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. 

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 -
"The 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.

[9] 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.

The state of nutritional science, 2016

Someone sent me a link to this paper the other day, it's not something I would have looked at otherwise. However, next time you read a "totality of the evidence" snowjob supporting guidelines on saturated fat consumption, this paper will probably have been thrown on the pile, weighting it a little bit further.

Finucane OM, Lyons CL, Murphy AM et al (19 authors).
Monounsaturated fatty acid-enriched high-fat diets impede adipose NLRP3 inflammasome-mediated IL-1β secretion and insulin resistance despite obesity.
Diabetes. 2015 Jun;64(6):2116-28. doi: 10.2337/db14-1098. Epub 2015 Jan 27.

Abstract
Saturated fatty acid (SFA) high-fat diets (HFDs) enhance interleukin (IL)-1β-mediated adipose inflammation and insulin resistance. However, the mechanisms by which different fatty acids regulate IL-1β and the subsequent effects on adipose tissue biology and insulin sensitivity in vivo remain elusive. We hypothesized that the replacement of SFA for monounsaturated fatty acid (MUFA) in HFDs would reduce pro-IL-1β priming in adipose tissue and attenuate insulin resistance via MUFA-driven AMPK activation. MUFA-HFD-fed mice displayed improved insulin sensitivity coincident with reduced pro-IL-1β priming, attenuated adipose IL-1β secretion, and sustained adipose AMPK activation compared with SFA-HFD-fed mice. Furthermore, MUFA-HFD-fed mice displayed hyperplastic adipose tissue, with enhanced adipogenic potential of the stromal vascular fraction and improved insulin sensitivity. In vitro, we demonstrated that the MUFA oleic acid can impede ATP-induced IL-1β secretion from lipopolysaccharide- and SFA-primed cells in an AMPK-dependent manner. Conversely, in a regression study, switching from SFA- to MUFA-HFD failed to reverse insulin resistance but improved fasting plasma insulin levels. In humans, high-SFA consumers, but not high-MUFA consumers, displayed reduced insulin sensitivity with elevated pycard-1 and caspase-1 expression in adipose tissue. These novel findings suggest that dietary MUFA can attenuate IL-1β-mediated insulin resistance and adipose dysfunction despite obesity via the preservation of AMPK activity.

This was a complicated and expensive piece of work, with no obvious COIs:
The work presented in this article has been supported by Science Foundation Ireland http://dx.doi.org/10.13039/501100001602 (grant SFI PI/11/1119). The CORDIOPREV and LIPGENE study subjects and investigators were funded by European Commission FP6 (grant FOOD-CT-2003-505944).

So has it been designed in such a way that it can tell us anything reliably about the effects of fats in human diets?

- The mice are C57BL/6 so get fat on diets that may not fatten humans,[1] and the diet is 45% fat, 35% CHO which is half sugar, plus casein. Trisun oil vs Palm oil used means PUFA was well-controlled. However, it also means we're looking at a particular type of SFA - palmitate and stearate - versus the generic MUFA oleic acid that's prolific in every fat, even the palm oil here.The mice fed more MUFA gained less weight than the mice fed SFA. Is this plausible? It's consistent with Delaney et al (2000).[2] However, this same evidence would predict that, had the SFA source been coconut oil, then the SFA mice would have gained less weight than the MUFA mice.

- SFA/MUFA intake of first human cohort (CORDIOPREV) is determined by plasma levels, which evry ful kno are controlled by CHO,[3] and this is clearly shown in supplementary table 3 where plasma SFA correlates with triglycerides but not HDL. Therefore, CORDIOPREV shows effect of CHO intake on IR as well as or instead of effect of SFA intake. It is well-known that sugar and SFA consumption are associated in epidemiology, and that is the likely explanation for what we see in supplementary table 3.


- Second human study (LIPGENE) compares effect of MUFA intervention in high-SFA people living in Scandanavia with same intervention in high-MUFA people living in Italy. Again, SFA/MUFA was determined by plasma levels. Even apart from this, I think there could be a few confounders within this arrangement that were not discussed in the paper. Results are shown in supplementary figure 6 here.

Interestingly, there is no discussion whatsoever of limitations vs strengths of the research in the paper.

Does this mean the results are wrong? Many studies show that MUFA is associated with better insulin sensitivity than SFA in high-carb diets, but the difference seems to disappear at higher fat intakes.
[Edit 1/4/16: the science for this is much less convincing than I was given to believe. Most studies show no difference. The KWANU study only showed a non-significant difference which disappeared at 47% fat. The effect is only seen in humans, when it is seen, with differences in fat type that are outside the normal range obtained in people freely choosing fatty foods, in other words at the same extra-physiological concentrations of the various fatty acids that are produced in the mouse studies.]
The mouse study "demonstrated that enrichment of obesigenic HFDs with MUFA can improve insulin sensitivity, reduce adipose IL-1β–mediated inflammation, and promote adipose hyperplasia compared with diets enriched with SFA". Promoting adipose hyperplasia might not be something everyone wants. A possible explanation is that more fat storage in subcutaneous adipose tissue (and somewhat higher rate of oxidation) from MUFA in the obesigenic diet results in less visceral and ectopic fat - the former (VAT) is more inflammatory than subcutaneous fat, the latter (ectopic fat in liver and pancreas) results in insulin resistance and type 2 diabetes.[4] But because of the mouse model used, this doesn't answer the question, what is an obesigenic diet in humans? The C57BL/6 mouse can't tell us what happens in humans if MUFA replaces carbohydrate instead of replacing SFA, but we have human studies showing that, e.g.[5] 

"As compared with the high-carbohydrate diet, the high-monounsaturated-fat diet resulted in lower mean plasma glucose levels and reduced insulin requirements, lower levels of plasma triglycerides and very-low-density lipoprotein cholesterol (lower by 25 and 35 percent, respectively; P less than 0.01), and higher levels of high-density lipoprotein (HDL) cholesterol (higher by 13 percent; P less than 0.005)."





[1] Borghjid S, Feinman R. Response of C57Bl/6 mice to a carbohydrate-free diet
Nutrition & Metabolism 2012;9:69

[2] DeLany, JP, Windhauser, MW, Champagne, CM, Bray, GA. Differential oxidation of individual dietary fatty acids in humans. Am J Clin Nutr October 2000;72(4):  905-911

[3] Volk BM, Kunces LJ, Freidenreich DJ et al. Effects of step-wise increases in dietary carbohydrate on circulating saturated fatty acids and palmitoleic acid in adults with metabolic syndrome. PLoS One. 2014 Nov 21;9(11):e113605. doi: 10.1371/journal.pone.0113605. eCollection 2014.

[4] Sattar N, Gill JMR. Type 2 diabetes as a disease of ectopic fat? BMC Medicine 2014; 12: 123

[5] Garg A, Bonanome A, Grundy SM, Zhang ZJ, Unger RH. Comparison of a high-carbohydrate diet with a high-monounsaturated-fat diet in patients with non-insulin-dependent diabetes mellitus. N Engl J Med. 1988 Sep 29;319(13):829-34.