kidneys detect and remove excess vitamin C through the urine. Because large amounts of vitamin C are not stored in the body, we need to consume it on a regular basis to maintain optimal levels. Unless there is a greater need, such as during illness or great stress, the body can only absorb a limited amount of vitamin C at one time. For example, almost 100% of a 200 mg dose of vitamin C is absorbed, but only about 50% of a 2,000 mg dose is absorbed, the rest is excreted through the bowels. For this reason, it is recommended that a person take vitamin C in divided doses throughout the day rather than one large dose.

The RDA for vitamin C is set at 75 and 90 milligrams per day for women and men respectively, plus 35 extra milligrams for those who smoke. While the RDA will certainly prevent scurvy, for optimal health, 200 milligrams a day is likely the minimum for healthy adults, although many holistically minded and functional medicine practitioners recommend 500-1000 milligrams a day.^{4 5 6 7}

Vitamin C is generally considered safe because the body can excrete any excess through urine or the bowels. At high doses (usually more than 2,000 mg) vitamin C can cause diarrhea, gas or stomach upset as the body excretes what it can’t presently use. To avoid this, use lower doses more frequently and slowly work up to higher amounts. Specific people who may want to exercise caution, especially of high dose vitamin C, include those with hemochromatosis (since vitamin C enhances iron absorption) and people predisposed to kidney stone formation.⁸ Long-term exposure to chewable and drinkable vitamin C may negatively affect dental enamel.

The chemical name of vitamin C is ascorbic acid. It occurs naturally in a wide variety of foods, and can also be synthesized from glucose. Much of the vitamin C in supplements is made from glucose derived from corn. Some manufacturers offer vitamin C that is from glucose derived from other starch sources such as tapioca (a.k.a. cassava), beet and sago palm. Because it would be prohibitively expensive to extract enough vitamin C from other food sources to make a supplement over 100 milligrams, the majority of vitamin C products are synthesized from glucose. All ascorbic acid is chemically identical regardless of source and there are no known differences in biological activity. Ascorbic acid is available in a variety of different forms.

Mineral salts of ascorbic acid, created when a charged mineral is bonded to ascorbate (the ion of ascorbic acid) are called mineral ascorbates. Because mineral ascorbates are considered to be “buffered” they are sometimes recommended for people with sensitive gastrointestinal tracts that may experience irritation (pain and/or diarrhea) when taking plain ascorbic acid. When a mineral ascorbate is taken, the mineral accompanying the vitamin C is also absorbed and used by the body, so it is wise to consider this when choosing a supplement, especially if you intend to take higher doses. Check the supplement facts panel to find out how much ascorbic acid and how much mineral is present in each serving. Mineral ascorbates that are available include: sodium ascorbate, calcium ascorbate, potassium ascorbate, magnesium ascorbate, zinc ascorbate, molybdenum ascorbate, chromium ascorbate, and manganese ascorbate

Foods that are naturally rich in vitamin C, especially citrus fruits, also tend to be excellent sources of water-soluble polyphenols called bioflavonoids. While some studies have shown enhanced absorption of ascorbic acid when taken with flavonoids, several others have shown no difference.^{9 10 11} Regardless, there is little doubt that bioflavonoids have many beneficial effects on their own and may more closely mimic the way ascorbic acid is found in foods. For more information on bioflavonoids see the Natural Grocers Customer Literature File titled Citrus Bioflavonoids.

Ester-C is a patented vitamin C that contains mainly calcium ascorbate, but also small amounts of vitamin C metabolites (which include dehydroascorbate and calcium threonate). Like other calcium ascorbates, Ester-C is “buffered” and the manufacturers claim that the metabolites enhance absorption and improve retention of vitamin C in the body and in particular the white blood cells. In small human studies, there is no difference in blood levels of vitamin C after taking Ester-Cversus ascorbic acid, but it does appear to result in higher concentrations and better retention of vitamin C in leukocytes (a type of white blood cell) compared to that achieved by ascorbic acid.^{12 13}

Not to be confused with Ester-C, ascorbyl palmitate is created when ascorbic acid is combined with palmitic acid (a fatty acid) creating fat-soluble vitamin C. It is sometimes used by the food industry as a preservative due to its antioxidant properties. In vitro (test tube) studies have found that ascorbyl palmitate protects cell membranes from oxidative damage.^{14 15 16} However, it is widely believed that ascorbyl palmitate is broken down into palmitate and ascorbic acid in the human digestive tract before being absorbed and therefore it is unlikely to make it to the cell membranes intact. The body is still able to use the ascorbic acid just as effectively, though, and ascorbyl palmitate is also likely to protect fat-soluble nutrients when included in supplements.¹⁷ Ascorbyl palmitate is perhaps at its most effective when used topically because it is more stable than other water-soluble forms of vitamin C and is used frequently in body care products.¹⁸

There are several foods that are naturally very high in vitamin C. Most of these foods are not common to the American diet but can be found in supplement form for those who wish to get their vitamin C strictly from foods.

