Archive for the ‘Diabetes’ Category

VeganHealth Update: Iron and Vegetarian Diets

Thursday, June 13th, 2013

I have been silent lately due to updating the Iron article at VeganHealth.org. In the past, it has been just a mishmash of bits I’ve written as needed. It is now a well-organized, tight piece (I hope).

One new addition worth mentioning is on type 2 diabetes. Excerpt:

“There is evidence that the beta cells of the pancreas, which produce insulin, are particularly susceptible to oxidation from iron due to their weak antioxidant defense mechanisms. A 2012 meta-analysis of prospective studies found that higher iron stores (6 studies) and higher intakes (5 studies) of heme iron [a type of iron found only in meat] at baseline were strongly associated with a higher risk of type 2 diabetes (1). Higher intakes of non-heme iron were not associated.

“A cross-sectional study from the USA found lower ferritin [stored iron] levels in lacto-ovo vegetarians (35 µg/l) than meat-eaters (72 µg/l). The vegetarians also had higher insulin sensitivity. Upon giving phlebotomies to 6 male meat-eaters to reduce their ferritin levels, their insulin sensitivity increased. The authors suggested that the lower ferritin levels could be a reason why vegetarians had greater insulin sensitivity (2).

“It is possible that the lower risk of type 2 diabetes in vegetarians (see Type 2 Diabetes and the Vegan Diet), which has been shown to be independent of body mass index, could be partially explained by their lower iron stores.”

Link to full article: Iron. Warning: It’s long and not required reading. :)

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References

1. Bao W, Rong Y, Rong S, Liu L. Dietary iron intake, body iron stores, and the risk of type 2 diabetes: a systematic review and meta-analysis. BMC Med. 2012 Oct 10;10:119. | link

2. Hua NW, Stoohs RA, Facchini FS. Low iron status and enhanced insulin sensitivity in lacto-ovo vegetarians. Br J Nutr. 2001 Oct;86(4):515-9. | link

VeganHealth.org Update: Near Vegan Diet Improves Type 2 Diabetes

Tuesday, February 12th, 2013

This study is from 2011 from the Czech Republic. I mentioned it in my post on the type 2 diabetes treatment meta-analysis that I made last week, Type 2 Diabetes Meta-Analysis: What Happened to the Vegan Diet?

I’ve also had it in my nutrition queue to read for some time. In fact, anyone who’s read this blog for awhile might be wondering how many studies might actually be lurking in my nutrition queue! Well, I’m happy to report that I had over 200 emails (many with studies attached) to go through last Friday at noon and it’s now down to 81. So, I’m catching up!

The reason this study got buried is because the abstract calls the diet “vegetarian,” rather than “vegan.” But once you read the study, you see that the “vegetarian” diet contained no animal products except for a maximum of one serving of low-fat yogurt per day – that’s as vegan as the diet used in Dean Ornish’s heart disease reversal study.

In fact, it makes me rethink that type 2 diabetes meta-analysis – they said they only included diets that had been studied at least twice, saying that only one study looked at a vegan diet and one looked at a “vegetarian” diet when in reality, the diets were virtually both vegan given that people in these studies tend to cheat a little bit anyway. Oh, well.

One difference is that the diet in the PCRM study was about 21% fat, whereas the diet in the Czech Republic study was…drum roll please…38% fat!

The rest of this post is copied from the blurb I just added to Type 2 Diabetes and the Vegan Diet at VeganHealth.org:

In 2011, researchers from the Czech Republic studied a vegetarian (near-vegan) diet compared to a conventional (control) diet for type 2 diabetes (1). The study tested only diet for 12 weeks and then combined diet and exercise for another 12 weeks. Animal products were limited to maximum of one portion of low-fat yogurt a day. The calories in both diets were limited (as distinct from the PCRM studies in which the vegan diet was unlimited in calories). The vegetarian diet was about 38% fat.

The vegetarian diet group had a greater reduction in diabetes medication (43% vs. 5%), HbA1c, waist circumference, and body fat. LDL cholesterol went down 8% in the vegetarian group only, but HDL cholesterol went up in the control group. Exercise caused the positive differences for the vegetarian diet to be even greater and also raised the HDL in the vegetarian group.

