Green Tea Has Vitamin C

Vitamin C Content of Tea

Wikipedia: Vitamin_C
Last Updated: Nov. 6, 2014

Quick summary:

Green tea contains vitamin C; black tea does not.
Green tea only has small amounts of vitamin C, around 2-10% RDA per cup.
The fresher the tea, and the less processed, the more vitamin C.

Vitamin C, also called ascorbic acid or ascorbate, is an essential vitamin and antioxidant that occurs in nearly all fresh fruits and vegetables. The vitamin C content of tea depends on how the leaf is processed; there are few studies that actually measure the vitamin C content of various teas[4], but a combination of the few existing studies and what is known about the overall chemistry of vitamin C points to a clear pattern.

Green tea, when fresh, contains vitamin C, whereas oxidized types, such as black tea, contain none or only trace amounts.

The vitamin C content of some green teas is large enough to make a measurable contribution to dietary vitamin C, but it is small enough that even the teas richest in this vitamin cannot be relied on as a primary source of vitamin C. Most teas, however, contain either no vitamin C or only trace amounts. A typical fresh orange, by contrast, tends to have over 100% of the US recommended daily allowance (RDA) of vitamin C.

A bowl of ranges Oranges, a fruit high in vitamin C, are often associated with the vitamin in our culture.

What is vitamin C?

Vitamin C is a naturally-occurring compound essential to the metabolism of all plants and animals. Humans produce only trace amounts of the vitamin, yet require larger concentrations of it, and thus must obtain it from their diet. Vitamin C is found, usually abundantly, in fresh fruits and raw vegetables. However, it breaks down over time, and also breaks down with heat, so cooked foods or foods stored for a long time contain dramatically less vitamin C than their fresh counterparts.[3]

Vitamin C is safe to consume in large quantities, and it is unlikely anyone would encounter any negative impacts from the quantities of vitamin C present in natural foods. The Linus Pauling Institute notes that the recommended daily allowance for vitamin C in the U.S. is based on prevention of deficiency-based diseases such as scurvy, and is much less than the amount of vitamin C required for optimal health and prevention of chronic diseases such as heart disease and cancer.[2] People subjected to increased oxidative stress, such as smokers, are thought to have greater vitamin C requirements.

How much vitamin C is in tea?

According to a study published in a 1997 book that focused mostly on Japanese teas[1], typical commercial green tea contains about 280 mg vitamin C per 100 grams of dried leaves. If all of this were transferred to a brewed cup of tea, and the tea were brewed with 2.5 grams per cup, a cup of green tea would contain 7mg of vitamin C. According to the current US guidelines of 90mg recommended daily allowance for an adult male (lower for females), 7mg would be just under 8% of the RDA of vitamin C. However, vitamin C breaks down over time, breaks down with heat, and not all of it will be transferred from the leaf into the brewed tea, so 7mg is an overestimate or theoretical maximum for a typical cup of tea.

The same book also published measurements of the vitamin C content of brewed cups of tea, and found that it was zero to negligible for black, oolong, and roasted green (hojicha) teas. For other green teas, it ranged from 2 to 10mg per cup (2-11% RDA); this study used 3 grams of tea per cup, steeping with boiling water for 3 minutes.

Loose-leaf green tea
Gyokuro is high in vitamin C among teas.

Which teas are highest in vitamin C?

Among the loose-leaf teas studied, only green teas contained substantial vitamin C. Gyokuro had the highest vitamin C content in the brewed cup, followed by sencha, kamairicha, and bancha. This study was limited to Japanese green teas, and did not examine Chinese teas. However, most Chinese green teas are pan-fired, and in this respect are most similar to kamairicha, which contained small, but measurable amounts of vitamin C.

Fresher tea contains more vitamin C

It is well-known that vitamin C breaks down over time once foods have been harvested.[3] We found mention of a Japanese study that claimed that the vitamin C content in green tea has completely or mostly broken down after three years of storage; this seems plausible, but we were unable to locate this study for verification.

Vitamin C in other types of tea, such as white tea or Pu-erh

Heating or blanching processes, like the steaming or pan-firing used to process green tea, are known to cause an immediate breakdown in some vitamin C, but preserve the remainder of the vitamin so it breaks down slowly.[3] According to this pattern, we would expect to find that white teas would initially have a greater Vitamin C content by weight than green teas, which have been heated during processing, but that over time, the Vitamin C in the white teas would break down more quickly than in green teas. However, we were unable to find any published studies measuring the Vitamin C content of white tea.

Pu-erh is a type of tea that does not fit cleanly into the other categories. We also could not locate published studies on Pu-erh tea's Vitamin C content. Pu-erh comes in two main types: raw (sheng) or green Pu-erh, which is similar in processing to green tea, and ripened/cooked (or shu/shou) Pu-erh, which is fully oxidized through a process that shares some things in common with the production of black tea. The analogy to black and green teas would suggest that fresh raw Pu-erh has some Vitamin C, but ripened Pu-erh probably has none or traces. But, as raw Pu-erh is usually aged for long periods of time (years) before drinking, and Vitamin C breaks down over time, the aged sheng Pu-erh that people commonly drink probably only contains traces of the vitamin.

Vitamin C in bottled teas

Bottled tea, or ready-to-drink teas, which have been pre-brewed and packaged in cans or bottles, generally do not contain appreciable amounts of vitamin C naturally, but they sometimes have Vitamin C added, both for nutritional value, and as a preservative. Because of its antioxidant activity, ascorbic acid can act as a natural preservative in place of other non-nutritious preservatives such as sodium benzoate. Because these drinks are subject to labelling requirements, you can simply read the nutritional label on the bottle or can to assess the vitamin content of these teas on a case-by-case basis.

Herbal teas and vitamin C

Herbal teas are a whole other topic in and of themselves. Some herbal teas, including hibiscus tea, have a very high vitamin C content. Fruit herbal teas containing whole dried berries can contain vitamin C as well, although much less than fresh fruit. Fruit flavoring, however, common in many blends, imparts no nutritional value.

Although it is hard to generalize, herbal teas consisting of leaves that have been dried with minimal processing will tend to contain some vitamin C, whereas those that have been roasted or allowed to oxidize (like red rooibos) tend not to contain appreciable amounts. But, as with tea, most herbal teas contain far less vitamin C than fresh fruits and vegetables.

Brewing an infusion from freshly picked herbs, like lemon balm or mint leaves taken from a garden, will also yield a much higher Vitamin C content of the brewed cup than using dried herbs, but less than eating the herbs raw.

References:

1. Takehiko Yamamoto, Chemistry and applications of green tea, CRC Press, p. 14, 1997.

2. Vitamin C, Micronutrient Information Center, Linus Pauling Institute, Updated 2009.

3. Preharvest and postharvest factors influencing vitamin C content of horticultural crops, Jan. 2000.

4. Carmen Cabrera et. al., Beneficial Effects of Green Tea-A Review, Journal of the American College of Nutrition, Vol. 25, No. 2, pp. 79-99, Apr. 2006.

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