Estimated mean requirement and safe level of intake for vitamin A, in Retinol Equivalents (RE) (1 RE = 1 mcg. of retinol or 6 mcg. of beta-carotene):
- Adolescents, 10–18 years: 330–400 (mcg RE/day, mean requirement), 600 (mcg RE/day, recommended safe intake)
- Adult females, 19–65 years: 270 (mcg RE/day, mean requirement), 500 (mcg RE/day, recommended safe intake)
- Adult females, 65+ years: 300 (mcg RE/day, mean requirement), 600 (mcg RE/day, recommended safe intake)
- Males: 300 (mcg RE/day, mean requirement), 600 (mcg RE/day, recommended safe intake)
Food sources, examples (RE per 100 grams).
Fresh fruits and raw and cooked fruit vegetables:
- Mango - 523
- Apricots - 260 (dry - 730)
- Cantaloup 322
- Squash, cooked 714
- Red pepper, raw - 580
Root (tubers) and green vegetables, flowers:
- Carrots, raw - 2574
- Sweet potato, cooked - 2180
- Dandelion, raw - 1400
- Spinach, raw - 674
- Spirulina - 28333
- Nori - 4895
Isaac Bashevis Singer
What do they know-all these scholars, all these philosophers, all the leaders of the world - about such as you? They have convinced themselves that man, the worst transgressor of all the species, is the crown of creation. All other creatures were created merely to provide him with food, pelts, to be tormented, exterminated.
Seed is an embryonic plant enclosed in a protective outer covering. The formation of the seed is part of the process of reproduction in seed plants. Seeds have been an important development in the reproduction and success of gymnosperms and angiosperms plants, that now dominate biological niches on land.
The term "seed" also has a general meaning of anything that can be sown, e.g. "seed" potatoes (tubers), "seeds" of corn or sunflower "seeds".
Many structures commonly referred to as "seeds" are actually dry fruits. Different groups of plants have other modifications, the so-called stone fruits (such as the peach) have a hardened fruit layer (the endocarp) fused to and surrounding the actual seed.
Nuts are the one-seeded, hard-shelled fruit of some plants with an indehiscent seed (acorn, hazelnut).