If you are remotely interested in nutrition, you have likely heard of at least one of the big nutrition documentaries available for streaming: Supersize Me, The Magic Pill, Forks Over Knives, and The Game Changers, just to name a few.
Recently, a new documentary series was added to the list: “You Are What You Eat: A Twin Experiment.” Briefly, the documentary follows a Stanford study, in which the researchers tested whether twins eating a vegan or omnivorous diet had different health outcomes. And not surprisingly, the media is all over this documentary! Half of the media claims that the new documentary proves that a vegan diet is the healthiest for all humans. The other half claims that the documentary is biased, flawed, and full of propaganda!
As for everyone watching the media headlines? We’re just as confused as ever.
To save you the time of watching the entire documentary series, I read the scientific article that the series is based on. Here is everything you need to know.
The WHY
Chronic diseases (think: heart disease) are incredibly common in the United States. “Plant-based” diets, including 100% vegan diets, have potential health and environmental benefits. In general, vegans tend to eat more fiber, phytonutrients, and certain vitamins and minerals than non-vegans. However, they tend to lack other vitamins and minerals (think: B12 and iron). In large population studies, vegans tend to have better health outcomes than non-vegans.
However, critics say that (1) not all vegans eat a healthy diet, and (2) a vegan diet might not actually be better than a healthy diet that includes animal products! So, should you really adopt a restrictive 100% plant-based diet? Or, could you just eat a healthier omnivorous (AKA: eating all foods) diet for the same health benefits?
The scientists sought to answer this question.
The HOW
Scientists recruited 22 sets of twins (44 people). The twins had to be reasonably healthy to participate in the trial, with LDL (“bad”) cholesterol “borderline high” at most. In each set of twins, one was assigned to the “healthy vegan” group, and the other was assigned to the “healthy omnivore” group.
For the first 4 weeks, all twins got healthy vegan or omnivorous meals delivered to their homes. For the following 4 weeks (or, weeks 5-8), they were instructed to purchase their own vegan or omnivorous food. They had health professionals available to help them create an eating plan that meet the criteria for their given group.
The scientists took several measures before the study started, at 4 weeks, and when the study ended at 8 weeks.
The RESULTS
Twins eating a vegan diet had a much greater decrease in LDL (“bad”) cholesterol than those eating the omnivorous diet. They also had lower fasting insulin and body weight at the end of the trial, even though weight loss wasn’t the “point” of the study. However, the difference in weight loss between groups was fairly minimal at only about 5lbs. There was no difference in other study outcomes, including HDL (“good”) cholesterol, vitamin B12, TMAO, glucose, and triglycerides.
In other words, the vegans faired better when it comes to some health outcomes, especially LDL-C! The omnivores and vegans had similar improvements in other important health outcomes.
The LIMITATIONS
First of all, this is only one study! To make health recommendations, clinicians need to consider all available evidence. This single study is important but should also be placed in context with other available research.
Next, the sample of twins is not necessarily generalizable to all people! These twins were relatively healthy, white, and had high incomes—which is super important given the high cost of certain healthy foods! Furthermore, we can’t say whether the vegan diet would be preferable in less healthy people, including those with very high cholesterol.
Third, people on the vegan diet had lower enjoyment of their food than those on the omnivorous diet. While the researchers did not assess this, it is possible that one or both groups would not sustain the dietary changes long term due to lack of enjoyment.
And lastly, the study funders and documentary producers are known to promote a vegan diet. So, the study results may be framed with a more pro-vegan slant than they would be with other funders and producers.
The CONCLUSION- Should you switch to a vegan diet after all?!
As with nearly everything in nutrition... it depends.
This study provides rationale that a vegan diet can be a fantastic, healthy choice! Following a well-planned vegan diet could likely improve your heart health, which is so important. However, as the authors acknowledge, vegan diets should be carefully planned so that you do not develop nutrient deficiencies.
Moreover, while the study shows that a vegan diet could be the best for lowering LDL-C, the omnivorous diet led to important health outcomes as well! For example, people in both groups improved their BMI and HDL cholesterol. So, even the well-planned omnivorous diet was health-promoting.
Perhaps most importantly, eating a 100% vegan diet is hard, and many people find it overly restrictive. And if you want to maintain a healthy diet in the long run, you MUST enjoy what you are eating! To that end, the authors recommend that future research assess a gradient of plant-based diets, including vegetarian diets, flexitarian diets, and other primarily plant-based diets. In all likelihood, people will get more health benefits as they eat more plants, even if they are technically omnivores.
So, what should you do?
Again… it depends on your unique needs, preferences, and circumstances.
Do you want to be vegan for ethical, environmental, or health-related reasons? Do it!
Do you want to continue to eat animal products, but incorporate more plant-based foods? Love it!
Do you want to find a healthy way of eating that is personalized to YOU, your life, and your unique needs? We are here to help.
Not sure what to eat, vegan or otherwise? Request a session with our registered dietitian online, call (833) 516-0454, or email info@LWell.com!
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