Salt and cardio-vascular disease: Policy and Science clash

The recent video we posted of Dr SalimYusuf’s PURE study had a section on sodium intake, where he showed that the lowest risk of cardiovascular events, cardiovascular deaths and all-cause mortality was associated with an intake between 3000 and 6000 mg of sodium per day (equivalent to 7 to 15g salt per day). The current US average sodium intake is 3800 mg placing the general population nicely within this sweet spot, although towards the lower end.

Current US and UK dietary recommendations recommend an upper limit at 2300mg of sodium (6g of salt) whilst cardiovascular recommendations by bodies such as the American Heart Association aim to reduce sodium intake to 1500 mg per day (approx 3.75 g salt). If the PURE study is right (and it is not alone in questioning the current guidelines), then these aspirations would do more harm than good.

How did such discrepancy arise? The problem may be the use of surrogate markers. The thinking goes like this: Salt raises blood pressure. Raised blood pressure increases CVD risk, so salt increases CVD risk. This kind of thinking was evident in 2011 when the American Heart Association (AHA) called for salt targets to be reduced to 1500mg per day.At the time MedPage Today explained:

The evidence linking salt intake with blood pressure — and the major adverse outcomes of heart disease, stroke, and kidney disease — is “impressive,”…

That evidence includes more than 50 trials assessing the blood pressure effects of salt, as well as a meta-analysis showing that cutting salt intake by about 1,800 mg per day lowered blood pressure by 5 mm Hg systolic and 2.7 mm Hg diastolic.

This is a “critically important public health issue,” according to Appel and colleagues, and this AHA advisory must be considered “a call to action.”

On the basis of this ‘A leads to B leads to C, therefore A leads to C’ thinking initiatives were instigated all round the world to reduce public consumption of salt. A task force of concerned scientists even formed a lobby group to put pressure on food manufacturers, which successfully led to reductions in added salt in manufactured foods.

However, within a short time of the AHA call to action reports started coming in contradicting this advice.

Over this period it is clear that scientists were becoming more and more irritated with the dogmatic approach of the AHA and government bodies, and by the last article were publicly calling the AHA anti-scientific!

Despite all of the research questioning the validity of further salt reduction US and UK policy remains stubbornly wedded to the ‘less is best trajectory’. In their 2016 survey the UK government reported proudly that average sodium consumption fell from 3500mg in 2005 to 3200 mg in 2014.

Their report claimed “Too much salt in the diet can raise blood pressure which increases the risk of heart disease and stroke. A reduction in average salt intake from 8g to 6g per day is estimated to prevent over 8000 premature deaths each year and save the NHS over £570million annually.”

Yet contrary evidence from studies including PURE would suggest that this is not simply futile but probably harmful. You would think that with the swathe of research challenging the low salt dogma that public policy would be questioning the wisdom of further reductions. Not a bit of it. Dr Alison Tedstone, chief nutritionist at Public Health England, makes no bones about it:

Our analysis makes clear that there is a steady downward trend in salt consumption. While people are having less salt than 10 years ago, we are still eating a third more than we should.

Many manufacturers and retailers have significantly reduced the salt levels in everyday foods. However, more needs to be done, especially by restaurants, cafes and takeaways.

The intransigence of health policy makers leads researchers to exasperation and despair. As one writer put it:

…the ‘salt hypothesis’ is rather like a monster from a 1950s B movie. Every time you attack it with evidence it simply shrugs it off and grows even stronger. – Malcolm Kendrick

In an interview with MedPage today researchers who found that patients with heart failure who ate more salt did better than those who ate less made the following statement which we have published before, but is such a gem it deserves another outing:

“We have had no basis for any of our recommendations regarding sodium restriction during the past 50 years, although these recommendations have changed a great deal (for no good reason). After this report, we still have no basis for any of our recommendations regarding sodium restriction. We were ignorant before; we are not any smarter now. Did we really need this report to tell us that we lack evidence for our recommendations regarding dietary sodium in patients with heart failure?”
Milton Packer, Professor in the Division of Cardiology, UT Southwestern

Further reading:

Salt vs sodium measurements

We made a boo-boo in out recent post (Cardiologist attacks diet dogma at 2017 symposium) where we summarised the findings from the PURE study regarding salt intake. We originally stated that 3 to 6 grams of salt per day appeared optimal but this should have read 3 to 6 grams of sodium per day.

