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Sunday, 15 May 2016

Dietary fat type - saturated or unsaturated - does it make a difference to glycaemic control?

This is a section from a paper I'm writing about hepatic glycogen control, this part concerns the effect of dietary fat type on the insulin response. Spoiler alert: you will be surprised how little sound evidence there is on a subject about which so many pronounce so confidently.

Carbohydrate feeding stimulates the release of glucagon from delta cells in the gut and pancreatic alpha cells.[1] Glucagon is the hormone that elevates blood glucose by stimulating gluconeogenesis, but this is a delayed response; the most immediate glucose-elevating effect of glucagon is to induce glycogenolysis. In healthy metabolism, after eating a carbohydrate meal the paracrine effect of the phase 1 insulin response rapidly suppresses this glucagon release and the hepatic endocrine action of insulin inhibits the action of glucagon in the hepatic parenchymal cell, so that both gluconeogenesis and glycogenolysis are fully inhibited.[2,3]

Figure 1: Showing glucagon and insulin response to carbohydrate in normal metabolism

In type 2 diabetes, the delayed insulin response to a carbohydrate meal results in a longer elevation of glucagon; hepatic insulin resistance also reduces the inhibitory effect of insulin on glucagon action in the liver.
What is the value of this normal brief glucagon response to carbohydrate feeding? Glycogenolysis is a glycolytic process (glycogen -> glucose-6-phosphate -> lactate) which generates ATP in the glycogen-storing parenchymal cell; a brief and minor increase in glycogenolysis might be a preparatory adaptation, priming the cell for rapid glycogen synthesis from incoming glucose.
The delayed insulin peak from the beta cell of the diabetic pancreas (suggested mechanisms include ectopic fat accumulation in the beta cell, and/or cytokine interference with its function) allows a longer action of glucagon that is maladaptive in the context of a carbohydrate meal, and therefore the consumption of carbohydrate causes post-prandial hyperglycaemia by stimulating the release of glucose from glycogen and inhibiting its non-oxidative disposal in persons with type 2 diabetes.
This is an immediate cause of elevated PPPG that is rapidly corrected once carbohydrate is restricted.
In a study of 6 subjects with diabetes a simulated phase 1 and phase 2 insulin release during a hyperglycaemic clamp resulted in a 90% suppression of hepatic glucose production at 20 minutes, compared to a 50% suppression at 60 minutes from a simulated phase 2 response alone.[4]
However, a study of enhanced phase 1 insulin response in 14 elderly patients with diabetes found that phase 1 insulin response was not important in the regulation of hepatic glucose output or peripheral glucose disposal in these patients.[5]

1:02 The differential effect of fat type on the phase 1 insulin response

Does the type of fat in the diet influence the phase 1 insulin response? Below is the insulin response to a mixed meal containing two different fats – butter (SFA) and olive oil (MUFA) in 10 women with gestational diabetes mellitus. It will be seen that the butter-containing meal provoked a more rapid insulin response, and as a result both insulin and glucose area-under-the-curve (UAC) was reduced with the butter meal, and post-prandial plasma glucose at 2 and 3 hours was significantly lower compared with the olive oil meal.[6]

Figure 3: Plasma glucose response to a meal with olive oil (MUFA) or butter (SFA) in women with gestational diabetes

This difference may be due to other factors present in the fats, as butter contains 3% c9t11 CLA and olive oil supplies 11% linoleic acid (LA), compared to 2% in butter. c9t11 CLA improves insulin sensitivity compared to LA in prediabetic men.[7] Elevated plasma levels of trans-palmitoleic acid, mainly found in dairy and ruminant fat, are also associated with a reduced incidence of diabetes and insulin resistance.[8,9]
Wistar rats fed soybean oil (60% LA) for 4 weeks had significantly lower glucose-stimulated insulin responses compared to rats fed lard (10% LA) whose insulin responses were similar to those of rats fed a low fat control diet.[10] A study of inhibition of fasting FFAs by nicotinic acid (NA), replaced by soybean oil (Intralipid) and heparin, in 10 healthy male subjects found that FFAs were essential for insulin response to glucose in fasting humans.[11] A further study in rats in which serum FFAs were inhibited by NA and replaced by infusions of soybean oil or lard with heparin found that serum saturated fatty acids were essential for the first-phase insulin response to glucose, which was suppressed by high levels of unsaturated fatty acids, which only supported a second-phase response.[12]

1.03 The differential effect of fat type on insulin sensitivity

While some feeding studies show that meals high in saturated fat result in higher glucose levels than meals high in monounsaturated fat, others show the opposite, while yet other studies find no difference, as summarized in Jackson et al 2005.[13] The saturated fat source most likely to be used in such feeding studies is palm oil, which is the dietary fat with the highest concentration of palmitic acid, which was mixed with cocoa butter, the dietary fat with the highest concentration of stearic acid, in the saturated fat arm of the feeding study in that paper, which showed higher glucose AUC in the saturated fat arm. Palmitic and stearic acids are the main endogenous saturated fatty acid products of de novo lipogenesis (DNL) and serum levels of these fatty acids are known to be correlated with the carbohydrate content of the diet. Thus such a study may not accurately represent the effects of the mixture of fats found in normal diets, especially in the context of a low carbohydrate diet. Of randomised long-term studies, the LIPGENE study found no effect of fat type, whereas the KANWU study, a study cited as showing a worsening of insulin sensitivity (albeit non-significant) after feeding saturated fat compared to monounsaturated fat for 3 months, noted that the favourable effects of substituting a MUFA diet for a SFA acid diet on insulin sensitivity were only seen at a total fat intake below median 37E%.[14,15]

