Plant sterols for children

Plant sterols are not recommended for normocholesterolemic children under five because children who are growing have a large need for cholesterol for normal development. There is also the fear that plant sterols, particularly esters, could affect the absorption of fat soluble vitamins. However, no direct evidence points at plant sterols being in some way dangerous for children. Studies with small amounts of plant sterols fed to infants have shown that neonates have the adaptive ability to increase their cholesterol synthesis [123-125]. In fact, infants are typically fed formula diets containing cholesterol concentrations 3–35 times lower than breast milk, with considerably higher levels of plant sterols [126]. There is the possibility that cholesterol, received in utero or administered to neonates, could affect gene expression and physiology later in life. This theory was initially based on the increased atherosclerosis incidence in adults fed formula rather than breast milk as infants [127], as well as higher cholesterol in men fed breast milk for less than 3 months as compared to more than 9 months [128]. This so called "cholesterol imprinting" hypothesis is now being explored in controlled animal models with microarrays [129]. Children with allergies to dairy routinely consume vegetable oils rich in plant sterols and less cholesterol, and thus have less cholesterol absorbed, but compensatory increases in cholesterol synthesis [130].

Most studies examining the effects of plant sterols in children have been conducted with hypercholesterolemic children [131-134]. Generally, plant sterols seem to be as effective in hypercholesterolemic children as in hypercholesterolemic adults. Some older studies in children must be interpreted with caution, as the preparations may have been crystalline [135]. Becker [132], for example, found that severely hypercholesterolemic children could be effectively treated with sitosterol, and that 3 g/d sitosterol combined with a half dose of bezafibrate was an effective way to reduce the bezafibrate dose. Intake of 1.7 g/d of plant sterols in ester form was effective in reducing total cholesterol levels, LDL cholesterol and apo B levels in children with familial hypercholesterolemia who followed Step I diet without any adverse effects [136]. No changes in concentration of lipid-adjusted carotenoids were reported except for lycopene, which decreased by 8.1%. This decrease was considered of minor biological and clinical importance[136]. The authors recommended an increase in the intake of fruit and vegetables to avoid the reduction in lycopene values when plant sterols were introduced to Step I diet of children with familial hypercholesterolemia.

In a crossover study, healthy 2–5 year old children consumed either 3 g/d plant stanol ester or 5 g/d insoluble wheat bran fiber for 2 weeks, then 10 g/d for the second two weeks [101]. Relative to baseline, LDL cholesterol levels were reduced 15.5% with stanol esters and 4% with the fiber diet. Stanol esters did not affect triacylglycerols or HDL cholesterol. The study showed that stanol esters reduced LDL cholesterol in normocholesterolemic children similarly to that found in normocholesterolemic adults and hypercholesterolemic adults and children. In healthy 6-year-old children who were on a low-saturated, low-cholesterol diet, daily intake of 1.5 g/d of plant stanol ester was effective in reducing total cholesterol and LDL cholesterol values by 5.4% and 7.5%, respectively [137]. The intake of plant stanol did not cause any adverse clinical effects, nor did it affect the levels of fat soluble vitamins; however, it did cause a 19% reduction in ratio of β-carotene to LDL cholesterol ratio.

Children consuming vegetable oil sterols in margarine for 13 months had serum concentrations of campesterol and sitosterol that were 75% and 44% higher than those in the control children, while serum cholesterol precursor sterol concentrations, indicative of cholesterol synthesis, did not differ between the two groups [138]. Thus, doubling dietary plant sterol intake almost doubles serum plant sterol concentrations in 13-mo-old children, but has no effect on endogenous cholesterol synthesis. Relative intestinal absorption of natural plant sterols from the diet in early childhood is similar to that in adults. In the older study of Mellies et al. [139], 300–900 mg/d of plant sterols led to a large accumulation of plant sterols in the plasma (0.44 mM) of normo and hypercholesterolemic children.

As in adults, in children, the apo E phenotype, could be a factor affecting the efficacy of plant sterols. Plant sterols, as an index of cholesterol absorption, were higher in adults or children with the E4/3 phenotype as compared with those with other phenotypes [140]. Lathosterol, an index of cholesterol synthesis, was also higher in children with E4/3 phenotype than in those with E3/3 or E3/2, indicating these children both absorb and synthesize more cholesterol [140]. The effect of phenotype of apo E on response to sterol intake was investigated in 6-year-old children [141]. Daily intake of 1.6 g of plant stanol was effective in reducing blood cholesterol and LDL cholesterol by 65 and 8%, respectively, in these children regardless of apo E phenotype. Thus, children with different apo E phenotype can achieve a reduction in their cholesterol levels by intake of plant sterol.

From the previous studies, it is clear that plant sterols are effective in reducing blood cholesterol in healthy as well as in hypercholesterolemic children. The only side effect reported is a reduction in levels in ratio of β-carotene to LDL cholesterol ratio and lycopene values, which could be balanced by increasing the intake of fruit and vegetable, especially those rich in carotenoids, as was the case in adult population [106].