The primary positive effect of the Columbian exchange was increased food supply and nutrients to the populations of both areas. Europe probably benefited more than the Americas with the introduction of potatoes and maize (corn) to that continent. The end result was a decided improvement in the diet of most Europeans as well as a decline in the overall cost of food. Europeans tended to live longer after the exchange, fewer children died in infancy, and there was a resultant explosion in the population. This exponential population growth was a substantial factor in the advent of the Industrial Revolution.
Just as Europe benefited from the exchange, so the Americas suffered. Although many useful crops such as wheat, barley and rye and livestock such as cattle and swine were introduced, so also were infectious diseases such as measles and smallpox to which the native population had no immunity. Fully 90 per cent of the pre-Columbian population of the Americas had disappeared within 100 years of Columbus' landing. Conversely, it is widely believed by historians that Spanish conquistadores returning to Europe were infected with the Syphillis baccilus in the Americas. Just as the people of the Americas had no immunity to European diseases; so Europeans had no immunity to this sexually transmitted disease. A virtual epidemic resulted which caused thousands of deaths. The exchange was therefore beneficial and harmful to both; yet much more disastrous to the Americas than to Europe.
A decidedly mixed result was the introduction of black slavery into the Americas. Slavery itself was an unmitigated holocaust, resulting in the death and cruel mistreatment of untold numbers of human beings. However, it was through this sad chapter that black culture was introduced to the Americas which has enriched its cultural flavor over time.