1.04 Recommendations regarding fat type in very low carbohydrate diets

The 2006 experiment by Krauss et al was a test of the hypothesis that saturated fat in a carbohydrate-restricted diet would influence the effect of the diet on the atherogenic dyslipidemia produced by hyperinsulinaemia in the context of insulin resistance.[16] Men (n=178) with a mean BMI of 29.2 (+/- 2) were randomized to four different diets – 54% CHO, 39% CHO, 29% CHO with 9% SFA, and 29 % CHO with 15% SFA, for twelve weeks, including a 5 week period of calorie restriction followed by a 4 week period of weight stabilization.
Concentrations of apo B, a measure of total atherogenic particle concentrations, as well as total:HDL cholesterol, an integrated measure of CVD risk, decreased similarly with both the higher- and lower-saturated-fat diets. Moreover, the changes in LDL cholesterol for both the lower- and higher-saturated-fat diets (−11 and 1 mg/dL, respectively) were considerably more beneficial than were those predicted on the basis of studies that used diets with a more conventional macronutrient composition (−1 and 9 mg/dL, respectively). The difference in LDL cholesterol between the two diets was due to the appearance of larger, less atherogenic LDL particles in those on the 15% SFA diet; both diets saw similar reductions in levels of atherogenic small, dense LDL (sdLDL) particles. The ratio between triglycerides and HDL cholesterol correlates with serum insulin and insulin sensitivity; the TG/HDL ratio was the same with both 9% and 15% SFA at 29% CHO.[17]

Fig 3: glucose response to fasting and carbohydrate-free diet

It is considered that very low carbohydrate diets partially mimic the fasting state. In a 2015 randomised cross-over study by Nuttall et al, 7 men and women with untreated type 2 diabetes were placed on a control diet (55% CHO, 15% PRO, 30% FAT), a carbohydrate-free diet (3% CHO, 15% PRO, 82% FAT), or fasted for 3 days.[18] On the third day of the carbohydrate-free phase, overnight fasted blood glucose concentrations were 160 mg/dl compared with 196 mg/dl in the standard diet and 127 mg/dl in the fasting phases. Carbohydrate restriction also led to a rapid drop in post-prandial glucose concentrations and glucose area-under-the curve decreased by 35% in the carbohydrate-free phase compared to the standard diet. It was found that carbohydrate restriction accounted for 50% of the reduction in overnight glucose concentrations and 71% of the reduction in integrated glucose concentrations in the fasted phase compared with the standard diet phase. It is notable that human depot fat, which is the major fuel source in the fasting state, consists of (approximately) 55% monounsaturated fat and 30% long-chain saturated fat, with the remainder consisting of smaller amounts of polyunsaturated fats and medium-chain saturated fats. It has been noted that a 50:50 mixture of ghee and olive oil has a fatty acid composition of 32% saturated fat (some of which is short and medium chain fatty acids, leaving 25-28% from the long-chain saturated fats, palmitic and stearic acids), 50% monounsaturated fat, and 7% polyunsaturated fat, approximating reasonably well the composition of human depot fat. Thus there is insufficient evidence to support recommendations restricting saturated fat in very low carbohydrate diets. However, there is some evidence for preferring full-fat dairy foods to other sources of saturated fat in the diet, with regard not only to glycaemic control but also cardiovascular risk, based on observational studies [19,20,21].
Adherence to diets is likely to be greatest when the rationale for choices is simple and convincing, when the diet is adequately nutritious, and when food is culturally appropriate – that is, when the diet is made up of foods that are already familiar and liked.
It should also be noted that both carbohydrate-free diets and fasting appear to be well-tolerated in the feeding studies we have described, with no adverse events reported during or after any study.


[1] Lund A, Bagger JI, Wewer Albrechtsen NJ et al. Evidence of Extrapancreatic Glucagon Secretion in Man. Diabetes. 2015 Dec 15. pii: db151541. [Epub ahead of print]

[2] Raskin P, Unger RH. Hyperglucagonemia and Its Suppression — Importance in the Metabolic Control of Diabetes. N Engl J Med 1978; 299:433-436.

[3] Sonksen P, Sonksen J. Insulin: understanding its action in health and disease. Br. J. Anaesth. (2000) 85 (1): 69-79.

[4] Luzi L, DeFronzo RA. Effect of loss of first-phase insulin secretion on hepatic glucose production and tissue glucose disposal in humans.
American Journal of Physiology - Endocrinology and Metabolism Published 1 August 1989 Vol. 257 no. 2, E241-E246

[5] Meneilly GS, Elahi D. Physiological importance of first-phase insulin release in elderly patients with diabetes. Diabetes Care. 1998 Aug;21(8):1326-9.

[6] Ilic et al, Comparison of the effect of saturated and monounsaturated fat on postprandial plasma glucose and insulin concentration in women with gestational diabetes mellitus. American Journal of Perinatology 1999

[7] Rubin D, Herrmann J, Much D, et al. Influence of different CLA isomers on insulin resistance and adipocytokines in pre-diabetic, middle-aged men with PPAR╬│2 Pro12Ala polymorphism. Genes & Nutrition. 2012;7(4):499-509. doi:10.1007/s12263-012-0289-3.

[8] Mozaffarian D, Cao H, King IB, et al. Trans-palmitoleic acid, metabolic risk factors, and new-onset diabetes in U.S. adults: a cohort study. Ann Intern Med. 2010 Dec 21;153(12):790-9.

[9] Yakoob MY, Shi P, Willett WC, Rexrode KM, Campos H, Orav EJ, Hu FB, Mozaffarian D. Circulating Biomarkers of Dairy Fat and Risk of Incident Diabetes Mellitus Among US Men and Women in Two Large Prospective Cohorts. Circulation AHA.115.018410 Published online before print March 22, 2016

[10] Dobbins RL, Szczepaniak LS, Myhill J, et al.  The composition of dietary fat directly influences glucose-stimulated insulin secretion in rats. Diabetes June 2002 vol. 51 no. 6 1825-1833.

