**4. Nutritional content of rose hips**

Rose hips are known to contain high amounts of nutrients and bioactive substances that positively impact health. The fruits are particularly rich in vitamins, especially vitamin C, A, and E, as well as carotenoids (including beta-carotene and lycopene), essential fatty acids [30], polyphenols (including flavonoids, proanthocyanidins, catechins), triterpene acid, galactolipid [27], and antioxidants. They also have a noticeable content of dietary fiber compared with other fruits [31]. Regarding the content of bioactive compounds in rose hip seeds, refer the review by Winther et al. [23].

The content of nutrients and bioactive compounds can vary significantly depending on the species [2], ripening state, and environmental factors such as location and growth conditions [27]. Therefore, all rose hips are not equal in terms of their nutritional and bioactive contents. In this chapter, the focus will be on the fruits from *R. canina* and *R. rugosa*, with emphasis on some of the substances that these two species are particularly rich in, such as, vitamin C, specific carotenoids, and antioxidants.

#### **4.1 Vitamin C**

Rose hips are some of the richest sources of vitamin C among fruits and vegetables. The water-soluble vitamin is a vital micronutrient, and longer periods of deficiency results in scurvy, a deadly disease that earlier cost the lives of millions of people around the world [32]. The amount of vitamin C needed to prevent scurvy is small (10 mg/day) [33], and the disease is rare in today's societies. However, during times of food crisis or war, when most of the cultivated fruits and vegetables are scarce, access to vitamin-C-rich food, such as rose hips, could play an important role in the prevention of scurvy. For example, during World War II, this was the case in the United Kingdom, where blockages on the sea traffic made it difficult to import citrus fruits from the warmer colonies, rose hips became the country's main sources of vitamin C. For this reason, the British government encouraged people to gather and consume rose hips growing in the wild, to avoid an outbreak of scurvy [34].

In the human body, vitamin C influences many different physiological functions, acting as an important antioxidant and a cofactor in the biosynthesis of neurotransmitters, carnitine, and collagen [35]. The vitamin is also essential to the immune system, where it is found in high concentrations in the leukocytes, the body's immune cells. When these cells are activated by ongoing infections, the local quantity of vitamin C raises many folds. In neutrophils, vitamin C is thought to act as an antioxidant, protecting the immune cells from self-destruction by the reactive oxygen species (ROS) they produce in their fight against foreign pathogens, such as viruses or bacteria [33]. Furthermore, a clinical trial showed that supplementation with dietary vitamin C, given in the form of kiwi fruits, could enhance the function of the neutrophils, by stimulating their movement toward the site of infection [36]. In line with this finding, another study indicated that when patients with impaired immune systems, who were experiencing recurring infections, were given adequate amounts of vitamin C in their diet, their infections ceased [37]. Vitamin C also impacts other aspects of our health such as our cognitive functions [38], mood and energy, and common symptoms of low vitamin C intake includes irritability, fatigue, and decreased antioxidant capacity [35].

The daily recommendation for vitamin C varies greatly from country to country, with 40 mg/day in India and the United Kingdom, to 110 mg/day in Germany and France [39]. However, some authors argue that the body needs 200 mg/day to sustain good health [33, 40]. The vitamin C content in rose hips differs among *Rosa* species (**Table 1**) [48]. Furthermore, the vitamin content varies also with other factors such as growth location [27, 41] and the ripening state of the fruits [27, 30]. Generally, fruits from *R. rugosa* generally contain high amounts of vitamin C, from 600–1090 mg/100 g dried fruits [25, 31, 42, 43]. In *R. canina* the vitamin content varies significantly, from


#### **Table 1.**

*Vitamin C content in selected berries, fruits and vegetables.*

274 to 2700 mg/100 g [41, 44, 45]. By contrast, in the few studies, where the content of vitamin C was compared in both strains, *R. canina* was found to contain significantly lower levels of the vitamin, as compared with the levels in *R. rugosa* [6, 27, 30].

#### **4.2 Carotenoids**

Rose hips from *R. rugosa* and *R. canina* are rich in carotenoids, including betacarotene and lycopene—plant color pigments that give fruits and vegetables their characteristic orange and red color [15]. Both carotenoids have well-known antioxidant effects [35], with lycopene being the most potent antioxidant among carotenoids [49]. Moreover, beta-carotene is a precursor for the biosynthesis of vitamin A, a fatsoluble antioxidant that is vital for our sight and skin. The vitamin is also essential for the immune system, such that one of the signs of vitamin A deficiency is an impaired resistance to infections [35]. While beta-carotene is the most abundant carotenoid in fruits and vegetables, lycopene-rich foods are fewer in number [50, 51]. Lycopene has recently gained a lot of attention in the field of health science, and a growing number of studies have linked the intake of this carotenoid with a decreased risk of cardiovascular disease [49, 52]. A meta-analysis from 2017 supports this indication of carotenoids by concluding that an increased intake of lycopene-rich food, including tomato products, could have a positive effect on blood pressure and endothelial function [53].

The content of beta-carotene and lycopene varies significantly in rose hips from both *R. canina* and *R. rugosa*. The fruits from *R. rugosa* have been shown to contain circa 11,4 mg/100 g of total beta-carotene [31], which is one of the highest contents among fruits and vegetables, ranking higher than carrots (9,7 mg/100 g). The beta-carotene

content in *R. canina* fruits varied in one study from 1,2 to 2,9 mg/100 g (measured as (all-E)-beta-carotene) [54], which is significantly lower. However, in a comparative study with both species, the amount of beta-carotene (measured as (all E)-betacarotene) was higher in *R. canina* fruits; 4.2 mg/100 g, compared with *R. rugosa* fruits; 3.2 mg/100 g [15].

It should also be noted that in the comparative study with both *R. rugosa* and *R. canina*, their content of (all-E)-lycopene ranged from 7.4 to 7.9 mg/100 g [15], which is higher than other well-known lycopene rich foods such as tomatoes (0.7– 4.2 mg/100 g), pink guava (5.2–5.5 mg/100 g), and like that in watermelon (2.3– 7.2 mg/100 g) [51]. In another study, fruits from *R. canina* had a significantly higher content of (all-E)-lycopene and total lycopene, ranging from 9 to 22.9 mg/100 g and 12.9–35 mg/100 g [54]. The amount of lycopene is known to vary significantly in fruits and vegetables. Factors that affect the content include ripeness of the fruits, quality of the soil, and weather temperature [51].
