Nutrition in Herbal Plants Used in Saudi Arabia.

Herbs are used for centuries by many people worldwide. This study derives insights into the use and content of herbs that are consumed among Saudi citizens. An online questionnaire was distributed to understand the basic information about Saudi citizens' preference and daily patterns of herbal plants that are usually used as drinks. Moreover, concentrations of fourteen elements in twenty-one herbal plants that were indicated in the previous questionnaire were collected from the local market and then analyzed using an Inductively Coupled Plasma Emission Spectrometry (ICP). Mint leaves were significantly higher in most of the nutrients analyzed, and mint was the most popular drink among participants, followed by green tea and anise. Most of the citizens preferred to drink one cup only at home and believed that herbs are good for their health and potentially could help them to sleep better. The outcomes derived from this research could help future assessments of diet patterns among Saudi citizens.

1. Introduction

Herbal plants, hereafter, herbs, are one of the most important sources of many elements that are vital for humans and animals' diet and are used to prevent or treat diseases. These elements are necessary nutrients to their lives and are, therefore, needed in food as the body cannot synthesize them [1]. Herbs play an important role in politics, romance, religion, and health [2], and they are still used by millions of people globally, in particular as medicine as there are more than 50 elements considered as a major component of enzymes and proteins [3]. And optimal uptakes of nutrients may reduce health risk [4]; therefore, their use is increasing globally due to their low side effects when used moderately [5]. Hence, knowing the exact elemental composition of food and other products is important to understand the nutritive value [6], while the use of low nutritive refined food products may affect health [7]. Moreover, some of these are essential nutrients to a certain limit, e.g., iron and copper, whereas others, e.g., lead and cadmium, are poisonous [5].

Most of the herbs are naturally grown in many regions around the planet and used from ancient times [8]. They are also used for culinary [9] cosmetics [10-12], and up to 80% of the world's population depend on plant-derived drugs for medical purposes [13]. Also, green tea is a good example of the use of herbs that started for centuries in China and Japan [6] and is still used nowadays. However, for safety reasons, it is advisable to assess different pollutants before delivering those herbs to the end user (consumer) [14].

Numerous attempts have been made to determine the element's content in plants around the world, e.g., Nigeria [15] and Malaysia [16]. However, a quick search in Scopus with the keywords “herbal plant” and “nutrient” revealed that most of the published papers are from Asia, i.e., India, China, Iran, and Malaysia. Saudi Arabia's market is rich with various herbal plants that citizens are using as “traditional medicine,” many of those are coming from Asia and Africa, while the rest are harvested locally. Studies concerning elemental content of these herbs that are acquired from the Saudi market are rare, whereas herbal preference among citizens and their knowledge base have not hitherto been performed. As a result, the outcomes of this research would serve as a base for further assessments related to herbal plants in Saudi Arabia and describe patterns of practices among Saudi citizens.

2. Materials and Methods

2.1. Questionnaire

To assess the public preference regarding herbal plants that are usually used on a daily basis by people in Saudi Arabia, a survey was carried out online in 2018. The participants were asked before starting the survey if they do drink herbal tea; if no, the survey was terminated. The panel respondents who were above 18 years old were invited to participate via Google survey online (https://gsuite.google.com/products/forms/). However, only 44 participants were under 18 which corresponds to 4% only; therefore, their answers were not excluded from the results. Demographic characteristics (i.e., questions about sex, age, and educational stage were asked to identify the range of participants) are shown in Supplementary Table S1. The questionnaire was designed to include the following: From where do you get your herbs, why do you drink herbal tea, does it help you sleep, where do you drink it, how many cups per day, how many scoops of the herb do you use per cup, and which herbs do you drink, along with options to choose from which are in Supplementary Table S2. The questionnaire was in the Arabic language; then, the results were translated to English.

2.2. Collection of the Samples

Twenty-one herbal plants that were indicated in the previous questionnaire (Table 1 and Figure 1) were collected from a local market in Dammam, Saudi Arabia, in 2018. The material was already dried; therefore, three replicated samples (n = 3) from each herb were directly ground in an agate mortar. The scientific name and family of each herb were further investigated using Encyclopedia Britannica (http://www.britannica.com) and Herbal Encyclopedia (https://www.cloverleaffarmherbs.com).

