Many Links

August 15th, 2014 by Jack Norris RD

Dr. Michael Greger of NutritionFacts.org has just released Latest in Clinical Nutrition: Volume 20. Lots on gluten in this one!

Ginny Messina has a great article on the latest wave of ex-vegans listening to their bodies in Disordered Eating, Restrictive Eating, and Ex-Vegans.

The Vegetarian Resource Group just posted What is the Amount of Oxalate in Seitan?

Dr. Kim A. Williams, the president-elect of the American College of Cardiology, suggests that patients go vegan in the New York Times article, Advice From a Vegan Cardiologist.

Research on Avocados: I’m In!

August 10th, 2014 by Jack Norris RD
Summary New research shows that avocados increase beta-carotene absorption and conversion to vitamin A while not increasing caloric intake when eaten in moderate amounts.

Two recent studies on avocados have made this dietitian start eating more.

The first was conducted at Ohio State University and examined whether eating avocado could increase vitamin A levels in the blood after meals (1).

Vitamin A is obtained from plant foods by eating carotenoids which the body can then convert into vitamin A. There is evidence that adding fat to meals can increase carotenoid absorption, which isn’t surprising given that carotenoids are fat-soluble. (See the VeganHealth.org article about Vitamin A for more info.)

The study showed that not only did adding 1/2 of an avocado to a high-carotenoid meal increase the amount of carotenoids absorbed, it also increased the amount of vitamin A in the blood by about 3 to 6 times compared to a high-carotenoid meal without avocado.

Some caveats:

– It’s not clear that the amount of vitamin A measured in the blood after a meal really indicates that someone has better vitamin A status.

– Some people are, apparently, “non-responders” and do not absorb more carotenoids when added to the diet. In this study, one participant (out of twelve) was found to be a non-responder and she was removed.

– The Hass Avocado Board provided some of the support for this study.

Increasing vitamin A isn’t necessarily needed by most people, but since vegans do not get a direct source of vitamin A, and many may not eat enough carotenoids, adding avocado to meals will help ensure that you’re efficiently utilizing carotenoids.

And why not? Avocados are delicious.

Of course, there is a reason why not – because avocados are high in fat.

It turns out that due to their high water and fiber content, avocados barely rise to the category of a medium energy dense food. A serving size is considered 1/2 of a medium-sized avocado or 70 g. One serving contains 4.6 g of fiber, 10 g of fat, but only 112 calories. As an extra bonus, it contains 340 mg of potassium (almost as much as a medium-sized banana).

This brings us to the second study, from Loma Linda University, looking at energy intake and satiety (feeling satisfied) when avocados are added to the diet (2).

There were three test meals: a control lunch without avocado, a lunch with the same amount of calories as the control lunch and including 1/2 of an avocado, and a control lunch plus 1/2 of an avocado.

The lunches with the avocados resulted in slightly less hunger over the next three hours, and the people who ate avocados with lunch ate less calories for their evening meal and snack (1194 vs. 1276 kcal; difference was not statistically significant). The meals in which avocado replaced other calories were the winners as those people ate 83 calories less for the day.

Again, there are caveats:

– This doesn’t mean that eating an avocado every day will lead to weight loss. At the very least, it’s evidence that adding one-half of an avocado a day won’t lead to eating more calories for most people.

– In the words of the authors, “The funding for this study was supported by a grant from the Hass Avocado Board, which had no role in the design and conduct of the study; in the collection, analysis, and interpretation of the data; or in the preparation, review or approval of the manuscript.”

Any time a study is supported by an industry group you have to be more skeptical. Even if the Hass Avocado Board had nothing to do with conducting the study, there may be an unconscious bias for a positive analysis. In this case, the Loma Linda University researchers suggest that a longer trial is needed “to evaluate the effects of daily avocado intake on measures of appetite sensation and weight management in free-living normal weight, overweight and obese adults.” In other words, it would be great if the Hass Avocado Board could fund some more research.

But that said, who else is going to fund studies like these? We might have to wait a long time before the government makes studying avocados a priority.

When I go to Chipotle, which is every few weeks, I normally ask them to really limit the guacamole they add. It can be comical how large the servings there get as ingredients pile up and by the time they get to the last item, the guacamole, there is already a massive amount of food on the tray, so I’m not inclined to change my ordering habits there.

