Salt and CVD

Posted by Andrew Wadge on April 20th 2007 in Science, safety and health

Scientific experts agree that excessive salt consumption increases the risk of high blood pressure which, in turn, increases the chance of cardiovascular disease (CVD).  That’s why the Agency has been campaigning for a reduction in the salt intake of the UK population. 

The latest phase of the Agency’s salt campaign was launched last month and focuses on the message that most of the salt we eat (75%) is already in the food we buy, so we need to check the label and pick the product with the lowest amount of salt.

So I was very interested to read the findings from a study published in the BMJ today, which suggests that cutting down on salt can reduce the risk of developing CVD. 

The study followed up participants who had taken part in a trial 10-15 years earlier, which had examined the effect of reducing salt intake on blood pressure. 

The researchers found that those people in the group that had reduced their salt intake had a 25% lower risk of CVD compared with the group who had not changed their salt intake. 

However, we need to be a bit cautious about these findings as direct measurements were not made of salt intake or blood pressure during the follow-up period and it is not clear if the reduction in CVD outcomes was related to blood pressure effects.

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FSA Salt Reduction Policy

Posted by Morton Satin (not verified) on 26/02/2008 - 22:11

Andrew,

The most recent research ( Shapiro, Y., Boaz, M., Matas, Z., Fux, A., & M. Shargorodsky, “The association between the renin-angiotensin-aldosterone system and arterial stiffness in young healthy subjects,” Clinical Endocrinology (OnlineAccepted Articles. doi:10.1111/j.1365-2265.2008.03176.x.) indicates that for healthy young adults, consumption of 2,300 mg Na/day or less will cause increase plasma aldosterone production leading to arterial stiffness.

This is a follow-on of a long series of studies on vascular compliance.

The reaction of the renin-angiotensin-aldosterone to low-salt intakes (anything less than 2300 mg Na/day) has been completely lost in this debate and, if ignored, will result in great harm to the public.

As a scientist, you know that despite vigorous salt reduction advocacy and populist media attention to this issue, the science will eventually come to the fore. I can only hope that no one suffers unintended consequences because of a rush to judgment and a need to be shown to be responsive to the public.

Fortunately, in the US, the FDA is taking a more cautious approach than the regulatory agencies in other countries and is evaluating all the scientific data before rushing ahead with any policies. They did this once before, when they delayed the acceptance of thalidomide, while the rest of the world eagerly accepted it without a full review of the science.

Salt consumption

Posted by Andrew Wadge on 16/05/2007 - 13:11

Thanks for your thoughts David. We don’t have any evidence to show that consumers are adding more salt to food than they were previously. Encouraging people to check labels is just one of our campaign messages and of course we do still want people to reduce the amount of salt they add themselves. Our salt website, salt.gov.uk, gives tips on how to do this.

The reason we are encouraging people to compare labels and choose the lower-salt option is that 75% of the salt we eat is already in everyday foods – a fact that is a surprise to many people. FSA research in February this year shows that 90% of those respondents claiming to be cutting down on salt are doing so by not adding it to their food – so we still need to do more to make people aware of the salt in the foods they buy and encourage them to check labels.

The 0.5g reduction in average salt intakes, from 9.5g to 9g, is a small but significant reduction. It illustrates that while some progress has been made, more work is required to achieve the goal of reducing average intakes to 6g.

When you mention the foods that we have identified as the major contributors to salt intake, I assume you are referring to meat products, bread, breakfast cereals and cheese. These foods account for about 43% of salt intakes in the UK diet. Staple foods such as bread can contribute quite a large proportion of people’s intakes, not because they are the highest-salt foods, but because people tend to eat a lot of them in the context of their whole diet. Reductions in the salt levels in such foods are very important and very welcome, but there’s still the rest of the diet to consider.

It is not unexpected that the reduction seen in people’s salt intakes is less than the reductions in individual foods, for a number of reasons. Firstly, the intake figure that we refer to is an average across many consumers with different diets, which may be lower or higher in salt. Secondly, people’s diets vary a great deal, both in terms of the types of foods they eat and the amounts – so some people will have larger amounts of high-salt foods in their diets (and therefore higher intakes of salt) than others. Because we are aware of these sorts of issues, we have always advised that consumers should try and consume high-salt foods less frequently and to eat less when they do have them.

We will continue to monitor salt intakes, with a further survey planned in 2007/08.

Hidden salt

Posted by Andrew Wadge on 11/05/2007 - 13:57

Thanks for your response Nick – you have made lots of interesting points, so apologies for not getting back to you earlier.

We do recognise that decreasing salt intakes to less than 6g a day would bring greater benefits. But since the average salt intake in the UK is currently about 9g a day, the target to reduce intakes to no more than 6g a day is a realistic goal. The 6g target is based on the recommendations of the Scientific Advisory Committee on Nutrition (SACN) and, if met, would be of major benefit to public health.

You also mention potassium. There is some evidence to suggest that eating more potassium may help to decrease blood pressure, but the same has also been shown for calcium and magnesium. What is more significant is the consistent evidence showing the beneficial effects on blood pressure of eating more fruit and vegetables. High consumers of fruit and vegetables tend to have a better diet overall (such as low saturated fat intakes and healthier lifestyles).

