Good news for men who eat soy.

As always soy in your diet is the best way to get it!

http://www.medpagetoday.com/MeetingCoverage/ENDO/46461

CHICAGO — Soy supplements won’t send testosterone levels plummeting in men with type 2 diabetes who already have low levels of the hormone, researchers reported here.

Testosterone levels actually rose with supplementation with either a soy protein bar or a soy protein bar that also contained phytoestrogens, Thozhukat Sathyapalan, MBBS, MD, of Hull York Medical School in England, and colleagues reported at the joint meeting of the Endocrine Society and the International Congress on Endocrinology here.

Some possible benefits in metabolic parameters were also seen with the phytoestrogen-containing soy bars, the group indicated.

“There’s no concern that soy will effect testosterone,” Sathyapalan said. “In fact, it can maybe have a positive effect.”

Some researchers have expressed concerns that the phytoestrogens in soy have estrogen-mimicking effects that may affect testosterone levels — particularly in men who already have low testosterone. These phytoestrogens include genistein and daidzein.

To assess whether these phytoestrogens can impact testosterone levels in men with type 2 diabetes who have borderline low testosterone levels, Sathyapalan and colleagues assessed 210 men with the condition who were between the ages of 55 and 70 and whose testosterone levels were below 12 nmol/L.

They were randomized to a 30-g soy protein cereal bar that either contained phytoestrogens (66 mg) or no phytoestrogens, eating two a day for the three months of the study.

Overall they saw an increase in testosterone levels in both study arms: “We thought there would be a reduction in testosterone levels, but there was an increase in testosterone levels in both groups,” Sathyapalan said at a press briefing.

Mean levels rose from 9.8 to 11.3 nmol/L in the combination group and from 9.2 to 10.3 nmol/L in the soy alone group, his group reported. No changes in estrogen levels were seen in either group.

The researchers also found that those taking the phytoestrogen bar had additional benefits in terms of metabolic parameters and cardiovascular risk.

Specifically, that group showed a significant drop in mean fasting plasma glucose, from 142 mg/dL to 116 mg/dL, compared with a slight uptick from 141 mg/dL to 151 mg/dL in the soy-alone group, as well as a drop in HbA1c not seen with soy alone.

Patients assigned to the phytoestrogen-containing bar also had a significant improvement in insulin sensitivity, with HOMA-IR scores falling from 7.2 to 2.5 compared with a rise from 10.2 to 11.3 for those on soy alone.

The phytoestrogens group also had a decrease in triglycerides, C-reactive protein, and diastolic blood pressure that wasn’t seen in the soy-alone group.

Sathyapalan said the results weren’t surprising given the fact that soy has long been used as a medical food in diabetes. He concluded, however, that further studies are needed to determine the differing effects of soy protein alone and soy protein plus phytoestrogens.

He added that he and his colleagues have also investigated the differences between these two cereal bars in postmenopausal women, finding that both improve bone turnover markers which could have implications for osteoporosis.

Another study, however, showed that soy supplementation may have ties to hypothyroidism; further study is needed to definitively determine if that is the case.