What’s the difference?

Salt is a simple compound sodium chloride, NaCl, composed of sodium and chlorine atoms in a 1:1 ratio. Sodium has an atomic mass of 23 and chlorine a mass of 35, so the the fraction by weight of sodium in salt is 23/58 = 40%; or said the other way round, 1 gram of sodium is found in 2.5g of salt. To make things even more confusing, sodium is often quoted in milligrams (mg) whilst salt is given in grams, so the conversion becomes: 1000mg sodium = 2.5g salt

Let’s put this to the test with a confusing pair of health policies: UK guidelines recommend you eat no more than 6g of salt per day, whereas US guidelines place the limit at 2,300 mg of sodium per day. How do these compare?

First, converting the US 2,300 mg of sodium to grams gives 2.3 g of sodium. Next, convert this to the equivalent amount of salt by multiplying by two and a half: 2.3g x 2.5 =  5.75g. This figure rounds to 6g. i.e. they are essentially recommending the same thing, but expressing them in different ways. (That’s the special relationship for you!)

Here is a handy table for converting between sodium, salt and teaspoons:

Salt in
grams
Sodium in mg Approx. equivalent to                Guidelines – daily limit
0.5 200 Average pinch of salt
2.5 1000 Half a teaspoon salt
3.75 1500 ¾ a teaspoon salt Recommended (AHA)
5 2000 One teaspoon salt
6 2400 1¼ teaspoons salt Upper limit (UK / US)
10 4000 2 teaspoons salt Current average consumption
15 6000 3 teaspoons salt Upper limit (PURE study*)

*The PURE study found that the lowest risk of cardiovascular and all-cause mortality was associated with a sodium intake of 3000 to 6000 mg per day. A concern I will look at in the next post is that public health policy does not take into account the lower limit, and assumes that less salt is always better. PURE and other studies suggest otherwise!

This sodium/salt mistake crops up a little too often and leads to confusion. For example MedPage Today, a respected medical news site, reported in 2011 that the American Heart Association had called for salt intake to be limited to 1,500 Mg. (I will write more about the conflict between this figure and the findings of the PURE study in my next post)

First off, I’m sure they meant milligrams (mg), not mega grams (Mg). Autocapitalising their title, put them out by a ‘trifling’ factor of one billion, but that’s forgivable. Where they really sowed confusion was by muddling up sodium and salt like I did. The AHA were calling for sodium intake to be reduced from 2300mg per day to 1500 mg per day (for adults), but MedPage reported these figures as salt not sodium.

One bemused commenter wrote “This article suggests 1 1/2 gms of salt a day, in the UK we are told 6gms per day”

So to clarify, the UK and US recommended upper limit is 2300 mg sodium per day (= 6 g salt), and the AHA recommendation is 1500 mg sodium (=just under 4g of salt). In contrast the PURE study found the ideal range was 3000 to 6000 mg sodium (=between 7.5 and 15g of salt per day).

Why then do researchers and nutrition labels quote sodium, not salt quantities? Because in principle at least, you could get sodium from sources other than sodium chloride. In practice non-salt sources of sodium are insignificant.

Anyway, hope that clears up the confusion about measuring sodium levels.

Next up I’ll tackle how the national guidelines are pushing us in the opposite direction to that suggested by the PURE study.

Cardiologist attacks diet dogma at 2017 Symposium

Video

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Dr Salim Yusuf speaking at the Cardiology Update 2017 symposium gives preliminary findings from the PURE study which followed 140,000 people in 17 countries, designed to address causation of cardiovascular disease.

He explains that the results indicate:

  • Greater fat intake is protective
  • Carbohydrates are harmful
  • High fat dairy is beneficial
  • Saturated fat from meat is neutral
  • Fruit is beneficial, but no additional benefit over 2 portions per day
  • Legumes are beneficial
  • 3 to 6 g/day sodium* intake optimal (vs US guidelines of 1.5g)
  • Eggs, fish and vegetables were neutral

*Edit 10/03/2017
Correction: I previously wrote 3 to 6 grams of salt per day, but have corrected this to 3 to 6 grams of sodium per day. This is equivalent to 7.5 to 15 g of salt per day.