The authors stated:

Several possible mechanisms may explain the beneficial effects of a vegetarian diet: higher intake of fibre, lower intake of saturated fat [and a higher polyunsaturated and saturated fatty acid (P⁄S) ratio], higher intake of non-heme iron and reduction in iron stores, higher intake of vegetable protein in place of animal protein, higher intake of antioxidants and plant sterols. A vegetarian diet was reported to reduce intramyocellular lipid concentrations and this, together with the effect on visceral fat which we observed, might be responsible for a substantial portion of the effect of a vegetarian diet on insulin sensitivity and enzymatic oxidative stress markers.

And, oddly enough:

Especially during exercise, it became evident in our trial that it was easier for subjects to follow a vegetarian diet than a conventional diabetic diet.

And I’m happy to report that VeganHealth.org’s Type 2 Diabetes and the Vegan Diet section is now up to date. I am considering paring down a lot of the details on that page – if anyone has read it and has an opinion on if you prefer the details or would like to see them pared down quite a bit, please let me know in the comments here. Thank you!

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Reference

1. Kahleova H, Matoulek M, Malinska H, Oliyarnik O, Kazdova L, Neskudla T, Skoch A, Hajek M, Hill M, Kahle M, Pelikanova T. Vegetarian diet improves insulin resistance and oxidative stress markers more than conventional diet in subjects with Type 2 diabetes. Diabet Med. 2011 May;28(5):549-59. | Link

Type 2 Diabetes Meta-Analysis: What Happened to the Vegan Diet?

Wednesday, February 6th, 2013

On the same day that the study showing vegetarians to have a 30% reduced risk of heart disease was released on PubMed, a meta-analysis of diets used to treat type-2 diabetes was also released (1).

The abstract mentions vegan diets:

“We included randomized controlled trials (RCTs) with interventions that lasted ≥ 6 mo that compared low-carbohydrate, vegetarian, vegan, low-glycemic index (GI), high-fiber, Mediterranean, and high-protein diets with control diets including low-fat, high-GI, American Diabetes Association, European Association for the Study of Diabetes, and low-protein diets.”

And their conclusion is:

“Low-carbohydrate, low-GI, Mediterranean, and high-protein diets are effective in improving various markers of cardiovascular risk in people with diabetes and should be considered in the overall strategy of diabetes management.”

Knowing that PCRM had conducted a clinical trial using a whole-foods vegan diet to treat type-2 diabetes with some decent success (more info), I was surprised that the vegan diet didn’t get mentioned in the conclusion. It turns out that they weeded out any diets that were not tested in at least two different trials. They did have some good things to say about the vegan diet in the paper and suggested more studies were needed. Ditto for the one trial using a vegetarian diet (2).

In terms of the other diets, they found that low-carbohydrate, low-GI, Mediterranean, and high-protein diets all reduced Hb A1c (a marker of blood sugar levels; lower is better), and all but the high-protein diets also improved lipid profiles.

What is the difference between a low-carbohydrate diet and a high-protein diet? A “low-carbohydrate diet” is defined as limiting carbohydrate to 20 to 60 g/day, which is very low. A “high-protein” diet is more than 20% of daily calories as protein, and generally has a higher amount of carbohydrate than the low-carbohydrate diets.

They defined a Mediterranean Diet as, ” rich in olive oil, legumes, unrefined cereals, fruit, and vegetables, low in meat and meat products, and with moderate contents of dairy products (mostly cheese and yogurt), fish, and wine.” They attributed the benefits of a Mediterranean diet to the higher monounsaturated fat (MUFA) content which has been shown “to have an impact on the lipid profile, insulin sensitivity, and postprandial glucose concentrations [blood sugar after a meal].”

I can’t vouch for the analytical methods used in this meta-analysis – there were an enormous amount of details comparing all sorts of different metrics – but the above are the author’s main points. They stated that no funding was received for the study.

