Connecting the Dots: Beetroot and Asthma

Abstract

Asthma is a persistent ailment that impacts the respiratory system and stands as a formidable public health challenge globally. Inhaled corticosteroids and bronchodilators, while effective in asthma management, are accompanied by side effects and high costs. Recently, nutraceuticals have gained significant attention as adjuvant therapy due to their promising outcomes. Given the antioxidant properties, nutrient richness, and an array of health benefits, beetroot and its bioactive compounds have been tested as an adjuvant therapy for asthma management. Although its main bioactive compound, betalains (betanin), has demonstrated promising results in mouse studies, beetroot juice has been found to worsen asthma. This review investigated the full spectrum of active compounds associated with beetroots to understand the underlying factors contributing to the conflicting findings. The finding suggests that individual bioactive compounds, such as phenolic compounds, flavonoids, nitrates, betalains, saponins, vitamins, fiber, and carotenoids, possess asthma-managing properties. However, the consumption of juice may exacerbate the condition. This discrepancy may be attributed to the presence of sugars and oxalates in the juice, which could counteract the beneficial effects of the bioactive compounds.

1. Introduction

Asthma is a chronic respiratory condition marked by airway inflammation and breathing difficulties [1]. In 2019, the Global Burden of Disease study reported an asthma prevalence of 3416 cases per 100,000 population, ranking it 34th among major disease burdens [2]. Asthma imposes a significant economic burden, costing $1.1 billion in low-income countries and $130.3 billion in high-income countries in 2023, with projections rising to $1.3 billion and $133.4 billion, respectively, by 2050, and it contributes to 461,000 deaths each year [3,4]. The disease is heterogeneous, with environmental triggers such as smoke, mold, and pollutants playing a role in oxidative stress and chronic inflammation through reactive oxygen species (ROS) production [5,6,7,8,9]. Despite the availability of treatments such as corticosteroids, leukotriene receptor antagonists, and beta-agonists, a substantial number of asthma cases remain poorly controlled, and side effects, including vomiting, infections, and weight gain, have also been reported in some cases [10,11,12,13,14,15,16,17,18,19,20,21,22]. Inhaled corticosteroids (ICS), in particular, may lead to side effects such as dysphonia, candidiasis, and in some cases, an increased risk of tuberculosis and other mycobacterial infections [23,24,25]. As a result, there is a growing need for adjuvant therapies to complement existing treatments, aiming to improve outcomes while reducing costs and side effects.

Dietary interventions, especially increased fruit and vegetable intake, have shown potential to improve asthma control due to their anti-inflammatory and antioxidant properties [26,27,28,29,30,31]. This has spurred interest in herbal and nutraceutical remedies as adjuncts or standalone therapies, including Curcuma longa L., nigella, and licorice root [32,33,34,35]. Roots of Curcuma longa L., nigella, and licorice root are some of the examples [36,37,38]. Among these, beetroot (Beta vulgaris), a rich source of phytochemicals, has gained attention for its potential role in asthma management [39].

Beetroot, belonging to the Chenopodiaceae family, is widely cultivated for its nutritionally rich roots [40,41,42]. Known as a garden or spinach beet, it ranks among the top plants with high antioxidant potential [43,44]. Its pharmacological properties stem from bioactive compounds, particularly betalains (e.g., betanin) and polyphenols, which enhance its antioxidant activity [45,46,47]. Betanin’s phenolic and cyclic amine groups boost its reducing capacity, offering antioxidant potential comparable to L-ascorbic acid [48].

Beetroot has been extensively studied for its potential health effects, such as anticancer, antiviral, neuroprotective, antibacterial, and anti-inflammatory potential [49,50,51]. Its high nitrate content contributes to ergogenic effects and blood pressure reduction [52,53]. Beetroot juice and chips have demonstrated reductions in obesity-related oxidative stress and inflammation [54]. However, the relationship between beetroot intake and asthma outcomes remains controversial. Betalains have shown anti-inflammatory effects in murine asthma models, reducing inflammatory markers, oxidative stress, and nitric oxide levels [55,56]. Conversely, another murine study found that beetroot juice exacerbated asthma symptoms [39]. Currently, no human studies have directly explored beetroot’s effects on asthma management. However, a study involving 76 participants reported that 70 mL of beetroot juice daily for seven days reduced cold symptoms associated with psychological stress, with the most notable benefits observed in the subgroup with asthma (n = 16) [57]. As per our knowledge, no review has been undertaken to analyze the evidence on the contradictory effects of beetroot and asthma.