[11] Dobbins RL, Chester MW, Daniels MB et al. 1998: Circulating fatty acids are essential for efficient glucose-stimulated insulin secretion after prolonged fasting in humans. Diabetes. 1998;47(10): 1613-1618,

[12] Stein DT, Esser V, Stevenson BE, et al. Essentiality of circulating fatty acids for glucose-stimulated insulin secretion in the fasted rat. J Clin Invest. 1996 Jun 15; 97(12): 2728–2735.

 [13] Jackson KG, Wolstencroft EJ, Bateman PA, Yaqoob P, Williams CM. Acute effects of meal fatty acids on postprandial NEFA, glucose and apo E response: implications for insulin sensitivity and lipoprotein regulation? Br J Nutr. 2005 May;93(5):693-700.

[14] Tierney AC, McMonagle J, Shaw DI et al. Effects of dietary fat modification on insulin sensitivity and on other risk factors of the metabolic syndrome--LIPGENE: a European randomized dietary intervention study. Int J Obes (Lond). 2011 Jun;35(6):800-9.

[15] Vessby B, Uusitupa M, Hermansen K et al. Substituting dietary saturated for monounsaturated fat impairs insulin sensitivity in healthy men and women: The KANWU Study. Diabetologia. 2001 Mar;44(3):312-9.

{16] Krauss RM, Blanche PJ, Rawlings RS, Fernstrom HS, Williams PT:
Separate effects of reduced carbohydrate intake and weight
loss on atherogenic dyslipidemia. Am J Clin Nutr 2006,

[17] Feinman RD, Volek JS. Low carbohydrate diets improve atherogenic dyslipidemia even in the absence of weight loss. Nutrition & Metabolism 2006;3:24.

[18] Nuttall FQ, Almokayyad RM, Gannon MC. Comparison of a carbohydrate-free diet vs. fasting on plasma glucose, insulin and glucagon in type 2 diabetes. Metabolism - Clinical and Experimental. 2015;64(2):253 – 262.

[19] Ericson, U, Hellstrand, S, Brunkwall, L, Schulz, C-A, Sonestedt, E, Wallstr├Âm, P, et al. Food sources of fat may clarify the inconsistent role of dietary fat intake for incidence of type 2 diabetes. AJCN 2015;114.103010v1

[20] Praagman J, Beulens JWJ, Alssema M et al. The association between dietary saturated fatty acids and ischemic heart disease depends on the type and source of fatty acid in the European Prospective Investigation into Cancer and Nutrition–Netherlands cohort. Am J Clin Nutr. ajcn122671

[21] De Oliveira Otto MC, Mozaffarian D, Kromhout D et al. Dietary intake of saturated fat by food source and incident cardiovascular disease: the Multi-Ethnic Study of Atherosclerosis. The American Journal of Clinical Nutrition. 2012;96(2):397-404. doi:10.3945/ajcn.112.037770.

Monday, 2 May 2016

A brief reading of the report of the new Kevin Hall study

Is the insulin theory of obesity over? Well I'd say it's over when people with diabetes using exogenous insulin to cover high-carb diets no longer have to worry about weight gain, and not before. But this is interesting research, and it proves if nothing else that Gary Taube's NuSci research initiative wasn't just set up to confirm his every thought.Kevin Hall discusses his new study here, with Yoni Freedhoff.

This research contradicts two things - one, the metabolic advantage theory of ketogenic weight loss.
It never made sense to me that wasting energy would make it easy to lose weight. That's "run off that coke" type illogic. The only thing that makes obese people lose weight sustainably is the repair of the appestat. The LCHF diet is great for this because without the carbohydrate foods that stimulate cravings, and with a belly full of fat, it's easy to get eating right again.
The second thing it contradicts is Taube's statement - more a guess or rule of thumb than a hypothesis - in GCBC that all weight loss diets that work, work because they restrict carbs and thus lower insulin. This is how a lot of weight loss diets work, but this study shows that, if calories are held even, the rate of weight loss needn't be proportionate to the lowering of insulin in every diet phase.
It also contradicts the idea that a ketogenic diet causes significant muscle loss. This happens at first, to a small amount, then it's reversed. It's not an ongoing problem that results in people wasting away - and these subjects were in a metabolic ward, so very limited in how much exercise they did.
There are two things the study does not do. It's an isocaloric comparison, so there's no test of which diet would have been more likely to cause free-living people to spontaneously eat and move the right amount to normalise weight. And it's not a study of weight gain, so says little about the metabolic and dietary conditions that made the subjects obese in the first place.
It is likely, but not clear from this report, that the subjects had lower insulin levels in both diet phases than they had while gaining weight or at baseline. If that is true, then the insulin hypothesis of obesity is doing just fine, but is in need of a little adjustment.
What's interesting to me is that what this study does say about LCHF diets confirms two statements in the 1950s and 1960s work of John Yudkin that I've been reading - there is no low carb metabolic advantage, and therefore they can only work as well as they do for weight loss if people spontaneously tend to eat the right amount when eating fat and protein.

Tuesday, 26 April 2016

Mediterranean diet score in stable heart disease, and, more thoughts on Ramsden et al.

This news article that made the rounds yesterday demonstrates how confirmation bias keeps the diet-heart hypothesis afloat.

Healthy eating key to heart disease

After 3.7 years' follow-up, a heart attack, stroke or death - termed a major adverse cardiac event - had occurred in 10.1 per cent of the participants. Such events occurred in 7.3 per cent of the people in the highest Mediterranean-diet bracket, 10.5 per cent in the next bracket down and 10.8 per cent in those who ate smaller quantities of the healthier foods.

"After adjusting for other factors that might affect the results we found that every one unit increase in the Mediterranean diet score was associated with a 7 per cent reduction in the risk of heart attacks, strokes or death from cardiovascular or other causes in patients with existing heart disease," Mr Stewart said.

