BACKGROUND: Oyster mushrooms (Pleurotus ostreatus, PO) are rich in β-glucans and other ingredients with cholesterol-lowering potential. While human intervention studies suggest that PO intake may reduce total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and triglycerides, current evidence remains limited due to methodological limitations of the studies. Thus, this study investigated whether regular intake of PO powder affects LDL-C concentrations in adults with moderately elevated LDL-C (primary aim). Moreover, the study explored the effect on other lipids (TC, high-density lipoprotein cholesterol, triglycerides), on apolipoproteins A1 and B and possible underlying mechanisms of action (secondary aims). METHODS: In a double-blind, randomized controlled trial, 46 adults (37 female, 9 male) with moderately elevated LDL-C (116-190 mg/dL) consumed a beverage containing 8.4 g PO powder providing 3 g of β-glucans or a beverage without PO daily over 4 weeks. Plasma concentrations of LDL-C, other lipids and apolipoproteins were measured before and after intervention. The concentrations of noncholesterol sterols in serum, normalized to cholesterol, were determined as validated surrogate markers for cholesterol absorption (sitosterol, campesterol, and 5α-cholestanol), cholesterol synthesis (lathosterol), and bile-acid synthesis (7α-hydroxycholesterol), along with ergosterol, a fungal-specific sterol. Expression of selected target genes involved in cholesterol metabolism was analyzed in blood. Statistical analysis included comparisons of the changes between the groups (treatment effect) and linear modeling. RESULTS: PO treatment did not modulate LDL-C; no treatment effect was observed for other lipids, apolipoproteins or gene expression (P ≥ 0.05 for all). However, after adjustment for sex, linear model analysis showed a reduction in markers of cholesterol absorption, especially in females (P < 0.05 for all). No effects were observed on markers of cholesterol and bile-acid synthesis (P ≥ 0.05 for all). Ergosterol was detectable in all serum samples after PO intake, confirming high compliance with PO treatment. CONCLUSIONS: Daily consumption of 8.4 g of PO powder over 4 weeks has no impact on LDL-C concentrations in adults with moderately elevated LDL-C concentrations. However, post-hoc analysis indicates a sex-dependent reduction in cholesterol absorption by PO consumption, especially in females, suggesting that PO may have the potential to beneficially modulate cholesterol metabolism. TRIAL REGISTRATION: Registration at German Clinical Trials Register; DRKS-ID: DRKS00033943; registration date: 21/03/2024. https://drks.de/search/de/trial/DRKS00033943.
Johnen et al. (Sun,) studied this question.