Spinach is an important leaf vegetable, now grown throughout the temperate regions of the world. It is most productive in cool seasons and climates, since heat will cause the spinach to go to seed too early. When cooked its volume is decreased by three fourths. Spinach loses much of its nutritional value with storage of more than a few days. While refrigeration slows this effect to about eight days, spinach will lose most of its folate and carotenoid content. This is worth considering when purchasing spinach out of season. If the product has been in transit (picked, cleaned, shipped and shelved) for more than one or two days it will need to be used almost immediately to have much nutritional benefit. This is in spite of the taste and appearance of the plant which may still seem fine.