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Reference

1. Ajala O, English P, Pinkney J. Systematic review and meta-analysis of different dietary approaches to the management of type 2 diabetes. Am J Clin Nutr. 2013 Jan 30. [Epub ahead of print] | link

2. Kahleova H, Matoulek M, Malinska H, Oliyarnik O, Kazdova L, Neskudla T, Skoch A, Hajek M, Hill M, Kahle M, Pelikanova T. Vegetarian diet improves insulin resistance and oxidative stress markers more than conventional diet in subjects with Type 2 diabetes. Diabet Med. 2011 May;28(5):549-59. (Abstract only) | link

Vegans have Lower Risk of Diabetes

Tuesday, October 11th, 2011

Vegans have a lower risk of developing diabetes!

Ho, hum. This is something we already knew, right? Well, not really. There have not been any prospective studies on the rates of diabetes for vegans. Until now, that is!

A report was just released from Adventist Health Study 2 that found that after 2 years of follow-up, vegans had a 60% reduced risk of being diagnosed with diabetes (1).

More information can be found in the VeganHealth.org article, Type 2 Diabetes and the Vegan Diet or by clicking on the link to the abstract below.

Reference

1. Tonstad S, Stewart K, Oda K, Batech M, Herring RP, Fraser GE. Vegetarian diets and incidence of diabetes in the Adventist Health Study-2. Nutr Metab Cardiovasc Dis. 2011 Oct 7. [Epub ahead of print]   |   Link

Red Meat & Heart Disease

Friday, May 28th, 2010

On March 5, news reports started to surface about a meta-analysis showing that processed meat, but not red meat, was linked to heart disease and diabetes. It was the first systematic review or meta-analysis of its kind, and the paper was released this month.

The authors broke meat down into three categories:

  • Red
  • Processed – might have included some poultry
  • Total – the above two categories combined

Averaged across studies, consumption levels in the lowest versus highest category of intake were (in servings per week):

Red – 1.1 vs. 8.3
Processed – 0.4 vs. 5.7
Total – 1.8 vs. 10.5

The results were:

Coronary Heart Disease

Per serving per day:
Red: 1.00 (0.81 – 1.23)
Processed: 1.42 (1.07 – 1.89)
Total: 1.27 (0.94 – 1.72)

Diabetes Mellitus

Per serving per day:
Red: 1.16 (0.92 – 1.46)
Processed: 1.19 (1.11 – 1.27)
Total: 1.12 (1.05 – 1.19)

Stroke

Per serving per day:
Total: 1.24 (1.08 – 1.43)
No other statistically significant findings.

In other words, more servings of red meat did not increase the risk of heart disease, diabetes, or stroke, while more servings of processed meat increased the risk of heart disease and diabetes. Only more servings of total meat increased the risk of stroke, but there was not nearly as much data for stroke.

This raised the question, “Could it be that non-processed red meat – and, by proxy, saturated fat – is NOT linked to heart disease?”

Before I go and do something that really annoys me, I want to point out that it really annoys me when people nickel and dime a study to death because it disagrees with their pre-drawn conclusions. That said, I do not think you can rule out the possibility that if the researchers had included white meat in their analysis, unprocessed meat could have been linked to heart disease and diabetes. There is some evidence that people who eat no red meat or poultry have lower rates of heart disease.

Additionally, how the variables were adjusted is not clear. The authors’ state:

If multivariable models were reported with and without additional adjustment for variables that could be either confounders or intermediates (eg, high cholesterol), the multivariable model without such variables was selected. If the only multivariable model included such variables, this was selected in reference to crude or minimally adjusted models.

What this means is that if a study adjusted their results for body mass, caloric intake, or cholesterol levels, those results might have been included in the meta-analysis. This would possibly make red meat look better than it actually is because, for example, if red meat increases cholesterol levels, but you then adjust for cholesterol levels, you will lose the effect of red meat. That said, these adjustments would also have affected the processed meats category and it was not enough to ameliorate those results.

The authors note the differences between processed and unprocessed red meats:

Per 50-g serving, processed meats contained modestly higher calories and percent energy from fat and lower percent energy from protein compared with 50 g of red meats. Consistent with lower protein content, processed meats also contained less iron. Processed meats contained relatively similar saturated fat and slightly lower cholesterol, the latter perhaps related to some processed meats being derived from pork and/or lower-cholesterol deli meats. Relatively small differences were present in contents of monounsaturated fat, polyunsaturated fat, or potassium. Largest differences were seen in levels of sodium, with processed meats containing 4-fold higher levels (622 versus 155 mg per serving), as well as 50% higher nonsalt preservatives including nitrates, nitrites, and nitrosamines… Nitrates and their byproducts (eg, peroxynitrite) experimentally promote atherosclerosis and vascular dysfunction, reduce insulin secretion, and impair glucose tolerance, and streptozotocin, a nitrosamine-related compound, is a known diabetogenic compound.

