A registered dietitian, or “diet whisperer,” according to Gardner, was on call to offer suggestions and answer questions regarding the diets during the duration of the study. The participants were interviewed about their dietary intake and kept a log of the food they ate.
Forty-three participants completed the study which, Gardner said, demonstrates how feasible it is to learn how to a prepare a healthy diet in four weeks.
“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, who is a professor in the Stanford Prevention Research Center. “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.”
Improving health
The authors found the most improvement over the first four weeks of the diet change. The participants with a vegan diet had significantly lower low-density lipoprotein cholesterol (LDL-C) levels, insulin and body weight — all of which are associated with improved cardiovascular health — than the omnivore participants.
At three time points — at the beginning of the trial, at four weeks and at eight weeks — researchers weighed the participants and drew their blood. The average baseline LDL-C level for the vegans was 110.7 mg/dL and 118.5 mg/dL for the omnivore participants; it dropped to 95.5 for vegans and 116.1 for omnivores at the end of the study. The optimal healthy LDL-C level is less than 100.
Because the participants already had healthy LDL-C levels, there was less room for improvement, Gardner said, speculating that participants who had higher baseline levels would show greater change.
The vegan participants also showed about a 20% drop in fasting insulin — higher insulin level is a risk factor for developing diabetes. The vegans also lost an average of 4.2 more pounds than the omnivores.
“Based on these results and thinking about longevity, most of us would benefit from going to a more plant-based diet,” Gardner said.
The vegan participants (and the omnivores to some extent) did the three most important things to improve cardiovascular health, according to Gardner: They cut back on saturated fats, increased dietary fiber and lost weight.
A global flair
Gardner emphasizes that although most people will probably not go vegan, a nudge in the plant-based direction could improve health. “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.
“What’s more important than going strictly vegan is including more plant-based foods into your diet,” said Gardner, who has been “mostly vegan” for the last 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.”
Gardner is a member of the Stanford Cardiovascular Institute, the Wu Tsai Human Performance Alliance, the Maternal and Child Health Research Institute, and the Stanford Cancer Institute.
The study was funded by the Vogt Foundation; the Stanford Clinical and Translational Science Award; and the National Heart, Lung and Blood Institute.
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