Table 1

Herbal plants used in this study.

Number	Name		Family	Part assayed
	Common	Scientific
1	Lemon balm	Melissa officinalis	Labiatae	Leaves
2	Anise	Pimpinella anisum	Umbelliferae	Seeds
3	Olive leaves	Olea europaea	Oleaceae	Leaves
4	Cinnamomum	Cinnamomum verum	Lauraceae	Tree bark
5	Rose	Rosa species	Rosaceae	Flowers
6	Chamomile	Matricaria chamomilla	Asteraceae	Flowers
7	Roselle	Hibiscus sabdariffa	Malvaceae	Flowers
8	Fennel	Foeniculum vulgare	Umbelliferae	Seeds
9	Marjoram	Origanum majorana	Labiatae	Leaves
10	Ajwain	Trachyspermum ammi	Apiaceae	Seeds
11	Mugworts	Artemisia vulgaris	Asteraceae	Leaves and twigs
12	Sage	Salvia officinalis	Labiatae	Leaves and twigs
13	Laurel leaf	Laurus nobilis	Lauraceae	Leaves
14	Licorice	Glycyrrhiza glabra	Fabaceae	Roots
15	Maidenhair	Adiantum	Polypodiaceae	Leaves and twigs
16	Curcuma	Curcuma longa	Zingiberaceae	Rhizome
17	Star anise	Illicium verum	Schisandraceae	Seeds
18	Thyme	Thymus vulgaris	Lamiaceae	Leaves
19	Green tea	Camellia sinensis	Theaceae	Leaves
20	Mint	Mentha	Labiatae	Leaves
21	Dried black lime	Citrus aurantifolia	Rutaceae	Fruit

Figure 1

Images of herbal plants acquired and analyzed, which correspond to plants in Table 1.

2.3. Chemical Analysis and Data Quality

Plant samples were already dried, then ground using a granite mortar, and photographed; then, 0.5 grams of the plant sample (i.e., leaves, stem, or seeds) was digested with 5 mL of concentrated HNO3 and 2 mL of H2O2 in polyethylene tubes at digestion systems for 2 hours at 100°C [17]. The digested samples were left to cool, then diluted to 45 mL with Milli-Q water (18.2 Ω/cm), then filtered with a Whatman filter paper of 44-micron size. Concentrations of fourteen elements: calcium (Ca), chromium (Cr), copper (Cu), iron (Fe), iodine (I), potassium (K), magnesium (Mg), manganese (Mn), molybdenum (Mo), sodium (Na), nickel (Ni), phosphorus (P), selenium (Se), and zinc (Zn), were analyzed using Inductively Coupled Plasma Emission Spectrometry (Shimadzu, model 9820). To confirm the quality of the analysis, replicates and PanReac AppliChem multielement standard solution between the 20 samples were used. The analytical recovery of the standards and the duplicated samples is reported in Table 1.

2.4. Statistical Analysis

Descriptive statistics and general linear models were used to test the effects of differences among herbs for every single element as well as Tukey's HSD (honestly significant difference) post hoc test was used to assess pairwise differences. Moreover, assuming that the average consumption of herbs is one spoon equivalent of 0.5 g, the estimated dietary intake (mg day−1) based on 70 kg body weight was calculated by dividing the nutrient concentration (mg kg−1) by 70. All statistics were computed using JMP v12 (Table 2).

Table 2

Summary of certified standards and the duplicated samples measured, along with the selected wavelength of each element analyzed.

Element	Symbol	Wavelength	% Recovery
			Standard	Duplicated samples
Calcium	Ca	220.86	99	86
Chromium	Cr	205.55	100	113
Copper	Cu	261.84	98	98
Iron	Fe	259.94	101	82
Iodine	I	178.28	112	89
Potassium	K	766.49	86	93
Magnesium	Mg	279.55	98	120
Manganese	Mn	260.57	96	88
Molybdenum	Mo	202.03	102	100
Sodium	Na	589.59	87	94
Nickel	Ni	231.60	100	94
Phosphorus	P	213.62	96	86
Selenium	Se	203.99	95	89
Zinc	Zn	213.86	98	95

3. Results

The range of participants who answered the online survey that was distributed through the social media was from 12 to 70 years old, with about 1200 participants in about 10 days (only 44 participants were under 18 years old which corresponds to 4% only; therefore, their answers were not excluded from the results). Female participants were the highest comprising about 77%, while male participants were only 23%. Details of age and sex along with the education level of participants are summarized in Supplementary Table S1.