The elements of the Mediterranean Diet Score can be found in the full paper and supplementary tables. It turns out foods like dairy, eggs, and tofu were also found to be protective but weren't included in the Med diet score; whereas lower meat intake wasn't protective but was included; and wholegrains weren't protective, but were included. Go figure.

Auckland University heart disease researcher, Professor Rod Jackson noted that the authors did not report on saturated fat consumption or fat consumption at all because they stated it had not been recorded reliably.

"However, the findings are quite consistent with the standard diet-heart hypothesis. A Mediterranean diet is low in saturated fat and was associated with lower risk of CHD [coronary heart disease].

"The Western diet score was based on consumption of refined carbohydrates, sweets and desserts, sugared drinks and deep-fried food. None of these foods except deep-fried foods, and only if the fat was saturated, are associated with CHD. They are associated with overweight/obesity and diabetes but the pro-fat lobby have always confused the issue by wrongly lumping obesity and diabetes with CHD.

" ... they are very different conditions and are trending in opposite directions."

This association of saturated fat and CHD seems to be a bit imaginary, but what is the explanation for junk foods having no association with CHD?
Well firstly, this was a very crude data collection effort, even by diet epidemiology standards. Many foods either weren't measured or were tucked away in the nearest category.
Secondly, because it depends on "diet scores" to aggregate non-significant associations, the non-significant association between deep fried food (the biggest source of omega-6 PUFA here) and CHD has been overlooked.
Thirdly, if you're going to eat less junk food, it is possible to replace it with "healthy" foods that aren't associated with benefit here. Namely wholegrain products, which are the densest calorie source in the Med diet score category. Imagine someone eating fewer biscuits and replacing that with wholemeal muffins. You could replace sugar-sweetened soft drink with fruit juice too - I'm not sure if that fits anywhere in these scores.Fourthly, this survey took place during another massive failed drug trial. A drug supposed to protect those with stable heart disease did diddly-squat. This data was salvaged from the wreckage. That's not a confounder that I can see, but I do find it interesting that this bit of context didn't make the papers.
Fifthly, there are some huge differences in smokers, BMI, education and income between the higher vs lower Med diet score groups. If these are associated with junk food intake and you're correcting for them, then you're correcting for a large association in the hope of leaving a smaller one intact. It's a wonder, with all its flaws, that this study arrived at any result resembling a plausible reality. But it did, in my opinion.


I wrote a letter to the Herald about this yesterday, but it wasn't published today, so here it is.

Dear sir,

     The standard diet-heart hypothesis says that saturated fat in the diet causes heart disease by raising LDL cholesterol. This notion has taken a bit of a drubbing recently, so it is understandable that Professor Rod Jackson interprets yesterday’s study, about a higher Mediterranean diet score protecting against heart attacks, strokes, and deaths in those with stable heart disease, in its favour. 
     However, this ignores two findings from this study; firstly, that the mean LDL cholesterol level was not significantly different (2.3 vs 2.2 mmol/L) across the “Mediterranean diet score” categories, and secondly, that the two traditional food sources of saturated fat measured, meat and dairy, were not associated with increased risk; in fact dairy was associated with reduced risk.
     Although wholegrains were included in the Mediterranean diet score, they were not associated with benefit by themselves, and it would, for instance, be possible from this data to show that a “Paleolithic diet score” of eggs, meat, fruit, vegetables and fish, but no grains, was associated with as much benefit as the Mediterranean diet score. Furthermore, the two Mediterranean foods which the earlier PrediMed intervention identified as being most beneficial, olive oil and nuts, were not even measured in the new study.
     The one reliable finding from this study is that, the more minimally processed, nutrient-dense foods you include in your diet, the healthier it is. Maybe this should be the new diet-heart hypothesis until a better one comes along.

yours, etc

Ramsden et al has been the gift that keeps on giving. I had some more thoughts about the kind of problems a high omega-6 intervention might run into which I appended to Steven Hamley's analysis of the MCE study here. The FADS2 polymorphism study I refer to is this one.

I notice that those defending omega 6 interventions in the BMJ rapid responses have cited the Farvid et al meta-analysis of observational studies. However Farvid et al did not control for omega 3 fatty acids at all and this is quite clearly stated, so cannot be cited to refute any Ramsden et al meta-analysis.
Further, this is a bizarre procedure. If experiments don't confirm observations from population studies, you can't just cite another population study to refute the experiments. Prof Brunner does this in the rapid responses using quite a minor observational study that used "dietary pattern" analysis, with a healthy "dietary pattern" including margarine, to refute the experiments. If this is the procedure of epidemiologists, no wonder we are where we are with this zombie hypothesis.

Edit: I dug up the Whitehall II study that Prof Brunner cited, and which he co-authored.

Increased CHD risk (hazard ratio for top quartile: 2.01, 95%CI 1.41-2.85, adjusted for age, sex, ethnicity and energy misreporting) was observed with a diet characterised by high consumption of white bread, fried potatoes, sugar in tea and coffee, burgers and sausages, soft drinks, and low consumption of French dressing and vegetables."
This was dietary pattern 1.
A higher score on dietary pattern 1 was associated with higher total cholesterol, lower HDL cholesterol and higher triglycerides. Dietary pattern 2 was characterised by higher consumption of red meat, cabbage, brussels sprouts and cauliflower, and lower consumption of wholemeal bread, jam, marmalade and honey, tofu and soy, buns, cakes, pastries, fruit pies and polyunsaturated margarine.
A higher score on dietary pattern 2 was associated with higher total cholesterol and higher triglycerides. 
Dietary pattern 2 showed a significant linear trend across quartiles with a higher dietary pattern score also associated with increased risk of CHD (Model 3, adjusted for age, sex and energy misreporting, ethnicity, employment grade, smoking, alcohol and physical activity, p less than 0.0001) however this relationship was no longer significant after further adjustment for BMI and blood pressure.(As far as I can see, the pattern 2 trend was never very significant and the dose-response of both patterns is all over the place. There are 6 possible statistical models for each pattern, and none in the table given reads as having anything like a 0.0001 p value).

