The time that a nutrient reserve will last if none is eaten varies. In general, our store of the
fat-soluble vitamins (A, D, E, K) will last a long time, because they are stored in body fat and
in the liver. But even for the nine water-soluble vitamins (B-l or thiamin, B-2, or riboflavin,
niacin, 8-6 or pyridoxine, folacin or folic acid, B-12 or hydroxocobalamin or cyanocobalamin,
biotin, pantothenic acid, and vitamin C or ascorbic acid) which are not stored in the same
the body's reserves will last for varying times. This is because there are often binding or
sites for them in body tissues. For example, folacin stored in the liver can last three months,
vitamin 8-12 stores in the liver may be sufficient for five years. With vitamin C, it would take
several months on a diet deficient in this vitamin for scurvy to develop.
Aside from storing vitamins, the body also usually has mechanisms for sparing nutrients in
supply or for dealing with one of their essential functions in another way. For example,
and phosphorus levels in blood can be maintained by hormones as well as vitamin D (although
will be at the expense of some of the calcium in bone).
The reason for advocating a food pattern providing all essential nutrients daily, at least at the levels of the RDIs (Recommended Dietary Intakes, see appendix 2), is to encourage safe long-term eating habits. It is not meant to imply that we would get into difficulty if we missed out on some nutrients on some days.