The majority of participants, i.e., 75% of the participants, have their herbal tea at home, and 22% of the participants drink it anywhere, whereas only 2% and 1% have it at the coffee shop or at work. Moreover, 79% of the participants believe that drinking herbal tea is good for health, while 15% prefer it just for the taste, 2% chose it for the smell, and 4% have other reasons. Interestingly, about 83% answered yes or maybe to the question about if they believe if the herbal tea would help them to sleep, while only 18% answered with no. Additionally, about 58% answered that they get it from their mothers or herb specialists, whereas 43% from the supermarket (Figure 2 and Supplementary Table S2).

Figure 2

Analyses of survey questions (from where do you get your herbs, why do you drink herbal tea, does it help you sleep, and where do you drink it?).

Furthermore, 71% (i.e., 852 participants) of the 1200 preferred to drink only one cup of herb a day; 60% out of those (852 participants) prepared it with only one spoon, 8% prepared it using two spoons, and only 3% used three spoons. Moreover, 20% (i.e., 240 participants) of 1200 preferred to drink two cups of herb a day; 20% of those (240 participants) prepared it with only one spoon, 5% prepared it using two spoons, and only 2% used three spoons. Finally, only 28 participants preferred three cups a day, and 1%, 0.3%, and 0.8% preferred one, two, and three spoons per cup, respectively (Figure 3 and Supplementary Table S2).

Figure 3

Analyses of survey questions (how many cups do you consume per day, and how many scoops of herb do you use per cup?).

The majority of the Saudi participants (about 85%) preferred to drink mint, followed by 69% favoring green tea and then 59% with anise. Moreover, Chamomile, Cinnamomum, Sage, Roselle, Thyme, Marjoram, and Fennel were intermediate with 44, 31, 30, 26, 22, 17, and 16% respectively while the rest (i.e., rose, curcuma, mugworts, ajwain, star anise, lemon balm, olive leaves, licorice, laurel leaf, maidenhair, and dried black lime) were ≤10% (Figure 4).

Figure 4

Analyses of the survey question, (which herbs do you drink?).

Most of the elements analyzed, i.e., Ca, Cu, Fe, Cr, Mn, Ni, and Se, were significantly higher in mint, maidenhair, green tea, dried black lime, and laurel leaf whereas Zn, Na, and Mg were significantly higher in mugworts, and K was significantly higher in both mugworts and curcuma. Moreover, P, Mo, and I were significantly higher in lemon balm, dried black lime, and mint, respectively (Table 3, Tukey's HSD, P < 0.05).

Table 3

Average ± standard error (SE) of fourteen elemental concentrations (mg kg−1) for twenty-one herbs (n = 3) collected from Saudi Arabia.

