Scientific Opinion on the substantiation of health claims related to iodine
and thyroid function and production of thyroid hormones (ID 274), energy-
yielding metabolism (ID 274), maintenance of vision (ID 356), maintenance
of hair (ID 370), maintenance of nails (ID 370), and maintenance of skin
(ID 370) pursuant to Article 13(1) of Regulation (EC) No 1924/2006[sup]1[/sup]
EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA)2
European Food Safety Authority (EFSA), Parma, Italy
Słowa kluczowe:
1. Charakterystyka żywności / składnika
The food constituent that is the subject of the health claims is iodine, which is a well recognised nutrient and is measurable in foods by established methods.
Iodine occurs naturally in foods and is authorised for addition to foods (Annex I of the Regulation (EC) No 1925/20064 and Annex I of Directive 2002/46/EC5). This evaluation applies to iodine naturally present in foods and those forms authorised for addition to foods (Annex II of the Regulation (EC) No 1925/2006 and Annex II of Directive 2002/46/EC).
The Panel considers that the food constituent, iodine, which is the subject of the health claims, is sufficiently characterised.
2. Znaczenie oświadczenia dla zdrowia człowieka
2.1. Funkcjonowanie tarczycy i produkcja hormonów tarczycy (ID 274)
The claimed effects are “thyroid function” and “production of thyroid hormones”. The Panel assumes that the target population is the general population.
The Panel considers that normal thyroid function and normal production of thyroid hormones are beneficial to human health.
2.2. Metabolizm energetyczny (ID 274)
The claimed effect is “energy metabolism”. The Panel assumes that the target population is the general population.
The Panel considers that normal energy-yielding metabolism is beneficial to human health.
2.3. Utrzymanie prawidłowego wzroku (ID 356)
The claimed effects are “eye health” and “visual function”. The Panel assumes that the target population is the general population.
“Eye health” has not been defined in the list. From the proposed wordings the Panel assumes that the claimed effect relates to maintenance of normal vision.
The Panel considers that maintenance of normal vision is beneficial to human health.
2.4. Utrzymanie prawidłowego stanu włosów (ID 370)
The claimed effect is “hair, nails skin”. The Panel assumes that the target population is the general population.
The Panel considers that maintenance of normal hair is beneficial to human health.
2.5. Utrzymanie prawidłowego stanu paznokci (ID 370)
The claimed effect is “hair, nails skin”. The Panel assumes that the target population is the general population.
The Panel considers that maintenance of normal nails is beneficial to human health.
2.6. Utrzymanie prawidłowego stanu skóry (ID 370)
The claimed effect is “hair, nails skin”. The Panel assumes that the target population is the general population.
The Panel considers that maintenance of normal skin is beneficial to human health.
3. Naukowe uzasadnienia wpływu na zdrowie człowieka -
Iodine is an essential constituent of the thyroid hormones, which have important modifying or permissive roles in growth and development and there is a large body of evidence indicating a crucial role for iodine in growth and development (Sadler et al., 1999; IoM, 2002; Garrow et al., 2000; Strain and Cashman, 2002). A wide spectrum of iodine deficiency disorders (IDD) have been observed, depending on the degree of deficiency and the life stage at which the deficiency occurs. These disorders range from mild goitre to the most severe forms of endemic cretinism (congenital, severe, irreversible mental and growth retardation). Other symptoms of severe IDD (arising from iodine deficiency in the foetus) include deaf-mutism, squint, disorders of stance and gait, and dry skin and swollen subcutaneous tissue (Delange, 2000; EVM, 2003; WHO, 2007).
3.1. Funkcjonowanie tarczycy i produkcja hormonów tarczycy (ID 274)
Iodine is an essential dietary element for mammals being required for the synthesis of the thyroid hormones thyroxine (T4, 3,5,3',5'-tetraiodothyronine), containing 65 % by weight of iodine, and its active form T3 (3,5,3'-triiodothyronine), containing 59 % by weight of iodine, as well as the precursor iodotyrosines (SCF, 2002).
The Panel concludes that a cause and effect relationship has been established between the dietary intake of iodine and normal thyroid function and normal production of thyroid hormones.
3.2. Metabolizm energetyczny (ID 274)
The biological function of the thyroid hormones T4, T3 and of iodotyrosines encompasses the regulation of energy-yielding metabolism and endocrine function by cellular oxidation, calorigenesis,
thermo-regulation, intermediate metabolism, protein and enzyme synthesis, nitrogen retention, gluconeogenesis and pituitary gonadotropins (SCF, 2002).
The Panel concludes that a cause and effect relationship has been established between the dietary intake of iodine and normal energy-yielding metabolism.
3.3. Utrzymanie prawidłowego wzroku (ID 356)
One reference was cited to substantiate the claim effect. The reference was a study on distribution of iodine in a porcine eye model following iontophoresis (Rieger et al., 1995).
The Panel notes that squint and eye problems result from severe foetal iodine deficiency rather than from IDD onset in adulthood.
The Panel notes that iodine has no specific role in the eye.
The Panel concludes that a cause and effect relationship has not been established between the dietary intake of iodine and maintenance of normal vision.
