Plant sterols are the plant kingdom’s cholesterol equivalent. They play key roles in plant cell wall health. Plant sterols help regulate:

  • Cell wall structure
  • Cell wall permeability
  • Activity of cell membrane bound enzymes

A useful analogy is to think of plant sterols as a gatekeeper that helps determine what gets into the cell and what stays out. 

Interestingly, early human diets were rich in phytosterols providing up to 1g /day. More traditional western diets provide much less, a paltry 150 mg. That’s an 85% decrease. Moreover, roughly only 10% of the phytosterols we ingest are absorbed. Therefore, you have to eat a bountiful amount to get the benefit. The primary plant sterols are:

  • beta-sitosterol
  • campesterol
  • stigmasterol
  • sitostanol
  • campestanol

Musculoskeletal Benefits of Phytosterols

As previously mentioned phytosterols have a similar chemical structure to cholesterol. High levels of cholesterol are associated with increased whole body inflammation and oxidative stress. Chronic inflammation and oxidative stress drive musculoskeletal disease including osteoarthritis (joint degeneration), osteoporosis(weak bones), and sarcopenia(loss of muscle mass and weakness).

Phytosterols have been shown to decrease cholesterol levels. In turn reducing chronic inflammation, oxidative stress and protecting joint, bone, and muscle.

While the exact mechanisms of cholesterol, inflammation, and oxidative stress reduction is still being defined, research suggests :

  • Phytosterols block the absorption of cholesterol in the digestive tract
  • Phytosterols dislodge cholesterol in cell walls and dampen the transmission of the inflammation signal  from outside of the cell to the inside
  • Phytosterols neutralize high energy oxygen free radical
  • Phytosterols boost production of key joint building blocks

Selected Evidence

1. Phytosterols Boost Joint Health

French researchers investigated the effect of a concentrated form of phytosterols (Avocado Soybean oil unsaponifiables) on a group of patients with hip arthritis. At the end of the study trial period, the treatment group on average exhibited less progression of arthritis by X-ray compared to the placebo group. Furthermore, the same authors looked at symptom relief using a similar extract on patients with knee and hip arthritis. After 3 months, the treatment group reported less pain, better function, and less NSAID use.  (Maheu et al. ARTHRITIS & RHEUMATISM Vol 41, No 1, January 19YX, pp 8I-91; Maheu et al. Ann Rheum Dis 2014;73:376–384.)

Chinese investigators examined the effects of stigmasterol on a rabbit model of osteoarthritis. The authors found that stigmasterol administration significantly reduced the production of enzymes, called matrix metalloproteinases(MMP), that destroy cartilage cells. (Wei-Ping C et al. Stigmasterol blocks cartilage degradation in rabbit model of osteoarthritis. Acta Biochim Pol. 2012;59(4):537-41)

Other Health Benefits:

There are other conditions that phytosterols may assist, although more research is needed and for some conditions results to date have been mixed. Those include:

  • Promotes heart health
  • Supports brain health
  • Promotes blood vessel health

Excellent Sources

Seeds, nuts, plant oils, whole grains, and legumes are top sources of phytosterols.                        


Phytosterols from natural foods are generally well tolerated. Optimal amounts can be obtained from a balanced, healthful diet. 

The European Scientific Committee on Foods has published an upper limit of 3 g/day. 

Excessive intake of supplemental phytosterols may cause GI symptoms such as nausea, indigestion, diarrhea, and constipation. 

Any consideration a supplementation should be discussed with a qualified health professional familiar with your unique medical history.


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Chen, W. P., Yu, C., Hu, P. F., Bao, J. P., Tang, J. L., & Wu, L. D. (2012). Stigmasterol blocks cartilage degradation in rabbit model of osteoarthritis. Acta Biochimica Polonica, 63(4), 537-541. doi:10.18388/abp.2016_1335

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Gylling, H., & Simonen, Piia. (2015). Phytosterols, phytostanols, and lipoprotein metabolism. Nutrients, 7(9), 7965-7977. doi:10.3390/nu7095374






 Lucas J. Bader MD

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