	Ca	Cr	Cu	Fe	I	K	Mg	Mn	Mo	Na	Ni	P	Se	Zn
Sage	429 ± 5de	339 ± 5bc	376 ± 3e	430 ± 4d	1210 ± 17defg	1970 ± 81ef	1467 ± 20cd	107 ± 2c	559 ± 8de	998 ± 80defg	388 ± 5c	1127 ± 23abcde	981 ± 12bcd	247 ± 5bc
Ajwain	345 ± 57de	203 ± 120c	269 ± 125e	159 ± 86d	724 ± 169ghij	1152 ± 179f	556 ± 398de	125 ± 9c	424 ± 62de	333 ± 173fg	233 ± 109c	840 ± 405 def	569 ± 116efgh	185 ± 15 ef
Anise	497 ± 6cde	299 ± 5bc	660 ± 14de	355 ± 5d	1087 ± 17efgh	9147 ± 116b	1503 ± 19cd	156 ± 6c	463 ± 8de	1303 ± 39defg	332 ± 5c	1447 ± 18abc	730 ± 8def	194 ± 3ef
Chamomile	323 ± 3e	274 ± 3c	308 ± 9e	360 ± 10d	1165 ± 49defgh	3855 ± 193de	981 ± 225cde	119 ± 3c	416 ± 1de	746 ± 86efg	309 ± 3c	1067 ± 169bcde	580 ± 18efg	190 ± 10 ef
Cinnamomum	309 ± 27e	156 ± 49c	153 ± 24e	69 ± 24d	608 ± 34ghij	2213 ± 179ef	249 ± 12e	138 ± 16c	302 ± 38e	390 ± 80fg	169 ± 21c	433 ± 34f	417 ± 32fghi	120 ± 7g
Curcuma	280 ± 25e	224 ± 4c	178 ± 41e	235 ± 16d	550 ± 53 hij	12133 ± 120a	907 ± 346de	135 ± 8c	327 ± 8e	342 ± 85fg	227 ± 8c	592 ± 14ef	388 ± 21ghi	121 ± 2g
Dried black lime	2693 ± 97a	1327 ± 48a	2977 ± 80ab	2533 ± 77a	2280 ± 76ab	6737 ± 155bc	1014 ± 36cde	834 ± 30a	1563 ± 304a	7467 ± 149bc	3050 ± 235a	1257 ± 43abcd	1317 ± 38a	251 ± 9abc
Fennel	610 ± 9cde	321 ± 7bc	593 ± 55de	293 ± 11d	1160 ± 20defgh	8750 ± 163b	1980 ± 21bc	177 ± 6c	516 ± 11de	2488 ± 998def	340 ± 8c	1587 ± 28ab	916 ± 23cd	197 ± 4def
Green tea	2623 ± 90ab	1293 ± 43a	3150 ± 121a	2607 ± 98a	2243 ± 97ab	7073 ± 286bc	990 ± 34cde	813 ± 28a	1267 ± 41ab	8433 ± 398bc	2860 ± 115a	1230 ± 55abcd	1297 ± 38ab	248 ± 10bc
Laurel leaf	2697 ± 85a	1327 ± 41a	2853 ± 186ab	2480 ± 121ab	2220 ± 145abc	6193 ± 315cd	1011 ± 31cde	834 ± 26a	1157 ± 66abc	6273 ± 496c	2607 ± 172a	1220 ± 58abcd	1287 ± 35ab	244 ± 9bcd
Lemon balm	453 ± 93cde	429 ± 2bc	388 ± 96e	555 ± 1d	1593 ± 3cde	1227 ± 116f	872 ± 602de	140 ± 1c	726 ± 3 cde	155 ± 62fg	146 ± 93c	1673 ± 13a	1200 ± 6abc	289 ± 3ab
Licorice	1610 ± 538abc	416 ± 16bc	823 ± 44de	573 ± 51d	1027 ± 27efghi	3847 ± 102de	2560 ± 92b	196 ± 4c	608 ± 19de	3067 ± 397de	472 ± 23c	1110 ± 32 abcde	944 ± 27cd	225 ± 9 cde
Maidenhair	2733 ± 67a	1347 ± 33a	3310 ± 80a	2723 ± 67a	2337 ± 85ab	7557 ± 169bc	1030 ± 25cde	845 ± 20a	1317 ± 33ab	9243 ± 167b	3047 ± 69a	1287 ± 30abcd	1340 ± 32a	257 ± 5abc
Marjoram	301 ± 109e	343 ± 27bc	425 ± 43e	451 ± 65d	1192 ± 150defg	2187 ± 175ef	1280 ± 52cde	123 ± 6c	520 ± 46de	858 ± 144efg	386 ± 53c	1130 ± 166abcde	874 ± 93 de	232 ± 9 cde
Mint	2753 ± 37a	1357 ± 19a	3327 ± 34a	2720 ± 25a	2383 ± 46a	7727 ± 91bc	1040 ± 15cde	852 ± 11a	1313 ± 18ab	9560 ± 140a	3087 ± 39a	1297 ± 18abcd	1347 ± 24a	259 ± 3abc
Mugworts	1213 ± 18cde	560 ± 7bc	1560 ± 40cd	779 ± 14cd	1497 ± 19def	12667 ± 133a	6083 ± 87a	335 ± 7bc	899 ± 10bcd	15267 ± 145a	655 ± 8bc	1427 ± 19abcd	1320 ± 15a	300 ± 2a
Olive leaves	568 ± 79cde	225 ± 42c	403 ± 71e	177 ± 33d	883 ± 75fghi	2467 ± 413ef	971 ± 130cde	128 ± 13c	437 ± 38de	407 ± 102fg	378 ± 87c	888 ± 124cdef	824 ± 125de	171 ± 12f
Rose	143 ± 1e	143 ± 1c	41 ± 5e	77 ± 4d	242 ± 22j	587 ± 19f	564 ± 121de	68 ± 2c	367 ± 167e	576 ± 41fg	126 ± 0c	418 ± 9f	167 ± 11i	86 ± 1g
Roselle	285 ± 70e	349 ± 5bc	419 ± 17e	375 ± 34d	1210 ± 15defg	1980 ± 26ef	1490 ± 26cd	243 ± 5c	576 ± 9de	659 ± 71fg	440 ± 17c	1073 ± 12 abcde	977 ± 6 bcd	244 ± 3 bcd
Star anise	204 ± 7e	153 ± 5c	191 ± 17e	139 ± 56d	395 ± 27ij	1122 ± 123f	514 ± 42de	172 ± 3c	352 ± 117e	54 ± 26g	162 ± 5c	427 ± 12f	254 ± 7hi	97 ± 3g
Thyme	150 ± 789bcd	762 ± 378b	1949 ± 876bc	1587 ± 735bc	1745 ± 427bcd	4185 ± 1891de	871 ± 184de	604 ± 243ab	902 ± 190bcd	3298 ± 1523d	1600 ± 761b	1055 ± 123bcde	1045 ± 171abcd	215 ± 26cdef
F ratio P value	22∗∗	26∗∗	35∗∗	36∗∗	31∗∗	67∗∗	38∗∗	31∗∗	17∗∗	93∗∗	38∗∗	10∗∗	39∗∗	43∗∗

