FAO Nutrition Meetings
    Report Series No. 40A,B,C
    WHO/Food Add./67.29


    The content of this document is the result of the deliberations of the
    Joint FAO/WHO Expert Committee on Food Additives which met at Rome,
    13-20 December, 19651 Geneva, 11-18 October, 19662


    1 Ninth Report of the Joint FAO/WHO Expert Committee on Food
    Additives, FAO Nutrition Meetings Report Series, 1966 No. 40; 
    Wld Hlth Org. techn. Rep. Ser., 1966, 339

    2 Tenth Report of the Joint FAO/WHO Expert Committee on Food
    Additives, FAO Nutrition Meetings Report Series, 1967, in press; 

    Food and Agriculture Organization of the United Nations
    World Health Organization


    Synonyms                     Polyglycerol fatty acid esters; Glyceran
                                 fatty acid esters

    Chemical description         Mixtures of polyglycerol esters of fatty
                                 acids of food fats.

    Structural formula


                                 Where the average value of n is no more
                                 than 3 and R is partly a fatty acid
                                 moiety or partly hydrogen radical.

    Definition                   Polyglycerol esters of fatty acids are
                                 mixtures of the esters of these fatty
                                 acids with the polyglycerol mixture.
                                 The commercial products will contain
                                 mono- and diglycerides when fats are
                                 used for transesterification with
                                 polyglycerol mixtures.

    Description                  Oleaginous substances, of a consistency
                                 depending on the fatty acids.

    Uses                         As emulsifiers.

    Biological Data

    Biochemical aspects

         The polyglycerol esters of fatty acids include large group of
    closely related compounds of complex composition. However, the
    individual components are found as normal constituents of the human
    diet, i.e. glycerol, glycerol mono-, di- and tri-fatty acid esters and
    individual fatty acids, with the exceptions of the artificially
    produced polymers of glycerol, polymers of certain fatty acids and the
    actual separate esters between these polymers. These latter compounds
    represent the toxicologically important constituents.

         In vitro experiments on lipase digestion of polyglycerol esters
    showed a slower rate of digestion than that of olive oil and the ester
    did not affect the lipase digestion of olive oil (Unilever Research
    Laboratory, 1966).

         Digestibility or caloric utilisation have been used to
    demonstrate metabolic conversion; 16 male and female rats were fed a
    diet containing 1 per cent. ground-nut oil and 9 per cent.
    polyglycerol ester or 10 per cent. ground-nut oil (as control) for 6
    and 12 weeks. Polyglycerol ester as an energy source was almost
    equivalent to ground-nut oil, as measured by growth rate.
    Digestibility was calculated as 92 per cent. In another experiment
    rats were kept on a restricted food intake (18 calories/day) for 17
    days. After realimentation with 9 per cent. polyglycerol ester and 1
    per cent. ground-nut oil, no adverse effect was noted on the animals'
    ability to gain weight. Rats fed polyglycerol ester for 54 days as 9
    per cent. of the diet showed no difference in composition of carcass
    fat, liver fat, liver free fatty, acids and liver phosphorus when
    compared with groups fed 1 per cent. or 10 per cent. ground-nut oil in
    the diet. Liver vitamin A levels were unaffected. A polyglycerol ester
    was shown to be absorbed by intestinal lymphatics, and chylomicron
    counts showed normal lipaemia. Suspensions in water were more slowly
    absorbed and reduced the rate of gastric emptying compared with
    ground-nut oil. The serum cholesterol level of rats was unaffected by
    the presence of 10 per cent. polyglycerol ester in a 42 per cent. fat
    diet (Unilever Research Laboratory, 1966).

    Acute toxicity

         Rat. Rats given single doses of 7, 14 and 29 g/kg body-weight
    of a polyglycerol eater by intubation showed no signs of any toxic
    effect. Repeated deals, with 10 g/kg body-weight daily over 5 days
    caused no deaths. Rats, injected i.p. with 1, 3 and 7 g/kg
    body-weight, showed no adverse effects; single doses of 10 g/kg
    body-weight caused some peritoneal reaction but no deaths (Unilever
    Research Laboratory, 1966).

