Describing something as “natural” does not make it more likely to succeed; as if Mother Nature is handing out tried and tested compounds like a kindly old woman handing out tea and biscuits. Also, there is no opposition between “nature” and man-made “chemicals” because nature is a monumental chemical factory. For example, levadopa (the main drug treatment for Parkinson’s) is a precursor to dopamine but dopamine is naturally occurring so why is it “unnatural” (implying harmful) to take it in tablet form? When does the manipulations of humans render nature (assumed to be good) into man-made (assumed to be bad)? Bread doesn’t occur in nature, it requires the manipulations of wheat and yeast by us, but is seen as natural. You could argue that bread uses “natural ingredients and not chemicals” but nature is made of chemicals!
Most natural remedies are based on subjective experience and the testimony of one person. It probably goes something like this: I eat some chocolate and find my symptoms improve; therefore, the chocolate must be helping me get better; simple cause and effect. However, this misses many other possible reasons for the improvement; normal variation in symptoms, the feeling I’m doing something to help myself, the sugar in the chocolate gives me more energy etc. There could be many contributing factors that are the cause (and many more that are incidental to the improvement).
For 400 years the “reductionist” approach of modern Science has separated out the potential causes and tested each one in turn to see which one has the biggest effect. For example, you want to know what causes water to heat up. First you add the same amount of water to a small container and a large container at room temperature (the variable you are testing is the size of container) but see no increase in temperature. The size of container does not cause water to heat up. Next, you fill two small containers with the same amount of water at room temperature but you put a flame underneath one container (the variable you are testing is presence of the flame): the water heats up! Therefore, the flame is the cause of warmth in the water. If you used one small container and one large container and applied the flame to the larger container it is impossible to see the real cause; the size of container and presence of the flame are both varying at the same time (the equivalent is happening in the chocolate example).
The method of Science (separate out the potential causes and test each one in turn) is immensely powerful. Modern life is build upon it. But Science, by its very nature and by the nature of the complex world it tries to describe, is slow and laborious; many variables need to be rigorously tested. In the void of knowledge and practical application (e.g. treatments for Parkinson’s) there can flow many spurious claims for cause and effect relationships (e.g. chocolate (cause) results in improvement (effect)). Without applying the Scientific method, care should be taken over such claims.