Scientific Opinion on the substantiation of health claims related to
gamma-linolenic acid (GLA) and maintenance of normal blood
LDL-cholesterol concentrations (ID 2661, 4452, 4453), maintenance of
normal blood pressure (ID 2662), reduction of menstrual discomfort
(ID 495, 640, 1773, 1775), contribution to normal cognitive function
(ID 1770), maintenance of the barrier function of the skin (ID 499, 591, 639,
676, 1554, 2003, 2065), “function of the cell membrane” (ID 1769),
maintenance of normal structure, elasticity and appearance of the skin
(ID 2660, 4296), and “anti-inflammatory properties” (ID 4454) pursuant to
Article 13(1) of Regulation (EC) No 1924/2006[sup]1[/sup]
EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA)2, 3
European Food Safety Authority (EFSA), Parma, Italy
Słowa kluczowe:
1. Charakterystyka żywności / składnika
The food constituents that are the subject of the health claims are "gamma-linolenic acid (GLA; C18: 3n-6) provided by evening primrose oil and/or borage (starflower) oil", "gamma-linolenic acid", "evening primrose oil (Oenothera biennis) contains gamma-linolenic acid", "borage oil (GLA= gamma linolenic acid)", "oenothera biennis-evening primrose-seeds oil", "long chain omega 6 polyunsaturated fatty acid GLA (gamma-linolenic acid)", "Borago officinalis", and "GLA (example from Borago officinalis, primrose oil, black currant seed oil)".
In the context of the proposed health relationships, wordings, conditions of use, and the clarifications provided by Member States, the Panel assumes that the food constituent that is the subject of the health claims is gamma-linolenic acid (GLA).
GLA is a n-6 long-chain polyunsaturated fatty acid which is present in small amounts in a variety of foods of both plant and animal origin and which can also be synthesised in the human body from its precursor linoleic acid (LA). GLA is a well recognised nutrient and can be measured in foods by established methods. This evaluation applies to GLA from all sources.
The Panel considers that the food constituent, gamma-linolenic acid (GLA), which is the subject of the health claims, is sufficiently characterised.
2. Znaczenie oświadczenia dla zdrowia człowieka
2.1. Utrzymanie prawidłowego stężenia cholesterolu LDL we krwi (ID 2661, 4452, 4453)
The claimed effects are "reduces lipids due to gamma-linolenic acid (GLA)", "reduces cholesterol due to gamma-linolenic acid (GLA)" and "helps to keep normal blood cholesterol". The Panel assumes that the target population is the general population.
In the context of the proposed wordings, the Panel assumes that the claimed effect refers to the maintenance of normal blood LDL-cholesterol concentrations.
Low-density lipoproteins (LDL) carry cholesterol from the liver to peripheral tissues, including the arteries. Elevated LDL-cholesterol, by convention >160 mg/dL (>4.1 mmol/L), may compromise the normal structure and function of the arteries.
The Panel considers that maintenance of normal blood LDL-cholesterol concentrations is a beneficial physiological effect.
2.2. Utrzymanie prawidłowego ciśnienia tętniczego (ID 2662)
The claimed effect is "helps to keep normal blood pressure". The Panel assumes that the target population is the general population.
The Panel notes that the claimed effect refers to the maintenance of normal blood pressure.
A claim on gamma-linolenic acid and maintenance of normal blood pressure has already been assessed with an unfavourable outcome (EFSA Panel on Dietetic Products Nutrition and Allergies (NDA), 2010). The references cited for this claim did not provide any additional scientific data which could be used to substantiate the claim.
2.3. Zmniejszenie dolegliwości związanych z miesiączką (ID 495, 640, 1773, 1775)
The claimed effects are "menstrual health", "hormonal regulation", and "supportive measure during menstrual cycle (helps relieve painful breasts)". The Panel assumes that the target population is women with premenstrual syndrome.
In the context of the proposed wordings and clarifications provided by Member States, the Panel assumes that the claimed effects refer to the reduction of menstrual discomfort, which can be assessed as changes in the severity of symptoms related to the premenstrual syndrome using validated questionnaires.
The Panel considers that reduction of menstrual discomfort is a beneficial physiological effect.
2.4. Udział w prawidłowym przebiegu procesów poznawczych (ID 1770)
The claimed effect is "cognitive and mental health". The Panel assumes that the target population is the general population.
In the context of the proposed wordings, the Panel assumes that the claimed effect refers to the contribution to normal cognitive function. Cognitive function includes memory, attention (concentration), learning, intelligence and problem solving, which are well defined constructs and which can be measured by validated psychometric cognitive tests.
The Panel considers that contribution to normal cognitive function is a beneficial physiological effect.
2.5. Utrzymanie prawidłowych funkcji ochronnych skóry (ID 499, 591, 639, 676, 1554, 2003, 2065)
The claimed effect is "skin health", "epidermic and connective tissue", and "essential fatty acid of importance for a healthy skin". The Panel assumes that the target population is the general population.