         Rabbit. Rabbits dosed orally with 10~29 g/kg body-weight showed
    no toxic effects.

    Short-term studies

         Rats. Thirteen rats maintained on 9 per cent. polyglycerol
    ester and 1 per cent. ground-nut oil for 17 weeks showed normal kidney
    function (Unilever Research Laboratory, 1966). Rats kept 22 weeks on 9
    per cent. PGE + 1 per cent. ground-nut oil showed no difference in
    weights of liver, kidney, adrenal, spleen and testes when compared
    with controls on 10 per cent. ground-nut oil. Gross autopsy and
    histological examination of liver revealed no abnormalities (Unilever
    Research Laboratory, 1966).

         Man. Thirty-seven volunteers, aged 19-24, were fed 2-20 g
    polyglycerol ester per day for 3 weeks in their diet. No abnormalities
    were detected in plasma proteins, serum amino-acids, thymol turbidity,
    serum bilirubin, total and free serum cholesterol, serum alkaline
    phosphatase, SGOT, SGPT, cholinesterase, cholesterol esterase, 24 hour
    urine volume, urinary creatinine, urea output, total and split faecal
    fat or total faecal nitrogen (Unilever Research Laboratory, 1966).

    Long-term studies

         Mouse. Groups of 25 male and 25 female mice were fed for 80
    weeks on either polyglycerol ester or ground-nut oil at 5 per cent. in
    their diet. No adverse effect on body-weight, food consumption,
    peripheral blood picture and survival rate were noted. Carcass fat of
    the test group showed no polyglycerol residues. The levels of free
    fatty acids, unsaponifiable material, fatty acid composition of
    carcass fat and organ weights were the same in test and control
    groups, except for the liver and kidney weights of female mice which
    were significantly higher. Microscopic examination of all major organs
    showed nothing remarkable (Unilever Research Laboratory, 1966).

         Rat. A test group of 22 rats, with a control group of 28B, were
    kept on a diet containing 1.5 per cent. of polyglycerol ester for 3
    generations and maintained for over one year without significant
    variation in fertility and reproductive performance. Gross and
    histological examination of the third generation revealed no
    consistent abnormality related to the test substance (Unilever
    Research Laboratory, 1966).

         In another experiment 28 male and 28 female rats were fed 5 per
    cent. polyglycerol ester or ground-nut oil in their diet for 2 years.
    No adverse effects on body-weight, food consumption, peripheral blood
    picture, and survival rate were noted. Liver function tests and renal
    function tests at 59 and 104 weeks were comparable between groups. The
    carcass fat contained no polyglycerol and the levels of free fatty
    acid, unsaponifiable residue and fatty acid composition of carcass fat
    were no different from controls. Organ weights, tumour incidence and
    tumour distribution ware similar in control and test groups. Complete
    histological examination of major organs showed nothing remarkable
    (Unilever Research Laboratory, 1966). 


         The toxicological assessment of this group of diverse but related
    substances is based an evaluation of satisfactory evidence for one
    member and assumes that alterations in the fatty acid distribution or
    polyglycerol content of individual members have no toxicological
    bearing and only affect the physical and emulsifying properties of
    each ester. The metabolic studies point to hydrolysis of these
    polyglycerol esters in the gastrointestinal tract and the utilization
    and digestibility studies justify the assumption that the fatty acid
    moiety is metabolized in the normal manner. Analytical studies have
    produced no evidence of cumulation of the polyglycerol moiety in body
    tissues. Human studies showed no adverse effects.

         It is desirable to have properly conducted biochemical studies on
    other members of this group, that do not conform to the specifications
    detailed above, to exclude-unforeseen effects.


    Level causing no toxicological effect

         Rat. 50 000 ppm in the diet, equivalent to 2500 mg/kg

    Estimate of acceptable daily intakes for man

                                      mg/kg body-weight1

       Unconditional acceptance             0-12.5
       Conditional acceptance               12.5-25


    Unilever Research Laboratory (1966) Unpublished report


    1 Calculated as total polyglycerol ester of palmitic acid.

    See Also:
       Toxicological Abbreviations
       Polyglycerol esters of fatty acids (WHO Food Additives Series 5)