Sterols (Sitosterol) and Sterolins (Sitosterolin)


These compounds have several interchangeable names. They are called sterols and sterolins, sitosterol and sitosterolin, and beta-sitosterol and beta-sitosterolin, which can also be written as B-sitosterol and B-sitosterolin. These compounds are the primary lipids that occur in most higher plants. The glycoside of sitosterol, which occurs in the same plants in substantially smaller amounts, is known as sitosterolin. These plant fats have chemical structures that are nearly identical to the animal fat known as cholesterol, with the only difference being an additional alkyl (ethyl) group at the C-24 position on the side chain of the sterols. It is interesting to note that sterols and sterolins exert their biological effects at relatively low concentrations.

Dosage Info

Dosage Range

From 1 to 2 capsules, 3 times daily. This equates to 60 to 120 mg of sterols and 600 to 1,200 mcg of sterolins daily.

Most Common Dosage

1 capsule, 3 times daily on an empty stomach. Each capsule contains 20 mg of plant sterols and 200 mg of plant sterolins. Therefore, a daily dose consists of 60 mg of sterols and 600 mg of sterolins.

Dosage Forms


Adult RDI

None established

Adult ODA

None established

Active Forms

Sitosterol and sitosterolin


Sterols and sterolins are absorbed from the intestinal tract along with other fats. Although these compounds are poorly absorbed, they exert their biological effects at extremely low concentrations, so limited absorption does not appear to be a problem.

Toxicities & Precautions


The use of sterols and sterolins has been found to be very safe and without any serious side effects.

Side Effects

At high dosage levels, occasional cases of mild constipation or diarrhea have been reported.

Functions in the Body

Immune Dysfunction

Correct underlying immune dysfunction by enhancing the production of T-helper 1-type cells, which stimulate the production of interleukin-2 (IL-2) and gamma interferon.

Natural Killer Cells

Increase the activity of natural killer cells (NK cells).


Normalize cortisol/DHEA ratios in the body.

Clinical Applications

Elevated Cholesterol

Numerous studies have reported that these compounds, which have chemical structures similar to cholesterol, inhibit cholesterol absorption and can be used clinically to lower elevated cholesterol levels. (1) , (2) , (3)

AIDS and HIV Therapy

The sterols and sterolins do not have direct anti-viral activity. However, they are able to cause a reduction in patients’ viral load due to their ability to stimulate the activity of cell-mediated immune responses, which regulate viral replication. (4) Sterols and sterolins selectively improve the cortisol/DHEA ratio, which may explain why they promote the secretion of type-1 cytokines while reducing the overproduction of type-2 cytokines, which is an important aspect of restoring the immune system in patients with HIV and AIDS. (5) , (6) , (7)


In conjunction with their regular medications, patients who took sterols and sterolins made significant improvements compared to those taking placebos. Those taking the sterols and sterolins exhibited greater weight gain and larger increases in peripheral blood lymnphocytes and eosinophils. (8)

Benign Prostatic Hypertrophy (BPH)

The results of two double-blind clinical trials have reported that men with BPH who took sitosterols exhibited substantial improvements in their symptoms. (9) , (10) In one of these trials, the benefits gained during 6 months of therapy were still evident at an 18-month follow-up.


Animal studies suggest that sterols and sterolins may be useful in the prevention and treatment of diabetes. In both normal and hyperglycemic rats, these compounds increase fasting insulin levels and reduce fasting glucose levels, possible by stimulating insulin secretion from Beta cells in the pancreas. (11) , (12)

Immune Enhancement

Studies in vitro and in humans reveal that when sterols and sterolins and are administered together, they cause a significant increase in the proliferative response of T-cells that are stimulated with phytohaemagglutinin (PHA). This indicates a substantial enhancement of the immune system and it was noted that very low doses of the sterols and sterolins are capable of producing these benefits in immune system response. (13) In a double-blind, placebo-controlled trial with individuals running a marathon race, the blood work those taking the sterol/sterolin combination revealed significant increases in total white blood cell count as well as remarkable improvements in individual lymphocyte subsets and better ratios of cortisol to DHEAs. (14)

Rheumatoid Arthritis

Studies report that the combination of sterols and sterolins have the remarkable capability to selectively inhibit the production of the highly inflammatory compounds known as interlukin-6 (IL-6) and tumor necrosis factor alpha (TNF-á), which suggests that these compounds may be useful in the treatment of rheumatoid arthritis. (15)


Studies indicate that sterols and sterolins may be beneficial in the prevention and treatment of cancer. (16) , (17) , (18) , (19)

Symptoms and Causes of Deficiency

Sterols and sterolins are not nutrients for humans, so no deficiency condition exists. However, people who do not consume abundant quantities of fresh foods are known to have more health problems and weaker immune systems. A lack of plant sterols and sterolins may be part of the problem.

