“Small studies do a poor job of reliably estimating the effects of medical interventions. For a small study [snip] to get published, it needs to show a big effect — no one is interested in a small study that found nothing.”
And:
“It’s still possible that fish oil has a slight beneficial effect, but it’s unlikely.”
Even if fish oil does not reduce all-cause mortality, it does not change my recommendations regarding DHA supplementation in vegans because it’s one thing to say that supplementing with DHA to increase DHA blood levels above average does not improve health, and another to say that there are no problems with having much lower than average DHA levels.
I thought this Wall Street Journal article about the JAMA study on Body Mass Index (BMI), Is Being Overweight Healthy?, was interesting though it didn’t address the reasons why higher BMI might be protective (as discussed in my original post).
“For instance, according to his BMI, one numbers-savvy researcher is overweight—a finding he rejects. “As a 6’3″ swimmer, I find myself falling in the lower part of the overweight category even though my body-fat percentage is very low and no one would say I was overweight,” said David Dunson, a biostatistician at Duke University. He said he knows athletes who lose muscle, not fat, when they fall off their exercise regimen, and then are counterintuitively reclassified from overweight to normal weight.
“It is hard to say how many people are misclassified by BMI. Steven Heymsfield, executive director of the Pennington Biomedical Research Center, an NIH-funded institution in Baton Rouge, La., who co-wrote a commentary accompanying the JAMA study, estimated about 5% to 10% of the U.S. population may be ill-served by BMI.”
“The perspective that is gaining support is one that points away from the scale, and toward healthy habits that are sustainable—that is, habits that not only support health, but that also don’t leave you feeling hungry and deprived.”
I have a plan for 2013 to increase my muscle mass a bit and have started researching some of the vegan fitness sites. One suggestion is to take a branched chain amino acids (BCAA) supplement right before and after workouts. Is there research showing it to be useful? Are there any health drawbacks? Are there any known vegan brands?
Answer:
There are three BCAA: leucine, isoleucine, and valine. They are essential amino acids (the body doesn’t synthesize them on its own), but are found prevalently in plant foods.
In their position paper, Nutrition and Athletic Performance, the American College of Sports Medicine (ACSM) and the Academy of Nutrition and Dietetics (AND) list BCAA in the category of “Ergogenic aids that do not perform as claimed.” (Ergogenic aid means something that increases the ability to exercise.)
Nancy Clark’s Sports Nutrition Guidebook (2003) doesn’t even list BCAA in the index, which is rather surprising given how often I get the question about them (three times in the last few weeks).
Usually, my pat answer is to cite the ACSM position paper and be done with it. But this time I decided to look into it more than I have previously. The only review article I found that promised to be of any value was a 2009 article A Primer On Branched Chain Amino Acids (PDF), by Starkie Sowers, CN, of Huntington College of Health Sciences.
It’s an impressive read, but once you delve into the abstracts of the citations, it loses its luster. My summary of the research I found is that taking BCAA before a workout can prevent fatigue and the metabolizing of muscle protein for energy, but so will eating any old protein or carbohydrate. The one clinical trial cited in Sowers’ review (and the only one I could find) actually found no effect of BCAA above carbohydrate in preventing exercise fatigue (2).
There appears to be very little research done on BCAA since the 90s. Anyone interested in seeing a list of studies can click here for those related to the clinical trial mentioned above.
If after reading the above, anyone still wants to supplement with BCAA, I do not know if there are vegan brands. That is a job for Google. ☺
References
1. Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. J Am Diet Assoc. 2009;109:509-527. | link
2. Davis JM, Welsh RS, De Volve KL, Alderson NA. Effects of branched-chain amino acids and carbohydrate on fatigue during intermittent, high-intensity running. Int J Sports Med. 1999 Jul;20(5):309-14. | link
Regarding your cholesterol article, I was wondering which plants contain cholesterol and how much. I saw some biscuits that contained .4 mg of cholesterol per 100 g of the product. The company claimed all ingredients were plant based, but there was quite a stir in a vegan forum regarding that cholesterol amount. Is there an article you can refer me to.
Answer:
Unbeknownst to most people, the labels on packaged food normally do not represent a laboratory analysis where the various nutrients have been directly measured. Rather, the company takes a list of ingredients and plugs them into a software package which then produces the label based on a combination of all the ingredients and serving size. If one of the ingredients they plug in typically contains cholesterol, then it will contain cholesterol in the result.