3.4. Utrzymanie prawidłowego stanu włosów (ID 370)
Six references were cited to substantiate the claimed effect. Five were textbooks and one was an opinion of a scientific body. One of the references provided state that iodine supplements have been claimed to assist in the treatment of hair loss, but does not provide any further information in relation to the claimed effect (EVM, 2003). The Panel notes that the references cited did not provide any scientific data that could be used to substantiate the claimed effect.
The Panel concludes that a cause and effect relationship has not been established between the dietary intake of iodine and maintenance of normal hair.
3.5. Utrzymanie prawidłowego stanu paznokci (ID 370)
Six references were cited to substantiate the claimed effect. Five were textbooks and one was an opinion of a scientific body. One of the references cited state that iodine supplements have been claimed to assist in the maintenance of healthy nails, but does not provide any further information in relation to the claimed effect (EVM, 2003). The Panel notes that the references cited did not provide any scientific data that could be used to substantiate the claimed effect.
The Panel concludes that a cause and effect relationship has not been established between the dietary intake of iodine and maintenance of normal nails.
3.6. Utrzymanie prawidłowego stanu skóry (ID 370)
Early symptoms of hypothyroidism include dry and itchy skin, whereas clammy skin is a common symptom of hyperthyroidism (EVM, 2003).
The Panel concludes that a cause and effect relationship has been established between the dietary intake of iodine and maintenance of normal skin.
4. Uwagi do zaproponowanego brzmienia oświadczenia
4.1. Funkcjonowanie tarczycy i produkcja hormonów tarczycy (ID 274)
The Panel considers that the following wording reflects the scientific evidence: “Iodine contributes to the normal production of thyroid hormones and normal thyroid function.”
4.2. Metabolizm energetyczny (ID 274)
The Panel considers that the following wording reflects the scientific evidence: “Iodine contributes to normal energy-metabolism.”
4.3. Utrzymanie prawidłowego stanu skóry (ID 370)
The Panel considers that the following wording reflects the scientific evidence: “Iodine contributes to maintenance of normal skin.”
5. Warunki i możliwe ograniczenia stosowania oświadczenia
-
Jod przyczynia się do prawidłowej produkcji hormonów tarczycy i prawidłowej czynności tarczycy
-
Jod bierze udział w prawidłowym metabolizmie energii
-
Jod przyczynia się do utrzymania prawidłowego stanu skóry
The Panel considers that in order to bear the claims a food should be at least a source of iodine as per Annex to Regulation 1924/2006. A Tolerable Upper Intake Level (UL) has been established for iodine as 600 μg/day in adults and during pregnancy and lactation. For children and adolescents UL was established as 200 μg/day for 1-3 years, 250 μg/day for 4-6 years, 300 μg/day for 7-10 years, 450 μg/day for 11-14 years and 500 μg/day for 15-17 years (SCF, 2002). The target population is the general population.
Wnioski
On the basis of the data presented, the Panel concludes that:
The food constituent, iodine, which is the subject of the health claims, is sufficiently characterised.
Thyroid function and production of thyroid hormones (ID 274)
The claimed effects are “thyroid function and production of thyroid hormones”. The target population is assumed to be the general population. Normal thyroid function and normal production of thyroid hormones are beneficial to human health.
A cause and effect relationship has been established between the dietary intake of iodine and normal thyroid function and normal production of thyroid hormones.
The following wording reflects the scientific evidence: “Iodine contributes to the normal production of thyroid hormones and normal thyroid function.”
Energy-yielding metabolism (ID 274)
The claimed effect is “energy metabolism”. The target population is assumed to be the general population. Normal energy-yielding metabolism is beneficial to human health.
The Panel concludes that a cause and effect relationship has been established between the dietary intake of iodine and normal energy-yielding metabolism.
The following wording reflects the scientific evidence: “Iodine contributes to normal energy yielding metabolism.”
Maintenance of vision (ID 356)
The claimed effect is “Eye health/visual function”. The target population is assumed to be the general population. Maintenance of normal vision is beneficial to human health.
The Panel concludes that a cause and effect relationship has not been established between the dietary intake of iodine and maintenance of normal vision.
Maintenance of hair (ID 370)
The claimed effect is “hair, nails skin”. The target population is assumed to be the general population. Maintenance of normal hair is beneficial to human health.
The Panel concludes that a cause and effect relationship has not been established between the dietary intake of iodine and maintenance of normal hair.
Maintenance of nails (ID 370)
The claimed effect is “hair, nails skin”. The target population is assumed to be the general population. Maintenance of normal nails is beneficial to human health.
A cause and effect relationship has not been established between the dietary intake of iodine and maintenance of normal nails.
Maintenance of skin (ID 370)
The claimed effect is “hair, nails skin”. The target population is assumed to be the general population. Maintenance of normal skin is beneficial to human health.
A cause and effect relationship has been established between the dietary intake of iodine and maintenance of normal skin.
The following wording reflects the scientific evidence: “Iodine contributes to maintenance of normal skin.”
Conditions and restrictions of use
The Panel considers that in order to bear the claims a food should be at least a source of iodine as per Annex to Regulation 1924/2006. The target population is the general population.