The funding sources for the study were the Bill & Melinda Gates Foundation/World Health Organization Global Burden of Diseases, Risk Factors, and Injuries Study; the National Heart, Lung, and Blood Foundation, National Institutes of Health; and the Searle Scholars Program. The authors listed no conflicts of interest.

In conclusion, processed meats increase the risk of heart disease and diabetes. Unprocessed red meat may not be harmful at the levels measured in this analysis, but there are still some unanswered questions before that should be considered definitive. Total red meat may increase the risk of diabetes and stroke.

How Unhealthy are Eggs?

Friday, January 15th, 2010

As foods go, eggs are very high in cholesterol. Back when it was thought that eating cholesterol caused an increase in blood cholesterol, people with high cholesterol or heart disease were warned away from eggs. But then it was found that while some people’s cholesterol levels rise significantly from eating cholesterol, most people’s do not. So where does that leave eggs?

The findings have been somewhat mixed over the years. The most recent paper I found was a 2008 report from the Physicians’ Health Study (a trial to study low dose aspirin and beta-carotene’s effects on the primary prevention of cardiovascular disease and cancer among US male physicians) (1). They found the following when comparing consumption of 7+ eggs per week to less than 1 per week:

  • No correlation with stroke or heart attacks
  • A 23% increased risk of mortality (1.23, 1.11-1.36)
  • A doubled risk of mortality among men with type 2 diabetes (2.01, 1.26-3.20)

These results were adjusted for age, body mass index, smoking, hypertension, vitamin intake, alcohol consumption, vegetable consumption, breakfast cereal consumption, physical activity, treatment group, atrial fibrillation, diabetes mellitus, hypercholesterolemia, and parental history of premature myocardial infarction.

The authors of this paper reviewed the previous literature on eggs and mortality:

“Limited and inconsistent data have been reported on the association between egg consumption and coronary heart disease. Among 514 Australian Aborigines, consumption of 2+ eggs per week was associated with a 2.6-fold increased risk of coronary heart disease in a prospective analysis (2). Mann et al. (3) reported a 2.7-fold increased risk of death with a higher egg consumption (6+ per week) among British subjects. In contrast, other large prospective cohorts with longer follow-ups did not observe any association between egg consumption and CHD or mortality (4-7).”

They discussed other research showing 7+ eggs increased the risk of heart disease in men and women with diabetes (5).

In conclusion, it appears that in comparison to less than one egg per week, eating 7+ egg per week could increase your risk of early death, especially if you have type 2 diabetes.

References

1. Djousse L, Gaziano JM. Egg consumption in relation to cardiovascular disease and mortality: the Physicians’ Health Study. Am J Clin Nutr. 2008 Apr;87(4):964-9.

2. Burke V, Zhao Y, Lee AH, et al. Health-related behaviours as predictors of mortality and morbidity in Australian Aborigines. Prev Med 2007;44:135–42. [PubMed: 17069878]

3. Mann JI, Appleby PN, Key TJ, Thorogood M. Dietary determinants of ischaemic heart disease in health conscious individuals. Heart 1997;78:450–5. [PubMed: 9415002]

4. Dawber TR, Nickerson RJ, Brand FN, Pool J. Eggs, serum cholesterol, and coronary heart disease. Am J Clin Nutr 1982;36:617–25. [PubMed: 7124663]

5. Hu FB, Stampfer MJ, Rimm EB, et al. A prospective study of egg consumption and risk of cardiovascular disease in men and women. JAMA 1999;281:1387–94. [PubMed: 10217054]

6. Nakamura Y, Okamura T, Tamaki S, et al. Egg consumption, serum cholesterol, and cause-specific and all-cause mortality: the National Integrated Project for Prospective Observation of Noncommunicable Disease and Its Trends in the Aged, 1980 (NIPPON DATA80). Am J Clin Nutr 2004;80:58–63. [PubMed: 15213028]

