Health & Wellbeing

Rare study on identical twins confirms vegan diet’s broad health boost

Rare study on identical twins confirms vegan diet’s broad health boost
The plant-based diet came out well ahead of a healthy omnivore eating plan
The plant-based diet came out well ahead of a healthy omnivore eating plan
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The plant-based diet came out well ahead of a healthy omnivore eating plan
The plant-based diet came out well ahead of a healthy omnivore eating plan

The fact that eating less meat improves cardiovascular health is not a new revelation, but previous studies supporting this have often been hampered by confounding factors such as genetics, background and lifestyle. Now, scientists have removed many of those variables, with a study on identical twins, pitting a healthy omnivore diet against a healthy vegan one.

Stanford University recruited 22 sets of identical twins who had grown up together, and who reported similar present-day lifestyles, for this eight-week meal-plan-controlled trial, in an effort to provide more robust data to support the existing body of evidence.

“Not only did this study provide a groundbreaking way to assert that a vegan diet is healthier than the conventional omnivore diet, but the twins were also a riot to work with,” said Christopher Gardner, a professor of medicine at Stanford. “They dressed the same, they talked the same and they had a banter between them that you could have only if you spent an inordinate amount of time together.”

Of the sets of twins, with a mean age of 39.6 years, more than three quarters lived with their sibling at the time of the study. And 69% of the participants reported that they were very similar to their twin.

Over the course of eight weeks, twins were randomly selected to either follow a healthy plant-based diet or a healthy omnivorous diet, with a delivery service providing nutritionist-designed meals for the first month. After this stage, the participants prepared their own meals in line with their specific eating directives.

The participants were assessed before, during and after the trial, with bloodwork, weigh-ins, feces testing and more. Those on the vegan diet had the most significant change in low-density lipoprotein cholesterol (LDL-C), dropping from 110.7 mg/dL to 95.5 mg/dL (compared to 118.5 mg/dL to 116.1 mg/dL in the omnivores). Optimal range is below 100 mg/dL.

It's also worth noting that the twins in the study generally already had reasonably healthy LDL levels, with Gardner expecting a more drastic drop for those with poorer baseline measurements.

The vegans also experienced around a 20% drop in fasting insulin and lost an average of 4.2 lb (1.9 kg) more than their meat-eating counterparts.

“Based on these results and thinking about longevity, most of us would benefit from going to a more plant-based diet,” Gardner said.

Both diet plans featured vegetables, legumes and whole grains heavily, while omitting refined sugars and starches. The plant-based regimen, of course, omitted all animal products, including eggs and milk, while the omnivorous plan included fish, chicken, eggs, cheese and dairy.

At the end of the two months, 43 participants had completed the study, which the researchers point out shows how easy it is to learn to prepare healthy dishes, something required of the twins once the 21-meals-a-week deliveries ended after week four.

“Our study used a generalizable diet that is accessible to anyone, because 21 out of the 22 vegans followed through with the diet,” said Gardner. “This suggests that anyone who chooses a vegan diet can improve their long-term health in two months, with the most change seen in the first month.”

Interestingly, and what will be presented in a future study, the twins on the vegan diet also tested younger, giving them a biological age less than their chronological age.

“A vegan diet can confer additional benefits such as increased gut bacteria and the reduction of telomere loss, which slows aging in the body,” Gardner said.

And while the researchers know a study will unlikely make anyone adopt a plant-based diet full-time (one vegan twin remarked that she ate less because she didn't want more whole grains or vegetables), the primary takeaway from this study is how effective cutting back on saturated fats, increasing dietary fiber and losing weight is to improving cardiovascular health.

“What’s more important than going strictly vegan is including more plant-based foods into your diet,” said Gardner, someone who has been “mostly vegan” for 40 years. “Luckily, having fun with vegan multicultural foods like Indian masala, Asian stir-fry and African lentil-based dishes can be a great first step.”

The study was published in JAMA Network.

Source: Stanford University

The reduction is nice, but it's concerning that the meat group started at 118, and the vegan group started at 110. Meaning the meat group was in average less healthy to begin with. Maybe subconscious boas when picking the people to go on the vegan diet.

The insulin change should be monitored.

I remember watching BBC do the same thing with twins, but they had the twins do tasks like cycling, performing mental tasks, even had them fake trading sticks etc. the vegans started to decline in every area, and the Olympic coaches recommended they take sugar when checking their blood after exercising after noticing it was not behaving how they would expect. However in that test the meat group was allowed refined sugar. (It was an attempt to be carb+protein only).

Interesting all the same.
It seems as if almost any edible substance may have benefit in certain circumstances. To me, it appears that the only way through to find the ultimate is real-time monitoring. I am dreaming of an A.I. diagnostic tool fast enough to analyze our bodies and minds while we eat to determine what structures we may be heading towards so we may steer in the direction preferred.
Mike Burns
Omni is typical = SAD Diet.
Why not compare vegan to my carnivore diet, Which cured my Type II, Kidney Disease,
80 LBS. weight loss, and a host of other problems. Super Curious. Saved my life.
The Blue Zones are the five areas of the world where people live the longest and healthiest lives. They have the highest populations of healthy centenarians. Only one of those zones is vegetarian (not vegan). The other four eat limited amounts of meat as well as eggs and cheese. We now know that cholesterol is not an absolute marker of health. It has a large genetic component and affects people differently. This study basically confirms the findings of Ornish as well as Esselstyn that reducing or eliminating animal products in your diet can improve markers of cardiovascular health. However, using a strictly vegan diet may only be necessary for people who are at high risk or already suffering from cardiovascular disease. The Blue Zones demonstrate that a plant-based diet including limited animal products also leads to optimum health and longevity.
Great article Bronwyn - although you didn't really emphasize the issues with the small sample size. @fen clearly took issue with normal variation in similar yet small sample sizes. With are massive sample size, the randomly assigned plant based vs omnivore dietary groups would normalize to the same LDL. For some reason in this study, the randomized plant-based group had lower initial LDL's which fen ascribed to unconscious bias??? I find the line regarding the twin who "remarked that she ate less because she didn't want more whole grains or vegetables." But this twin study again supports a plant based diet better controlling insulin levels. Known that for years!
Hmmm. No bias here.

"Dr Gardner reported receiving funding from Beyond Meat outside the submitted work. Dr J. L. Sonnenburg is a Chan Zuckerberg Biohub investigator."
Did I not read in a fairly recent at article in New Atlas about low LDLs not being so good for your health? Confusingly opposed to the former article?
Losing 4.2 lbs by the vegans might have something to do with the results and show how hard to keep weight on with just veggies. It does seem to have some bias in this.
Steve Barry
It appears the endgame here is longer life. I would much rather live my limited life eating things that I enjoy rather than ekeing out a few more miserable years at the end of my life. Quality over quantity!
Heh, research funded by "Beyond Meat"!
Is this piece a joke?
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