**5. Rose hip as a medicinal plant**

As mentioned previously, rose hips are used worldwide as folk medicine and sometimes also as food. In this section, the focus is on the medicinal properties of the fruits. Prescription medicine that is purchased from a drug store often has documented dose dependency, indicating that the more you take of the remedy, the more impact there will be on the body. An interesting question is—can such dose dependency be shown for an herbal remedy like rose hip? It should also be stated that whatever is indicated for rose hip as regards the effect on different diseases, is only relevant for the subspecies being considered or tested, as such effects may not be relevant for other rose hip subspecies. Furthermore, the active ingredients in the shells of the rose hips are very different from that within the seeds (**Figure 5**) [23]. A product consisting of shells alone can therefore have very different content regarding the amount of different active ingredients when compared with a product consisting of seeds alone or the combination seeds and shells—not to speak about preparations made from the leaves or roots of rose hip [23]. The content of active ingredients, besides what is related to differences within species and subspecies [15, 58], is also dependent of where the plant is grown—on the soil, number of hours with sun and altitude [41] as earlier stated.

The best method for demonstrating the medicinal properties of drugs is the randomized, double-blinded, placebo-controlled study. Unfortunately, established pharmaceutical companies are rarely interested in herbal remedies. Therefore, much of the research on the different species of rose hip has been performed only in animal models or in *in vitro* systems. Due to the huge variations in rose hip species and subspecies, as regards their content of active ingredients, the version of rose hip species/ subspecies tested and sometimes also the manufacturing process will be stated. So far, the temperature at which the rose hips are dried during the manufacturing process of the herbs has been found to be very important [23]. This insight was first made by a Danish farmer, Erik Hansen, who recognized that he often lost his farm animals (e.g., cattle or horses), when their body temperature went above 42°C for a few hours. Upon coupling this observation with the knowledge that some of his friends also died when their body temperature went beyond 42°C even for short periods, Erik Hansen postulated that likewise, maintaining the rose hips to temperatures above 40°C for hours during the drying process would also be detrimental for the bioactive components in the fruits that have beneficial health effects. Hence, he invented and standardized a new method for storing rose hip for the winter season. In this process, the rose hips are never heated to more than 40°C. Moreover, the seeds and shells are separated and dried separately before milling, resulting in a rose hip powder, which

**Figure 5.** *One rose hip fruit with seeds exposed.*

still contains all that was in the fruit on the day of harvest, except for the well-known itching hairs, which are removed. Eating the powder containing seeds and shells is therefore like eating a rose hip fruit picked from a bush. Refer **Figure 6** for the dried seeds and shells before and after the milling process. This methodology is in sharp contrast to rose hip products from Chile (a major exporter of rose hip worldwide), where the seeds are often removed from the fruits, before drying them at high temperatures resulting in powders, which are more brownish in color [23]. Only very few rose hip preparations have been tested in well-designed clinical trials. But there are many different preparations available in the health stores. However, the content of active ingredients is very dependent on how the powder (if powder) was produced and if an extraction, then how was the extraction methodology, for that particular product. In addition, one should consider whether the preparations include shells or seeds only or a combination of seeds and shells.
