According to legend, once the only known asparagus was green. But, around the sixteenth century, following a large hailstorm that destroyed all the tips of the asparagus that came out of the ground, people had to eat only the part that was saved, namely that under the soil, the white one, because it had not been reached by the sunrays. In fact, both green and white asparagus all belong to the same species, asparagus officinalis. But green asparagus are grown out of the ground and take on a green color following exposure to the sun's rays, while white asparagus grow under the soil and are harvested before the plant emerges from the ground. Green asparagus is typically less woody and fibrous and more flavorful. But do the differences between the two types of asparagus stop there or do they also involve the nutritional profile? Today let's try to figure it out.
White and green asparagus, properties in common
Asparagus provides vitamins, such as groups B, E and K, and mineral salts, such as calcium, potassium, magnesium, selenium and zinc (Pegiuo et al, Metabolites, 2020). Both types of asparagus, green and white, contain saponins, which are substances with antioxidant, antibacterial and cholesterol-lowering properties, also useful to stimulate the immune system (Negi et al, Pharmacogn Rev, 2010). Asparagus, as well as other vegetables such as crucifers or garlic, are also a source of substances containing sulfur, useful to protect the plant itself from attacks but also for human health thanks to an anti-tumor and anti-inflammatory action. These substances are present in both green and white asparagus. In particular, in both types, a substance that until a few years ago was completely unknown, called asparaptine, was recently observed, which acts as an ACE inhibitor and is therefore very useful in controlling blood pressure and in protecting kidney health (Miyoshi et al., Anal Sci, 2018).
Green and white asparagus, the differences
Asparagus also contains antioxidant flavonoids but, unlike what we have seen so far, here the color of the asparagus can make the difference. In fact, green asparagus contains rutin, a powerful antioxidant with anticancer properties and a protective action for the heart, brain and blood vessels. Rutin is observed in a greater quantity towards the tip of the vegetable and then gradually decreases. Rutin was also found in white asparagus but in significantly lower quantities (Pegiou et al, Metabolites, 2020). Vanillic acid, with its neuroprotective properties, has been found only in green asparagus, as was quercetin, a substance with an immunostimulating and anti-inflammatory effect (Kobus Cisowska et al, Cencia rural, 2019). On the other hand, white asparagus, as a consequence of hardening after harvesting, contains high quantities of ferulic acid, an antioxidant with an antitumor and antidiabetic action, also useful to protect the brain from neurodegeneration (Srinivasanet al, J Clin Biochem Nutr, 2007). However, in general, green asparagus has a higher antioxidant power than white asparagus, precisely because exposure to the sun is crucial for the accumulation of anti-age and anti-radical substances (Pegiou et al, Metabolites, 2020). Finally, green asparagus contains a higher amount of vitamin C, white asparagus, in comparison, may contain less than half (Papoulias et al, Int J Mol Sci, 2009).
And what happens with cooking?
In asparagus cooking increases the amount of antioxidants, even by 30%, it is thought because in this way the asparagus becomes softer and it is easier to extract the antioxidant substances present (Papoulias et al, Int J Mol Sci, 2009). Although one might expect the opposite, cooking asparagus does not alter the amount of vitamin C, but as long as the cooking time does not exceed ten minutes, otherwise there is a drastic reduction of this vitamin, even by 50% (Papoulias et al, Int J Mol Sci, 2009).
