Cardiometabolic Effects of Omnivorous vs. Vegan Diets in Identical Twins
jamanetwork.com
jamanetwork.com
> Fifth, our study was not designed to be isocaloric; thus, changes to LDL-C cannot be separated from weight loss observed in the study.
Only for the first month. And if it didn't satisfy them sufficiently study dropout or cheating would become more likely. They appear to have been allowed to 'cheat' formally, anyway.
: Participants also purchased and consumed snacks to meet their energy requirements following guidance from health educators.
: Although weight loss was not discouraged, our diet design did not include a prescribed energy restriction and was not intended to be a weight loss study. Participants were told to eat until they were satiated throughout the study.
I'm more interested in their exclusion criteria, as this makes their study less generalizable to populations who may need it:
: We excluded participants who weighed 45.36 kg (100 lb) or less, had a body mass index (calculated as weight in kilograms divided by height in meters squared) of 40 or higher, had an LDL-C level of 190 mg/dL or higher (to convert to millimoles per liter, multiply by 0.0259), had a systolic blood pressure of 160 mm Hg or higher or diastolic blood pressure of 90 mm Hg or higher, or were pregnant.
aka half of the entire study duration. As for "satisfaction" it didn't: diet satisfaction was reported lower in the vegan group. But while there may have been cheating, we know that the vegan group was consuming less calories, because they lost more weight. If they had been provided the same number of calories, that would tell us that they were cheating less or something similar. Because they were not though, we have no idea how much of it is due to some advantage of the diet vs. the difference in provided meals. The issue is not that this problem disproves advantages of a vegan diet. The problem is it makes it impossible to know. They have hopelessly confounded with a factor that we know is incredibly important in nutrition related health outcomes.
And the authors know it too:
>Fifth, our study was not designed to be isocaloric; thus, changes to LDL-C cannot be separated from weight loss observed in the study.
I personally think that this one throw away sentence is far too small for what is probably the largest methodological issue in the study.
Again, this problem doesn't disprove anything about vegan diets, it just makes it nearly impossible to learn anything from this study.
They were specifically told to snack as needed.
Given that they were told to eat until satisfied, and report that they were less satisfied, it seems that this study "proves" that the vegan diets used in this study are less satisfying than omnivorous diets, at least on average for a cohort who aren't used to vegan eating.
6-8 ounces per day is less than the average American consumes (average daily American consumes ~12 ounces/day), but I also don't think that you'd call the average American diet a "healthy" omnivore diet. The study diet would come out to 180ish lbs per year, which is more than 3x the global average.
It's certainly more meat than I eat per day.
It seems weird to, when comparing "healthy" diets, to make sure that the two are "different enough" instead of starting from a "this is what we thing a healthy version of this diet is, on it's own".
They aren't quite guaranteeing there will be a difference, but you are pretty close.
This seems a pretty large methodological issue, and at a bare minimum is going to make me disagree with the characterization of "healthy" omnivorous diet that the authors use.
This study has a lot going for it, primarily the fact that it's actually a randomized control study (which is almost unheard of in nutrition). The fact that it's a twin study on top of that is even better. But it's low sample size and short duration (8 weeks), are two pretty big marks against it.
But given their choices in diet, I think that the strongest result that can possible come out of this is "Don't eat more meat than the average European" (5 ounces per day), which is very far from saying that "a Vegan diet is better than a healthy omnivore diet".
If I had a sum up: this is a very good study but the authors take a much stronger position than the design justifies.
-edit- I missed that these diets were not caloricly equivalent. The Vegan diet was lower calorie. That....almost entirely trashes the results and interpretation. It definitely explains the weight loss and likely the cholesterol as well. It is incredibly disappointing to see what was probably a very expensive and rare example of a random controlled trial in nutrition marred by some pretty major problems in the design of the diets.
I think "less than the average American consumes" is a more accurate indication of an omnivorous diet than "3x the global average", because the global average is filled with malnourished populations.
Even when looking at the 5 ounce average for European diets, that's still including a lot of impoverished countries.