But Chipotle aside, the research above has already made me add more avocado to my daily eating habits. Congratulations to the Hass Avocado Board – you’ve made a believer out of me!

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References

1. Kopec RE, Cooperstone JL, Schweiggert RM, Young GS, Harrison EH, Francis DM, Clinton SK, Schwartz SJ. Avocado Consumption Enhances Human Postprandial Provitamin A Absorption and Conversion from a Novel High-β-Carotene Tomato Sauce and from Carrots. J Nutr. 2014 Aug;144(8):1158-66. | link

2. Wien M, Haddad E, Oda K, Sabaté J. A randomized 3×3 crossover study to evaluate the effect of Hass avocado intake on post-ingestive satiety, glucose and insulin levels, and subsequent energy intake in overweight adults. Nutr J. 2013 Nov 27;12:155. | link

Vegan Kids, Dr. G on Diabetes, Ginny on Almond Milk

July 29th, 2014 by Jack Norris RD

We just added a new child to the Real Vegan Children page. This page lists kids who have been “vegan since conception.” The new child is Zander Earl and his mother provides an interesting and extensive write-up.

Dr. Greger recently highlighted an exciting study at NutritionFacts.org in his video, Preventing Prediabetes By Eating More. In this study, adding 5 cups of pulses (beans and peas) per week to the diets of people at risk for type 2 diabetes resulted in improvements similar to counseling patients to reduce food intake by 500 calories per day.

Dr. Greger also recently came out with a new DVD, Dr. Greger’s 2014 Year-in-Review Presentation.

Ginny Messina posted an interesting article, Vegans Drink Almond Milk Because It’s Cruelty-Free–Not Because It’s Hip. Excerpt:

“I like almond milk, but I rarely drink it. I actually don’t drink plant milk much at all, but when I do, it’s always soymilk. I want the protein it provides, and it’s also easy on the environment.”

Lower Cancer Rates in Vegans

June 16th, 2014 by Jack Norris RD
Summary A report out this month shows vegans and vegetarians in EPIC-Oxford to have lower cancer rates than regular meat-eaters.

The Oxford arm of the European Prospective Investigations Into Cancer (EPIC) has released a report showing that after an average of 14.9 years of follow-up, vegetarians (.88, .82-.95) and pesco-vegetarians (.88, .80-.97) each have a 12% lower risk of cancer than other meat-eaters (1).

Breaking the participants into smaller diet groups showed that vegans had a 19% lower risk of cancer:

Pesco – .88 (.80, .97)
Lacto-ovo – .89 (.83, .96)
Vegan – .81 (.66, .98)

I have updated the General Cancer section of the VeganHealth.org article, Cancer, Vegetarianism, and Diet. If you go there, you can see that the findings for vegans were similar to those in the Adventist Health Study-2 (AHS-2), the other ongoing study containing a large number of vegans.

Unlike the findings for vegans and diabetes, the statistical significance of these findings for cancer are not large. I like confidence intervals to be tighter before I get too excited about saying a vegan diet can prevent a disease. However, the consistency between EPIC-Oxford and AHS-2 should provide some assurance.

Some notes on these findings:

– The results above are not adjusted for body mass index (BMI). Adjusting for BMI slightly changed the findings for vegetarians (.90, .93-.96) and for vegans (.82, .68-1.00).

– The previous report from EPIC-Oxford had followed participants through 2005 while this current report followed them through 2010. In the intervening years, cancers increased 50%.

– Diets were assessed at baseline and after 5 years; 88% of the participants remained in their original diet category.

– No single specific cancer type could explain the differences between the diet groups; to date there has been very little consistency found between the various cancers (such as colorectal) and diet group.

Reference

1. Key TJ, Appleby PN, Crowe FL, Bradbury KE, Schmidt JA, Travis RC. Cancer in British vegetarians: updated analyses of 4998 incident cancers in a cohort of 32,491 meat eaters, 8612 fish eaters, 18,298 vegetarians, and 2246 vegans. Am J Clin Nutr. 2014 Jun 4. | link

Odds and Ends

May 31st, 2014 by Jack Norris RD

Nutrition-wise, I have been working on a resource on zinc for the Vegetarian Nutrition Dietetic Practice Group.

The only new info from that research that I had not been considering before is that people who eat a lot of soy and who take calcium supplements might have higher zinc needs. Since I fall into both those categories, I’m wondering if that’s why I seem to benefit so much from zinc. I’m happy to report that I still have not gotten more than the mildest and shortest of colds since starting zinc supplements a number of years ago.