The paper states that French dressing (21% PUFA according to wikipedia) had no independent association with CHD, and gives no information about independent associations with polyunsaturated margarine.

Sunday, 10 April 2016

The Tragedy of William Stark, who conclusively proved that eating crap will kill you, by a process of self-experimentation, in 1770, a fact which more people should pay attention to.

How did I not know about William Stark MD?

Born in Birmingham of an Irish mother and a Scottish father, he studied philosophy in Glasgow and medicine in Edinburgh and at the University of Leiden before going to work as a doctor in London in 1765.

"The person on whom these experiments are tried is a healthy man, about twenty-nine years of age, six feet high, stoutly made, but not corpulent, of a florid complexion, with red hair."
However, the Doctor who attended his final hours writes "He was of a fair complexion, tall, of a thin make, and healthful."

In 1769 Stark began a series of dietary experiments with observations on the effects of bread and water over a two week period. He included data about the weather, weight loss or gain, stool number and characteristics, and sexual frequency (was there an unfortunate Mrs Stark?).

He followed this up - without a break or ""washout" period of normal diet - with bread, water and 4oz and 8 oz of sugar daily.

During the third period of this experiment he one day ate some meat, and drank some wine. At the end of this second fortnight Stark felt "perfectly hearty, my head clear, often hungry, but never had any desires."

Stark's subsequent experiments are too many to list, but included flour and suet, flour and olive oil (he gained the same amount of weight on each). By now he has scurvy - his gums are black and he has lost a tooth, which began to hurt on the sugar diet. Then he began to live freely on animal food, milk and wine, and recovered his health and spirits - but not for long. Thinking that his afflictions were in fact due to sugar, Stark resolved to test this hypothesis with a return to the bread, sugar, and water diet, eating 6 oz sugar per day over 5 days without his gums being affected, but with the usual loss of desire. For a week in November 1769 he ate bread, beef and water, and "on the third day of this period I began to have desires, which were considerable in the night. On the fifth day, Venus semel". (Semel means once in latin; the expression Venus bis, or twice, appears more often in the text).

Stark then tries living only on lean, well-boiled beef, with its gravy (cooking water and juices).
"In two or three hours after a meal of ten or twelve ounces of meat with its gravy, I became hungry, and was particularly so every night at bed-time. I never had any wind in my stomach, and very seldom passed any downwards. My spirits, at all times very good, were somewhat raised after each meal; but my sleep was every night disturbed by dreams, a circumstance which was new to me. I commonly awoke very early in the morning, and found myself lively and well refreshed : and although I had not slept my usual time, I was never drowsy of an evening. I had sometimes weak desires at the beginning of this period, but none afterwards. My stools resembled in colour, the rust of iron."

For the next 5 days he added fat to the beef, and slept more soundly. He then spent 2 weeks on flour and suet, in order to compare the effect of flour with that of lean beef.
"During the second period I found the diet begin to disagree with me -, I lost my appetite, and was seized with severe head-achs, with uneasiness at my stomach and bowels, and great part of the tallow passed through my body assimilated. I was thirsty, and greatly troubled with wind, upwards and downwards. I also at this time observed a considerable increase in my urine.

Having been extremely uneasy during the night of the second of December, and having no appetite for food on the morning of the  third, I thought proper, though my appetite returned in the afternoon, to abstain from food the whole day, and next morning was quite well.
      Suspecting that the bad effects of the preceding diet were owing to the quantity, and not the quality of the tallow, I diminished the quantity during the last period, and had then the satisfaction to find the diet agree with me perfectly well. My bowels were quite easy, and I was not troubled with wind, with thirst, or with head-aches, and no part of the tallow remained undigested."
Over Christmas of 1769, Stark enjoyed a diet of flour and marrow oil.
"I found myself remarkably well on this regimen, and thought my spirits raised by it ; though this might be only opinion, as it is difficult on such Subjects to distinguish between fancy and reality. I sometimes had desires. Venus semel, during the first period.
Finding the oil of marrow so mild in the bowels, and at the same time so agreeable a food, I increased it".

After trying suet again, he notes "Is it not evident, then, that an excess in the use of oils, is more hurtful to the body, than an excess in any other article of food ? and that, of course, we ought to be particularly careful in regulating the quantity and quality of the oils we employ in diet."

Remember those words. On February the 4th 1770 Stark began a diet of bread and honey, which caused him considerable internal distress, then followed it with bread and 4oz Cheshire cheese for 2 days. This left him "feeble, uneasy, sighing and moaning". He wrote,
"Does not an excess in sweets give a still greater shock to the constitution than an excess in fats? Is there any other article of food so hurtful as either, taken immoderately?"
He took his last meal, of bread and rosemary tea, on the 18th February 1770, while a hurricane raged outside.

The doctor who attended him wrote "For several months before his death he had been employed in making experiments upon himself, of the effects of different kinds of food ; among the last was that of honey and flour made into a pudding, upon which he had lived several days, and which seemed to be extremely diuretic at first, as he made considerably more water than the liquor he drank. At last it brought on a diarrhoea, for which he ate Cheshire cheese, to the quantity of a quarter of a pound, without any other food, and that seemed to bind his body so much that he had not been at stool for five days. When he was taken ill, on Sunday, the 18 th of February, 1770, he sent for Mr. Hewson to bleed him, when he complained of his head and in his belly. The blood was somewhat fizzy."

William Stark died on the 23rd February 1770. His friend James Carmichael Smith, who became Physician Extraordinary to the King, posthumously edited his papers into this 1788 edition. It includes many pages of statistical tables recording his observations. 