Your third point is that getting people to check labels is not going to work. We disagree on that. It isn’t always easy to interpret food labels, but it is getting easier with front-of-pack labelling and more and more products listing the amount of salt they contain, as well as sodium. We are not expecting people to tot up the salt in absolutely everything they eat every day – hardly anyone has the time for that. We do want people to compare the labels on similar products and choose the lower-salt option. And we believe that if people do this, it will help to lower their salt intake.

As you point out, some foods give no indication of the amount of salt they contain. This is because, under the current rules, nutrition labelling is voluntary unless a nutrition claim such as ‘low salt’ is made. Foods that carry a nutrition label are required to state the amount of sodium in 100g. Current rules don’t require this to be expressed as salt. However, the Agency recognises that information on salt would be more helpful than sodium and that’s why the UK Government has made a public commitment to press the European Commission to introduce mandatory nutrition labelling, including labelling of salt.

You are right that most people don’t realise that 75% of the salt we eat is already in everyday foods, which is why this is one of the key messages of the Agency’s salt campaign. We want people to be more aware of this - and of course to check the label.

Finally, a typical bacon butty – based on two slices of white bread, three rashers of bacon, a bit of butter and tomato ketchup – might contain over 4g of salt. Of course, the actual salt content will depend on the type of bread and bacon and how big the sandwich is. It is possible for people to work this out for themselves if the ingredients of their sandwich are labelled to say how much salt they contain. But as I’ve already said, our campaign is not about a nationwide maths challenge – it’s about raising awareness that some foods are high in salt and that, most importantly of all, the man or woman on the street can reduce their salt intake by checking the label and choosing the lower-salt option.

Salt consumption

Posted by David (not verified) on 09/05/2007 - 11:03

Andrew

I hate to disagree with you but you recently published a piece of information that should cause you to re-evaluate this position.

The results of the survey that you published concerning salt consumption showed a drop from 9.5 to 9g per day for the average adult.

Whilst this is welcome, it represents a reduction of just over 5%, much less than the reductions that have been made in the salt content of the foods that the FSA identified as the major contributors to salt intake. This would seem to strongly suggest a significant element of add back of removed salt by the consumer.

You are in danger of creating a belief in the consumer that they themselves do not have to change anything in their behaviour but simply read labels to find lower salt alternatives and then anything they do to it is irrelevant.

Salt reduction

Posted by Andrew Wadge on 27/04/2007 - 13:02

I'll respond to David's comment first. Thanks for posting, David. Yes, you’re right, the Agency is still saying that 75% of the salt we eat comes from the foods we buy.

This has been a central message in our salt campaign because we want to raise awareness that the choices people make in the shops have a big effect on their salt intake. But that doesn’t mean that we don’t recognise the very significant progress made by the food industry in reducing salt levels. It is important to highlight this work, which is ongoing.

The 75% figure is referring to the proportion of a person’s total salt intake. So we’re not saying that people are still getting the same amount of salt from foods they buy as they were three or four years ago. But we don’t have any evidence at the moment to suggest that there has been a change in the proportion of salt intake from bought foods and from salt added by the individual. We will reassess this statistic when we have new data from the National Diet and Nutrition Survey in 2009/10.

Of course, there are lots of changes happening, both in relation to people’s eating habits – more ready meals and more eating out, for example – and in relation to reformulation. And most of the time we don’t know immediately what impact this is having on intakes of salt or other nutrients. So we continue to give advice on the best and latest data that is available to us.

Hidden Salt

Posted by Nick (not verified) on 26/04/2007 - 18:51

I believe that high salt intake does more than increase blood pressure: it hardens the arteries, causes the kidneys to gradually deteriorate and contributes to many 'western' illnesses. So obviously reducing salt intake is an excellent objective. However, the research shows that even more than 3g/d is too much and really one needs as little as 1.2g/d. The public do not know this and think that < 6g is OK. It is time to come clean.

The importance of potassium containing foods has a bearing because the more potassium you consume (in fruit & veg), the more easily the body tolerates sodium. 5/day is good, but not enough to supply potassium requirements. People need to be advised to focus on potassium containing fruit and veg. It is not just bananas, its oranges, tomatoes and a whole range.

Getting people to check labels is not going to work. Firstly it is confusing - not many know how to convert sodium into salt. Tins etc contain a mixture. Furthermore, many salt containing foods, such as tinned salmon, carry no indication of salt content at all. So just how are you supposed to work out your daily consumption?

Most people think that as long as they do not add salt to their food, they are OK. They do not realise that BREAD, BACON, Processed meats, Cheese, some breakfast cereals all carry high levels of salt and these are popular foods. It is probably because except for bacon, these foods do not ctaste salty. Can you tell me how much sodium there is in a bacon butty? How do you expect the consumer to work it out?? Please explain.

Regards,

Nick

Salt Reduction

Posted by David (not verified) on 23/04/2007 - 11:15

Andrew

Why are the FSA continuing to use the same figure that they have done for the past 3-4 years of 75% of salt from foods purchased and ignoring the significant reductions that food manufacturers have made in salt content. Is it not time you updated your figures as continued use of this figure would suggest you are failing in your aim of reducing the salt in foods, something that is just not true.