Vitamin deficiencies in our diet will affect our health within a few days

False. There is no need to be unduly concerned about dietary indiscretions for a day or two. In the bodies of healthy people, there are stores of vitamins and other essential nutrients in reserve. This will be more certain where a wide variety of foods has been regularly eaten along with enough food to meet the overall energy needs of regular physical activity.

The time that a nutrient reserve will last if none is eaten varies. In general, our store of the four fat-soluble vitamins (A, D, E, K) will last a long time, because they are stored in body fat and also in the liver. But even for the nine water-soluble vitamins (B-l or thiamin, B-2, or riboflavin, 8-3 or 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 manner, the body's reserves will last for varying times. This is because there are often binding or holding sites for them in body tissues. For example, folacin stored in the liver can last three months, and 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 short supply or for dealing with one of their essential functions in another way. For example, calcium and phosphorus levels in blood can be maintained by hormones as well as vitamin D (although this 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.