Asparagus (Asparagus officinalis) is a fast growing crop high in folate and other nutrients. It is one of the best sources folate next to orange juice. Folate keeps down blood levels of homocysteine, which is a culprit in atherosclerosis and heart disease. Folate is essential for pregnant women. Folate deficiency can lead to birth defects like neural tube disorders. Green asparagus (Asparagus officinalis) is a healthy and nutritious vegetable, containing antioxidants, such as rutin, ascorbic acid, tocopherol, ferulic acid and glutathione. Rutin accounts for an important percentage of the antioxidant activity in asparagus (Tsushida, Suzuki, & Kurogi, 1994). Among 23 commonly consumed vegetables, antioxidant activity of asparagus, based on dry weight, has been ranked as the greatest (Vinson, Hao, Su, & Zubik, 1998).
Rutin is a relatively heat-stable antioxidant compared to ascorbic acid in asparagus. Commercially canned asparagus contained 0.16 ± 0.01 mg/g wet weight of rutin, which was less than 42% of that in fresh processed asparagus (Sun et al.,2007).
The green, white, or sometimes purple spears boast high concentrations of cancer-fighting antioxidants, including vitamins A, C, and E. Green asparagus has the highest levels. According to the National Cancer Institute, asparagus contains more of the antioxidant glutathione than any other fruit or vegetable, making it one of the key antioxidant foods. Glutathione fulfills numerous cellular functions, including detoxifying the body of carcinogens, protecting cell membranes and DNA from toxic compounds, participating in immune function, and recycling vitamins C and E, which are important for eye health, into active forms. Lightly steaming asparagus preserves the most glutathione. The tender tips hold most of this immune-boosting antioxidant.
Asparagus also maintains digestive health by supplying a dose of fiber and a special carbohydrate called inulin. This carbohydrate is indigestible to us, but readily consumed by intestinal bacteria. It promotes the growth of these beneficial bacteria, who in turn keep harmful gut bacteria at bay.
Asparagus deteriorates rapidly after harvest and becomes more fibrous with the development of a bitter flavour. It is, therefore, important to handle and process fresh asparagus quickly, to reduce the post-harvest losses and increase the economic return for farmers. Asparagus is preserved by canning, pickling, freezing and drying.
Green asparagus is a rich source of rutin (quercetin-3-rhamosylglucoside), a flavanoid. The levels of rutin in green asparagus shoot normally range from 0.03% to 0.06% on fresh weight basis. Rutin is a potent antioxidant and a scavenger of free radicals. Rutin has been reported to possess certain beneficial biological activities which include:
Reduction of oxidative damage
On average, fresh asparagus shoots contain 0.24 (tip portion) to 25 mg (base partion) per 100 g fresh weight of protodioscin. The levels of protodioscin in the crowns are around 25 mg/100g fresh weight.
Protodioscin has been reported to possess the following bioactivities:
Cytotoxicity against a number of human cencer cell lines
Reduction in bone loss
Improving sexual performance
Sun, T., Tang, J., & Powers, J. R. (2007). Antioxidant activity and quality of asparagus affected by microwave-circulated water combination and conventional sterilization. Food Chemistry. 100 (2), 813-819.
Tsushida, T., Suzuki, M., & Kurogi, M. (1994). Evaluation of antioxidant activity of vegetable extracts and determination of some active compounds. Journal of the Japanese Society for Food Science and Technology-Nippon Shokuhin Kagaku Kogaku Kaishi, 41(9), 611–618.
Vinson, J. A., Hao, Y., Su, X. H., & Zubik, L. (1998). Phenol antioxidant quantity and quality in foods: vegetables. Journal of Agricultural and Food Chemistry, 46(9), 3630–3634.