The primary aim of this review is to summarize the key compounds commonly found in beetroot and to explore their potential role in asthma, including both benefits and adverse effects. By examining existing studies, the review seeks to determine whether the effects of these individual compounds, regardless of their food source, could provide insights into the potential of beetroot supplementation in alleviating asthma symptoms.

2. Bioactive Analysis of Beetroot

Bioactive compounds present in beetroot in high levels include betalains, coumarins, carotenoids, ascorbic acid, vitamin A, vitamin E, vitamin K, thiamine, riboflavin, niacin, pyridoxine, cobalamin, folate, pantothenic acid, cyanocobalamin, sesquiterpenoids, triterpenes, polyphenols, flavonoids (including astragalin, tiliroside, rhamnetin, rhamnocitrin, and kaempferol), saponins, fiber, and nitrate (Figure 1). Beetroot also contains lower levels of betaine and glycine [45,58,59,60,61,62,63]. A significant amount of oxalic acid (400 to 600 mg/100 gm fresh weight) is also reportedly present in beetroot [64,65,66].

Table 1. Concentration of bioactive compounds in beetroot.

Reference	Compound	Concentration per 100 gm or L−1 of Juice
[67]	Dietary fibre	3.8 g
	Sucrose	9 g
	Oxalic acid	0.2 g
	Folate	77 ug
	Thiamine	0.026 mg
	Riboflavin	0.019 mg
	Niacin	0.39 mg
	Pyridoxine	0.09 mg
	Vitamin C	4 mg
	Alpha tocopherol	0.1 mg
	Vitamin E	0.07 mg
	Beta carotene	5 ug
[62,68]	Gallic acid	65.93 ± 45.38 mg
	Chlorogenic acid	2.29 ± 2.09 mg
	Caffeic acid	0.77 ± 0.28 mg
	Ferulic acid	1.71 ± 0.76 mg
	Myricetin	0.30 ± 0.109 mg
	Luteolin	0.13 ± 0.003 mg
	Quercetin	0.010 ± 0.009 mg
[63]	Betanin	128.7 ± 22.0 mg

lists the bioactive compounds present in beetroot and their approximate concentrations

3. Comparison of Bioactive Compounds in Beetroot Formulations

Beetroot gel has been reported to contain the highest total phenolic content (SD 1.98 ± 0.03 mg·g⁻¹) compared to beetroot juice (SD 1.01 ± 0.03 mg·g⁻¹), cooked beetroot (SD 2.79 ± 0.23 mg·g⁻¹), chips (SD 0.75 ± 0.06 GAE mg·g⁻¹), and beetroot powder (SD 0.51 ± 0.07 GAE mg·g⁻¹) [69,70]. A comparative analysis of total polyphenols and antioxidant activity in beetroot pulp waste extracts using methanol, ethanol, and aqueous solvents revealed that the methanol extract of beetroot pulp waste had the highest polyphenol content, measuring 220 mg TAE/100 gm, surpassing the levels found in ethanol and aqueous extracts. However, the aqueous extract showed higher total antioxidant activity (10,735 to 91,225 μmoles of ascorbic acid/100 gm) compared to methanol and ethanol extracts [71]. Composition analysis of beetroot juice indicated the presence of gallic acid in the highest concentration, followed by caffeic, syringic, and ferulic acids, accounting for approximately 3% of the total phenolic content [64]. Results of another study explained that the fermentation process enhances the free phenolic acid content after extraction [72]. In contrast, reduced phenolic content was reported after freeze-drying and spray-drying, possibly due to the water-soluble nature of phenols [69].

On average, beetroot contains 0.41 to 1.16 mg/g of flavonoids [73]. The nutritional composition of most commercial beetroot juices is reported to include total flavonoid 2.02–2.36 mg/100 gm [64]. A comparative study of flavonoid content among beetroot juice, gel, and chips indicated that the highest levels were found in beetroot gel (mean 1.37 ± SD 0.03), followed by beetroot juice (mean 0.42 ± SD 0.01) and beetroot chips (mean 0.31 ± 0.02) [73]. Fermentation processing reportedly has negative effects on free flavonoids (such as kaempferol) and positive effects on the conjugated flavonoid (such as rutin) content of beetroot [72].

