Plant stanols and sterols ( phytosterols ) in lowering cholesterol

• there is evidence that plant sterols/ stanols help in lowering total and low density lipoprotein (LDL) cholesterol levels and that this effect is additive to that achieved by dietary fatty acid manipulation:
  • plant sterols (also known as phytosterols) are found naturally in a range of plant sources such as vegetable oils, nuts, grains, wood pulp, seeds and leaves. Typical diets commonly include sitosterol, campesterol and stigmasterol along with smaller amounts of plant stanols (which are saturated plant sterols) like sitostanol
  • plant sterols/ stanols are similar in chemical structure to cholesterol. The presence of a methyl or ethyl group in their side chains means that, compared to cholesterol, plant sterols are minimally absorbed in the gut
  • plant sterols are thought to decrease the absorption of dietary and endogenously derived cholesterol in the intestine and a number of mechanisms for this effect have been suggested. This reduction in absorption of cholesterol increases hepatic uptake of LDL and reduces blood LDL levels, although there are compensatory mechanisms that increase the rate of endogenous cholesterol synthesis which limit the magnitude of the effect
  • although strict vegetarians will consume between 600-800 mg of plant sterols/ stanols each day, the typical daily intake ranges from 160-400 mg/ day which is thought to have little effect on cholesterol absorption
    
  • the esterification of plant sterols/ stanols (by the attachment of a fatty acid) has increased their solubility in fat and allowed them to be incorporated into spreading fats and other fat-based products like mayonnaise
    
    
• studies suggest that the consumption of about 2-3g/ day of plant sterols/ stanols reduce LDL cholesterol levels by between 9%-20% although there is considerable variation amongst individuals:
  • no or little effect on high density lipoprotein cholesterol or triglyceride levels has been reported -the reduction in LDL cholesterol levels has been found in both adults and children with hypercholesterolaemia, in those with normal blood cholesterol levels, in people with Type II diabetes and in postmenopausal women with CHD
  • plant stanol ester margarines have also been shown to be an effective adjunct to hypercholesterolaemia treatment using statins and fibrates
    
    
• consumption of plant sterol/ stanol esters for up to 12 months produced no evidence of adverse effects:
  • plant sterols can reduce the absorption of carotenoids in the gut (1) - however there is evidence that dietary advice to consume an additional daily serving of a high-carotenoid vegetable or fruit when consuming spreads containing sterol or stanol esters maintains plasma carotenoid concentrations while lowering LDL-cholesterol concentrations significantly (2)
  • additional monitoring of the effects of foods containing plant-derived sterol/ stanol esters on fat soluble nutrient levels has been recommended by some (3)
  • those individuals with homozygous sitosterolaemia should restrict their intake of plant stanols/ sterols
  • to date there are no studies which have examined the effect of these substances on pregnant women (1)
    
    
• thus, until the results of long-term studies are available, it has been recommended that (1):
  • foods containing high levels of plant-derived sterol/ stanol esters are considered as an additional option for risk reduction in adults with hypercholesterolaemia
  • these fats should be used to supplement a healthy diet, containing plenty of fruit and vegetables

NICE state (4):

• do not advise any of the following to take plant stanols or sterols for the prevention of CVD:
  • people who are being treated for primary prevention
  • people who are being treated for secondary prevention
  • people with CKD
  • people with type 1 diabetes
  • people with type 2 diabetes

Reference:

• (1) British Heart Foundation (Factfile 3/2002). Cholesterol lowering: stanols and sterols.
• (2) An increase in dietary carotenoids when consuming plant sterols or stanols is effective in maintaining plasma carotenoid concentrations. Am J Clin Nutr. 2002 Jan;75(1):79-86.
• (3) Australian Heart Foundation's Nutrition and Metabolism Advisory Committee. (1999) Plant sterols and stanols: a position statement from the Heart Foundation's Nutrition and Metabolism Advisory Committee.
• (4) NICE (July 2014).Lipid modification - Cardiovascular risk assessment and the modification of blood lipids for the primary and secondary prevention of cardiovascular disease