ID 379 -
Magnez
PL: Magnez
EN: Magnesium
Pdf: magnesium
Oświadczenie (2)
- układu sercowo-naczyniowego
- obrotu
- ciśnienie krwi
1. Charakterystyka żywności / składnika
The food constituent that is the subject of the health claims is magnesium, which is a well recognised nutrient and is measurable in foods by established methods.
Magnesium occurs naturally in foods and is authorised for addition to foods (Annex I of Regulation (EC) No 1925/20066 and Annex I of Directive 2002/46/EC7). This evaluation applies to magnesium naturally present in foods and to 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, magnesium, which is the subject of the health claims, is sufficiently characterised.
2.5. Utrzymanie prawidłowego ciśnienia tętniczego (ID 344, 366, 379)
The claimed effects are “cardiovascular system”, “blood pressure” and “circulation”. 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 normal blood pressure.
Blood pressure is the pressure (force per unit area) exerted by circulating blood on the walls of blood vessels. Elevated blood pressure, by convention above 140 mmHg (systolic) and/or 90 mmHg (diastolic), may compromise the normal arterial and cardiac function.
The Panel considers that maintenance of normal blood pressure is a beneficial physiological effect.
3. Naukowe uzasadnienia wpływu na zdrowie człowieka -
Magnesium is an essential nutrient and serves as a cofactor for over 300 enzymes involved in biological processes. Magnesium is part of the Mg-ATPase complex and is essential for oxidative phosphorylation; it has roles in energy metabolism, mineral homeostasis, calcium metabolism, and neuromuscular and endocrine function (IoM, 1997; SCF, 2001; Volpe, 2006).
In the human body, 50 to 60 % of magnesium is located in the bone. Part of it is readily exchangeable with serum and therefore bone represents a magnesium store. The remaining magnesium is mainly intracellular; extracellular magnesium represents only 1 % of the total magnesium content of the body.
Because magnesium is mostly within cells or in bone, assessment of magnesium status is difficult (Rude and Shils, 2006).
Manifestations of magnesium deficiency include signs related to bone and mineral metabolism, neuromuscular and psychological manifestations (e.g. positive Chvostek and Trousseau signs, spontaneous carpal-pedal spasm, seizures, vertigo, ataxia, nystagmus, athetoid and choreiform movements, muscular weakness, tremor, fasciculation, wasting, depression, psychosis, hallucinations, confusion), symptoms related to potassium homeostasis, and cardiovascular manifestations (Rude and Shils, 2006; FAO/WHO, 2001; O'Brien, 1999). Most of the early symptoms of magnesium depletion are neurological or neuromuscular; thus, a decline in magnesium status produces loss of appetite, nausea, muscular weakness, vomiting, fatigue, lethargy, staggering and, if the deficit is prolonged, weight loss (FAO/WHO, 2001; Volpe, 2006). Progressively increasing with the severity and duration of deficiency are signs such as hyperirritability, hyperexcitability, muscular spasms and tetany, leading ultimately to convulsions (FAO/WHO, 2001).
3.4. Utrzymanie prawidłowego ciśnienia tętniczego (ID 344, 366, 379)
The references provided for the substantiation of the claimed effect included textbooks, a website from a government body, a reference from an authoritative body on prevention, detection, evaluation and treatment of high blood pressure that did not mention magnesium, publications on magnesium- containing medicinal waters, narrative reviews and references that were either very general or did not address relevant endpoints, and one intervention study on the effects of dietary modifications on blood pressure. Endpoints addressed were ischaemic heart disease; clinical and analytical aspects related to magnesium; magnesium metabolism, deficiency and supplementation; sport; myocardial infarction; tension headaches and muscle tension; stress and neuropsychiatric disorders; and various cardiovascular aspects including atherogenesis. The Panel considers that no conclusions can be drawn from these references for the scientific substantiation of the claimed effect.
One meta-analysis of randomised controlled trials (RCTs) (Jee et al., 2002), a systematic review of epidemiological and intervention studies (Burgess et al., 1999), and three intervention studies on the effects of magnesium on blood pressure in humans were provided (Borello et al., 1996; Itoh et al., 1997; Kyriazis et al., 2004).
The Panel notes that the meta-analysis and the systematic review included trials that cannot be used for the substantiation of the claim (e.g. uncontrolled trials and trials with pharmacologically treated hypertensive subjects in which the evidence provided does not establish that interactions between magnesium intake and pharmacological treatment can be excluded), and that in one of the intervention studies magnesium was administered intravenously, which is not a route considered relevant for human nutrition (Kyriazis et al., 2004). The Panel considers that no conclusions can be drawn from these references (Jee et al., 2002; Burgess et al., 1999; Kyriazis et al., 2004) for the scientific substantiation of the claim.