Betalains are found in the Caryophyllales family of plants. These pigments are nitrogenous compounds derived from the amino acid tyrosine and classified as betacyanin and betaxanthin [46]. The mean concentration of betacyanin and betaxanthins in red beetroots ranges from 400 to 2100 mg/kg and 200 to 1400 mg/kg, respectively. Betalains are reported in the range of 0.8–1.3 g/L in fresh juice of seven varieties of beetroot. The betacyanin to betaxanthin ratio was similar in all seven varieties of beetroot (juice), i.e., 1.75 to 1. Among all components of betalains, the vibrant red color of beetroot is mainly due to the presence of betanin, which makes up between 75 and 95 percent of the total betalain content [42]. A study investigating betalain components in beetroot juice found betanin in the highest concentration among other components [44,64,74]. Silva et al. compared the betanin content in different formulations of beetroot and demonstrated that freeze-dried beetroot chips had the highest betanin content (mean 1274 ± SD 0.01), followed by beetroot juice (mean 298.5 ± SD 0.03), gel, and cereal bar [42,69]. Spray-dried beetroot powder was reported to contain betacyanin around 283.3–302.7 mg/100 gm [75]. Whilst comparing the effect of processing on betanin losses, Sawicki et al. reported that crunchy beetroot slice production using microwave-assisted vacuum drying resulted in the retention of 78.9% betanin content, followed by boiled beetroot (62.5%) [76].

Total betalains, betacyanin, and flavonoid contents are significantly reduced when beetroot is heat dried. However, there is a positive association between betaxanthins, phenolic content, and heat treatment for drying [77]. Beetroot waste dried at 70 °C was found to contain 81.31 ± 0.69 betalain in 9 mg/gm DM [78]. The pH and water, along with exposure to heat, light, oxygen, enzymatic activities, and metal ions, can highly influence the extraction of betalain [79]. Spray drying has a negative impact on the violet pigment concentration of beetroot juice [75].

Beetroot gel was found to contain the highest levels of NO₃ (390 mg/100 gm) compared to beetroot chips (279 mg/100 gm) and juice (217 mg/100 gm) [69,70,73]. Furthermore, beetroot juice reportedly contains significantly higher levels of NO₃ than beetroot powder and the cooked form [69]. Saponins are mainly plant-derived triterpene glycosides [80] and are documented to exhibit bioactive properties (e.g., antiviral and antihyperglycemic). Beetroot gel has been reported to contain three times higher amounts of saponins, 22 mg/gm, than beetroot juice [73]. However, Baiao et al. reported saponin content in beetroot chips (mean 6371.00 ± SD 1.2) was higher than that in Beetroot gel (mean 2200.00 ± SD 0.17) and juice (mean 2599.00 ± SD 1.27) [42]. Studies suggest that saponin content in beetroot may be influenced by harvest conditions [81] and beetroot processing methods [70].

Yashwant et al. reported the presence of micronutrient vitamins in beetroot, such as 2 μg of vitamin A, 80 μg of folate, and 0.031, 0.027, 0.331, 0.145, and 0.067 mg of thiamine, riboflavin, niacin, pantothenic acid, vitamin B6, respectively, and 3.6 mg of ascorbic acid in each 100 g of fresh beetroot [43]. The vitamin C content of beetroot is highly influenced by cultivation, weather, and spatial distribution [82,83]. According to Pavlovic et al., vitamin C is reportedly present in the range of 10.05 to 11.65 mg/100 gm of beetroot [84]. Beetroot juice was found to contain 256, 3054, 413, 218, and 912 (mg/100 gm) of phosphorus, potassium, calcium, magnesium, and iron, respectively, exceeding the amount found in spray-dried beetroot juice [85].

Beetroot cereal bars reportedly contain the highest level of dietary fiber, potentially due to the presence of other cereals (mean 4.07 ± SD 0.14), which is followed by beetroot gel (mean 3.71 ± SD 0.10), chips (mean 3.22 ± SD 0.63), and juice (mean 0.91 ± SD 0.31) [70,86].