The results (F ratio and Pvalue: =0.05 > P > 0.01; =P < 0.01) from ANOVA. Different letters a, b, c, and d indicate significant differences among different herbs for every single element (Tukey's HSD multiple comparison post hoc test, P < 0.05).

4. Discussion

The Recommended Dietary Allowance (RDA) is the sufficient amount of required nutrients that are needed for healthy individuals, which are established by the Food and Nutrition Board [18]. Herbal plants are one of the major resources of these nutrients and, therefore, the amount of nutrients in plants is one of the criteria that makes it favorable to use [6], although the paucity of these nutrients can lead to disease [1]. Many of them are essential nutrients for humans; e.g., iron is basic to hemoglobin and many enzymes, while calcium and phosphorous are essential components to bones, magnesium is important to all biosynthetic processes, and zinc is basic to many enzymes that are involved in metabolic pathways [19].

The estimated dietary intake (mg day−1) in this study compared to the RDA varied among different elements. That is, Ca, K, Mg, Na, P, and Zn were within the recommended range of intake for males and females (Table 4) while Cr, Cu, I, Mo, and Se were higher than the range of the reported values and finally Fe and Mn were intermediate with seven herbs (i.e., black lime, green tea, laurel leaf, maidenhair, mint, mugworts, and thyme; Table 4) out of twenty-one being higher than the RDA values reported by Dell Valle et al. [20].

Table 4

Median nutrient intake values by herbs based on 70 kg body weight (mg day−1).