A healthy diet, on definition alone, is not going to be found in impoverished countries.
And of course, all of this is ignoring that this study is hopelessly confounded with caloric differences between the two diets.
I believe the median is going to be more like 6-8oz. In other studies I've come across it has been observed that a relatively small percentage of the US population (15%?) has meat consumption that greatly outsizes the typical American, which skews the results. Apparently there is a significant sub-population of Americans that get most of their calories from meat.
The author is a vegan Indian-American cook, and her recipes are delicious and easy for me to follow as a moderately-experienced home cook. The first I tried was her tofu palak paneer (https://rainbowplantlife.com/vegan-palak-paneer-with-tofu/) but pretty much everything I've made has been a hit.
There’s a lot more data that probably will come out of this study but the key to it is that it helps us eliminate genetic factors from many known effects.
I would note that eight weeks is not terribly long for a radical dietary change. Presumably, the baseline consumption for participants was more akin to the omnivore diet. What would the study results look like at 4+ months duration? Would vegans creep back up to their original baseline as their body and habits adapted?
You know how they're trying to grow cultured meat? I think it's pretty neat and all but what I would like to see is a scenario where they grow some chicken oocytes in a lab that then grow eggs. To me that seems like an easier way to get to lab grown animal products than trying to get the taste/texture and appearance of stuff grown in a lab to approximate that the stuff that spends it's life in the body of an animal that is on a farm.
The apex of this kind of invention would be a little biomechanical appliance in your kitchen about the size of atoaster or microwave that you put electricity, water, and protein slurry into and out pop perfect little eggs.
Usually I think of potatoes when thinking about a perfect food.
It looks like the trial was designed to skew the results. The trial becomes comparing a short term dieting plan to a full meal plan. It’s known that short term fasting and calorie restricted meals do improve health overall.
However full vegan I could never do. There might be a few meals that I enjoy, but not enough to keep my will to live through a year.
What you describe probably comes mostly from fat + carbs.
I'm not vegan, but this was the first time I've had vegan food and felt both full and "wow, this was amazing".
That's why the most satisfying vegan food (such as Indian food mentioned by a sibling comment) has lots of coconut milk, ghee, oil, or more recently, avocado.
Though I think there's definitely something about biting into the protein too, which is a big part of what Beyond Meat goes for.
In this randomized clinical trial of the cardiometabolic effects of omnivorous vs vegan diets in identical twins, the healthy vegan diet led to improved cardiometabolic outcomes compared with a healthy omnivorous diet.
Would like to see a couple of the middle ways peppered in (pescetarian, vegetarian).
The real question is what's the difference on longevity and very long-term quality of life
Also weight isn’t even the right metric. Body composition is what we should care about when judging a diet.
https://www.msn.com/en-us/health/wellness/chronobiologist-an... from: https://news.ycombinator.com/item?id=38513782
: One hypothesis has to do with our DNA damage repair systems, which are regulated by the circadian clock. Food contains a mixture of nutrients and toxins. Plants produce toxins to avoid being eaten, such as psoralen, which is abundant in celery. Snacking at night introduces toxins that, at that hour, our repair systems are not ready to eliminate. There is also speculation that the major epidemic of epithelial cancers, such as colon cancer, in the U.S. is because of this.
Basically plants may be good in general, but become problematic to long-term health if, like anything else, eaten close to bedtime.
Edit: For god's sake downvoters, read what I wrote and THINK ABOUT IT before downvoting. I AM A VEGETARIAN, AND LIKE EATING VEGAN. I'm just warning people that VEG EATING LATE AT NIGHT comes with it's own RISK FACTORS. So YES, PLEASE DO CONSIDER A VEGAN DIET, BUT ALSO EAT HEALTHY BY NOT EATING CLOSE TO BEDTIME OR NIGHT SNACKING!!! OTHERWISE YOU MAY INCREASE YOUR CANCER RISK FROM EATING CERTAIN VEGETABLES CLOSE TO BEDTIME!!!!!!