In the context of the proposed wordings and clarifications provided by Member States, the Panel assumes that the claimed effects refer to the maintenance of the barrier function of the skin by contributing to the maintenance of skin hydration.
The Panel considers that maintenance of the barrier function of the skin is a beneficial physiological effect.
2.6. Funkcje błon komórkowych (ID 1769)
The claimed effect is "function of the cell membrane". The Panel assumes that the target population is the general population.
Cell membranes may have different structures and functions depending on their composition and the cell type to which they belong. The Panel notes that several properties of cell membranes have been mentioned in the proposed wordings and that a specific effect related to the function of cell membranes has not been identified.
The Panel considers that the claim is general and non-specific and does not refer to any specific health claim as required by Regulation (EC) No 1924/2006.
2.7. Utrzymanie prawidłowej struktury, elastyczności i wyglądu skóry (ID 2660, 4296)
The claimed effects are "helps to maintain elasticity, tenderness and health of skin, structure and function of skin and mucous membrane" and "membranes cell structure". The Panel assumes that the target population is the general population.
In the context of the proposed wordings, the Panel assumes that the claimed effects refer to the maintenance of the normal structure, elasticity and appearance of the skin.
The Panel considers that these claims do not refer to a function of the body as required by Regulation (EC) No 1924/2006.
2.8. Właściwości przeciwzapalne (ID 4454)
The claimed effect is "anti-inflammatory due to gamma-linolenic acid (GLA)".
Inflammation is a non-specific physiological response to tissue damage that is mediated by the immune system. Adequate inflammatory responses are of primary importance for the defence against injury of any origin. In the context of the proposed wordings, the Panel assumes that the target population is patients with clinical conditions (e.g. atopic eczema, mastalgia), in which a reduction of inflammation could represent a therapeutic target for the treatment of the condition.
The Panel considers that the reduction of inflammation in the context of chronic clinical conditions is a therapeutic target for the treatment of the condition and does not comply with the criteria laid down in Regulation (EC) No 1924/2006.
3. Naukowe uzasadnienia wpływu na zdrowie człowieka
3.1. Utrzymanie prawidłowego stężenia cholesterolu LDL we krwi (ID 2661, 4452, 4453)
A claim on gamma-linolenic acid and maintenance of normal blood cholesterol concentrations has already been assessed with an unfavourable outcome (EFSA Panel on Dietetic Products Nutrition and Allergies (NDA), 2010).
The additional evidence that was provided to substantiate the claim reports on a three-month uncontrolled open label supplementation study addressing the effects of primrose oil consumption on blood lipids in 20 hyperlipidaemic subjects (Viikari and Lehtonen, 1986). The Panel considers that no conclusions can be drawn from this uncontrolled study for the scientific substantiation of the claimed effect.
The Panel considers that the references cited for this claim did not provide any additional evidence to change the outcome of the previous evaluation.
3.2. Zmniejszenie dolegliwości związanych z miesiączką (ID 495, 640, 1773, 1775)
The references provided for the scientific substantiation of this claim included textbooks, monographs, editorials, notes to the editor and general reviews, which did not provide any original data which could be used for the scientific substantiation of the claim. One human study was unrelated to the food constituent which is the subject of the health claim. A systematic review as well as two animal and several human studies were unrelated to the claimed effect. These included references on the effect of GLA consumption on hormonal profiles of women with premenstrual syndrome, menopausal flushing, eicosanoid synthesis and rheumatoid arthritis. The Panel considers that no conclusions can be drawn from these references for the scientific substantiation of the claimed effect.
Some intervention studies on cyclical and non-cyclical mastalgia have been provided. The Panel notes that only cyclical (but not non-cyclical) mastalgia has been proposed to overlap to some extent with the premenstrual syndrome. Two uncontrolled, open label intervention studies on the effects in women of evening primrose oil on cyclical (Cheung, 1999) and both cyclical and non-cyclical (Qureshi and Sultan, 2005) mastalgia, and one case-series report on the effects in women of evening primrose oil on cyclical and non-cyclical mastalgia (Gateley et al., 1992), were provided. The Panel considers that no conclusions can be drawn from these open-label, uncontrolled studies for the scientific substantiation of the claimed effect.
A systematic review of human intervention studies which investigated the effects of evening primrose oil consumption on the treatment of premenstrual syndrome was provided. All the individual studies which were provided separately in the consolidated list and which are pertinent to the claim were considered in this review (Budeiri et al., 1996).