	Ca	Cr	Cu	Fe	I	K	Mg	Mn	Mo	Na	Ni	P	Se	Zn
Sage	6	5	5	6	17	27	21	2	8	14	6	16	14	4
Ajwain	4	2	5	2	8	15	3	2	5	5	4	6	7	3
Anise	7	4	10	5	15	132	21	2	7	18	5	21	10	3
Chamomile	5	4	4	5	17	55	14	2	6	11	4	15	8	3
Cinnamomum	5	2	2	1	9	32	4	2	5	6	2	7	6	2
Curcuma	4	3	2	4	8	174	10	2	5	5	3	9	5	2
Dried Black lime	40	20	43	37	33	97	15	12	18	105	40	19	19	4
Fennel	9	5	9	4	17	124	28	3	8	49	5	23	13	3
Green tea	37	18	45	37	33	101	14	12	18	120	41	17	19	4
Laurel leaf	39	19	42	35	31	91	15	12	17	91	38	17	18	4
Lemon Balm	8	6	5	8	23	17	5	2	10	2	1	24	17	4
Licorice	22	6	12	9	14	54	37	3	9	39	7	16	13	3
Maidenhair	40	20	48	40	34	110	15	12	19	133	44	19	19	4
Marjoram	4	5	6	6	16	30	18	2	7	11	5	17	12	3
Mint	40	20	48	39	34	111	15	12	19	137	44	18	19	4
Mugworts	17	8	23	11	22	183	88	5	13	219	9	21	19	4
Olive leaves	8	3	7	3	13	41	14	2	6	5	5	13	13	3
Rose	2	2	1	1	3	8	9	1	3	8	2	6	2	1
Roselle	5	5	6	6	17	28	21	3	8	9	6	15	14	4
Star anise	3	2	3	3	5	18	7	2	3	1	2	6	4	1
Thyme	22	12	40	30	30	85	15	12	15	63	30	16	16	3
Males (9 to >70 y)∗	1000–1300	0.03–0.04	0.07–0.09	8–11	0.1–0.2	4500–4700	240–420	1.9–2.3	0.03–0.05	1200–1500	—	700–1250	0.1	8–11
Females (9 to >70 y)∗	1000–1300	0.02–0.03	0.07–0.09	8–18	0.1–0.2	4500–4700	240–320	1.6–1.8	0.03–0.05	1200–1500	—	700–1250	0.1	8–9

RDA values from [20]

Moreover, in this study, two-thirds of the participants were females, indicating a higher rate of use among females; this rate of female users was observed by the findings of Alghamdi et al. [21]. The growing interest of females to herbal drinks, e.g., tea, might be due to the daily news of their benefits that ranged from the protection of hip structure in elderly women [22] to cancer potential treatments and risks caused by diabetes [23].

While there is no explanation why the majority drink only one cup of herbal tea preferring it at home compared to the work place, and around half of the participants acquire it from their moms or specialists, yet, in general, about 79% of the participants believed that herbal tea is good for their health compared to smell and taste, and 83% believed that it may help them sleep. Similarly, a recent study on two hundred patients in Saudi Arabia found that 76% of the patients with chronic illness had used herbal medicine [21], compared to a lower range of 10 to 52% in western countries [24]. And a higher range of migrants of about 75% uses herbal medicine in the west [25].

Mint was the most popular herb among Saudi citizens, followed by green tea and anise. In Australia, mint comes as number seven of most sold herbs and spices in the supermarket for 2013 with about $2151500 of sales value [26]. However, many studies documented the effect of green tea as a potential treatment preventing cancer [27, 28]. Furthermore, most of the nutrients, i.e., Ca, Cu, Fe, Cr, Mn, Ni, and Se, were significantly higher in mint, maidenhair, green tea, dried black lime, and laurel leaf, whereas nutrients' concentrations in this study, particularly, Zn, Na, K, and Mg, were significantly higher in mugworts compared to other herbs, which is coherent with early Chinese beliefs of the medical benefits of mugworts, as well as France in the middle ages, where they used it to protect babies from cold [2].

Nevertheless, these herbs must be used with care, as many reports have documented the presence of toxic heavy metals and undeclared pollutants, e.g., in Asia [29-31] and Africa [32, 33].

5. Conclusion

The concentration of nutrients carried out was depending on the plant species analyzed; most of the herbs analyzed were within the RDA limits. However, participants who selected many cups per day or many spoons per cup could be at risk of bioaccumulation. In this study, mint leaves were significantly higher in most of the nutrients analyzed, and mint was the most popular drink among Saudi citizens, followed by green tea and anise.