Hydroponic Production of Reduced-Potassium Swiss Chard and Spinach: A Feasible Agronomic Approach to Tailoring Vegetables for Chronic Kidney Disease Patients

Abstract

Tailored foods are specifically suitable for target groups of people with particular nutritional needs. Although most research on tailored foods has been focused on increasing the nutrient content in plant tissues (biofortification), in populations with specific physiological conditions, it is recommended to reduce the uptake of specific nutrients in order to improve their health. People affected by chronic kidney disease (CKD) must limit their consumption of vegetables because of the generally high potassium (K) content in the edible parts. This study aimed to define an appropriate production technique for two baby leaf vegetables, spinach (Spinacia oleracea L.) and Swiss chard (Beta vulgaris L. ssp. vulgaris), with reduced K tissue content, minimizing the negative effects on their crop performance and overall nutritional quality. Plants were grown in a hydroponic floating system. The K concentration in the nutrient solution (NS) was reduced from 200 mg/L (K200, the concentration usually used for growing baby leaf vegetables in hydroponic conditions) to 50 mg/L over the entire growing cycle (K50) or only during the seven days before harvest (K50-7d). The reduction of K in the NS resulted in a significant decrease of K tissue content in both species (32% for K50 and 10% for K50-7d, on average), while it did not, in general, compromise the crop performance and quality traits or the bioaccessibility of K, magnesium, and calcium. The production of reduced-potassium leafy vegetables is a feasible tailored nutrition approach for CKD patients in order to take advantage of the positive effects of vegetable consumption on health without excessively increasing potassium intake.

Characterization of Micronutrients, Bioaccessibility and Antioxidant Activity of Prickly Pear Cladodes as Functional Ingredient

“…This low Ca bioaccessibility could be related to oxalate presence; in fact, this compound can combine with Ca and others minerals to form insoluble compounds, reducing their availability [ 34 ]. Similar results about Ca and K bioaccessibility were found in different leafy vegetables [ 40 , 41 ]. These elements are essential for human health, to maintain the electrolyte balance involved in many different bodily processes including bone growth, muscle and nerve functionality, and also to prevent osteoporosis diseases, as described by several authors [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ].…”

“…An ion exchange chromatography (Dionex DX120, Dionex Corporation, Sunnyvale, CA, USA) was performed with a conductivity detector, as reported by D’Imperio et al [ 41 ]. For the determination of anion contents, 0.3 g OFI dry sample was treated with a solution of 3.5 mM (Na 2 CO 3 ) and 1 mM (NaHCO 3 ) for 30 min in orbital shaker, 50 rpm, at room temperature.…”

Posidonia Natural Residues as Growing Substrate Component: An Ecofriendly Method to Improve Nutritional Profile of Brassica Microgreens

“…A promising approach is biofortification. It consists in increasing the content or the bioavailability of nutrients, e.g., vitamins (mainly folate and vitamin A), minerals (calcium, iron, silicon, boron, iodine, zinc, and selenium) and bioactive compounds (polyphenols and carotenoids) in plant foods, in order to ameliorate their nutritional profile in terms of their contribution to satisfy the Recommended Daily Allowance (RDA) for nutrients ( White and Broadley, 2009 ; D’Imperio et al, 2016 , 2019 , 2020 ; Montesano et al, 2016 ; Smoleń et al, 2017 ; Gonnella et al, 2019 ). This approach allows improving the nutritional quality of different crops by using several strategies, such as genetic engineering, conventional breeding, and agronomic techniques ( Carvalho and Vasconcelos, 2013 ).…”

Boron Biofortification of Portulaca oleracea L. through Soilless Cultivation for a New Tailored Crop

“…The total phenol (TP) content was determined according to the Folin-Ciocalteu method by using the extraction methods reported by D'Imperio et al, (2019) [27]. Briefly, 200 mg of lyophilized sample were mixed with 10 mL of solvent mixture (MeOH:H 2 O:CH 3 COOH, 79:20:1% v/v/v).…”

“…Furthermore, by acting on the mineral composition of the NS, it is possible to increase or reduce the concentration of target ions in plant tissue to obtain tailored vegetables for specific nutritional requirements [21][22][23][24][25]. For example, some authors [26,27] reported the use of NS with different potassium (K) levels to obtain low-potassium vegetables suitable for people affected by chronic kidney disease. On the other hand, Gonnella et al,) [22] proposed the use of iodine-biofortified Brassica vegetables for preventing iodine (I) deficiency and related human disorders, while biofortification for silicon and calcium has been proposed to obtain vegetables suitable for women in premenopausal conditions [21][22][23].…”