As a rule, the USDA nutrient database, which most of these nutrition label generating software applications are based on, just assumes a cholesterol amount of zero for plant foods. Take a look at raw baby carrots at PeaCounter. It lists cholesterol as zero, but it also lists the “data points” as zero. In other words, they didn’t measure it, they just assumed it to be zero.
I don’t know all the ins and outs of the process of producing labels for all foods, and it would seem to me that normally, for biscuits, the company would be plugging in basic nutrients and if they were of plant origin, they would not register any cholesterol on a nutrition label. But in this case, I would guess that the .4 mg of cholesterol shown on this supposedly vegan food was simply a result of inaccurate ingredients plugged into the software. It definitely wasn’t that they included enough plant foods with cholesterol that the cholesterol actually registered in a laboratory analysis.
Here is an article that lists the cholesterol amounts in some plant foods:
Behrman EJ, Gopalan V. Cholesterol and plants. The Journal of Chemical Education. 2005. 82(12):1791. | link to pre-publication PDF
And here are a few of the listings for comparison:
Smith-Lemli-Opitz Syndrome (SMOS) is a genetic mutation that impairs the body’s ability to produce its own cholesterol. This very small group of people (1 in 20,000) would need cholesterol in their diet. Any suggestions on how to answer this? Are there any vegan cholesterol sources?
Answer:
The listing for Smith-Lemli-Opitz Syndrome Treatment & Management at Medscape says, “Currently, no treatment has proven effective for patients with Smith-Lemli-Opitz syndrome (SLOS). Potentially, cholesterol supplementation is a logical treatment because it may be expected to raise plasma and tissue cholesterol levels…. Therapeutic trials are underway.”
Someone with SMOS should be under the care of a physician who is probably instructing them (or their parents) as to whether they need cholesterol supplementation and how much they need in their diet.
I am not aware of any vegan sources of cholesterol with which someone could supplement. My understanding is that some plants contain cholesterol, but only in miniscule amounts. For committed vegans, obtaining eggs from someone with companion chickens would be a way to get cholesterol in the diet while causing minimal or no harm to animals. Oysters, clams, or mussels might be another option.
In my work, I come across people all the time who claim they would like to be vegan but because of food allergies, food sensitivities or a certain medical condition (like multiple sclerosis), they need to consume animal products for optimal health. What is the best way to respond to such claims?
Answer:
There are plenty of people with food allergies or sensitivities that are vegan, so it might be beneficial to let such people know that there may be many others like them but who have succeeded at being vegan.
I would find out more about their condition and find out what they think meat is providing for them, and then suggest plant food alternatives to provide the same nutrients. With many medical conditions, people just think they need protein, which should be easy to solve.
Here are some articles on food allergies and being vegan that might help you:
If you know of someone with a specific condition who is saying this and you can find out more about it, feel free to email me and I’ll see if I can add anything of value.
I am always happy to try to help any people my readers might come across who want to be vegan but think they have a condition that prevents it. But, I ask that the people with the condition write me ̵ I won’t initiate contact with the person with the condition as that can be awkward. 🙂
You might have heard about the meta-analysis released January 2 in the Journal of the American Medical Association, Association of All-Cause Mortality with Overweight and Obesity (1), which found that “overweight” people, based on body mass index (BMI) had a lower risk of mortality than what is considered a healthy BMI.
Before I had a chance to read the study myself, I came across a USA Today article, Experts weigh in on the dangers of extra pounds, quoting the well-respected nutritionist, Dr. Walter Willett from Harvard School of Public Health, about the JAMA study:
“The most serious problem in the paper is that the normal-weight group included a mix of lean and active people, heavy smokers, patients with cancer (and) other conditions that cause weight loss, and frail elderly people who had lost weight due to rapidly declining health. Because the overweight and obese groups were compared to this mix of healthy and ill persons who have a very high risk of death, this led to the false conclusions that being overweight is beneficial and that grade 1 (moderate) obesity carries no extra risk. The new statistics are completely misleading for anyone interested in knowing about their optimal weight. … The paper is a pile of rubbish.”
Yikes! That’s quite a rip on the JAMA study’s authors. Not only that, but why would a research group put so much effort into a meta-analysis but fail to adjust for some of these obvious confounders, and why would JAMA publish it?! But Willett’s criticisms would explain how they could have reached such a counter-intuitive finding and all would still be good in the nutrition universe.
I read the study fully intending to find the criticisms by Dr. Willett to be valid. Alas, I did not. From my reading of the paper, they did adjust for smoking and age, and analyzed the study for any bias due to “frail elderly people.” They did some testing to make sure previous heart disease and cancer were not affecting the results.