Stark even measured his perspiration in the last days of his life.
Stark's death is attributed to scurvy, as can be seen by the restorative effect on his health when his diet included meat or fruit, but that's probably not the whole story. He proved to my satisfaction that you need to watch what you eat if you want to stay alive; that animal foods are a blessing, and that, if you wish to continue in desire and keep your teeth, beware the grains and sugars, and be particularly careful in regulating the quantity and quality of added fats and oils.

Thursday, 7 April 2016

On second thoughts, that vegetarian genomic study did show that not eating animals is not good for you.

Generally, a study that purported to show that vegan and vegetarian diets are harmful would be welcomed by meat eaters, who get a lot of pseudoscientific criticism from members of those groups, some of it disguised as sober science.
But no-one was much impressed by the Pune vs. Kansas study. Even Tom Naughton wrote it off as meaning the same thing the head of the NZ vegetarian society said it meant - that omega-6 seed oils just aren't good for us anyway.

But I thought about this, and, not so fast.
Seed oils high in omega 6 are harmful for the descendants of long lines of vegetarians because such people, because of an adaptation to the virtual absence, from their diets, of DHA and AA (arachidonic acid), the very long-chain PUFAs found in animal flesh and organ meats, have a more efficient version of the genes involved in synthesizing these fats from alpha-linolenic acid (ALA) and linoleic acid (LA). Too much LA overwhelms these enzymes, which only seem to be loosely regulated, and results in an excess of inflammatory AA products and an inadequacy of very long chain omega 3s.

So this adaptation is good for vegetarians eating traditional diets, as in Pune where the traditional fat source would have been ghee, with a little mustard seed oil added. Low in omega 6, balanced in omega 3, enough hearty saturated dairy fat to protect against the diabetogenic effect of a diet high in both starch and sugar.

But think about it - this adaptation isn't some random lucky fluke. For one gene to dominate over another like this, there needs to be some significant and sustained reproductive advantage.
Reproductive advantage means one or more of these - greater fertility, fewer stillbirths, fewer complications of pregnancy, lower mortality early in life, greater attractiveness to a mate.

The vegetarian PUFA polymorphism flourished because, in the past, people without it, eating vegetarian diets, suffered some combination of infertility, stillbirth, dangerous pregnancy, early mortality, or plain butt-ugliness.

Its incidence at present is 70% in South Asians, 53% in Africans, 29% in East Asians, and 17% in Europeans. That to me indicates a burden of suffering and infertility in South Asians in the past, to produce this result - that's how evolution works, that's how Nature selects. If you're European, the chances are that you do need AA and DHA in your food, unless you want to take your chances with lots of vegetable oil - which seems to me a very second-rate, artificial, and dicey way of getting there.

Note that some vegans do think it's okay to eat bivalve shellfish, which can't feel pain (or rather, probably don't feel more pain that plants do, but who knows what that is). This would supply more than enough DHA and AA. However, PETA takes the hard line on this, like the Buddhist who won't swat a zika-carrying mosquito.
But then, PETA is Neal Barnard's baby and he's a dietary cholesterol zealot, so their ban on shellfish might not be as strictly ethical as they claim. Dr Barnard "advises people to avoid added vegetable oils and other high-fat foods as well as refined sugar and flour". Well good for him but it is hard to see where the AA and DHA will come from for the majority of Europeans on this diet.

Maybe veganism is a bit like statinism - enough of the people it's going to harm will drop out of the trial early for the long-term results to look a bit encouraging. It would be interesting to see if long-term vegans in European populations have in fact self-selected for the FADS2 polymorphism common in Pune.

Thursday, 31 March 2016

Silymarin for type 2 diabetes - significant effects on glucose and lipids from a safe OTC herbal.

This study has an interesting backstory.

Hepatitis C (mainly genotype 4) infects nearly a quarter of the Egyptian population. This is the highest rate of HCV infection I've heard of in any country; however the Nile Valley is probably the ancestral home of HCV's transmission to humans.

Egypt is not a rich country and drug treatments for Hep C are expensive, not to mention dangerous and unreliably effective till recently. Consequently a lot of Egyptians use alternative remedies, usually sourced from EU pharmacopoeias. Silymarin (a standardised mik thistle extract) and a German spirulina extract are two of the most popular; I wrote some time ago about their relative effect on hepatitis C infection.

Edit - the spirulina and silymarin in that earlier study was supplied by Beovita-Safe Pharma, a Joint German Egyptian Company, Katzbachstr. 29, D-10965 Berlin. There is no mention of the supplier of silymarin in the latest study, but it may be from the same source.

These remedies are so widely used in Egypt that Egyptian pharmacologists have investigated their safety and effectiveness with unusual thoroughness. It's not a big leap from treating the fatty liver of chronic hep C infection to seeing if silymarin will improve type 2 diabetes. This is a disease highly associated with NAFLD, and abnormal liver function is thought to be a primary cause of diabetic insulin resistance and dyslipidemia.

Effect of Silymarin Supplementation on Glycemic Control, Lipid Profile and Insulin Resistance in Patients with Type 2 Diabetes Mellitus. (full text here)

Amany Talaat Elgarf 1, Maram Maher Mahdy 2, Nagwa Ali Sabri 1
International Journal of Advanced Research (2015), Volume 3, Issue 12, 812 – 821.
 1. Department of Clinical Pharmacy, Faculty of Pharmacy, Ain Shams University, Cairo, Egypt. 2. Department of Internal Medicine and Diabetes, Faculty of Medicine, Ain Shams University, Cairo, Egypt

Note that Ain Shams is a proper medical school, the 3rd oldest in Egypt, founded in 1950.