Beetroot is also a good source of oxalic acid, containing around 400 to 600 mg oxalic acid/100 gm fresh weight. Wruss et al. examined the difference in oxalic acid content among seven varieties of beetroot juice and reported 412 mg/L as the average oxalic acid content with a coefficient of variation of 21 percent [64]. The oxalic acid content in the powder of two beetroot varieties was reported as 9583.33 mg and 9166.67 mg/100 g for DetR and CrimG, respectively [87]. Beetroot pulp waste (after separation of juice) was found to have an insignificant amount of oxalic acid, i.e., 0.24 mg/100 g [71]. Heat treatment is considered an efficient approach to reduce oxalate content [88]. Lisiewska et al. reported that freeze-dried beetroot had the highest level of oxalate (soluble) compared to initial levels recorded before freezing [89]. On the other hand, boiling followed by sun drying resulted in reduced oxalic acid content in beetroot [87]. Moreover, microwaving and then hot air drying led to total oxalate loss in beans [90,91]. Ultrasonication is a non-conventional method for significantly eliminating oxalate content [90], and a combination of ultrasonication and temperature treatment successfully retains the bioactive compounds in beetroot juice [92]. Moreover, a study reported that finely sliced rye seedlings naturally contain oxalate oxidase, and beetroot juice treated with finely sliced rye seedlings had significantly reduced oxalate levels [93]. A study examined the effects of deoxilation with calcium ions on the antioxidant activity of beetroot juice. The results indicated a slight decrease in the total antioxidant capacity of deoxalated beetroot juice, 32.42 mg/gm, compared to whole beetroot juice, 48.38 mg/gm ascorbic acid equivalent (AAE). However, there were no differences in flavonoid and phenolic content. Also, an increased percentage of hydroxyl radical scavenging activity was recorded for deoxalated beetroot juice than that for beetroot juice. Also, lipid peroxidation inhibition activity was higher in concentrated deoxalated beetroot juice than in ascorbic acid (standard control) [94].

Beetroot is considered a valuable crop due to its high sucrose content [95], representing more than 98 percent of the total sugars in beet [96]. Baião et al. reported the sugar content of raw beetroot as 6.76 gm/100 gm. Additionally, the study finding suggests the sugar content of cooked/boiled, canned, and fresh juice of beetroot as 7.96 gm/100 gm, 5.51 gm/100 gm, and 6.6 gm/L, respectively [73]. Kazimierczak et al. determined the sugar levels in different commercially available beetroot juices produced from fermented, pure pressed, and concentrates of beetroot, either pure or in combination with the juice of apple or lemon. The total sugar content was in the range of 1.73 to 7.85 gm per 100 gm [68]. Sucrose content in beetroot juice has been reported as (SD 8.8 ± 0.03 g/100 gm). However, chips were analyzed to contain (SD 14.6 ± 0.01 mg/100 gm), followed by gel (SD 8.1 ± 0.05 g/100 gm) [97]. Beetroot juice prepared using a centrifuge blender reportedly contained (SD 963.41 ± 13.98 mg·g⁻¹) total sugars, of which (SD 930.40 ± 13.65 mg·g⁻¹) was sucrose. The total sugar and sucrose content of freeze-dried beetroot chips were (SD 627.96 ± 11.39 mg·g⁻¹) and (SD 603.27 ± 10.30 mg·g⁻¹), respectively. Beetroot powder and cooked beetroots had (SD 444.05 ± 26.08 mg·g⁻¹) and (SD 249.51 ± 0.22 mg·g⁻¹) total sugars, respectively, while sucrose content in beetroot powder and cooked beets was (SD 429.48 ± 25.96 mg·g⁻¹) and (SD 241.37 ± 0.25 mg·g⁻¹ ) [69].

Overall, beetroot is a good source of various bioactive compounds, oxalates, and sugars, particularly sucrose. However, the composition of these compounds is highly influenced by cultivators and beetroot processing methods.

4. Bioavailability of Beetroot’s Bioactive Compounds

Phenolic compounds in beetroot exhibit varied bioavailability influenced by their chemical structure and gastrointestinal digestion. In vitro studies report a 72.93% loss in total phenolic content post-digestion, with gastric digestion reducing phenolic levels to 1/3–1/8 of baseline values [98,99,100] Specific compounds like caffeic and p-coumaric acids were undetectable post-stimulated gastrointestinal digestion (SGD), while chlorogenic acid levels surprisingly increased 2.5-fold [99]. Similarly, flavonoid bioavailability is affected by hydroxyl groups, with in vitro digestion resulting in a 63.63% loss in total flavonoids [99,101].

Dietary nitrate undergoes bacterial conversion to nitrite in the oral cavity, forming nitric oxide (NO) in the stomach under favorable conditions. NO promotes smooth muscle relaxation, but impaired bioavailability has been linked to pulmonary hypertension [102].

Betalains have low oral bioavailability and lack hepatic metabolism. Betanin shows 35% reduced absorption, while indicaxanthin is highly bioavailable, retaining activity through paracellular absorption [103,104]. In vitro digestion studies reveal significant losses of betacyanin (96.07%) and partial retention of betaxanthins (27%) [99]. Heat treatment minimally affects betalains, with beetroot juice retaining 80% of its antioxidant activity [48,70,105].