• Acerola, sometimes called West Indian or Barbados cherry, is a type of tropical stone fruit that is believed to be native to the Yucatan but now grows from southern Texas to northern South America. The small red fruits typically contain about 1,500 mg of vitamin C per 100 grams. Acerola is also a good source of carotenoids and bioflavonoids.^{19 20}
• Rose Hips are the berries produced by rose bushes. In addition to high amounts of polyphenols, flavonoids and carotenoids, rose hips are very high in vitamin C, ranging from between 30 and 1,300 milligrams per 100 grams. ^{21 22}
• Amla, also known as Indian gooseberry and amalaki, grow on trees indigenous to tropical regions of Southeast Asia. It is one of the most important medicinal plants in Ayurveda where it is used to treat a wide range of complaints. Amla is generally believed to contain high amounts of vitamin C, although its actual vitamin C content is debated. It does contain high levels of antioxidants, such as polyphenols.²³
• Camu Camu is a fruit native to the Amazon. It also contains abundant polyphenols and high vitamin C ranging from 400 to 10,000 milligrams per 100 grams of camu camu.^{24 25 26}

Products that are exclusively food sourced tend to have lower amounts of vitamin C per serving than a product that contains isolated ascorbic acid, and the vitamin C content is likely to fluctuate based on growing methods, cultivar, and region, so look for standardized products that declare their vitamin C content. Products that are solely derived from food sources will list the amount of the food in the supplement facts panel. In addition to these food-only products, several manufacturers have added one of these vitamin C rich foods to isolated ascorbic acid products. It is not always clear from the front label what category a product falls into, so be sure to read the supplement facts panel to know exactly what you are getting.

Whole food vitamin C is ascorbic acid “grown” into a food medium, which creates a final product that provides all of the cofactors needed for the body to fully assimilate the nutrients. Similarly, food-based vitamins include a food complex that may consist of fruit and vegetable concentrates combined with ascorbic acid. Proponents say they enhance digestion and absorption of the vitamin C compared to isolated ascorbic acid.

Once you have decided on the form of vitamin C you would like to use, you’ll need to decide which delivery method works best for you. Since the bioavailability of most delivery forms appears to be equal, this is largely a matter of preference.²⁷

Capsules and Tablets are convenient for everyday use and for travel and are available in a wide variety of milligrams.

Liquids are flavored, and often, sweetened vitamin C in liquid. They are an easy and very palatable way to take vitamin C and are good for those who have trouble swallowing, for children, and for adding to smoothies or other beverages.

Powders are great for adding to smoothies or other beverages or for those with difficulty swallowing. Powders allow you to customize the vitamin C dose. Beware, though, vitamin C powder tends to be very tart.

Fizzy Powder becomes effervescent when added to water. Nearly all of the fizzy vitamin C products available also contain other vitamins and minerals, including electrolytes. These products are tasty and are packaged in single serving packets so they are easy to use on the go.

Timed-Release/Slow-Release vitamin C products are specially formulated to release their vitamin C gradually over a longer period of time. In theory, slowing down the rate at which ascorbic acid is released into the stomach should increase absorption over the long term with fewer pills, however studies are lacking.

Chewable or Gummy vitamin C products are often more palatable to children, but be aware that they can contain significant added sugar. Also, children can mistake chewables and gummies for candy, so be sure to keep them well out of the reach of little ones.

Liposomal – Liposomes are tiny fat-soluble vehicles that encapsulate a compound and carry it to the body’s cells. Phospholipids (the same fats that make up cell membranes) are the most common encapsulation material. In one small human study oral liposomal vitamin C lead to higher blood concentrations of vitamin C than an equal amount of oral un-encapsulated vitamin C and provided antioxidant protection similar to other vitamin C formulations.²⁸

References Available Upon Request