Forty patients were randomly assigned to receive either silymarin capsules 140 mg three times daily (n=20) or identical placebo capsules three times daily (n=20) for 90 days. Full clinical history and fasting blood samples were obtained to determine FBG , HbA1c, FSI, full lipid profile, MDA , hs-CRP levels as well as HOMA-IR at the beginning and at the end of the study.

These results are pretty impressive. Firstly, the control group is getting worse in every parameter tested over the study period, and many of the differences are significant.
Meanwhile, the silymarin arm sees some striking improvements. The authors highlight a rise in HDL from 23 (CI 12.0 - 52.0) to 38.5 (CI 14.0 - 65.0) mg/dl, which is consistent with an improvement in HOMA-IR and a drop in fasting insulin from 
15.2 (8.4-20.7) to 11.2 (9.3-15.6) uIU/mL. Over the same 3 months insulin rose to 19.7 (9.4-24.4) uIU/mL in the placebo group.

Also impressive is the drop in LDL-C and LDL-C. LDL-C drops from 131.9 (69.0-218.6) to 94.0 (58.8-154.2) mg/dl, and VLDL-C drops from 34.3 (19.0-47.0) to 20.8 (16.6-35.0) mg/dl.
Remember that a diagnosis of diabetes is one of the criteria for prescribing statins. Statins can lower LDL-C, but they won't lower blood glucose, in fact they double the chance of it rising into the diabetic range. Silymarin, on the other hand, lowered fasting BG from 252.5 (174.0-395.0) to 162.0 (109.0-391.0) mg/dl (while it rose 20% in the placebo arm during the same period). HbA1c dropped from 10.4 (8.0-12.3) to 8.5 (6.3-12.3) %.

Basically, a safe OTC supplement seems to be able to give the benefits of metformin and statins combined, with a minimal risk. The safety of silymarin is recorded in dozens of long term Hep C studies of various types.
Would silymarin have benefits for people on low-carb diets who see a large rise in LDL, or whose blood glucose control still isn't perfect? I think it might be worth trying. 

Thursday, 24 March 2016

The Smoking Gun - the Role of PUFA in Non-Alcoholic Liver Disease

The smoking gun

Public health experts are gradually accepting the idea that sucrose and fructose are, like alcohol, causes of fatty liver disease (non-alcoholic liver disease - NAFLD - and its inflammatory development, non-alcoholic steatohepatitis - NASH).
After all, sugar is unnecessary and, like alcohol, the rogue macronutrient, associated with pleasure rather than nutrition. There’s little or no evidence that there is ever likely to be a health benefit from replacing starch or fat with sugar.
Sugar was first equated with alcohol in a liver disease model by CH Best, co-discoverer of insulin, in 1949,[1] a fact which has a nice aptness to it, because NAFLD is often the first stage that leads to type 2 diabetes and, if you’re not very careful about the quality of food and the calories and carbs, insulin-dependence.

On the other hand, there is little mainstream acceptance of the idea that polyunsaturated fat plays a role in these diseases, with the honorable exception of Canada’s recent obesity report; yet the scientific evidence that dietary fats of 5% or more PUFA are essential for the development of alcoholic liver disease (ALD) is very strong. (See here and here)

Polyunsaturated fat is the Golden Boy of public health – seed oils have saved the world from heart disease, supposedly, so the public presentation of evidence that they promote other diseases has always faced an uphill battle.

For a start, PUFA is a small part of the diet and isn’t measured with great accuracy in epidemiological studies. Its harms are interactive with two other nutrients – sugars and alcohol – the excess consumption of which may not be reported as accurately or honestly as intake of other foods.

Anyway, this new study tells us that the genes that encode proteins (enzymes) needed for the metabolism and detoxification of alcohol are upregulated in NAFLD. I can’t get full-text for this, but the abstract is informative.
“Alcohol-metabolizing enzymes including ADH, ALDH, CYP2E1, and CAT were up-regulated in NAFLD livers. The expression level of alcohol-metabolizing genes in severe NAFLD was similar to that in AH.”

“[I]ncreased expression of alcohol-metabolizing genes in NAFLD livers supports a role for endogenous alcohol metabolism in NAFLD pathology and provides further support for gut microbiome therapy in NAFLD management.”[2]

Well yes, there is definitely a role for probiotics and prebiotics (which now include long-chain saturated fats) in NAFLD and ALD management. But the idea that NAFLD is caused by endogenous alcohol production in all but a few cases seems preposterous to me. Alcoholic liver disease is associated with drunkenness, alcoholism, and thiamine depletion. Are these seen in patients with NAFLD?
However, was alcohol involved, there would be the same disease-promoting role for PUFA seen in ALD.

Why else would alcohol-metabolising enzymes be upregulated? We didn’t evolve drinking alcohol, so why did this enzyme system come to exist?
It exists originally for the metabolism of polyunsaturated fats into eicosanoids, that is to say, into inflammatory molecular messengers, and for the removal of oxidised PUFAs.

For example, if you feed oxidized linoleic acid to rats, their expression of aldehyde dehydrogenase (ALDH) increases.[3] The alcohol dehydrogenase (ADH) enzyme in leeks breaks down essential fatty acids into aromatic metabolites (sure, a leek isn’t a human, but it shows that ADH enzymes act on PUFAs in the absence of alcohol, which is what we want to know). [4]And if you feed PUFAs to cultured hepatoma (HepG2) cells, which is the cell culture model for liver diseases, you get this:

“After 2 hours of cultivation, the lipid peroxide (LPO) in the DHA group increased 600% compared with control, and was much higher than in the groups treated with the other FAs, with LNA > LA > OA > PA. CYP2E1 induction increased with greater effect as the degree of unsaturation of OA, LA, and DHA increased.”[5]

PA was palmitic acid, and had no effect on PKC activity, the marker of cellular stress in the experiment.

CAT is catalase, a heme enzyme which degrades H202 to water and oxygen, the end of this detox disassembly line.

