Dietary salt reduction essential for BP control
Reducing salt intake is one of the most practical ways to help tackle hypertension, according to data presented at AFCC 2018.
“It is recommended to take less than 5 g of salt per day,” said Dr Jorge Sison, a cardiologist from Manila, Philippines, citing evidence showing that high salt intake doubles the risk of coronary heart death, cardiovascular death, and all-cause death. [Public Health Nutr 2003;7:245-250; J Hum Hypertens 2002;16:761-770]
Moreover, chronic exposure to excessive salt leads to nonreversibility of an elevated blood pressure (BP), consequently leading to morbidities such as cardiac hypertrophy, renal damage, stroke, heart failure, and premature death, among others, added Sison. “[Chronic exposure leads to a] progressive increase in baseline BP level … There is no turning back [to normal levels].”
The nonreversibility could be attributed to the renal mechanism for salt-dependent hypertension, noted Sison, as chronic high salt intake resets the renal threshold for salt excretion. “Our ability to excrete the salt we have taken in [is reduced].” Other factors could be the increased peripheral resistance and the subnormal vasodilation to salt load. [Nat Med 2008;14:64-68]
Individuals who are “salt-sensitive”, ie, those with intrauterine growth retardation, low nephron mass, history of renal injury, genetic abnormalities, and exposure to exogenous agents such as steroids, should also be cautious about salt intake, said Sison. Ageing is another factor, as this reduces an individual’s capacity for salt excretion, he added.
Sison presented evidence demonstrating the benefit of reduced urinary salt excretion in both normotensive and hypertensive individuals. In a meta-analysis, salt reduction resulted in a dramatic improvement in systolic BP, more so among hypertensive individuals. [J Hum Hypertens 2002;16:761-770] Another meta-analysis showed similar findings, noting BP reduction in both hypertensive (by 5.1/2.7 mm Hg) and normotensive (by 2.0/1.0 mm Hg) adults with reduced salt consumption. [Cochrane Database of Syst Rev 2004;1:CD004937]
Nearly 80 percent of the salt in our diet comes from manufactured or processed food (hidden salt), while 12 percent comes from natural sources and 11 percent from “conscious” sources (added at the table and during cooking). [J Am Coll Nutr 1991;10:383-393]
Given the high incidence of unhealthy salt consumption, adhering to a healthy diet is essential, said Sison. One strategy would be through gradual reduction of consumption of food with high salt content, particularly manufactured or processed food.
Active promotion of gradual salt reduction may also be facilitated through public health campaigns to raise consumer awareness on salt levels in food and the health benefits of salt reduction. It is important to reiterate to consumers that the health benefits of reducing salt intake outweigh its culinary benefits (ie, improved flavour and shelf-life, increased water binding capacity in meat), he added.
“Our taste buds adapt to gradual salt reduction … It only takes a [while] to enjoy food with less salt and reveal subtle flavours. Healthy eating habits is key,” said Sison.
Reducing dietary salt consumption may also play a significant role in addressing the obesity epidemic, given the association between high salt intake and obesity, added Sison. [Hypertension 2008;51:629-634]