A total of 12 studies were identified in the systematic review, two of which were not accessible to the Panel even after having made all reasonable efforts to retrieve them, five of which were available in summary form only and for which the details provided in the abstracts did not allow a full evaluation (e.g. exclusion criteria not reported, randomisation not specified, assessment of response unclear/insufficient) (Casper and Powell, 1987; Hunter and Wilson, 1987; Mansel et al., 1987; Massil et al., 1987; Ockerman et al., 1986), and two of which were open label, uncontrolled studies, which are inappropriate to assess the effects of an intervention on self-reported symptoms where a high placebo effect can be expected (Brush, 1982; Larsson et al., 1989). The Panel considers that no conclusions can be drawn from these references for the scientific substantiation of the claimed effect.
The remaining three studies were randomised, double-blind, placebo-controlled interventions which used capsules containing 9 % GLA (45 mg/capsule), 72 % linolenic acid (about 350 mg/capsule) and 12 % oleic acid (i.e. evening primrose oil) as intervention (Collins et al., 1993; Khoo et al., 1990; Puolakka et al., 1985). Paraffin capsules were used as placebo in two of the studies (Collins et al., 1993; Khoo et al., 1990) whereas in the third study the placebo was not reported (Puolakka et al., 1985). The Panel notes that GLA is quantitatively a minor component in the evening primrose oils used in these studies, and that the studies are not controlled for the effects of the other fatty acids in evening primrose oil. The Panel considers that no conclusions can be drawn on the effects of GLA per se on premenstrual syndrome symptoms from the studies provided.
The Panel concludes that a cause and effect relationship has not been established between the consumption of gamma-linolenic acid and a reduction of menstrual discomfort.
3.3. Udział w prawidłowym przebiegu procesów poznawczych (ID 1770)
Four references were provided to substantiate the claimed effect, including three narrative reviews and one systematic review. The narrative reviews summarised research on the effect of dietary gamma-linolenic acid on human health and nutrition, and did not provide original data for the scientific substantiation of the claimed effect. The systematic review was unrelated to the food constituent, which is the subject of the health claim. The Panel considers that no conclusions can be drawn from these references for the scientific substantiation of the claimed effect.
The Panel concludes that a cause and effect relationship has not been established between the consumption of gamma-linolenic acid and contribution to normal cognitive function.
3.4. Utrzymanie prawidłowych funkcji ochronnych skóry (ID 499, 591, 639, 676, 1554, 2003, 2065)
The references provided in relation to this claim were narrative reviews that did not provide original data which could be used for the scientific substantiation of the claimed effect. Some of the references addressed the effects of GLA in combination with other food constituents (e.g. green tea polyphenols and vitamin E) on different health outcomes, including the stratum corneum barrier function, or the effects of GLA and GLA-containing oils on health outcomes unrelated to the claimed effect (e.g. nerve transmission, inflammatory diseases, premenstrual syndrome). The Panel considers that no conclusions can be drawn from these references for the scientific substantiation of the claim.
The references provided also reported on human intervention studies using evening primrose oil, borage oil and other GLA-containing oils for the prevention of atopic dermatitis/eczema in high risk subjects and/or for the treatment of symptoms in subjects with diagnosed atopic dermatitis/eczema. The Panel notes that these references relate to the treatment of symptoms of a human disease and considers that patients with atopic dermatitis/eczema are not representative of the general population with respect to the status of the skin. The Panel considers that no conclusions can be drawn from these references for the scientific substantiation of the claimed effect.
One open-label, uncontrolled intervention study, which investigated the effects of consuming either 1.5 g or 3 g of borage oil daily (360 or 720 mg GLA, respectively) in 29 elderly subjects for two months on various skin parameters including transepidermal water loss (TEWL) and skin hydration, was provided (Brosche and Platt, 2000). The Panel considers that no conclusions can be drawn from this uncontrolled study for the scientific substantiation of the claimed effect.
One randomised, double-blind, placebo-controlled study in healthy adults investigated the effect of evening primrose oil on skin moisture, TEWL, redness, firmness, elasticity, fatigue resistance and roughness (Muggli, 2005). Subjects were randomised to consume evening primrose oil in capsules (3x2 daily) containing 57.5 mg GLA per capsule or placebo capsules (containing medium-chain triglycerides) for 12 months. Skin parameters were assessed at baseline, and at 4 and 12 weeks of the intervention. Differences between groups at each time point for each parameter were assessed. The Panel notes that the fatty acid composition of the test and placebo oils was not reported, and it is not possible, therefore, to assess whether appropriate control for fatty acids other than GLA in evening primrose oil was undertaken. Moreover, the primary outcome of the study was not identified, and there was no correction for multiple comparisons. The Panel considers that no conclusions can be drawn from this study for the scientific substantiation of the claimed effect.