The control groups for the studies in the meta-analyses were typically people with a BMI of from 18.5 to < 25 or from 20 to < 25. The study found that people with a BMI of 25 to < 30 had a statistically significant 8% reduced risk of mortality (.92, .88-.96). People with a BMI of 30 to < 35 had essentially the same risk of mortality. It wasn’t until you got to the group of people with a BMI of 35 or greater that risk of mortality significantly increased.
So, what could be going on here? Well, a BMI of 18.5 to 20 has often been considered to be unhealthfully thin, but from what I gleaned from the paper’s discussion, excluding such people did not appreciably affect the results.
BMI doesn’t account for muscle mass, as Willett alludes to above, but it is hard to believe that there were enough muscle-bound people in the meta-analysis to confound the results to any significant degree.
Willett went on to say in the interview:
“In the last several years, two other major analyses, involving the collaborative efforts of more than 150 scientists, have been conducted on the relation of body weight to mortality…these studies showed clearly that both overweight and all grades of obesity are associated with increased mortality.”
In contrast, the JAMA authors mention that their results are consistent with two previous meta-analyses. And they give some reasons why being overweight might be associated with lower risk of mortality:
“Possible explanations have included earlier presentation of heavier patients, greater likelihood of receiving optimal medical treatment, cardioprotective metabolic effects of increased body fat, and benefits of higher metabolic reserves.”
Occam’s razor would dictate that the best explanation is simply that it’s healthier to be “overweight,” and I don’t like doing backwards somersaults to wish away findings that, had they gone the intuitive way, would be unquestioned as solid. That said, given the prevalence of type 2 diabetes and the fact that vegans have been shown to have a much lower rate of type 2 diabetes and much lower average BMIs, I’m not going to try to gain weight. But it’s a little demoralizing to have one of the most basic ideas in nutrition ̵ that being overweight is not better than being a normal weight ̵ significantly questioned.
In conclusion: Rubbish? Not from what I can tell. Food for thought? Yes. As is often the case, this isn’t the last word.
Reference
Flegal KM, Kit BK, Orpana H, Graubard BI. Association of all-cause mortality
with overweight and obesity using standard body mass index categories: a
systematic review and meta-analysis. JAMA. 2013 Jan 2;309(1):71-82. | link
This was different than my typical interview as the host, Erin Sullivan, asked a lot of interesting questions that I don’t normally get, but that I think many vegans are wondering about. We weren’t able to cover everything, so there will be a Part 2.
2. Please share this blog!
I was talking to a vegan advocate and supporter of this blog and we were trying to figure out how to get the information about staying healthy out to more vegans. The best thing we came up with is just for vegans who know about it, to share it with others. I know that some people might be hesitant to share my information because it can make a vegan diet seem hard, but here is an example of where it has paid off which I received just today:
“I directly credit my final willingness to make that leap [to becoming vegan] to your nutritional research presentation, especially as veganism applies to athletes. That information, presented so honestly, specifically, and with no misleading window-dressing or skewing of facts, is what gave me the confidence to try it out and we are thriving!”
It is important that vegans make sure they get enough calcium, vitamin B12, and iodine so that down the road, they don’t have an irreversible health problem. This doesn’t only help them, but it will prevent them from going on to tell everyone how unhealthy a vegan diet made them. In addition to sharing this blog, sharing the nutrition recommendations for vegans at VeganHealth.org can also help vegans who might otherwise have no idea about such things.
Two days later, after a reader brought it to my attention, I posted a Follow-Up, pointing out that the authors had not included physical activity as a variable in their multivariable adjustment model. For a number of reasons, I suspected that if they had adjusted for physical activity, the finding that vegans have lower cancer rates would no longer be statistically significant.
I have since corresponded with one of the authors of the paper, Yessenia Tantamango, who told me that when they included physical activity in the multivariable analysis (in the model that did not include BMI), vegans had a cancer rate of .85 (.73-.99) which is statistically significant.
The original finding for the vegan cancer rate was .84 (.72-.99). An upper confidence interval limit of .99 is only of borderline significance; if it were 1.00 it would not be considered significant. In other words, I realize we are splitting hairs here. But I wanted to follow-up to let readers know that after adjusting for physical activity the finding was still statistically significant and so, by conventional nutrition science standards, it is legitimate to say that vegans had a lower rate of cancer in this study and there is reason to think it was due to their diet.
Reference
Tantamango-Bartley Y, Jaceldo-Siegl K, Fan J, Fraser G. Vegetarian diets and the incidence of cancer in a low-risk population. Cancer Epidemiol Biomarkers Prev. 2012 Nov 20. | link
