多鹽少鹽

The Lancet今期的Editorial 講吃鹽的硏究, 我在下面貼了出來。我沒有看整份報告, 因為好幾個月前開始, 看全篇要先付錢, 這篇要美金30多元, 我反正對醫學常識一知半解, 所以省了這錢。對上兩篇的留言充滿激情, 我答不上嘴, 於是晚宴歸來, 換下話題, 讓陰虛火旺的人冷靜一下, 免傷肝脾。

Evidence-based medicine has become the bedrock of treatment guidelines, but why does evidence-based medicine not translate into evidence-based policy? Governments and health organisations around the world are advocating salt intake be reduced, but little robust evidence exists to support a reduction in salt for the general population. Indeed, the few randomised controlled trials (RCTs) available have not strongly supported the benefit of salt reduction in normotensive populations. There is no real disagreement that high salt intake is associated with high blood pressure, and most studies indicate that high blood pressure is associated with more cardiovascular events. The level at which salt intake is regarded as high is not, however, agreed. Even more concerning is that evidence for the benefit in the advocated target levels of salt intake is virtually absent; there are no RCTs measuring health outcomes when sodium intake is less than 2·3 g (5 g of salt).

The paper by Andrew Mente and colleagues in today's Lancet provides reasonable evidence that current dietary levels of salt in most populations are associated with the lowest incidence of cardiovascular events. More importantly, they show the proposed reductions to below 3 g of sodium intake daily are likely to result in harm in both hypertensive and normotensive people. Although not from an RCT, these data are as robust as the data used to advocate reductions to low levels. At the very least, these data should demand re-evaluation of the wisdom of reducing levels of dietary salt without high grade evidence to support such reductions.

Before non-legislated salt reduction programmes are imposed, the public should demand that the harms, as well as the benefits, are based solely on robust scientific evidence. Enacting potentially harmful changes without strong supportive evidence should be avoided.

近年各國政府都呼籲國民為保健康減鹽減糖, 已被視為天經地義的看法。減糖似乎毫無爭議, 尤其是二型糖尿病這種唬人的因素, 所謂糖當然包括很快便轉變成糖的澱粉質食物, 而不是單指肉眼可見的糖。人到中年以後, 新陳代謝逐漸減慢, 對糖的警覺就特別高了。

Eating too LITTLE salt may INCREASE your risk of a heart attack or stroke, claims controversial new research

It has long been held that a diet high in salt is dangerous to the heart, raising the risk of heart attack and stroke.

But, in a dramatic U-turn, the scientific evidence has suggested the opposite can also be true.

A global study has found that, contrary to past belief, low-salt diets may not be beneficial.

Rather, they can increase the risk of cardiovascular disease and death, compared with average salt consumption.

The study, published in the reputable Lancet journal, has garnered strong reaction, with one expert declaring his 'disbelief', while others are critical of the study's methods, and calling its findings into question.

The research was carried out by investigators at McMaster University and Hamilton Health Sciences.

They analyzed more than 130,000 people across 49 countries, focusing on whether the relationship between sodium (salt) intake and death, heart disease and stroke differs in people with high blood pressure compared to those with normal blood pressure.

Their findings showed that regardless of whether people have high blood pressure, low-salt intake is linked to a greater incidence of heart attacks, stroke, and deaths compared to average intake.

Dr Andrew Mente, lead author, and associate professor of clinical epidemiology and biostatistics at McMaster's Michael G. DeGroote School of Medicine, hailed the findings 'extremely important' for those suffering high blood pressure.

He said: 'While our data highlights the importance of reducing high salt intake in people with hypertension (high blood pressure), it does not support reducing salt intake to low levels.

(Daily Mail Australia 21 May 2016)

我食鹽多過你食米是上一代的口頭禪, 現代的潮語會怎樣講我就不知了。近年盡量戒咸, 以防血壓高。可是, 科學又好像不很科學了, 多吃鹽會引致血壓高、中風和心臓病, 另一方面, 少吃鹽也同樣會引起這些疾病, 究竟我應該信那個講法? 晚宴歸來, 拚命灌水, 沖淡一下那些糖、鹽、味精。香港人又再登世界長壽榜首, 同一天的報導, 那80多歲的老伯卻要尋求安樂死, 說來也諷剌。