7. Nakamura Y, Iso H, Kita Y, et al. Egg consumption, serum total cholesterol concentrations and coronary heart disease incidence: Japan Public Health Center-based prospective study. Br J Nutr 2006;96:921–8. [PubMed: 17092383]

PCRM’s DVD: A New Approach to Nutrition for Diabetes

Monday, August 31st, 2009

I recently watched a DVD from Physician’s Committee for Responsible Medicine (PCRM): A New Approach to Nutrition for Diabetes. I would suggest recommending it to anyone you know who has type II diabetes and is eating a mainstream diabetes diet.

The DVD is based on a clinical study PCRM did in which they had good success in treating people with type II diabetes. The thrust of the DVD is that people with type II diabetes can stop counting carbohydrates and calories while at the same time becoming healthier by eating a primarily whole foods vegan diet.

I was happy to see that they strongly emphasized the need to take vitamin B12 if you are on a vegan diet.

I have two suggestions for the DVD.

First, I think they should recommend eating some nuts, at least an ounce a day. Nuts have been shown to have positive effects for type II diabetes, as well as for heart disease and weight loss which are two big concerns for most people with type II.

Second, they recommend avoiding foods with a high glycemic index, but I wish they had made a distinction between glycemic index (how fast a food causes your blood sugar to rise) and glycemic load (how much sugar is absorbed into your blood). In some cases, such as with a carrot, a healthy food without much sugar can have a high glycemic index but a low glycemic load (more info on that here).

But these are minor points in what is overall a very good DVD that could be of great benefit to people with type II diabetes.

Quick Update on Low-Fat Vegan Diets for Type 2 Diabetes

Friday, April 17th, 2009

Ginny Messina has written an interesting, short post about low-fat diets in response to my article about vegan diets and type 2 diabetes.

Type 2 Diabetes and the Vegan Diet

Thursday, April 16th, 2009

A week ago, a study was released showing that Seventh-day Adventist vegans have a 68% lower rate of type 2 diabetes than non-vegetarian SDAs. The finding was highly significant, with a confidence interval of .25 to .41. This is one of the most statistically significant findings I’ve ever seen from a nutrition study.

Where were all the media stories reporting this?!

There is one bit of caution – this study was cross-sectional, not prospective. That means we don’t know if the finding was because vegans don’t contract diabetes as often, or if people with, or prone to, diabetes are less likely to go vegan.

In addition to this SDA study, results were recently released from a study using a vegan diet to treat type 2 diabetes. The researchers found that a low-fat vegan diet resulted in lower body weight, cholesterol, triglycerides, blood glucose, and diabetes medications.

You can find more information in the article, Type 2 Diabetes and the Vegan Diet, that I just posted to VeganHealth.org.

Vegan Diet for Type 1 Diabetes

Friday, March 13th, 2009

Someone recently wrote me asking for information on eating a vegan diet and Type 1 diabetes. Type 1 diabetes is when your body is not making any insulin and so you have to take insulin injections. The person writing me said that even though she could take more insulin to deal with the higher amount of carbohydrate in a vegan diet, “more and more research shows that type ones can build up an insulin resistance if too many carbohydrates are consumed.”

I have only had a question from someone with Type 1 diabetes about two previous times and do not currently know anyone with Type 1 diabetes eating a vegan diet. I do not know of any published studies on the subject, so any advice I give is fairly theoretical. I responded by saying:

“A whole foods vegan diet has been shown to be beneficial for Type 2 diabetes in three studies that have been conducted on people with Type 2. I am actually working on an article combining the results of these studies. A lot of the benefit of such a diet is due to lower caloric intake, which probably won’t help someone with Type 1. However, I could see that the higher fiber content of a whole foods vegan diet could release carbohydrates more slowly into your blood and result in lower insulin needs, even if the carbohydrates are a higher percentage of your diet.”

I also enclosed an article from a 1999 Vegetarian Dietetic Practice group newsletter that addressed Type 1 diabetes in vegetarian children.

I’m wondering if there is anyone out there who has been vegan for awhile and has Type 1 diabetes, who can help this person (and myself) know more about their experience.

Thank you!