In much the same way that carbohydrate-rich foods can negatively affect diabetics, foods high in purine can have a serious impact on those with a condition called gout. Gout is essentially a crystallization of excess uric acid not processed by the intestines and kidneys. These crystalline deposits tend to collect in the feet and other major joints, leaving the sufferer in a nearly-constant state of pain unless deposit-busting medications are prescribed.
Gout was originally considered a disease of wealth, because only those who could afford a diet rich in purine seemed to contract it.
Today we know that foods high in purine are only one of several contributors to gout. Compromised kidney function or circulatory problems may also be factors. The standard medical advice for gout patients is to begin a diet with no more than 15% protein consumption per day. Not all meats have high levels of purine, but it is still better to restrict protein intake rather than risk temptation from the richer meats and proteins.

Some of the foods rated high in purine include the following: sweetbreads (internal organs), anchovies, sardines, canned liver, kidneys, hearts, meat extracts (broths and bouillon), gravies, and various canned seafoods. Other foods which contain slightly lower levels of purine include wild game and lentils. These are usually the items found on a typical do not eat list for gout patients. Other protein sources such as nuts or ground beef are limited to one serving per day.

As with other restrictive diets, the idea is to reduce the amount of a substance which cannot be naturally rendered harmless. Many healthy people can safely consume larger quantities of purine-rich foods with few problems. Those on high protein diets for weight loss are often encouraged to consume foods high in purine. As long as the body continues to flush away excess uric acid through the kidneys, high protein diets only increase the risk of developing gout, but do not cause the condition directly.
Eating excessive amounts of any foods, whether it be processed carbohydrates or purine, is rarely a good idea from a health perspective, but foods high in purine should be limited to an occasional treat, not a daily part of an average diet.