“Heart disease risk”, “raised cholesterol”, “Statins” – these six words are guaranteed to strike fear into almost anyone who has been unfortunate enough to be cursed by their local witch doctor wielding these hexed mantras. For years the public psyche has been hyper-sensitised to these terms through incessant media reporting and public health messages. Continue reading
“Vegetarian diets make you depressed” the article said. Tell me about it! Just being around vegetarians makes me depressed, I thought.
The article in question was in Medical Express (Sep 11th). It was reporting on a study of 10,000 people from the UK which found twice the rate of depression among the 350 ‘committed vegetarians’ in the cohort. What was also apparent was that those who had been vegetarian longest – the most committed – had the highest rates of depression. The researchers suggest that low levels of seafood, B12 and high levels of phytoestrogens may be to blame.
After reading this I felt a little sad for all my vegetarian friends, so started digging around to see if there was a support group out there. Well it seems there is, and it’s called the Labour Party…(!)
So believe it or not, Depressed Vegetarians for Corbyn is a thing! Baffling. But at least they are helping each other come to terms with their depression. First up, they can buy one of these these beautiful T-shirts:
And there is even a twitter page just for them: https://twitter.com/corbeanies
So what’s the link between being a depressed vegetarian and supporting Jeremy Corbyn? The more I thought about this, the more I started questioning the scientists. Perhaps, I wondered, It’s not the lack of B12 or seafood causing the depression, but rather their hopeless political ambitions? Either way, it’s no wonder they are depressed!
Laying out the problem
Our recent post on bitters, left me with a lot of questions.
If bitter tastes indicate the presence of toxins and thereby help us avoid poisonous foods, why do they stimulate such positive physiological responses? Why would some of those responses protect us from metabolic diseases like diabetes and cancer? If bitter taste is merely a warning to avoid a particular food, then why do many traditions revere bitter foods? How do we explain why adults develop a taste for bitter foods that as children they found repulsive? Why does folk law say “Good medicine always tastes bitter”?
After a lot of pondering I think I’ve got an answer but to make sense of it I need to lay out what I see as the relevant parts of the puzzle first.
Read time: 16 minutes (3100 words)
In our recent post ‘Amazing results challenge guidelines in new study‘, we looked at research that came to exactly the opposite conclusion to that of The American Heart Association who currently recommend replacing saturated fat with MUFAs and omega-6 PUFAs. The researchers concluded:
recommendations of supplementation with these fatty acids in the general diet should be revised.
The public at large are confused by what they see as flip-flopping over dietary issues: butter is bad one week, but ‘back’ the next. Many people find it hard to believe that such an authoritative body as the American Heart Association could be wrong. How can a few small researcher groups and flag-waving bloggers (like us!) possibly be right? Surely august bodies like the AHA sort through the data and discard the poor quality studies? Surely they can be trusted to do due diligence on our behalf?
These are reasonable thoughts for people to have and they are not wrong to think like this, but such convictions rely on our public agencies not slipping into the kinds of confirmation bias that science is supposed to protect us from.
In a recent Op-Ed Gary Taubes (science journalist and author of the best selling book Good Calories Bad Calories) tackles this topic head on. Continue reading
…served here with scrambled eggs and smoked salmon.
✓Gluten-free ✓Grain-free ✓Sugar free ✓Low-carb ✓Dairy-free option
Here’s one for the hunter-gatherers amongst you: If you are lucky enough to come across this excellent wild-mushroom, it’s easy to cook, mild flavoured, melt in the mouth and looks pretty on the plate… Continue reading
- A new study challenges the dietary guidelines for heart health
- MUFAs and omega 6 PUFAs not effective at reducing atherosclerosis risk
- Omega 3 fish oils reverse triglycerides and weight gain in an animal model of insulin resistance, despite increased calories
Read time: 9 minutes (1400 words)
Guidlines for prevention of heart disease have shifted in recent years away from a simplistic ‘reduce total fat’ message towards a more nuanced emphasis on the type of fat. The current American Heart Association (AHA) recommendation is to ‘replace saturated fats with monounsaturated (MUFA) and polyunsaturated (PUFA) fats.’
