Source / Discoveries

Findings: The authors do not report relevant financial disclosures.


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Improvements in fatty acid metabolism occurred for women who switched from their usual omnivore diet to a vegetarian diet, according to a study published in Nutrition, Metabolism & Cardiovascular Diseases.

European American and African-American women switching to a vegetarian diet exhibited significant changes in metabolites and metabolites of saturated, unsaturated, and unsaturated fatty acids. However, the changes in plasma concentrations of acyclarnitines, which reflect the completeness of fatty acid oxidation, varied by racial group.

Silver is a research professor of medicine and director of the Vanderbilt diet, body composition and human metabolism at Vanderbilt University Medical Center.

The metabolic response to switching from a predominantly animal-based diet to a predominantly plant-based diet may improve the ability of dietary fat to be oxidized and used as an energy source rather than being stored and contribute to excess body fat. , ” Heidi J. Silver, PhDRD, research professor of medicine and director of the Vanderbilt Diet, Body Composition and Nucleus of Human Metabolism at Vanderbilt University Medical Center, told Healio. “However, the individual metabolic response to a dietary intervention of any kind varies, and here we see a change in the response of fatty acid metabolism by race / ethnicity. Therefore, there is no one-size-fits-all diet. ”

Silver and colleagues conducted an upcoming group study of 20 European American and 18 African-American women in the Nashville, Tennessee area. Participants were aged 18 to 40 years and had a BMI with a normal weight between 18.5 kg / m2 and 24.9 kg / m2With Study was created to assess the acute effects of the new vegetarian diet. European-American and African-American participants were compared by age, BMI, level of physical activity, and energy demand. Each woman served as her control to compare the results of pre-intervention and post-intervention. One group of women enrolled from October 2017 to February 2018 and the second group from November 2018 to February 2019. After a basic test visit on the first day, participants switched to a vegetarian menu without meat, fish, poultry, eggs or products of milk from days 2 to 5. A final testing visit was performed on day 6. Anthropometric measures, blood and urine samples were collected for all 6 days of the study.

No change in energy intake

Participants had no difference in energy intake or body weight with the vegetarian diet. The percentage of energy from carbohydrates increased by about 10%, with no difference between European American women and African-American women. There was no change in the percentage of energy from total fat intake, but the intake of saturated fatty acids decreased by about 50% in both groups, and the ratio of saturated fat intake to unsaturated fat decreased 50% in both groups (P <.001 for both).

Participants had a high regulation of many fatty acids, including a 25% to 30% increase in multiple long-chain unsaturated fatty acids and long-chain unsaturated fatty acids. There was also a 25% to 30% difference in plasma concentrations of long-chain saturated fatty acids. The changes occurred simultaneously with a 42% decrease in the ratio of stearic acid to oleic acid (18: 0/18: 1) and a decrease of 27% in the ratio of palmitic acid to palmitoleic acid (16: 0/16: 1).

Fatty acid metabolite changes vary by race

Increases in circulating concentrations of conjugated metabolites of carnitine metabolism fatty acid have been observed. Changes in nonanoylcarnitine, hexanoylcarnitine, laurylcarnitine, decanoylcarnitine, and 5-dodecenoylcarnitine concentrations varied by race. There was a tendency towards a significant diet by racial interactions for seven other fatty acid metabolites.

“The optimal diet for each individual should be personalized, taking into account not only that individual’s demographics, but also an individual’s specific metabolic needs and an individual’s specific metabolic health problems,” Silver said. “Furthermore, the optimal diet for each individual depends on how that individual responds to the diet in relation to factors that may increase or decrease the risk for chronic diseases such as type 2 diabetes and cardiovascular disease.”

The researchers also noted changes in circulating metabolite levels that may result from changes in the intestinal microbiome, including low regulation of the aromatic amino acid metabolites phenylalanine, tyrosine, and tryptophan. There were also changes in plasma and urine in intestinal fermentation products involved in aromatic amino acid metabolism. The plasma concentration of trimethylamine N-oxide was reduced by 33% with the vegetarian diet. There was a 1.2-fold increase in circulating oleoil ethanolamide and a 1.4-fold increase in circulating N-oleoil taurine. Other changes in the microbiome metabolite were observed in urine samples.

Silver said more randomized controlled trials are needed to investigate the long-term cardiometabolic effects of vegetarian and vegan diets, especially in obese adults and those trying to lose weight or maintain weight loss.

For more information:

Heidi J. Silver, PhD, RD, can be reached at heidi.j.silver@vumc.org.