Oxalate, an antinutrient absorbed at 10–15%, binds minerals, reducing their bioavailability. An in vitro study observed a 43–65% reduction in mineral content in beetroot juice post-digestion [106,107,108].

5. Bioactive Compounds in Asthma Management: Implications for Beetroot Use

Phenolic compounds, such as gallic acid, ferulic acid, sinapic acid, caffeic acid, and chlorogenic acid, are known for their protective effects against chronic inflammation, including airway inflammation and asthma [109,110,111,112,113,114,115,116,117,118]. Flavonoids in beetroot, particularly kaempferol, have shown promise in reducing airway inflammation by lowering type 2 inflammatory cytokines (IL-13 and IL-5) and eosinophils in in vitro models of allergic airway inflammation [119]. Kaempferol also helps reduce mucus secretion, airway inflammation, oxidative stress, and airway remodeling [120,121,122,123,124,125,126]. Other flavonoids, such as rhamnetin 3-rhamnoside and quercetin, exhibit antioxidant and anti-inflammatory properties, with quercetin also promoting vasodilation [127,128,129,130]. Astragalin has been reported to reduce inflammatory cytokines and oxidative stress, while rutin decreases nitric oxide (NO) and reactive oxygen species (ROS) levels, offering protection from bronchial inflammation [125,131,132,133]. Tiliroside has demonstrated anti-inflammatory, anti-allergy, and antioxidant activities [134]. However, novel flavonoids like betagarin, betavulgarin, and cochliophilin found in beetroot remain understudied.

The role of nitric oxide (NO) in inflammatory respiratory diseases, including asthma, is complex. During stable phases of disease, NO can act as an anti-inflammatory, but in acute or severe stages, it may exacerbate inflammation [135]. In asthma, NO has a dual role: at normal levels, it is anti-inflammatory, but higher concentrations of inducible NO can worsen symptoms [136].

Fractional exhaled nitric oxide (FeNO) is a sensitive marker for diagnosing eosinophilic airway inflammation. However, dietary nitrates can increase FeNO levels, potentially leading to misinterpretation of inflammation severity. Studies show that sodium nitrite nebulization may have protective effects for asthmatic patients [136]. Additionally, supplementation with beetroot juice (400 mg nitrate) has reduced global sickness among young asthmatics, though FeNO levels increased post-intervention [57]. Beetroot juice has also shown inhibitory and anti-inflammatory effects on lipopolysaccharide-induced NO production [48].

Supplementation with betalains-rich beetroot juice has shown promising antioxidant and anti-inflammatory effects in preclinical asthma models. For instance, daily doses of 500–600 mL of freshly made juice containing 159.6 mg betacyanin and 79.3 mg betaxanthins improved antioxidant profiles in animals [137]. High doses of betanin reduced NO, reactive oxygen species, myeloperoxidase activity, and TNF-α in zebrafish with cigarette smoke-induced respiratory inflammation [138]. In OVA-induced asthma mouse models, purified betanin (60–180 mg/kg/day) significantly reduced IL-4, IL-5, IL-13, IL-17A, and eotaxin [56]. Betalain supplementation decreased eosinophils, IgE, IL-4, and TNF-α while increasing INF-γ [55]. However, studies reveal mixed results. An oral dose of 8 mL/kg beetroot juice with 45.07 mg betanin/100 mL failed to reduce inflammatory cytokines but increased catalase and total inflammatory cell counts in an asthma model [139].

In contrast to the studies mentioned above, an oral dose of 8 mL/kg beetroot juice containing betanin (mean 45.07 ± 1.53 mg/100 mL) and vulgaxanthin (mean 20.30 ± 0.69 mg/100 mL) did not reduce inflammatory cytokine levels but significantly increased catalase activity and total inflammatory cell count in an OVA-sensitized and challenged mouse model of asthma [39]. However, a mixed-population study including physician-diagnosed subjects with well-controlled asthma examined the effects of beetroot juice (commercially prepared) on cold symptoms. This study documented reduced cold symptoms, global sickness, and FeNO levels. Interestingly, the beneficial effects were more pronounced among asthmatic subjects [57]. These discrepancies warrant further exploration of experimental designs and asthma endotypes.