For the purpose of this post, I am going to put aside my objection to the demonising of saturated fats and instead focus on the MUFA / PUFA alternatives recommended by the AHA. Similarly, I am not going to challenge the cholesterol hypothesis nor debate the merits or otherwise of lowering LDL cholesterol here. Instead I am going to look at a recent paper that studied the effects of MUFAs and PUFAs on atherosclerosis risk.
- Supplementation with n-3, n-6, n-9 fatty acids in an insulin-resistance animal model: does it improve VLDL quality? Lucero et al. Food and function (The Royal Society of Chemistry), May 2017
Note the terms n-3, n6- and n-9 in the title of this paper; these are just shorthand for omega-3 polyunsaturated fatty acids (ω3 PUFAs), omega-6 polyunsaturated fatty acids (ω6 PUFAs) and omega-9 monounsaturated fatty acids (ω9 MUFAs). I’ve made a quick reference guide for these below, showing typical foods high in each kind of fat:
The role of triglycerides in cardiovascular disease
Cardiovascular disease is often preceded by insulin resistance during which changes to the cholesterol delivery system increase the risk of atheroma formation in the artery wall. One of the hallmarks of insulin resistance is an increased production in very low density lipoproteins (VLDL) which are high in triglycerides.
The following is a quick explanation about triglycerides which you can skip if it’s a bit too much or you are already familiar with the subject…
The relevance of triglyceride-rich VLDL
VLDL is a carrier protein, produced by the liver, which transports triglycerides from the liver to the adipose (fat) tissue. It is important to note that these triglycerides are primarily endogenous i.e. manufactured by the body, rather than coming directly from dietary sources.
VLDL and triglycerides are raised principally by (1) Excess caloric intake from any source and (2) Carbohydrates (and especially fructose). In the former case the formation of VLDL can be seen as the body packing away and storing excess calories which are transported to the adipose tissue where they can be stored for a rainy day as fat.
In the case of carbohydrates, triglyceride rich VLDL is manufactured as a response to overwhelming surges in blood glucose that cannot be dealt with sufficiently by insulin induced uptake by the organs, especially muscle and liver glycogen stores. Indeed some have said that raised blood triglycerides are a reliable marker of carbohydrate consumption.
If cells become insulin resistant they stop taking up glucose effectively, increases the need for diversion of calories into the endogenous VLDL pathway. Hence insulin resistance is characterised by raised triglycerides.
Fructose has some unique metabolic problems as it does not trigger insulin, so cannot be taken up by cells as quickly as glucose. Instead it has to be processed by the liver, which can easily be overwhelmed, turning the excess into triglyceride rich VLDL.
It should not be surprising then, that the rats used in the study I am reviewing here, were made insulin resistant by feeding with sugar water (30% sucrose water) for 12 weeks. Sucrose is equal parts glucose and fructose, so their water contained 15% of each of these sugars.
So the aim of this study was to see how different dietary fats affect the dislipidemia associated with insulin resistance, especially the triglycerides. To do this the rats in this study were split into 5 groups: A control group on standard diet, whilst the other four were all made insulin resistant by feeding 30% sucrose water for 12 weeks. Of the four insulin resistant groups one was supplemented with n3 PUFAs, one with n6 PUFAs and one with n9 MUFAs.
It’s a pretty obvious experiment to undertake, and at this point you might rightly be asking why? Hasn’t this has all been done before? Surely the science on such a basic question is settled? With 60 years of American Heart Association advice you would think they had the science to back up their assertions and advice, wouldn’t you?
Well, shockingly, you would be wrong. As the authors note:
To our knowledge no studies have addressed the impact of dietary n-3, n-6 and n-9 fatty acids on VLDL composition and size in the [insulin resistant rodent] model.
There are several reasons why this basic question has not been answered before:
- Many previous studies looking at the effects of PUFAs on insulin resistance have applied n6 and n3 together, with only a few addressing n6 alone
- Previous studies evaluating n3 fish oils have used cod liver oil, which contains high levels of vitamin A, D and cholesterol, which could affect the findings.
