Soy, also known as soya, is a bean that comes from the soy plant, which grows in Asia. Soybeans are a popular food, often added to soups and salads. Soy protein is used in tofu, soy milk and an array of dairy and meat substitutes. It is also added to foods commonly consumed in Asia, including tempeh – a type of cake – and miso.
Past research has hailed the health benefits of soy. A 2011 study reported by Medical News Today, for example, claimed a soy-rich diet could protect against prostate cancer.
In this latest study, published in the journal Menopause, researchers at the Wake Forest School of Medicine in Winston-Salem, NC, wanted to see whether a soy-rich diet could protect against atherosclerosis – a risk factor for heart disease whereby the arteries become blocked by fatty substances (plaques), restricting blood flow.
Study ‘stresses importance of getting into good cardiovascular shape before menopause’
To reach their findings, the team fed premenopausal monkeys with either a diet high in animal protein, or a diet rich in protein from high-isoflavone soybeans.
The team then induced menopause in the monkeys by removing their ovaries, before assigning the animals to one of four groups. Two groups carried on eating either a soy-rich or an animal protein-rich diet, while another two groups swapped to diets opposite to what they were following before menopause.
At the end of the 34-month follow-up, the researchers found that the monkeys that ate the soy-rich diet before and after menopause had good cholesterol levels, while cholesterol levels significantly improved for those that swapped to a soy-rich diet after menopause.
The team found, however, that when it came to monitoring plaque progression in the monkeys, no statistically significant differences were found between any of the groups.
But they note that monkeys that ate a lifelong diet rich in soy had much lower levels of complicated plaque in their arteries, compared with the other groups. Furthermore, the monkeys that had small plaques in their arteries prior to moving to the soy-rich diet after menopause demonstrated reduce plaque progression.
Overall, the researchers say their findings indicate that following a soy-rich diet prior to or very early after menopause could benefit heart health.