Hi Maria, if I had to rank order your various choices for why people choose natural products, based on Grocery Retail Consultancy experience, and a myriad of studies around organic, natural, clean foods and sustainable soft goods (apparel) & beauty and general consumer sciences work, here's what i can discern:

1. because they think natural products are healthier? (personal health benefits are generally the most likely connection point and tie to value propositions for brands/ grocers/natural goods producers in appealing to consumers and the broad selling point marketers position to bring awareness and drive sales)
1b. because they are recommended for specific health treatments? (solving or aiding specific personal health issues is a subset/ or more of a targeted approach to number 1)
2. because they want to conserve the environment? (this could tie into personal health as well, but if we think of it more external or tangential to personal health, the logic is self explanatory... revealing another tie to or more targeted approach to selling personal health and wellness)
3. due to the flavor or smell? (this is more preferential based where a personal experience with the product (or reading reviews) must occur (the brand or marketer would have successfully had to intercept the person and pique their interest enough to get them to physically seek out more info). With that in mind I don't think (flavor or smell) necessarily fits in with the other more psychological, behavioral drivers. It is involved in the decision making process but isn't likely to occur until the shopper is already in the funnel

Here are some additional categories to explore as potential drivers to natural products:
Price
Quality
FDA/ other certified seals of approval
Convenience
Nutrition Contents
Endorsements (non regulatory, maybe Celeb or Expert options)
Claims

Thank you for your question. Please don't hesitate to ask any additional or clarifying questions on the above.
-jahnia

I choose natural/organic products because some other ingredients scare me. There's little to no long term research on a lot of them...meanwhile I don't think turmeric or lavender can hurt me!

Secondly, I have a dog and I don't want weird chemicals around my fur baby :) I think if it's bad for a dog it'll probably be discovered that it's bad for humans later too.

Hope this helps!

A particular product or service is often chosen by an individual because it matches a perceived individual need by the consumer. The timing associated with awareness of need and learning about a match from the product is what determines eventual success if the product. It is about timing.

Most of the other respondents have addressed this topic. Beyond their points, which essentially address personal health and safety and environmental considerations, I would add one other: "natural" can provide jobs for people who might not otherwise be able to participate in certain sectors of the economy.

I can only answer for myself as I have not conducted research on the subject. I buy natural products and attempt to eat organic food because I believe they are healthier and less likely to cause allergic reactions and inflammation. Due to my allergies I prefer to stay away from all chemicals as I don't know what is going to negatively affect my breathing. I've been eating the same thing for three-plus years, Chipotle and green smoothies, and my doctor says I have the best blood numbers she's ever seen and to "keep doing what you are doing."

Earth-Friendly, produced and grown naturally, eco-friendly, anti-irritant/allergic, no-side effect, 

Dear Maria,
They choose natural products because of most of the points you have mentioned above but in case of flavor and smell, some of the natural products have unpleasant smell and flavor which may not be preferable to patients. However, they are more effective and have no side effects. Also, they are good for health and the treatment is mostly permanent.

Maria,
I do believe that all of your reasons are factors, but that it comes down to the individual consumer segments to identify the most compelling for each segment. Grouping consumers into attitudinal or personality buckets would offer the potential to target groups separately based on their specific beliefs and desires.