December News Round-Up

Just by chance, much of the nutrition news this month fits in with the theme of Christmas dinner.

What Christmas dinner looks like around the world

I shared my traditional (grain-free) Christmas dinner this year in a recent post, but this article looks at the traditional festive fare in other countries. For example, the Puerto Rican national dish is the roast suckling pig known as lechón. And my roast turkey seems quite unadventurous compared to the Norwegian sheep’s head!  (Independent 25th Dec)

Organic animal produce contains more omega 3

christmas-dinner-turkey

My Christmas turkey and vegetables were all organic as were most of the dairy products I used. So I was pleased to see on Knowridge (12th Dec) that ‘in the largest study of its kind, an international team of experts led by Newcastle University, UK, has shown that both organic milk and meat contain around 50% more beneficial omega-3 fatty acids than conventionally produced products.’

And organic veggies are higher in salvestrols, but that’s another story ;-)

If you overdid the goose fat, cream and butter this Christmas, or ate more than your share of that juicy beef or pork joint, take heart from the following cheering news!

Eating more than the recommended quantity of red meat does not affect heart risk says analysis

beef-joint

The Mail Online (20th Dec) reports on a study analysing the effects of eating more red meat than is commonly recommended and its effect on heart disease parameters. The study authors conclude ‘During the last 20 years, there have been recommendations to eat less red meat as part of a healthier diet, but our research supports that red meat can be incorporated into a healthier diet,’

Saturated fat may not increase heart disease risk after all

christmas-pudding4Milk (in the tea), cream and butter (in my Christmas pudding). Full fat dairy products – but not reduced fat versions – are increasingly being shown to be healthy. 

Medical Health Today (27th Dec) A Norwegian study placed 38 men on a very high fat, low carb diet for 12 weeks. Cardiovascular risk markers improved. The lead author concludes: “that most healthy people probably tolerate a high intake of saturated fat well, as long as the fat quality is good and total energy intake is not too high. It may even be healthy.”

Knowridge (11th Dec) A longitudinal study of 15,000 Brazilian adults found that “for each additional serving of full-fat dairy products people consumed, their risk for having metabolic syndrome decreased by 13%.” The researchers concluded that dietary recommendations to avoid full-fat dairy intake are not supported by their findings.

Quote of the month

“The alleged health risks of eating good-quality fats have been greatly exaggerated. It may be more important for public health to encourage reductions in processed flour-based products, highly processed fats, and foods with added sugar,” FATFUNC study author Simon Dankel.

[my emphases]

If you had a low-fat Christmas and after reading the above studies are now regretting it, the following advice should help get you back on track. Self Magazine (27th Dec) has a pretty good article 19 healthy fats you should be eating. Also, this article, 7 tips on low-carb Mediterranean-Style eating, is worth a look (Tips On Love & Life, 27th Dec)

Nuts are for life, not just for Christmas!

It’s a tradition to have bowls of nuts at Christmas, but there are good reasons to include nuts in your diet all year round. Observer (12th Dec) discusses the health benefits of all kinds of nuts. (Personally I don’t touch peanuts)

Don’t hold back on the seasoning this season

I seasoned my turkey with plenty of salt and pepper. As we have discussed previously on this blog, salt should not be demonised. An article on Knowridge (12th Dec) made the point clearly this month:

A large worldwide study has found that, contrary to popular thought, low-salt diets may not be beneficial and may actually increase the risk of cardiovascular disease (CVD) and death compared to average salt eating.

In fact, the study suggests that the only people who need to worry about reducing sodium in their diet are those with hypertension (high blood pressure) and have high salt consumption.

The Microbiome and Circadian rhythms
or how overindulging and late nights play havoc with your liver

I just wanted an excuse to include this beautiful graphic. But, no, really, this is a very good article – top notch science writing! As the title says it’s about the interplay between the microbiome and the body clock – especially the liver. If you have given your liver a hard time over the festive season – dodgy food, eating times and late nights – you should probably read this article (The Conversation, 1st Dec)

OK, I can’t think of a seasonal connection for these last few items…
No, wait, how about…

Three odd presents you find at the bottom of your Christmas stocking:

Time magazine (28th Dec) has an unusually clear article on the science behind the ketogenic diet, including quotes from several key researchers. Worth a read.

