Mangiare troppo sale accelera il processo di invecchiamento in chi ha problemi di peso.
Lo rivela uno studio americano della Georgia Regents University di
Augusta. Sebbene sia già risaputo che il sodio comporta un aumento della
pressione, con il rischio di ictus e infarto, per la prima volta questi
elementi sono stati messi in connessione con l'invecchiamento cellulare.
Gli scienziati hanno scoperto che il consumo di grandi quantità di sale
negli adolescenti in sovrappeso o obesi porta a un 'accorciamento' dei
telomeri rispetto ai coetanei che seguono una dieta regolare e più
povera di sale.
Ogni volta che una cellula si divide, i telomeri
diventano più corti e quando sono troppo corti le cellule smettono di
dividersi e muoiono.
Studi precedenti avevano già reso noto che
alti livelli di grasso corporeo accelerano l'accorciamento dei telomeri,
ma questa recente ricerca americana ha fatto luce sul fatto che il
sodio presente nel sale sembra lavorare in stretta connessione con
l'obesità per accelerare ulteriormente gli effetti già conosciuti,
coinvolgendo in questa problematica anche i più giovani.
Il
responsabile dello studio, Haidon Zhu della Georgia Regents University,
ha infatti dichiarato al 'Daily Telegraph': "Anche nei ragazzi più
giovani abbiamo riscontrato queste problematiche. L'ipotesi suggerisce
che alti livelli di sodio e obesità possano cooperare per accelerare
l'invecchiamento cellulare.
Diminuendo l'assunzione di sodio si
rallenta il processo di invecchiamento, elemento cardine nello sviluppo
di malattie cardiache. L'abbondanza di sodio in una dieta deriva dal
consumo di cibi troppo elaborati, quindi i genitori possono aiutare i
figli cucinando alimenti freschi più spesso e sostituendo la frutta alle
patatine come snack".
Il team di Zhu ha lavorato su 766
adolescenti, suddivisi in gruppi in base al consumo di sodio. Si tratta
di valori che oscillano tra i 5 grammi di sale al giorno fino ai 10, a
fronte di un consumo raccomandato che in molti paesi non va oltre i 6
grammi. La ricerca, presentata al convegno dell'American Heart
Association a San Francisco, suggerisce inoltre una possibile
connessione con le infiammazioni.
ENGLISH VERSION :
Obese teens with a high salt intake 'at risk of accelerated cellular aging'
Cells may age faster in obese teenagers who have a very salty diet,
according to new research presented at the American Heart Association's
Epidemiology & Prevention/Nutrition, Physical Activity and
Metabolism Scientific Sessions 2014.
Experts already know that the
protective ends on chromosomes - called telomeres - shorten as we age,
and that some physical and lifestyle factors can cause this shortening
to become advanced. These factors include smoking, a lack of physical
activity and having high body fat.
The new research, though, is the first study to find that sodium intake also has an impact on telomere length.
To examine the extent to which telomere length is influenced by an
interaction of sodium intake and body fat, the researchers divided 766
teenagers between 14 and 18 years old into two groups based on their
diet.
The teenagers who were in the lowest half of reported sodium
intake consumed an average of 2,388 mg of sodium per day, whereas the
teens in the highest half of reported sodium intake consumed an average
of 4,142 mg per day.
Even the teens in the lower sodium group were
consuming much more salt than the American Heart Association's
recommended 1,500 mg per day, however.
To what extent did weight influence telomere length in teens with high sodium intake?
The researchers used a type of ratio called "T/S ratios" to describe
the relationship between the length of a telomere compared with the
length of a single gene.
They found that the T/S ratio in obese
teens with a high sodium intake was 1.24 versus 1.32, while the T/S
ratio of normal-weight teenagers with a high sodium intake was 1.29
versus 1.30.
This shows that the telomeres were significantly
shorter in obese teens who had a high sodium intake. But in the teens of
a normal weight who had a high sodium intake, there was no significant
difference in telomere length.
Fast Facts about sodium The average American consumes about 3,400 mg of sodium a day.
More than 75% of our sodium consumption comes from processed and restaurant foods.
The six most popular foods containing high levels of sodium are
breads, cold cuts and cured meats, pizza, poultry, soup and sandwiches.
"Even in these relatively healthy young people, we can already see the
effect of high sodium intake, suggesting that high sodium intake and
obesity may act synergistically to accelerate cellular aging," says Dr.
Haidong Zhu, lead author of the study and assistant professor of
pediatrics at Medical College of Georgia, Georgia Regents University in
Augusta.
Obesity increases sensitivity to salt and also causes
inflammation. This might explain why having a high sodium intake had
such a pronounced difference in the overweight teens.
"Lowering
sodium intake may be an easier first step than losing weight for
overweight young people who want to lower their risk of heart disease,"
Zhu says.
"The majority of sodium in the diet comes from processed
foods, so parents can help by cooking fresh meals more often and by
offering fresh fruit rather than potato chips for a snack."
Other
findings presented at the American Heart Association meeting included
research on how a behavioral intervention can encourage adults to reduce
the amount of sodium in their diet. The intervention involves using
more herbs and spices in food as an alternative to salt. |