- Assessment of MUFAs (n9) have usually used olive oil, which contains a broad range of phytochemicals which may be responsible for the beneficial heart effects observed in those studies, rather than the actual monounsaturated fats it contains.
To get round these problems ithe researchers used the following oils:
- n3: fish oils from pressing whole fish, hence low in vitamin A and D.
- n6: linoleic acid rich sunflower oil, low in phytonutrients
- n9: high oleic sunflower oil
Rodent diets contained 15% w/w of each oil, which represents about 35% by calories i.e. similar to a standard western diet.
What they found was striking and deserves some careful reflection.
To make the findings a little easier to appreciate I have made a graph of some of the key results, but tables with all the study data are provided at the end of the post.
Triglycerides (■) and Liver fat (■)
The effects of the high sucrose feeding, as expected was a jump in triglycerides, which can be seen between the Reference and IR results above. Dramatically, supplementation with n3 fish oils almost completely reversed this dyslipidemia, returning VLDL particles to normal. Whilst remarkable, this is in line with previous epidemiological, human and animal studies that have shown n-3 PUFA have positive physiological effects on IR and lipid metabolism.
n6 and n9 oils, however, only weakly attenuated these harmful changes, failing to reverse the atherogenic state of the VLDL particles. This casts doubt on the validity of the American Heart Association recommendations.
In the case of the MUFA (n9), previous studies using olive oil have shown greater improvements in insulin resistance parameters, but as already noted, olive oil contains a broad range of bioactive phytochemicals (e.g. sterols and polyphenols). By using high oleic sunflower oil this study has been able to show that MUFAs do not of themselves produce these beneficial effects.
In relation to MUFAs this is particularly important as many processed food uses high MUFA oils that are low in phytonutrients as these can impart undesirable flavours.
Accumulated liver fat follows a similar pattern to plasma triglycerides. Again, n3 oils produce the best reductions in damage caused by insulin resistance.
Weight gain (■) and Calorie intake (■)
Some of the most surprising results were seen in relation to caloric intake and weight gain. All groups of rats could eat ad libitum, yet in the n3 fish oils and n9 MUFA groups caloric intake was considerably raised. Extraordinarily, despite this those fed the n3 fish oils had no weight gain during this trial, whilst those fed the n9 high oleic oil had the most weight gain.
Rats fed the n6 sunflower oil supplemented diet had lower caloric intake than the n3 and n9 groups, but still gained more weight than the n3 group.
The authors of this study conclude:
In insulin resistance, while n-3 PUFA showed expected favorable effects, supplementation with n-6 PUFA and n-9 MUFA did not prevent atherogenic alterations of VLDL. Thus, the recommendations of supplementation with these fatty acids in general diet should be revised.
The authors seem somewhat nonchalant about the n3 fish oils, but it is worth reflecting for a moment just what those fish oils did: the rats were drinking insane quantities of sugar, eating a hyper caloric diet, yet avoided most of the effects of insulin resistance and weight gain. That’s a pretty impressive feat as far as I can see!
Implications for diet
This study looked at the effects of fat choice in the context of insulin resistant animal models. The results support and extend previous research in humans and epidemiological studies. Taken together these point to certain food choices: fish, seafood and olive oil are good choices based on these results; Omega 6 vegetable oils such as sunflower, safflower, corn and soya oils are best avoided, as are low-polyphenol MUFAs like high oleic oil and possibly filtered rapeseed (Canola) oil. A high quality fish oil supplement seems prudent too.
Based on the ideas suggested by this study cold pressed rapeseed oil is potentially interesting as like extra-virgin olive oil, it contains high levels of phytonutrients, but unlike olive oil it has significant levels of alpha linolenic acid (ALA), a short chain n3 fatty acid. Based on the results above I would expect it to have beneficial metabolic effects possibly similar to or slightly better than Olive oil. Well that’s my prediction. So lets see…
I searched Pubmed for “rapeseed cardiovascular”. Sure enough, in one of the first studies I found [Baxheinrich et al, 2012] patients with metabolic syndrome (which is just one step down from full blown insulin resistance), were placed on a low calorie diet enriched either with olive oil (high n9 MUFA, low n3 ALA) or cold pressed rapeseed oil (high n9 MUFA high n3 ALA) for six months. Although both groups improved similarly on many metabolic measures (body weight, systolic blood pressure, cholesterol, and insulin levels), the cold pressed rapeseed group had significantly lower triglycerides. That said rapeseed oil is probably less suitable than olive oil for high temperature cooking as the ALA it contains is very heat sensitive. Still, its a good choice for salad dressings and mayonnaise!
