New Netflix show examines how a vegan diet can increase lifespan

A new Netflix documentary has become one of its most-watched shows this week, after it sparked intrigue over an experiment involving sets of twins who went on different diets and their results later compared.

You Are What You Eat: A Twin Experiment is a limited series based on research led by Stanford Medicine. The trial study compared vegan and omnivore diets undertaken by the twins, which researchers said allowed them to overcome factors like genetic differences, upbringing and lifestyle choices, which often hamper diet studies.

The trial, which took place from May to July 2022, consisted of 22 pairs of identical twins, with a total of 44 participants.

Each twin was assigned either a vegan or an omnivore diet. Both diets included healthy foods with no sugars and refined starches, with the vegan diet featuring no meal or animal products and the omnivore diet including chicken, fish, eggs, cheese, dairy, and other animal-sourced foods.

It was led by Christopher Gardner, a professor of medicine and nutrition scientist at Stanford University. In the show, he said the goal of the study was to “show people the power we have at the end of our forks”.

The series also featured other medical experts, including epidemiologist and ZOE co-founder Tim Spector. Speaking about gut health and diet, he said: “Our gut microbes, they produce all the chemicals that keep us alive and make us live longer.

“There are certain microbes that are associated with unhealthy foods, and there are others that are associated with healthy foods, and the ratio of these is really important.

“If we eat healthy foods, we get more and more species, more diversity. You will actually acquire a healthier gut microbiome.”

Does going vegan lead to longer life?

The results of the study were published in November 2023, but is drawing more attention now after the show’s release on Netflix on 2 January.

It found that, overall, twins who were on the vegan diet saw their cholesterol levels, insulin levels, and body weight drop significantly more compared to the omnivore participants.

According to Gardner, the results could be attributed to the vegan participants improving their cardiovascular health by cutting back on saturated fats, increasing dietary fibre and losing weight. He suggested that a vegan diet - or a diet that has a high amount of plant-based foods - could improve health and lead to a longer lifespan.

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

The omnivore participants also saw improvement in their cholesterol levels, insulin levels, and body weight, but the change was less pronounced compared to the vegans. “A vegan diet can confer additional benefits such as increased gut bacteria and the reduction of telomere loss, which slows ageing in the body,” Garner said.

However, Dr Alexis Missick of UK Meds tells Yahoo UK that, while vegan diets have been linked to a lower risk of some cancers, heart disease and obesity, not all vegan diets are nutrient-rich.

“Some vegans may eat more processed and sugary foods, which may not be as beneficial for health. More research is needed to conclude whether a vegan diet may result in greater longevity,” she warns.

She acknowledges that eating a diet high in animal product can increase the risk of developing health issues. “In particular, eating meats which are high in fat, especially saturated fat, can raise cholesterol levels in the blood, increasing your risk of coronary heart disease.”

Should you go completely vegan?

While the Netflix show leans heavily towards encouraging viewers to adopt a vegan diet, Gardner said that it’s far more important to change your diet by adding more plant-based foods than to make a switch to veganism overnight.

He said in a statement: “What’s more important than going strictly vegan is including more plant-based foods into your diet. Luckily, having fun with vegan multicultural foods like Indian masala, Asian stir-fry and African lentil-based dishes can be a great first step.”

Dr Missick adds: “Someone who is reluctant to go completely vegan could make the following changes to their diet to be healthier whilst still eating some animal-based foods:

• Try meat-free Mondays to reduce meat consumption

• When making a meal, use double the amount of vegetables you usually would and half the amount of meat

• Bulk out recipes like bolognese with vegetables or lentils to reduce the amount of mince you use,

• Swap out processed foods in your diet with whole plant foods like nuts, seeds, whole grains and fruits and vegetable

Read more about diet and nutrition:

• Is a vegan diet good for your gut health? Experts weigh in (Yahoo Life UK, 6-min read)

• Expert predicts the 'superfoods' of 2024 that will benefit gut health (Yahoo Life UK, 4-min read)

• How to eat 30 plants a week to boost gut health, according to Tim Spector (Yahoo Life UK, 5-min read)