Many links I’ve wanted to share with readers have been building up and so I’m going to knock them all out in one post right here.

Regarding the report suggesting saturated fat intake has no bearing on heart disease (see Saturated Fats in the News), Dr. Rose Marie Robertson of the American Heart Association wrote a response worth sharing: Chief Science Officer ‘sets record straight’ about diet, science, AHA.

Examine.com is a website with a panel of health writers who research a wide array of nutrition supplements and other topics. They appear to do an excellent job of assessing the research. Along with the Linus Pauling Institute at Oregon State University and the Office of Dietary Supplements, I can see Examine.com as being one of my go-to sites for seeing what research is out there.

Speaking of go-to sites, Dr. Michael Greger of NutritionFacts.org has just released Latest in Clinical Nutrition: Volume 19.

On March 10, the Washington Post ran an article (originally appearing in NewScientist) suggesting that many species of invertebrates feel pain: Do lobsters and other invertebrates feel pain? To summarize the article: octopi, squid, lobsters, crabs, and shrimp: yes. Insects: no.

Speaking of invertebrates and pain, there is a movement among some animal protectionists to promote bivalveganism. See The Ethical Case for Eating Oysters and Mussels – Part 2 at Sentientist. The author, Diana Fleischman, argues that bivalveganism can solve many of the nutrition dilemmas posed by vegan diets such as B12, iron, omega-3s, and zinc. It does seem like a decent solution for people who find it hard to thrive on vegan diets.

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Soy and Childlessness

May 15th, 2014 by Jack Norris RD
Summary A cross-sectional study from AHS-2 has found an association between eating more soy and an increased rate of not becoming pregnant or having a child. The study was cross-sectional and had some limitations. It should not be considered proof that soy causes childlessness.

A report from Adventist Health Study-2 was recently released examining the association between soy intake (measured as isoflavones) and childlessness (1).

The authors write:

“The results suggest that when the isoflavone intake exceeds approximately 40 mg per day, the overall lifetime risk of never becoming pregnant increased by 13% and that of ever giving birth to a live child was reduced by approximately 3%. The associations were consistently found to be stronger in women who reported having had difficulties in becoming pregnant (1 straight year or more without success to become pregnant).”

40 mg of isoflavones per day is the equivalent of about 2 servings of soy per day.

There are some reasons not to conclude that soy causes childlessness:

• The author’s stated that, “One major limitation in our study is that we are not able to distinguish with certainty between involuntary and voluntary childlessness.”

• The finding for never becoming pregnant was 1.13 (1.02, 1.26) for women eating 40 mg of isoflavones per day compared to those eating only 10 mg. This is barely statistically significant.

• It was a cross-sectional study with relatively weak findings. Cross-sectional studies can indicate what should be studied prospectively and in clinical trials, but cannot prove causation.

• The researchers did a lot of testing with many different models, the results of which didn’t always agree. The authors stated in their discussion, “[G]iven the somewhat exploratory nature of our analyses and the many statistical tests conducted, we do not believe that [an inconsistency they found] deserves much emphasis at this point.” Indeed – that could apply to their main finding.

Despite the limitations, if someone is having a hard time becoming pregnant, cutting out the soy might be something to try.

The study is linked to in the reference below and is free to the public.

I have updated the VeganHealth.org article, Soy: What’s the Harm?

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References

1. Jacobsen BK, Jaceldo-Siegl K, Knutsen SF, Fan J, Oda K, Fraser GE. Soy isoflavone intake and the likelihood of ever becoming a mother: the Adventist Health Study-2. Int J Womens Health. 2014 Apr 5;6:377-84. doi: 10.2147/IJWH.S57137. eCollection 2014. | link

EPIC-Oxford: Kidney Stone Risk for Vegetarians not Increased

May 4th, 2014 by Jack Norris RD
Summary

A report from EPIC-Oxford did not find a higher risk of kidney stones among vegetarians (which included vegans).

Because many vegetarians and vegans eat a high-oxalate diet, I have been interested to see if a prospective study might find a higher risk of kidney stones.

A recently released report from EPIC-Oxford measured the risk of being hospitalized for a kidney stone over the course of five years for people in various diet groups (1). Vegetarians (including vegans) had a 31% lower risk (.69, .48–0.98) as compared to high meat-eaters.