For those of you who like to dig into the data here are some key tables from the study:
(1) Composition of diets; (2) Intakes and body weight; (3) Effects on adipose tissue/liver and serum parameters
- Supplementation with n-3, n-6, n-9 fatty acids in an insulin-resistance animal model: does it improve VLDL quality? Lucero et al. Food and function (The Royal Society of Chemistry), May 2017
- Dietary Fat Recommendations 1957–2015 Focus shifts from total fat to type of fat. American Heart Association (pdf)
- Effects of a rapeseed oil-enriched hypoenergetic diet with a high content of α-linolenic acid on body weight and cardiovascular risk profile in patients with the metabolic syndrome. Baxheinrich et al, British Journal of Nutrition, 2012
- Can rapeseed oil replace olive oil as part of a Mediterranean-style diet? Hoffman & Gerber, British Journal of Nutrition, 2014
🔍Click to enlarge. Please feel free to share.
I made this little infographic to illustrate the four main classes of fats. It gives typical sources of each and an example molecule from that group. Hope you find it useful. Please feel free to share!
There have recently been a number of articles making pronouncements on the original paleo diet, as eaten by our paleolithic ancestors. At the end of last year, December 2016, we had…
- Ancient leftovers show the real Paleo diet was a veggie feast (New Scientist)
- Secrets of the paleo diet: Discovery reveals plant-based menu of prehistoric man (Eureka Alert)
Then in March this year…
- Some Neanderthals Were Vegetarian (National Public Radio)
- Some Neanderthals were vegetarians (The Independent)
The more recent articles appeared following a paper by Laura Weyrich et al. published in Nature, March 2017, titled Neanderthal behaviour, diet, and disease inferred from ancient DNA in dental calculus. Afifah has written a post about the herbal medicines these Neanderthals were using, and we are going to publish a guest post addressing the vegetarian claim shortly.
The December articles on paleo veggies were prompted by an Israeli study (Melamed et al. PNAS) which identified the remains of a wide variety of plant food remains in a cave in the Levant (modern Israel). The 780,000 years old remains are unusual as plant materials are rarely preserved at such sites, so this paper provides some insight into the plants resources used by our ancient ancestor homo erectus.
The remnants include no fewer than 55 different species including roots, seeds, nuts, fruit and leaves. Many of these resources were seasonal and some required simple processing and cooking. Here is the New Scientist Video that accompanied their article, which, I think you will agree, has a touch of the Blue Peter about it:
You would think from the headlines that evidence that our ancestors ate a wide variety of plant foods is new or somehow overturns Paleo Diet thinking. The media portrays the Paleo Diet as consisting largely of red meat, but that is wrong. Since its inception, proponents of the modern Paleo Diet such as Professor Lauren Cordain have argued that we should be eating more like hunter-gatherers. That has always meant both the gathering part (eating plant foods) as well as the hunting bit (eating animal products).
What is strange about the recent media pronouncements is that the research that stimulated them is perfectly in accordance with Paleo Diet principles. It seems as if the media are spinning these stories for the sake of headlines, which makes them, in the lingo of the day, fake news does it not?
A careful reflection on the details of the foods identified in the Melamed study suggest a number of subtle paleo principles we might all like to take on board:
1. Increase the range of plant foods eaten
Few of us eat as wide a variety of plant foods as these ancient hominids. Modern hunter gatherers also tend to eat a far wider range of plant foods than typical modern humans. Not only does eating a range of plant foods increase the range of phytonutrients ingested, but it also reduces the exposure to the anti-nutrients found in any one plant source.
