Much empirical research has already been conducted in order to analyze how speculation affects commodity and especially food prices. This paper examines the effects of speculation based on the most recent research. It is time to break with the innumerable studies examining the same material, yet always reaching different conclusions. Investigations using econometrics prove neither an influence of speculation on prices, nor the contrary. This paper explains however that speculation influences spot prices of commodities and food if it creates a significant excess demand over a significant time period. In this case speculation might be seen as harmful and unethical, why regulation should be discussed.