Soy Isoflavones

The shape comes from observational data, so it maps an association rather than a demonstrated causal curve. Nonlinearity cleared significance for recurrence only; for breast-cancer death and death from any cause it did not, and most of the reduction there sat between 20 and 40 mg a day.

Diet was self-reported, and soy eaters may differ from others in weight, diet quality and health behaviour that no adjustment removes. Only recurrence reached significance; both death-rate estimates crossed the line of no effect. Diagnoses ran from 1991 to 2006.

The tamoxifen-user estimate, unlike the non-user one, still includes no effect within its range of uncertainty, so the near-identity is between point estimates rather than between two equally firm results. Every study pooled is observational, with self-reported diet.

Forty-six of the 62 trials, three-quarters of them, carried a high risk of bias in three or more quality domains. Against a typical starting point of several flushes a day, four-fifths of one is a real change and a small one. The night-sweats interval is wide enough to rule out almost nothing.

The trials were too dissimilar to combine, so the review's only pooled estimate is of red clover, a different plant. Four trials of extracts delivering more than 30 mg of genistein a day did consistently reduce flushes, so the negative verdict is not uniform across preparations.

The largest of those changes is 7 mg/dL, under 5 percent of a typical level. Reductions were bigger in people who started with high cholesterol, so anyone starting from normal should expect less. Only 11 trials, none of them published after 2006.

The rise in thyroid stimulating hormone only just cleared significance, its interval reaching down to 0.001. The pooled trials disagreed sharply with one another. Everyone studied was thyroid-healthy and presumed iodine-replete, so the worry that soy matters more when iodine is scarce goes untested.

Twenty-five percent of twelve people is three people, so the familiar claim that a quarter to a third of Westerners are producers is consistent with this study rather than established by it. Its lasting contribution is the test, not the prevalence, and the work was done at a company that sells soy.

This is a professional body's clinical report rather than primary data, and it is nearly two decades old. Its published abstract states that it reviews potential harms without saying what it concluded about them, so nothing about safety can be read off it. The market figure is United States only.

Only 190 of the 600 enrolled were still taking part at fourteen, and children who leave a study rarely do so at random. Families chose the feeding method, so whatever tracks with that choice tracks with these results. Heart-rate and autonomic differences between groups are reported and unexplained.

Twelve of the 18 studies are case-control, a design in which people recall their past diet after already knowing their diagnosis. The literature stops in 2004. Eight studies gave no menopause-specific result, and six of those did not support an association at all.

Most outcomes are synthesised narratively rather than pooled, so there are few numbers behind the verdict. The reassurance covers soy as food, not concentrated extracts, which is the distinction the 100 mg line marks. It was conducted at a naturopathic college, which has an interest in the answer.

Every included study is observational with self-reported intake, so soy eaters may simply differ from other patients. The authors describe their own overall-survival finding as limited evidence and confine it to postmenopausal patients. The search stops in January 2018.

Bone turnover chemistry is a surrogate: it is neither bone density nor fracture. The temptation is to lead with pyridinoline at 12 percent lower, and its interval runs from 25 percent lower to 1 percent higher. Doses across the pooled trials ranged nearly tenfold, from 30.9 to 300 mg a day.

The measurements are from 1999, and brands, formulations and processing have all changed since, so treat them as an order of magnitude rather than as current values. Composite samples were used, which averages out the brand-to-brand and batch-to-batch variation a shopper actually meets.

No pooled effect size was reported for these five trials, so the size of the null cannot be stated. The wider review they sit inside is a narrative synthesis rather than a meta-analysis for most of its outcomes. It was conducted at a naturopathic college, which has an interest in the answer.

Heterogeneity is high, 67 percent for frequency and 86 percent for severity, so the pooled figures sit on trials that contradict one another. The results are percentages, not flushes per day, which flatters a small absolute change. A co-author directs the industry-funded Soy Nutrition Institute.

Whether soy pills ease hot flushes is unsettled because the reviews disagree first about whether trials this varied can be combined at all, and only then about the answer. That is why more studies have not settled it.

Two of the five authors have soy-industry ties, one directing an institute funded by the United Soybean Board, and the same group produced the earlier analysis this one updates. Dihydrotestosterone was left out of the pooled outcomes, and it is the one androgen a soy effect has been reported for.

Soy's clean record on male hormones leaves out dihydrotestosterone, the one androgen a crossover trial saw fall by 9 to 15 percent. Both can be true because they measured different things; nobody has pooled the hormone that moved.

This states what these two studies were built to measure, not that no such comparison exists anywhere in the wider literature. Both are small: 160 women in the trial, and 41 in the producer-status study, of whom 12 were non-vegetarians.

The label states the interaction without citing the studies behind it or saying how much absorption is lost. It is one manufacturer's label for one brand, and generic levothyroxine carries its own separate labelling. A drug label is a regulatory summary rather than a study.

The label names soybean flour and soy formula but gives no figure for how much absorption they cost and cites no study, so it cannot say how much a soy meal matters to the dose.

The abstract gives p values and directions but no effect sizes, so how much bone was saved cannot be stated. Whole-body density is the weakest endpoint measured, and the sites where people actually fracture were null. The 80 mg arm showed nothing, so two doses do not make a dose-response.

Thirty-five men at one centre, all young and healthy, so nothing here reaches older men or any clinical outcome. Other hormones moved in inconsistent directions across timepoints, which is what measuring several hormones at three timepoints tends to produce.

This one trial shows dihydrotestosterone falling in 35 young men on soy, with or without isoflavones. It cannot show the fall holds across trials or matters for health; that needs the hormone pooled, which nobody has done.

The remit was peri- and postmenopausal women taking isolated isoflavone supplements, so it says nothing about men, children, premenopausal women or soy as a food. The opinion is ten years old.

The lead author directs the Soy Nutrition Institute, funded by the United Soybean Board and its member companies; that is the largest declared conflict in this evidence base and it points toward the review's conclusion. Its verdicts are narrative judgments, not pooled effect estimates.

Twelve women, a single dose, no blinding, and the trial was funded and run by the company that makes the supplement tested. One dose cannot detect anything that builds up over weeks of taking the two together. Everyone enrolled was healthy and stably treated, not newly diagnosed.

A single isoflavone supplement dose left levothyroxine absorption untouched, yet the drug's label warns against soybean flour and soy formula. What separates the two is the form of soy, protein against isolated isoflavones.

A position statement inherits whatever its panel weighted, and produces no new estimates of its own. The recommendation covers hot flushes and night sweats only, and says nothing about soy for bone, cholesterol or cancer outcomes.

A menopause society declining to recommend soy is not the same as soy failing: its Level II grade means the evidence is limited or inconsistent. The listing cannot say whether soy eases hot flushes, only that the panel would not back it.