Among the 20 RCTs which investigated the effects of magnesium supplementation on blood pressure considered in the meta-analysis by Jee et al. (2002), which were also included in the systematic review by Burgess et al. (1999), 15 (including Itoh et al., 1997) were performed in subjects with no pharmacological treatment for hypertension. The number of subjects ranged from 13 to 461, magnesium doses from 10.0 to 40 mmol/day, and intervention periods between 3 and 24 weeks. Seven trials were crossed over, eight had a parallel design, and all but one were double blind. One trial observed a significant decrease (Purvis et al., 1994) and one trial a significant increase (Nowson and Morgan, 1989) in systolic blood pressure in the magnesium group compared to controls, whereas two trials observed a significant decrease (Widman et al., 1993; Witteman et al., 1994) and two trials a significant increase (Nowson and Morgan, 1989; Patki et al., 1990) in diastolic blood pressure. The Panel notes that no significant differences between the magnesium and control groups were observed on either systolic or diastolic blood pressure in ten trials (Capuccio et al., 1985; Zemel et al., 1990; Lind et al., 1991; The TOHP (trials of hypertension prevention) Collaborative Research Group, 1992; Ferrara et al., 1992; Plum-Wirell et al., 1994; Sanjuliani et al., 1996; Itoh et al., 1997; Sacks et al., 1998; Doyle et al., 1989), including the two trials with the largest sample sizes (The TOHP (trials of hypertension prevention) Collaborative Research Group, 1992; Sacks et al., 1998, with n=461 and n=153, respectively). The Panel also notes that the third largest study (Witteman et al., 1994, n=91) observed a significant reduction in diastolic blood pressure only. The Panel considers that the evidence provided by these studies for a blood-pressure lowering effect of magnesium is weak and inconsistent.
The remaining trial, which was not included in the meta-analysis, was a double-blind RCT (Borello et al., 1996) which reported on the effects of magnesium supplementation (200 mg/day of magnesium oxide) in 83 mildly hypertensive patients without previous anti-hypertensive treatment (n=42 in the magnesium group, n=41 in the placebo (unspecified) group). All patients had periodic measurements of blood pressure and heart rate taken. In addition, a 24-hour ambulatory blood pressure monitoring was performed at the beginning and end of the study. A statistically significant reduction in systolic blood pressure was observed at the 12-week follow-up in the magnesium group compared to the placebo (148.5+/-7.1 mmHg versus 155.2+/-8.2 mmHg; p<0.01), whereas no significant difference was observed in diastolic blood pressure. The more robust 24-hour ambulatory monitoring of blood pressure showed no significant differences in systolic or diastolic blood pressure values between groups. The Panel considers that the findings of this study are not consistent regarding an effect of magnesium on blood pressure.
As regards epidemiological data, low dietary magnesium intakes have been reported to be inversely associated with blood pressure (Rude and Shils, 2006). The mechanism by which magnesium might affect blood pressure is not clear (Rude and Shils, 2006). In the systematic review by Burgess et al., 1999, five epidemiological studies were considered. Two were performed in women: one showed an association between a diet high in magnesium and a reduced risk of hypertension (based on self- reported blood pressure), the other, performed in the same population four years later after a modification in the food frequency questionnaire used to assess magnesium intakes, showed no association. Two studies performed in men did not show a clear association. The other study in both sexes showed a correlation between magnesium intake and measured blood pressure in women but not in men. The Panel considers that the epidemiological evidence for a relationship between magnesium intake and blood pressure or prevention of hypertension is weak and inconsistent.
In their joint Guidelines for the Management of Arterial Hypertension, the European Society of Hypertension (ESH) and the European Society of Cardiology (ESC), in line with other authoritative bodies, stated that the evidence for a blood pressure lowering effect of supplemental magnesium is inconsistent (Mancia et al., 2007). In their scientific statement on dietary approaches to prevent and treat hypertension (Appel et al., 2006), the American Heart Association considered data as insufficient to recommend supplemental magnesium as a means to lowering blood pressure.
In weighing the evidence, the Panel took into account that no conclusions could be drawn from the meta-analysis and the systematic review for the scientific substantiation of the claimed effect owing to the inclusion of studies that cannot be used for the substantiation of the claim, that in 16 RCTs in subjects with no pharmacological treatment for hypertension evidence for a blood-pressure lowering effect of magnesium was weak and inconsistent, and that in five epidemiological studies evidence for a relationship between magnesium intake and changes in blood pressure or prevention of hypertension was weak and inconsistent.
The Panel concludes that the evidence provided is insufficient to establish a cause and effect relationship between the dietary intake of magnesium and maintenance of normal blood pressure.
5. Warunki i możliwe ograniczenia stosowania oświadczenia
The Panel considers that in order to bear the claim a food should be at least a source of magnesium as per Annex to Regulation (EC) No 1924/2006. Such amounts can be easily consumed as part of a balanced diet. The target population is the general population. No Tolerable Upper Intake Level (UL) has been established for magnesium normally present in food and beverages. An UL for older children and adults has been established for readily dissociable magnesium salts and compounds like magnesium oxide in nutritional supplements, waters or added to food and beverages (SCF, 2001).
Warunki i możliwe ograniczenia stosowania oświadczenia
12mg/j