Dietary Sources

Small quantities of sterols and sterolins occur naturally in fruits, vegetables, seeds, and nuts. However, food processing and some cooking procedures cause a substantial loss of these compounds.


  1. View Abstract: Heinemann T, Kullak-Ublick GA, et al. Mechanisms of action of plant sterols on inhibition of cholesterol absorption. Comparison of sitosterol and sitostanol. Eur J Clin Pharmacol. 1991;40(Suppl 1):S59-63.
  2. Miettinen TA. Regulation of serum cholesterol by cholesterol absorption. Agents Actions Suppl. 1988;26:53-65.
  3. Pollak OJ. Effect of plant sterols on serum lipids and atherosclerosis. Pharmacol Ther. 1985;31(3):177-208.
  4. View Abstract: Breytenbach U, Clark A, Lamprecht J, Bouic P. Flow cytometric analysis of the Th1-Th2 balance in healthy individuals and patients infected with the human immunodeficiency virus (HIV) receiving a plant sterol/sterolin mixture. Cell Biol Int. 2001;25(1):43-9.
  5. Clerici M, Bevilacqua M, Vago T, et al. An immunoendocrinological hypothesis of HIV infection. Lancet. Jun1994;343(8912):1552-3.
  6. Bouic PJD. Immunomodulation in HIV/AIDS: The Tygerberg/Stellenbosch University experience. AIDS Bulletin. Sep1997;6(3):18-20.
  7. O’Garra A. Interleukins and the immune system 1. Lancet. Apr1989;1(8644):943-7.
  8. View Abstract: Donald PR, Lamprecht JH, Freestone M, et al. A randomised placebo-controlled trial of the efficacy of beta-sitosterol and its glucoside as adjuvants in the treatment of pulmonary tuberculosis. Int J Tuberc Lung Dis. Dec1997;1(6):518-22.
  9. View Abstract: Berges RR, Kassen A, Senge T. Treatment of symptomatic benign prostatic hyperplasia with beta-sitosterol: an 18-month follow-up. BJU Int. May2000;85(7):842-6.
  10. View Abstract: Berges RR, Windeler J, Trampisch HJ, et al. Randomised, placebo-controlled, double-blind clinical trial of beta-sitosterol in patients with benign prostatic hyperplasia. Beta-sitosterol Study Group. Lancet. Jun1995;345(8964):1529-32.
  11. View Abstract: Ivorra MD, D'Ocon MP, Paya M. Antihyperglycemic and insulin-releasing effects of beta-sitosterol 3-beta-D-glucoside and its aglycone, beta-sitosterol. Arch Int Pharmacodyn Ther. Nov1988;296:224-31.
  12. View Abstract: Ivorra MD, Paya M, Villar A, et al. Effect of beta-sitosterol-3-beta-D-glucoside on insulin secretion in vivo in diabetic rats and in vitro in isolated rat islets of Langerhans. Pharmazie. Apr1990;45(4):271-3.
  13. View Abstract: Bouic PJD, Etsebeth S, Liebenberg RW, et al. Beta-sitosterol and beta-sitosterol glucoside stimulate human peripheral blood lymphocyte proliferation: Implications for their use as an immunomodulatory vitamin combination. Int J Immunopharmac. 1996;18(2):693-700.
  14. View Abstract: Bouic PJ, Clark A, Lamprecht J, et al. The effects of B-sitosterol (BSS) and B-sitosterol glucoside (BSSG) mixture on selected immune parameters of marathon runners: inhibition of post marathon immune suppression and inflammation. Int J Sports Med. May1999;20(4):258-62.
  15. View Abstract: Bouic PJD. Sterols/Sterolins, the natural, nontoxic immunomodulators and their role in the control of rheumatoid arthritis. Arthritis Trust of America. 1998;3-6.
  16. View Abstract: Nair PP, Turjman N, Kessie G, et al. Diet, nutrition intake, and metabolism in populations at high and low risk for colon cancer. Dietary cholesterol, beta-sitosterol, and stigmasterol. Am J Clin Nutr. Oct1984;40(4 Suppl):927-30.
  17. View Abstract: Awad AB, Chen YC, Fink CS, et al. beta-Sitosterol inhibits HT-29 human colon cancer cell growth and alters membrane lipids. Anticancer Res. Sep1996;16(5A):2797-804.
  18. View Abstract: Raicht RF, Cohen BI, Fazzini EP, et al. Protective effect of plant sterols against chemically induced colon tumors in rats. Cancer Res. Feb1980;40(2):403-5.
  19. View Abstract: Muti P, Awad AB, Schunemann H, et al. A plant food-based diet modifies the serum beta-sitosterol concentration in hyperandrogenic postmenopausal women. Nutr. Dec2003;133(12):4252-5.