The Mirror Online (2nd Dec) reports on a case of herbal poisoning. A woman nearly died after making tea from what she thought was comfrey leaves, but is suspected of being foxglove (digitalis). Writing in BMJ Case Reports Dr Mathew Kurian Vithayathil said “This case illustrates how limited knowledge of plants can be potentially fatal.”

The Telegraph (28th Dec) tells of 6 people who fell ill after drinking raw milk in Cumbria which was infected with Campylobacter bacteria. This is, to my knowledge, the first case in the UK in many, many years. To get some perspective on the risks of raw milk see our post on the subject here.

Result! A thoroughly festive news round up!

HAPPY NEW YEAR
and good eating and health in 2017!
~ Afifah and Keir

 

May News Round-Up

In_the_News_May· Potatoes and hypertension
· Antibiotics, depression and phages
· Gluten debate
· Low-carb diets good for diabetes
· Salt does not raise BP (yet again)
· Medical errors – high death toll
· Vitamin D & sunshine
· 50y of changing UK food habits

Potato consumption linked to raised blood pressure

The Guardian (17th May) covered this story as well as any, after a study found that those who ate potatoes four or more times per week had a small, but significant, increased risk of hypertentsion (high blood pressure) compared to those eating them less than once per week. This link applied to boiled, mashed or baked potatoes and chips (aka French fries), but weirdly, not to crisps (aka potato chips in the USA). The study authors, suggest the effect is caused by the high carb content raising blood sugar. Interestingly, they point to trials that show high protein and high fat diets lower blood pressure. (See BMJ paper here).

Grass-Fed Nation: Book Review

The Telegraph (26th May) reviews a new book by Graham Harvey, script writer of The Archer’s agricultural story lines and one of the excellent speakers at our Grass Fed Meat Revolution in 2014.

Unfortunately, British dairy farming is moving in the opposite direction with the creeping introduction of US style mega-dairies (now numbering 100+), where cows are raised permanently indoors. The Telegraph (1st June) reports on this disturbing trend.

Antibiotics, depression and resistance – Phages to the rescue?

The Mail (24th May)  reports on Israeli research showing that just one course of antibiotics is linked to an increased incidence of depression, probably due to changes in gut microbes.

Even more depressing is the news that a woman in the US was found to have a bacterial infection that is resistant to colistin – the antibiotic of last resort (BBC News, 27th May).

The belated fightback by British doctors, however, is starting to bite with The Telegraph (25th May) reporting that GPs have slashed their use of antibiotics in the last 12 months. Was this due to their growing awareness of over-prescription and a public spirited determination to tackle the problem? Or was it because the government brought in financial incentives to encourage them? Oh… the latter. Well I never.

Phage

Phages attack a bacteria (Wikimedia)

With few new antibiotics on the horizon, research is turning to alternative means to treat infections, including bacteriophages – viruses that target and kill specific bacteria. The Independent (26th May) reports one such advance, with a phage found in a pond which attacks a type of multi-drug resistant bacteria. Interestingly, phage therapy was widely developed in the former USSR during the cold war, as they did not have access to western antibiotics. Phage therapy is still widely used in Russia, Georgia and Poland. You can read more in this 2014 Nature article.

Gluten controversy

The gluten-free ‘fad’ comes in for criticism with headlines such as “Gluten-Free Diets Are Not Necessarily Healthier, Doctors Warn” (Live Science 25th May, ). Yes indeed, gluten-free bread, biscuits, cakes and other simulacra are often chock-full of additives in an attempt to recreate gluten’s unique glutinousness. Additionally, gluten-free flours (like rice and corn) can be high in heavy metals such as arsenic, which has resulted in at least one recorded case of arsenic poisoning. So, yes, we concur: avoid all grains and don’t go shopping down the gluten free aisle! Eat more fish, meat, fruit, nuts and vegetables, i.e. real food as opposed to ‘products’ or as I like to call them ‘food like substances’.

The Mail (16th May) reports that supermarket gluten free bread is high in fat (shock horror), suggesting that this is a problem. To my mind, it’s not the fat you should worry about (although I wouldn’t reckon on the quality of their industrial oils), it’s the grain and chemical concoctions that are dodgy. My coconut keto-bread recipe is mega-high fat and grain free. Alternatively, my almond bread is versatile, delicious and can be toasted and made into sandwiches. Both are low GI, nutrient dense alternatives, not fake food.