A second randomised, double-blind, placebo-controlled study in healthy adults investigated the effect of evening primrose oil on skin moisture, TEWL, redness, firmness, elasticity, fatigue resistance and roughness in healthy adults in an experimental model (i.e. topical application of a 2 % solution of sodium dodecyl sulphate in distilled water for 24 hours) of skin irritation (Muggli, 2007). Subjects were randomised to consume evening primrose oil in capsules (3x2 daily) containing 57.5 mg GLA
per capsule, or oil-containing placebo capsules (composition not reported) for 84 days. Skin parameters were assessed at baseline, and at 28 and 84 days of the intervention. Differences between groups at each time point for each parameter were assessed. The Panel notes that the fatty acid composition of the test and placebo oils was not reported, and it is not possible, therefore, to assess whether appropriate control for fatty acids other than GLA in evening primrose oil was undertaken. Moreover, the primary outcome of the study was not identified and there was no correction for multiple comparisons. The Panel considers that no conclusions can be drawn from this study for the scientific substantiation of the claimed effect.
The Panel concludes that a cause and effect relationship has not been established between the consumption of gamma-linolenic acid and maintenance of the barrier function of the skin.
Wnioski
On the basis of the data presented, the Panel concludes that:
The food constituent, gamma-linolenic acid (GLA), which is the subject of the health claims, is sufficiently characterised.
Maintenance of normal blood LDL-cholesterol concentrations (ID 2661, 4452, 4453)
The claimed effects are ―reduces lipids due to gamma-linolenic acid (GLA)‖, ―reduces cholesterol due to gamma-linolenic acid (GLA)‖ and ―helps to keep normal blood cholesterol‖. The target population is assumed to be the general population. Maintenance of normal blood LDL-cholesterol concentrations is a beneficial physiological effect.
A claim on gamma-linolenic acid and maintenance of normal blood cholesterol concentrations has already been assessed with an unfavourable outcome and the references cited for this claim did not provide any additional evidence to change the outcome of the previous evaluation.
Maintenance of normal blood pressure (ID 2662)
The claimed effect is ―helps to keep normal blood pressure‖. The target population is assumed to be the general population. It is noted that the claimed effect refers to the maintenance of normal blood pressure.
A claim on gamma-linolenic acid and maintenance of normal blood pressure has been assessed with an unfavourable outcome and the references cited for this claim did not provide any additional scientific data that could be used to substantiate the claim.
Reduction of menstrual discomfort (ID 495, 640, 1773, 1775)
The claimed effects are ―menstrual health‖, ―hormonal regulation‖, and ―supportive measure during menstrual cycle (helps relieve painful breasts)‖. The target population is assumed to be women with premenstrual syndrome. In the context of the proposed wordings and clarifications provided by Member States, it is assumed that the claimed effect refer to the reduction of menstrual discomfort. A reduction of menstrual discomfort is a beneficial physiological effect.
A cause and effect relationship has not been established between the consumption of gamma-linolenic acid and a reduction of menstrual discomfort.
Contribution to normal cognitive function (ID 1770)
The claimed effect is ―cognitive and mental health‖. The target population is assumed to be the general population. Contribution to normal cognitive function is a beneficial physiological effect.
A cause and effect relationship has not been established between the consumption of gamma-linolenic acid and contribution to normal cognitive function.
Maintenance of the barrier function of the skin (ID 499, 591, 639, 676, 1554, 2003, 2065)
The claimed effect is ―skin health‖, ―epidermic and connective tissue‖, and ―essential fatty acid of importance for a healthy skin‖. The target population is assumed to be the general population. In the context of the proposed wordings and clarifications provided by Member States, it is assumed that the claimed effects refer to the maintenance of the barrier function of the skin by contributing to the maintenance of skin hydration. Maintenance of the barrier function of the skin is a beneficial physiological effect.
A cause and effect relationship has not been established between the consumption of gamma-linolenic acid and maintenance of the barrier function of the skin.
“Function of the cell membrane” (ID 1769)
The claimed effect is ―function of the cell membrane‖. The target population is assumed to be the general population.
The claim is general and non-specific and does not refer to any specific health claim as required by Regulation (EC) No 1924/2006.
Maintenance of normal structure, elasticity and appearance of the skin (ID 2660, 4296)
The claimed effects are ―helps to maintain elasticity, tenderness and health of skin, structure and function of skin and mucous membrane‖, and ―membranes cell structure‖. The target population is assumed to be the general population. In the context of the proposed wordings, it is assumed that the claimed effects refer to the maintenance of the normal structure, elasticity and appearance of the skin.
The claims do not refer to a function of the body as required by Regulation (EC) No 1924/2006.
“Anti-inflammatory properties” (ID 4454)
The claimed effect is ―anti-inflammatory due to gamma-linolenic acid (GLA)‖. In the context of the proposed wordings, it is assumed that the target population is patients with clinical conditions (e.g. atopic eczema, mastalgia), in which a reduction of inflammation could represent a therapeutic target for the treatment of the condition.
The claim does not comply with the criteria laid down in Regulation (EC) No 1924/2006.