Other bioactive compounds in beetroot, such as saponins and vitamins, have been explored for their potential role in asthma management. For instance, asparagus cochinchinensis extract enriched with saponins demonstrated anti-inflammatory effects in OVA-induced asthma models [140]. Similarly, specific types of saponins and ginseng saponins have shown promise in managing asthma by mitigating oxygen deprivation and histamine effects, which are significant in allergic asthma [141,142,143,144].

Vitamin C is widely recognized for its antioxidant and anti-inflammatory properties, with studies demonstrating its efficacy in high doses for alleviating asthma symptoms [145,146]. When combined with calcitriol, vitamin C has been shown to reduce inflammation, oxidative stress, and airway remodeling in asthma-induced mouse models [147].

Beetroot contains all eight B-complex vitamins, though their link to asthma is underexplored [63,148]. Evidence from studies indicates varied associations: riboflavin intake shows a negative correlation with allergy [149], and long-term supplementation with vitamin B-6 (200 mg/day for 5 months) improved asthma symptoms in children [150]. Similarly, carotenoids such as alpha and beta-carotene, lutein, and lycopene are inversely correlated with asthma symptoms [151].

Cross-sectional studies highlight strong negative associations between asthma and high vitamin C intake [152]. and between folate, B-6, and B-12 intake and asthma and atopy in children [153]. The role of vitamin E is mixed, with some studies suggesting benefits in alleviating symptoms while others show no effect [154]. Low vitamin K intake is linked to an increased asthma risk [155]. Deficiencies in selenium, iron, and manganese have also been associated with exacerbated asthma symptoms, though evidence on the benefits of mineral supplementation remains inconclusive [156,157,158,159].

Fiber intake is negatively associated with asthma symptoms, with higher fiber consumption linked to improved lung function and reduced inflammation [160,161,162,163]. In a randomized trial, inulin supplementation (12 g/day) improved asthma control and reduced sputum eosinophils [164]. Conversely, oxalates are positively associated with bronchial obstruction, inflammation, and epithelial degeneration, contributing to respiratory issues [165,166,167].

High-carbohydrate diets, particularly starch and sucrose, are linked to asthma exacerbation in children and murine models [168,169,170].

To sum up, beetroot’s bioactive compounds benefit asthma management, but oxalates and sucrose may exacerbate it. Figure 2 summarizes these effects, while

Table 2. Comparison of factors affecting the availability of betalains, oxalates, and sugars.

Metrics	Betalains	Oxalates	Sugars
Solubility	Water soluble [171]	Water soluble (Na+, K+, and NH4+) and insoluble (Ca2+, Fe2+, and Mg2+) salts [172]	Water soluble [173]
pH	Stable at 3–7 [174]	↓ In alkaline medium [175]	Stable at pH 5–11, ↓ pH 3 over time [176]
Heat treatment drying	↓ Betacyanin ↑ Betaxanthins [77]	↓ Concentration [88]	↓ Concentration [69,177]
Freeze drying	↑ Concentration [42,69]	↑ Concentration [89]	↑ Concentration [69,177]
Spray drying	↓ Concentration [75]	↑ Concentration [178]	↑Concentration [69,177]
Fermentation	↓ Concentration [179]	↓ Concentration [180]	↓ Concentration over time [181]
Ultrasonication	↑ Concentration [92]	↓ Concentration [90]	↓ Concentration over time [182]
Calcium salts (calcium chloride)	-	↓ Concentration [183]	Forms complexes with calcium ions (e.g., Calcium hydroxide) [184]

Abbreviations: Na⁺, sodium cation; K⁺, potassium cation, NH₄⁺, ammonium cation; Ca²⁺, calcium cation; Fe²⁺, ferrous cation; Mg²⁺, magnesium cation; pH, potential of hydrogen; ↓, decreased; ↑, increased.

summarizes factors influencing their availability.

6. Conclusions

In conclusion, the evidence presented highlights the potential benefits of beetroot for asthma management due to its bioactive compounds, including polyphenols, flavonoids, saponins, vitamins, nitrate, fiber, and betalains. However, the antinutrient oxalate and sucrose may pose risks in asthma management. An ideal beetroot-based supplement could involve formulations with reduced oxalic acid and sucrose and increased betanin concentration. Processing techniques like microwave treatment, boiling, sun-drying, ultrasonication, and calcium salts could lower oxalate and sucrose levels. Assessing the impact of these techniques on betalain composition, particularly betanin, is critical. Comprehensive clinical studies are necessary to confirm the therapeutic potential, mechanisms, and safety of deoxalated, reduced-sucrose beetroot formulations or purified betalains for asthma treatment.