What is the difference between green and white asparagus? The latter is grown without photosynthesis, which is the process used by plants to convert sunlight into energy. Both are the same species of plant, Asparagus officinalis.
So how is white asparagus white, does it grow in the dark? Yep. It is grown underground with a layer of soil, mulch, and dark plastic tarp covering it. This prevents the spears from getting any sunlight and therefore, it remains a pale whitish-yellow color. On the other hand, the green variety is grown normally, with unobstructed access to light.
How is that possible? I thought plants needed light to grow?
Of course that leads to the logical question, how is it possible for it to grow without getting any sunlight? The answer is similar to how it's possible for seeds to sprout without light. The seeds of plants have stored nutrition in them and they also take in energy from nutrients in the soil. However this can only take them so far. You can sprout seeds without light but they will eventually die. If asparagus is permanently deprived of light, it will eventually die. The part of the vegetable we eat is the early shoot of the root as it sprouts above the ground.
With or without light, that will happen. Though it would be impossible for the plant to reach full maturity - 4 to 6 feet in height with leaves - if it were 100% deprived of light. For dietary purposes, since we only care about the first early shoots of it, that's not much of a concern for us and hence, why growing the pale white "vampire" version works just fine.
What does white asparagus taste like?
It does not taste like the traditional green variety. Rather, it tastes like corn or sweet cabbage, a more milder flavor which has been described as having a more sophisticated taste of bitterness. Speaking of which, that's why it's necessary to peel the bottom two-thirds of the spears. Not only is the skin thicker on that part, but it also has an extra-bitter taste; too bitter for most peoples' palates.
Does it make your urine or pee smell? Yes, this is not a myth. Both green and white asparagus creates a not-so-pleasant scent for most people due to our how body digests it. It's broken down into various types of sulfur, such as dimethyl sulfide. What else do you find that in? It may not be the same type, but sulfuric compounds are a primary component of skunk spray. Though it's in plenty of other foods we eat too, such as garlic. However for some unknown reason, not everyone can smell it themselves. It has been estimated that up to 40% of people cannot. A recent study has suggested there may be a genetic component as to why some people cannot smell the foul urine scent created by asparagus (1).
Is there vitamin K and antioxidants in it?
Just because it's the "stinky pee" vegetable doesn't mean you should avoid it. One of the biggest health benefits associated with asparagus is being high in vitamin K. If you eat 1 cup of the green type, you will be getting about 91 micrograms worth, which is equal to 114% of the daily value for adults. Although it doesn't get as much fanfare as more popular vitamins like C, vitamin K is extremely important for healthy blood clotting, your bone formation, and it has been suggested as possibly being beneficial for minimizing brain damage in some health conditions and diseases like Alzheimer's (2). But is there a difference in how much vitamin K is contained in white asparagus?
Surprisingly, the USDA nutrition database contains 14 entries for this vegetable in various forms but none of those reference the white variety. You can literally go through the first 100 entries in Google and look at all the articles making vague claims for the nutrition facts such as "rich in vitamin K" or "high in vitamin K" but none of them cite a source or amount in micrograms. Therefore without having a trusted source to verify the exact content, it would be reckless to say one way or another whether it's a "high" or "low" amount. With that disclaimer said, we would expect that the white variety still contains an above average amount of K. How it compares to the amount in the green is impossible to say without knowing both measurements.
One thing we can say for sure is that sadly, there is not much antioxidant content in white asparagus. In fact, how much antioxidants green asparagus has is over 7.5 times the amount of the white version.
USDA Database for the Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2 - Prepared by Nutrient Data Laboratory, Beltsville Human Nutrition Research Center (BHNRC), Agricultural Research Service (ARS), U.S. Department of Agriculture (USDA) - May 2010