Anthocyanins are water-soluble pigments found in plants that are responsible for blue, red, purple, and black colors. They belong to a larger class of pigment molecules called flavonoids. Anthocyanins serve several functions in plants, including pollinator attraction, photoprotection, and pest deterrence. In humans, they act as antioxidants and may offer health benefits. The red colors of autumn leaves come from anthocyanins.
Examples of Anthocyanins and Their Colors
There are many anthocyanins and there derivatives. Here are some anthocyanin examples, a list of some plants containing them, and their color ranges. Most anthocyanins are natural pH indicators that change color depending on whether conditions are acidic, neutral, or alkaline.
| Anthocyanin | Sources | Color |
|---|---|---|
| Cyanidin | Grapes, blackberries, blueberries, cranberries, raspberries, apples, red cabbage | pH < 3: Red pH 3-11: Purple pH > 11: Blue |
| Delphinidin | Delphiniums, violets, Concord grapes, cranberries, pomegranates | pH < 3: Blue pH 3-11: Purple pH > 11: Red |
| Malvidin | Primula (primrose) flowers, red wine, blueberries | acidic: Red neutral: Red basic: Blue |
| Pelargonidin | Red geraniums, strawberries, blackberries, red radishes, kidney beans | Red |
| Peonidin | Peonies, roses, morning glories, cranberries, plums, black rice, black bananas | pH < 3: Red pH 3-5: Yellowish-pink pH 5-8: Reddish purple pH > 8: Blue |
| Petunidin | Petunias, chokeberries, muscadine grapes | dark red to dark purple |
Function in Plants
Plants store anthocyanins in vacuoles in all tissues, including flowers, fruits, leaves, stems, and roots. The pigments serve a variety of functions:
- Attracting pollinators and herbivores that disperse seeds
- Protecting against cold stress
- Deterring herbivores that are attracted to the color green
- Allelopathy: For example, the red anthocyanin in maple leaves stunts the growth of nearby saplings.
Anthocyanin Benefits
Anthocyanins act as antioxidants in vitro and in vivo. However, scientific studies of anthocyanin benefits in humans yield mixed results.
In 2010, the European Food Safety Authority found no evidence of a beneficial antioxidant effect from including anthocyanins in the diet. Anthocyanins are approved for coloring food in the European Union (color code E163), but a 2013 study determined that too little is known about their safety and toxicology for them to be approved as a food additive or supplement. The exceptions are red grape skin extract and black currant extract, which are safe as additives. Similarly, anthocyanins are not approved food color additives in the United States, except for grape juice, grape skin, and fruit or vegetable juice.
However, some peer-reviewed studies indicate anthocyanins improve blood sugar metabolism, help prevent high blood pressure and heart disease, improve cholesterol levels, and inhibit breast cancer cell growth. Notable studies include a 2010 report in Nutrition Reviews on cardiovascular health, a 2011 study in the American Journal of Clinical Nutrition, and a 2017 study in the British Journal of Pharmacology on the effect of anthocyanins on cancer prevention and treatment. These studies indicate the necessity for further research into anthocyanin health benefits, but nutritionists agree deeply-colored fruits and vegetables are part of a healthy diet.
Foods High in Anthocyanins
Anthocyanin-rich foods are deeply-colored fruits, seeds, and leaves in the colors black, red, blue, or purple.
This table lists representative anthocyanin levels for various foods. Note levels are not exact, as they depend on time of harvest, fruit maturity, quality, and other factors.
| Food | Anthocyanin (mg per 100 g) |
|---|---|
| Black crowberry | 4180 |
| Purple corn | 1642 |
| Aronia (chokeberry) | 1480 |
| Norton grape | 888 |
| Black raspberry | 589 |
| Wild blueberry | 558 |
| Açaí | 410 |
| Raspberry | 365 |
| Concord grape | 326 |
| Marion blackberry | 317 |
| Red currant | 80-420 |
| Black currant | 190-270 |
| Queen Garnet plum | 277 |
| Black bean | 213 |
| Red cabbage | 150 |
| Cherry | 122 |
| Blue corn (maize) | 71 |
| Black rice | 60 |
Other foods containing anthocyanins include eggplant, cranberry, violet petals, apples, peaches, and black soybeans.
Not all red or purple plants get their color from anthocyanins. For example, the color in beets, cacti, and amaranth comes from betalains. Plants contain either anthocyanins or betalains, not both.
References
- Archetti, Marco; Döring, Thomas F.; Hagen, Snorre B.; et al. (2011). “Unravelling the evolution of autumn colours: an interdisciplinary approach”. Trends in Ecology & Evolution. 24 (3): 166–73. doi:10.1016/j.tree.2008.10.006
- Cassidy, A.; O’Reilly, É.J.; Kay, C.; et al. (2011) “Habitual intake of flavonoid subclasses and incident hypertension in adults”. Am J Clin Nutr. 93(2):338–347. doi:10.3945/ajcn.110.006783
- Davies, Kevin M. (2004). Plant pigments and their manipulation. Wiley-Blackwell. ISBN 978-1-4051-1737-1.
- European Food Safety Authority (April 2013). “Scientific opinion on the re-evaluation of anthocyanins (E 163) as a food additive”. EFSA Journal. 11 (4): 3145. doi:10.2903/j.efsa.2013.3145
- Khoo, H. E.; Azlan, A.; Tang, S. T.; Lim, S. M. (2017). “Anthocyanidins and anthocyanins: colored pigments as food, pharmaceutical ingredients, and the potential health benefits”. Food & Nutrition Research. 61(1): 1361779. doi:10.1080/16546628.2017.1361779
- Lin, B.W.; Gong, C.C.; Song, .HF.; Cui, Y.Y. (2017). “Effects of anthocyanins on the prevention and treatment of cancer”. Br J Pharmacol. 174(11):1226–1243. doi:10.1111/bph.13627