These are potent phytochemicals found in a variety of botanical sources. There are a number of different sterols and these include the principal phytosterol, which is known as sitosterol.
In addition to sitosterol the most common sterols include campesterol, sitostanol and stigmasterol. The glucoside of sitosterol is known as sitosterolin and in plants it is always found together with the sterol. The ratio of sterol to sterolin varies in the plant kingdom ranging from 5% to 10% but in some cases being higher as in the case of potatoes.
Sterols are essential cell membrane components and the maintenance of adequate serum levels in humans seems to be necessary for an efficient immune system. Seeds are the richest source of the sterols and sterolins and yet, the refining processes applied by the food industry render the staple foods useless because they remove the sterols and sterolins to make the product more appealing to the eye.
For instance, in order to prevent precipitation of the fats in so-called "cold pressed oils," the oil is heated and refined to remove the sterols / sterolins. Sterols and sterolins have been shown to modulate the functions of the T-Cells both in vitro and in vivo by enhancing their cellular division.
Recent research conducted by Professor Patrick Bouic and his research team at the University of Stellenbosch Medical Faculty and published in the International Journal of Immunopharmacology, is providing an entirely new medical approach to the treatment of auto-immune diseases and other chronic diseases which only manifest themselves when the afflicted individuals are at cause. International medical and scientific interest on this breakthrough has been overwhelming.
Sitosterol assists in the conversion of linoleic acid to polyunsaturated fatty acids. This process is essential for the conversion of the Omega 6 fatty acids to prostaglandins and leukotrienes. Prostaglandins and leukotrienes are hormone like substances which are involved in immune support; they assist in the reduction of thrombo-embolic disorders by reducing platelet aggregation and they also assist in the reduction of inflammatory metabolites.
Sitosterol can be metabolized to pregnenolone and therefore to DHEA and the other hormones derived from pregnenolone and its analogues. In the human body there is a steady decline with age in the production of DHEA, which is the master hormone responsible for the synthesis of oestrogen, progesterone, testosterone, cortisol and others.
By the age of 70 the DHEA production can be down to 10% or 20% of the levels found in a twenty year old, thus sitosterol supplements have an enormous potential for supporting the endocrine system in elderly people and, by implication, increasing their longevity.
Research abstract on BetaSitosterol
Title: beta-sitosterol for the treatment of benign prostatic hyperplasia: a systematic review.
Wilt TJ ; MacDonald R ; Ishani A
The VA Coordinating Center of the Cochrane Collaborative Review Group in Prostatic Diseases and Urologic Malignancies, 13/Minneapolis, VA, USA.
BJU Int, 83(9):976-83 1999 Jun
OBJECTIVES: To conduct a systematic review of the evidence for the efficacy of beta-sitosterol in men with symptomatic benign prostatic hyperplasia (BPH). METHODS: Studies were identified through Medlinetrade mark (1966-98), EMBASEtrade mark, Phytodok, the Cochrane Library, bibliographies of identified trials and review articles, and contact with study authors and pharmaceutical companies. Randomized trials were included if: men had symptomatic BPH; plant extract preparations contained beta-sitosterols; a control group received placebo or a pharmacological therapy; and treatment duration was >/=30 days. Study characteristics, demographic information, enrolment criteria and outcomes were extracted. RESULTS: Four trials comprising a total of 519 men met the inclusion criteria. All were double-blind and lasted 4-26 weeks. Three studies used nonglucosidic beta-sitosterols and one used a preparation that contained only beta-sitosterol-beta-d-glucoside. Compared with placebo, beta-sitosterol improved urinary symptom scores and flow measures. For the two studies reporting the International Prostate Symptom Score (IPSS), the weighted mean difference (WMD) against placebo was 4.9 IPSS points (95% confidence interval, CI,-6.3 to-3.5). The WMD for peak urinary flow rate was 3.91 mL/s (95% CI 0.91 to 6.90, four studies) and for residual volume the WMD was 28.62 mL (95% CI-41.42 to-15.83, four studies). Beta-sitosterol did not reduce prostate size. The trial using pure beta-sitosterol-beta-d-glucoside (WA184) showed no improvement in urinary flow measures. Withdrawal rates for men assigned to beta-sitosterol and placebo were 7.8% and 8.0% (not significant), respectively. CONCLUSION: beta-sitosterol improves urological symptoms and flow measures. However, the existing studies are limited by short treatment duration and lack of standardized beta-sitosterol preparations. Their long-term effectiveness, safety and ability to prevent the complications of BPH are unknown.
Research abstract on BetaSitosterol
Title: beta-Sitosterol activates the sphingomyelin cycle and induces apoptosis in LNCaP human prostate cancer cells.
von Holtz RL ; Fink CS ; Awad AB
Department of Physical Therapy, Exercise, and Nutrition Sciences, State University of New York at Buffalo 14214-3000, USA.
Nutr Cancer, 32(1):8-12 1998
Epidemiological evidence has shown that men consuming a low-fat, high-fiber diet containing high amounts of plant products have a lower risk of prostate cancer than men consuming a Western diet. One of the main differences between these two diets is the type of dietary fat, including dietary sterols. This study was undertaken to compare the effect of two dietary sterols on prostate cancer cells in vitro. Beta-Sitosterol (SIT), the most common plant sterol, and cholesterol, an animal sterol, were compared for effect on LNCaP cell growth, differentiation, apoptosis, and sphingomyelin cycle intermediates. Cells were treated for up to seven days with sterols delivered by a cyclodextrin vehicle. Compared with cholesterol, SIT (16 microM) decreased growth by 24% and induced apoptosis fourfold, which was accompanied by cell rounding and a 50% increase in ceramide production. No effect was observed on differentiation as measured by prostate-specific antigen and prostatic acid phosphatase, although total acid phosphatase increased with SIT treatment for up to seven days. The results suggest that the decrease in cell number and increase in apoptosis associated with SIT treatment are mediated by activating the sphingomyelin cycle.
Research abstract on BetaSitosterol
Beta-sitosterol (BSS) and its glycoside (BSSG) are sterol molecules which are synthesized by plants. When humans eat plant foods phytosterols are ingested, and are found in the serum and tissues of healthy individuals, but at concentrations orders of magnitude lower than endogenous cholesterol. Epidemiological studies have correlated a reduced risk of numerous diseases with a diet high in fruits and vegetables, and have concluded that specific molecules, including b-carotene, tocopherols, vitamin C, and flavonoids, confer some of this protective benefit. However, these epidemiologic studies have not examined the potential effect that phytosterols ingested with fruits and vegetables might have on disease risk reduction. In animals, BSS and BSSG have been shown to exhibit anti-inflammatory, anti-neoplastic, anti-pyretic, and immune-modulating activity. A proprietary BSS:BSSG mixture has demonstrated promising results in a number of studies, including in vitro studies, animal models, and human clinical trials. This phytosterol complex seems to target specific T-helper lymphocytes, the Th1 and Th2 cells, helping normalize their functioning and resulting in improved T-lymphocyte and natural killer cell activity. A dampening effect on overactive antibody responses has also been seen, as well as normalization of the DHEA:cortisol ratio. The re-establishment of these immune parameters may be of help in numerous disease processes relating to chronic immune-mediated abnormalities, including chronic viral infections, tuberculosis, rheumatoid arthritis, allergies, cancer, and auto-immune diseases.