VITAMINA C: L’ACIDO ASCORBICO O CALCIO ASCORBATO

La vitamina C è una delle sostanze più conosciute efficaci e sopratutto senza nessuna controindicazione. In più, è un potente antiossidante contro i radicali liberi; va ribadito che la vitamina C funziona  bene in acqua sia come intracellulare che extracellulare. Inoltre, la vitamina C incrementa l’azione di una vitamina antiossidante, la vitamina E, che ha funzioni liposolubili cioé che si scoglie nei grassi.

E’ importante sapere che gli animali sono capaci di produrre vitamina C in maniera naturale, mentre che noi esseri umani abbiamo perso questa capacità, proporzionare questa vitamina al nostro corpo è fondamentale, e la possiamo ottenere mediante alimenti come la frutta fresca e soprattutto le verdure.

Dall’Antichità fino ai primi anni del XIX secolo, i marinai sviluppavano una malattia chiamata scorbuto. Lo scorbuto causava contusioni, ferite di difficile guarigione, sanguinamento delle gengive e debolezza generale. Questa malattia era dovuta alla carenza di vitamina C e il trattamento dello scorbuto consisteva nel  semplice consumo d’agrumi.

Qualche secolo dopo, Albert Szent-Gyorgyi, un fisiologo ungherese, ha isolato il principio attivo, definendola come anti-scorbuto, e successivamente come acido ascorbico o vitamina C.  È importante sapere che una delle multifunzione della vitamina C è quella di aumentare la produzione di collageno nel corpo. Il collageno è molto importante per i nostri tessuti connettivi quali i tendini ed le cartilagini. Oltre a queste funzioni, la vitamina C  può anche offrire altri vantaggi:

1. Stress

Una meta-analisi ha rivelato che la vitamina C è utile per le persone che presentano un sistema immunitario indebolito a causa dello stress. Inoltre, i fumatori, le persone alcoliche e persone con obesità (situazioni di stress organico) hanno  livelli  di vitamina C molto bassi. Quest’ultimo è importante perché la vitamina C è una vitamina molto sensibile.

2. Influenza

La vitamina C, o più correttamente Acido Ascorbico, è una molecola idrosolubile che svolge numerose funzioni essenziali: tra queste pare che sia stata riconosciuta la sua capacità di prevenire e ridurre i sintomi del raffreddore comune; l’argomento è comunque tutt’ora controverso.

3. Circolatorio.

Le persone che hanno una maggiore concentrazione di vitamina C nel sangue hanno un rischio minore (42 %) di subire un ictus (CVA) che quelli con un livello più basso. Un’altro studio ha rivelato che 500 mg. di vitamina C tutti giorni abbassano la pressione sanguigna in un 10 %.

4. L’invecchiamento della pelle.

Prima, La vitamina C ha funzioni a livello intracellulare e anche a livello extracellulare. Infatti, uno studio pubblicato sull’American Journal of Clinical Nutrition ha esaminato la relazione tra l’assunzione di nutrienti e l’invecchiamento della pelle in 4.025 donne, in età compresa tra 40-74 anni. E’ stato cosi osservato che le donne che assumevano vitamina C erano meno proclivi ad avere rughe e pelle secca. In somma, loro avevano un migliore aspetto della pelle in generale.

Inoltre, gli studi dimostrano che la vitamina C può avere un effetto sinergico insieme ad altri anti ossidanti e sostanze anti-infiammatori aiutando cosi a combattere il cancro. In diabetici è stato dimostrato che la vitamina C può aiutare a controllare livelli di glucosio nel sangue.

In piu si è visto che le persone con problemi di stomaco trovano interessante l’utilizzazione di vitamina C perché può aiutarli a proteggergli contro l’azione ossidativa causato dal batterio Helicobacter pylori che è la principale causa delle ulcere e gastriti dello stomaco.

La dosi di vitamina C dovrebbe essere superiore alla dose giornaliera raccomandata (RDA), 60mg. La maggior parte degli studi hanno utilizzato 500 mg. al giorno per migliorare la salute.

Qui il problema è che per raggiungere 500 mg. dobbiamo mangiare molta frutta e verdura, nonostante, ci siano molti integratori di vitamina C.

Dobbiamo sapere che alcune persone soffrono d’irritazione a causa della vitamina C (acido ascorbico),  Per loro c’è  una forma di vitamina C che non acida: ad esempio l’ascorbato di calcio, l’ascorbato di potassio, ecc. Così, potreste evitare qualsiasi problema gastrointestinale.

Pedro Encinas

Dietista sportivo e Fisioterapista

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