2. Eat seasonal food
This is really part of eating a wider range of plant foods and means we give our body a rest from any anti-nutrients when that food is out of season. Another plus is that seasonal foods can be higher in nutrients than those that are grown out of season under artificial light: that’s why winter tomatoes and early season strawberries often taste so insipid (taste being evidence of nutrients. Read ‘The Dorito Effect’ for more info on this amazing area of science).
3. Grow your own
Our ancient ancestors couldn’t preserve foods by canning and freezing. The freshest foods you can eat are those that you have just picked from your own garden, minutes before eating them. Here at Rosemary Cottage we grow a lot of our own fruit, berries, and veg (in fact we have a blog just about this here). They are packed with flavour and much higher in nutrients than supermarket varieties which are often picked under-ripe and have sat around for a couple of days on the shelves or have been flown half way round the world in a low oxygen ‘protective atmosphere’. If you haven’t got a garden or allotment you can buy living salads, mustard and cress, or growing herbs which provide the same fresh-food benefits.
4. Eat wonky, small, damaged and organic veggies
Studies have shown that fruit and veg that have been exposed to harsh environmental conditions often have higher levels of nutrients as these compounds are primarily plant defence compounds. The perfect, class 1 fruit and veg we are offered in the supermarket have been overly pampered, sacrificing nutrients for looks. Many of the phytonutrients in veggies are concentrated in the colourful skins. Cherry tomatoes therefore pack more nutrients per kilo than their larger cousins as they have a larger surface are to volume ratio. Another benefit is that buying wonky veg increases farm profits and reduces food waste.
Organic fruit and veg tends to be less perfect, more blemished, usually class 2. Possibly for this reason they often have higher levels of nutrients (European Journal of Clinical Nutrition)
5. Include close-to-wild foods
It is a fact that many modern fruit and veg have been bred to increase water, sugars and starches and to be less bitter or sour – all of which has diluted the phytonutrients. Consequently, some of the most nutrient dense plant foods are those that have had the least selective breeding such as the following.
- Leaves: Water cress, rocket, parsley, purslane, coriander leaf, miners lettuce, samphire, seaweed, tea
- Fruit: Blueberries, red and white currents, blackberries, raspberries, alpine strawberries, olives, capers, sour cherries
- Seeds: All nuts and seeds, coffee
- Roots: Salsify, scorzonera, oca, pink-fir apple potatoes, water chestnuts, tiger nuts
- Shoots: Sprouted seeds, mustard and cress, bamboo shoots, asparagus, sprouting broccoli
- Flowers: Artichokes, borage, nasturtium, calendula
Many of the above need only be eaten in relatively small quantities as it is often the toxins in these plants that stimulate our immune system, so you don’t want to over do them. (See our post: The chemical warfare on your plate). For example, health benefits of tea and coffee seem to peak at 4 to 5 cups per day and the benefits of tree nuts levels off at 30g per day. In some cases over doing it can actually lead to harm: for example spinach, which if consumed every day can lead to kidney stones due to its high oxalic acid content. Daily juicing of spinach is therefore unwise, despite ‘green smoothie’ proponents waxing lyrical about it. (Read here about some of the problems with oxalates)
I’ve made a nice info-graphic of some wild-like foods you might want to try. Although they are not always easy to come by I have seen all of these in supermarkets or farmers markets over the last year or so. I have several of them in my current garden, and have eaten all of them at one time or another. How many have you tried?
A little thought about the paleo veg principles above makes it clear why paleo veganism must have been a rare or intermittent occurrence. Few paleo veggies contain sufficient calories to sustain life, and due to their anti nutrients eating them in large quantities or for prolonged periods could easily lead to problems. Furthermore, the wild foods that are sufficiently high in calories (nuts, seeds and some tubers) would need to be available in quantity, year round, or starvation would be a very real risk. Changing availability and seasonality mean it is unlikely our ancestors were vegans for extended periods, although there would no doubt have been times when animal food sources were limited and they would have been forced to get by on plants alone. In short – humans are and have always been highly adaptable omnivores.