The other diet groups were:

Moderate meat-eaters, 50–99 g of meat per day – 0.80 (.57–1.11)
Low meat-eaters, < 50 g of meat per day – 0.52 (.35–0.80)
Fish-eaters – .73 (.48–1.11)

Oxalate intake was not measured.

I have updated Oxalate at VeganHealth.org with this info.

The authors also found a correlation between zinc intake and kidney stones. However, this finding barely reached statistical significance and the rate of kidney stones were very low in this population (.6% over five years). Kidney stones were not a common enough side effect in the recent Cochrane Database Analysis of clinical trials on zinc to be mentioned in their report.

Considering all of this, I am not worried that a modest zinc supplement will lead to a kidney stone.

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If you like my posts, please like my posts! Or share them. Thank you!

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References

1. Turney BW, Appleby PN, Reynard JM, Noble JG, Key TJ, Allen NE. Diet and risk of kidney stones in the Oxford cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC). Eur J Epidemiol. 2014 Apr 22. [Epub ahead of print] | link

Medscape Report: Calcium & Vitamin D Decreases Fractures & Cancer

April 28th, 2014 by Jack Norris RD

On April 2, 2014, Medscape sent out a Special Report that included a link to a video and article, Calcium + Vitamin D: Surprises From Long-term Follow-up. You probably need to sign up for a free account to view the article.

Here are some excerpts from the article which was about the Women’s Health Initiative study:

“In this large trial, more than 36,000 postmenopausal women aged 50-79 years were randomly assigned to treatment with a combination of calcium carbonate at a dose of 1000 mg elemental calcium plus vitamin D3 400 IU daily, or placebo.

“We now have 3 lines of evidence of benefit for calcium plus vitamin D supplementation: the reduction in hip fracture seen among adherent women, the reduction in vertebral fracture in the intention-to-treat analyses, and the improvement or better results for bone mineral density…

“In terms of all cancers, among the women who had low baseline intake of vitamin D, there was a statistically significant 9% reduction in total cancer with supplementation, and also a marginally significant 9% reduction in all-cause mortality.”

The report also said that there was no increase in cardiovascular disease for women taking supplements.

Tips for New Vegans

April 26th, 2014 by Jack Norris RD

I have changed the title of the VeganHealth.org article I was Vegan for a While, But… to Tips for New Vegans.

While most of the facts are the same, I have substantially changed the wording to a more friendly tone and included a link to The Plant Plate, Ginny Messina’s vegan food guide pyramid.

I hope people find it useful for informing new vegans about the nutrition issues they should be aware of when going vegan. (Link)

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Clinical Trial of DHA Supplementation in Vegans

April 25th, 2014 by Jack Norris RD
Summary

A 172 mg DHA / 82 mg EPA supplement for 2 months increased levels in vegans to those typical of fish-eaters.

A recently released study measured the omega-3 status of vegans and then placed those with low omega-3 status on an EPA/DHA supplement for two months (1).

The cross-sectional part of the study found that 166 vegans had an average EPA level of .63% (of total fatty acids in red blood cells) and an average DHA level of 2.4%. In comparison to other studies that have measured the percentage of EPA/DHA in meat-eaters in similar ways, those numbers are on the low side, especially for EPA.

The researchers compared a group of the male vegans to a group of male soldiers deployed to Iraq who had very low fish intakes and the vegans had significantly higher levels of EPA and slightly lower levels of DHA.

The researchers then took a group of vegans with low omega-3 levels and gave them a supplement of 172 mg DHA and 82 mg EPA for 2 months. EPA went from about .6% to .8% and DHA increased from about 2.3% to 3.25%.

In other words, this supplementation schedule was adequate for raising EPA/DHA levels to those typical of fish-eaters.

I have updated Omega-3 Fatty Acid Recommendations for Vegetarians with this information.

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If you like my posts, please like my posts! Or share them. Thank you!

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References

1. Sarter B, Kelsey KS, Schwartz TA, Harris WS. Blood docosahexaenoic acid and eicosapentaenoic acid in vegans: Associations with age and gender and effects of an algal-derived omega-3 fatty acid supplement. Clin Nutr. 2014 Mar 14. pii: S0261-5614(14)00076-4. doi: 10.1016/j.clnu.2014.03.003. [Epub ahead of print] | link