The pilot study studied the effects of 25 or 50 milligram doses of Linnea's 7-hydroxymatairesinol (HMR) lignan on the number of hot flushes amongst 20 post-menopausal women, and found that the higher dose led to a reduction from an average of 4.3 hot flushes per day to 2.0 after eight weeks. Moreover, Donald Brown N.D. told NutraIngredients.com at Linnea's booth at last week's SupplySide West trade show in Las Vegas that only one adverse event was documented during the study, with no drop-outs from the study. "Contrast this with a recent study using flax in which half the women complained of side effects with abdominal bloating and gas being the most common," he said. Lignans have a weak oestrogen-like activity and in humans HMR is converted into a mammalian lignan called enterolactone. Epidemiological studies have linked enterolactone to a reduced risk of certain hormone-related health conditions including breast cancer. Benefits have also been reported for cardiovascular health. The randomised, double-blind, single dummy, parallel group, pilot study, led by Jay Udani M.D. from Medicus Research in Northbridge, California, also included a pharmacokinetic study to quantify blood levels of HMR and enterolactone. The results will be submitted for publication in a peer-review journal next year, said Brown. NutraIngredients.com has not seen the full data. For the pharmacokinetic study, 12 women aged 50 to 75 took a 25 milligram dose of the plant lignan HMR. Blood samples were drawn after 30 and 60 minutes, and then every hour for 24 hours, then after 36, 48 and 72 hours. According to a release from Linnea, serum enterolactone levels increased three-fold, peaking after 24 hours. Levels were sustained over 72 hours. For the parallel group study, 20 women were randomised to receive either 25 or 50 mg of HMR ever day for eight weeks. Supplementation with the high dose was associated with a 37 per cent reduction in the incidence of hot flushes after four weeks, and a statistically and clinically significant 53 per cent reduction after eight weeks. The lower dose (25 mg) did not produce statistically significant decreases in hot flush incidence after four weeks. After eight weeks, a statistically but not clinical significant reduction was observed, said Brown. "This pilot study nicely sets the stage for a larger placebo-controlled study," he said. A hot flush, or hot flash in North America, is often described as a flush of intense warmth across much of the body that may be accompanied by sweating, reddening of the skin, or, occasionally, cold shivers. Different lignans are metabolized differently. The main lignan from flaxseed, secoisolariciresinol diglucoside (SDG), is metabolised by microflora in the human gut firstly into enterodiol (END) and then enterolactone (ENL). However, 7-hydroxymatairesinol (HMR), is metabolised to form mostly enterolactone (ENL) and some 7-hydroxyenterolactone (HENL), but no enterodiol. "This is an important distinction," said Robin Ward, vice president for Linnea, "because a large number of studies have shown that high circulating enterolactone levels are associated with lower risks of hormone-mediated cancer such as breast cancer, as well as with cardiovascular health."
A daily supplement of lignan from Norway spruce (picea abies) could reduce the incidence of hot flushes by over 50 per cent, suggests a new clinical trial from the US.