“The effects of linoleic and intake on catalase and other enzymes were investigated by feeding 0, 1, 5 or 10% corn oil diet to rats previously fed a fat-free diet. Rats fed more than 1% corn oil for 2 weeks showed significant increases of glutathione peroxidase and superoxide dismutase in liver cytosol when compared to the controls fed no corn oil. Peroxisomal catalase activity especially was increased.”[6]
So, with a very cursory search, I found that the 4 enzymes found upregulated in ref. [2] metabolise PUFAs, and are upregulated when they are present in quantity.
No endogenous alcoholism is needed to explain this result.

The next question – how does the presence of excess fructose drive this enzyme system? Alcohol upregulates the enzyme system because it degrades alcohol, and PUFA is then caught up in the activated enzymes; but what role does sugar play?

Edit: this is a good place to include recent human evidence for this theory.

5-Hydroxyicosatetraenoic acid (5-HETE) and 9-Hydroxyoctadecadienoic acid (9-HODE) are eicosanoid metabolites of linoleic acid (omega 6 PUFAs). In this Polish study,

Patients (n=12) with stage I NAFLD had a significantly higher level of HDL cholesterol and a lower level of 5-HETE. Patients (n=12) with grade II steatosis had higher concentrations of 9-HODE. Following the six-month dietary intervention, hepatic steatosis resolved completely in all patients. This resulted in a significant decrease in the concentrations of all eicosanoids (LX4, 16-HETE, 13-HODE, 9-HODE, 15-HETE, 12-HETE, 5-oxoETE, 5-HETE) and key biochemical parameters (BMI, insulin, HOMA-IR, liver enzymes).
Conclusion: A significant reduction in the analyzed eicosanoids and a parallel reduction in fatty liver confirmed the usefulness of HETE and HODE in the assessment of NAFLD."[7]

Steatosis resolved completely after 6 months on a diet in which LA was restricted to 4% of energy and sugar to 10%. Though the diet was low in fat (20-35% of energy) dairy was favoured as a source of fat -
type of fat included in the diet was easy to digest, such as cream, butter, oil or milk...The total omega-3 and omega-6 fatty acids consumption was approximately 0.5% E for omega-3 and 4% E for omega-6."

In 2004 the average omega 6 content of the Polish diet was 5.21% "
much higher than the recommended upper limit (3% of energy)." (link) As the NAFLD diet was individually calorie-restricted, the total amount of omega-6 would have been close to the total giving the recommended 3% in the normal diet.

We also find reversal of fatty liver disease, associated with obesity and type 2 diabetes, in the recent pilot trial of Unwin et al, where subjects were told to avoid sugar, grains, and other carbohydrate-dense foods.[8]
"In place of carbohydrate-rich foods, an increased intake of green vegetables, whole-fruits, such as blueberries, strawberries, raspberries and the “healthy fats” found in olive oil, butter, eggs, nuts and full-fat plain yoghurt were advocated."
A 50/50 mix of butter and olive oil (for example) gives a fat of around 6% omega 6; nuts and poultry, which are not necessarily foods eaten every day, supply somewhat higher amounts; in the context of a diet around 60-70% fat, these instructions should amount to a high-fat diet that is not excessively high in omega 6; however the effects of carbohydrate restriction on NAFLD are significant even when fat composition is 15% PUFA in a 60% fat, 8% carbohydrate diet, as in the experiment of Browning et al.[9]

These various examples of fatty liver reversal diets seem to indicate the synergy of sugars, carbohydrates, and polyunsaturated fat in the NAFLD dietary model.

[1] C. H. Best, W. Stanley Hartroft, C. C. Lucas, and Jessie H. Ridout. Liver Damage Produced by Feeding Alcohol or Sugar and its Prevention by Choline. Br Med J. 1949 Nov 5; 2(4635): [1001]-1004-1, 1005-1006.

[2] Zhu R, Baker SS, Moylan CA, et al. Systematic transcriptome analysis reveals elevated expression of alcohol-metabolizing genes in NAFLD livers. The Journal of Pathology Volume 238, Issue 4, pages 531–542, March 2016

[3] Hochgraf E, Mokady S, Cogan U. Dietary Oxidized Linoleic Acid Modifies Lipid Composition of Rat Liver Microsomes and Increases Their Fluidity. J. Nutr. 127: 681–686, 1997.

[4] Nielsen GS, Larsen LM, Poll L. Formation of Volatile Compounds in Model Experiments with Crude Leek (Allium ampeloprasum Var. Lancelot) Enzyme Extract and Linoleic Acid or Linolenic Acid. J. Agric. Food Chem. 2004, 52, 2315-2321

[5] Sung M, Kim I. Differential Effects of Dietary Fatty Acids on the Regulation of CYP2E1 and Protein Kinase C in Human Hepatoma HepG2 Cells. J Med Food 7 (2) 2004, 197–203

[6] Iritani N, Ikeda Y. J Nutr. Activation of catalase and other enzymes by corn oil intake. 1982 Dec;112(12):2235-9.

[7] Maciejewska D, Ossowski P, Drozd A, et al. Metabolites of arachidonic acid and linoleic acid in early stages of non-alcoholic fatty liver disease - A pilot study. Prostaglandins Other Lipid Mediat. 2015 Sep;121(Pt B):184-9. 

[8] Unwin DJ, Cuthbertson DJ, Feinman R, Sprung VS (2015) A pilot study to explore the role of a low-carbohydrate intervention to improve GGT levels and HbA1c. Diabesity in Practice 4: 102–8.

Browning JD, Baker JA, Rogers T et al. Short-term weight loss and hepatic triglyceride reduction: evidence of a metabolic advantage with dietary carbohydrate restriction. Am J Clin Nutr. 2011 May; 93(5): 1048–1052.