In the same Mail Online article is a video reporting on links between gluten and depressions. Worth a click:

Gluten-Depression-video

High-fat, low-carb diet takes on the mainstream – round two, ding ding!

The National Obesity Forum came out fighting this month with “Official advice on low-fat diet and cholesterol is wrong, says health charity” the Guardian (23rd May). They argue (as do I), that type 2 diabetes can be better managed on a low-carb diet, rather than the recommended low-fat approach. However, this has lead to a string of pugilistic condemnations from the nutritional orthodoxy. Public Health England weighed in calling the report “irresponsible” while The British Dietetic Association, warned that advising people to eat more saturated fat “could be extremely dangerous”. (The Observer 28th May)

However, we think The Telegraph (31st May) gets in the final knock-out punch with “Low-carb diet helps control diabetes, new study suggests”.

That study was conducted after an online revolt by patients in which 120,000 people signed up to the “low-carb” diet plan launched by diabetes.co.uk in a backlash against official advice.

By rejecting guidelines and eating a diet low in starchy foods but high in protein and “good” saturated fats, such as olive oil and nuts, more than 80 percent of the patients said that they had lost weight, with 10 percent shedding 9kg or more.

More than 70 per cent of participants experienced improvements of blood glucose, and a fifth said they no longer needed drugs to regulate blood glucose by the end of the ten-week plan. (my emphasis)

KERPOW! Take that British Dietetic Association. WHAM! Stick that in your low-fat pipe National Health England.

U turn on salt recommendations? Probably not…

Further challenges to the orthodoxy were found in Mail Online (20th May) reporting on a study published in the lancet, in which “a global study 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.”

Of course this led to the usual condemnatory remarks from WHO representatives who labelled the study as ‘bad science’.

My view is that lowering salt may be beneficial for some individuals with hypertension, especially those with genetic SNPs for salt metabolism, but for most of the population their is little evidence of benefit. You can see the numerous conflicting studies linked to salt here, and read our post on salt here.

Iatrogenic deaths

Medical errors have been identified as the third leading cause of deaths in the US, causing over 251,000 deaths annually, after heart disease and cancer, respectively, according to researchers at Johns Hopkins University. (Care2, 5th May, BMJ, 3rd May)

According to the study, “Medical error has been defined as an unintended act (either of omission or commission) or one that does not achieve its intended outcome, the failure of a planned action to be completed as intended (an error of execution), the use of a wrong plan to achieve an aim (an error of planning), or a deviation from the process of care that may or may not cause harm to the patient.” Amazingly, no form of medical error ever appears as a cause of death on a death certificate.

The situation is no less rosy on this side of the pond, with the Mail Online (10th May) reporting “Thousands of heart victims killed by poor care: More than 33,000 people died needlessly over the past few years because of shocking flaws in NHS treatment”. I don’t need telling about the hundreds of patients that have come to me over the years after being so poorly served by an incompetent NHS, indeed my own mother died from heart surgery that ‘went wrong’. Her surgeon humbly admitted to me personally that if he hadn’t done the operation she would still be alive. For all that, he still absconded from the hospital presumably back to Egypt, and I have not pursued that story further!

Vitamin D and Sunshine

Well, we had a handful of sunny days in May, so I suppose we can’t complain…

Our related post: Human photosynthesis – Beyond vitamin-D

Info-graphic of the month: Changes in British food shopping, 1974-2014

33CB339100000578-3571702-Graphs_show_the_biggest_rise_in_which_food_categories_families_p-a-38_1462357927762

The above graph, courtesy of The Mail (4th May), shows changing UK food habits over the last half century. Interesting! What do you think?

Tweet of the month

May-Tweet

 

December News Round-Up

Out with the old (veg oils) in with the new (lard, butter and coconut oil)

Looking back over 2015, I realise I forgot to share a November story, but it’s such an important topic that I want to bring it in here. The Daily Mail (November 8th) reports research that found that cooking in vegetable oils (sunflower and corn oil) produced dangerous levels of toxic aldehydes, whereas cooking in lard, butter and coconut oil did not. Olive oil was somewhere in between, being the best of the liquid oils. Continue reading