Scientific Opinion on the substantiation of health claims related to
vitamin D and normal function of the immune system and inflammatory
response (ID 154, 159), maintenance of normal muscle function (ID 155)
and maintenance of normal cardiovascular function (ID 159) 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:
Vitamin D
cardiovascular function
health claims
immune system
inflammatory response
muscle function
2. Znaczenie oświadczenia dla zdrowia człowieka
2.1. Prawidłowe funkcjonowanie układu odpornościowego i prawidłowy przebieg reakcji zapalnej (ID 154, 159)
The claimed effect is “immune system” and “vitamin D3 has long been known to aid in calcium absorption, but new research shows that D3 also plays a role in cardiovascular function and supports
healthy inflammatory response”. The Panel assumes that the target population is the general population.
The Panel considers that contribution to the normal function of the immune system and a healthy inflammatory response are beneficial physiological effects.
2.2. Utrzymanie prawidłowego funkcjonowania mięśni (ID 155)
The claimed effect is “muscle growth, development and function”. The Panel assumes that the target population is the general population.
The Panel considers that maintenance of normal muscle function is a beneficial physiological effect.
2.3. Utrzymanie prawidłowego funkcjonowania układu sercowo-naczyniowego (ID 159)
The claimed effect is “vitamin D3 has long been known to aid in calcium absorption, but new research shows that D3 also plays a role in cardiovascular function and supports healthy inflammatory response”. The Panel assumes that the target population is the general population.
The Panel considers that maintenance of normal cardiovascular function is a beneficial physiological effect.
3. Naukowe uzasadnienia wpływu na zdrowie człowieka -
Vitamin D can be obtained from dietary sources or can be synthesised in the body by exposure to UV-radiation from the sun. Even though it is more suitable to refer to vitamin D as a hormone, vitamin D resembles true vitamins, since humans deprived of solar exposure depend on a food source. Synthesis of vitamin D in the skin by the action of sunlight is insufficient to meet requirements in some European countries, especially during winter months when there is little sunlight exposure.
Vitamin D is biologically inactive and requires successive hydroxylations; first in the liver, where 25-hydroxyvitamin D (25-OHD) is formed, and the next hydroxylation in the kidneys form 1,25-dihydroxyvitamin D (1,25-(OH)2D), which is the biologically active form of vitamin D. 1,25-(OH)2D interacts with a specific nuclear receptor in its target tissues that results in a biological response. The major target tissues for 1,25-(OH)2D are the intestine and bone; however, nuclear receptors for 1,25-(OH)2D have been identified in several other tissues and in cultured tumour cells. Serum concentration of 25-OHD is accepted as a valid marker of vitamin D status.
The principal physiological function of vitamin D in all vertebrates including humans is to maintain serum calcium and phosphorus concentrations in a range that supports cellular processes, neuromuscular function, and bone ossification. Vitamin D accomplishes this goal by enhancing the efficiency of the small intestine to absorb dietary calcium and phosphorous, and by mobilising calcium and phosphorus from the bone.
Vitamin D also has other functions in tissues not primarily related to mineral metabolism. One example is the haematopoietic system, in which vitamin D affects cell differentiation and proliferation including such effects also in cancer cells. Vitamin D furthermore participates in the process of insulin secretion. The active metabolite of vitamin D, 1,25(OH)2D, regulate the transcription of a large number of genes through binding to a transcription factor, the vitamin D receptor (VDR) (SCF, 2002).
3.1. Prawidłowe funkcjonowanie układu odpornościowego i prawidłowy przebieg reakcji zapalnej (ID 154, 159)
Vitamin D plays a regulatory role in the functioning of the immune system. A vitamin D receptor (VDR) was identified in peripheral mononuclear cells and in both T-helper 1 (Th1) and T-helper 2 (Th2) cells. 1,25(OH)2D reduces the inflammatory response of Th1 cells, suppresses antigen presentation by dendritic cells, suppresses proliferation and immunoglobulin production and retards the differentiation of B cell precursors into plasma cells, exerting an inhibitory action on the adaptive immune system. 1,25(OH)2D increases expression of cathelicidin (LL-37), an antimicrobial peptide thought to be important for the innate immune system, especially against Mycobacterium tuberculosis (Bikle, 2009; Cantorna et al., 2008; Khazai et al., 2008).
The Panel concludes that a cause and effect relationship has been established between the dietary intake of vitamin D and contribution to the normal function of the immune system and healthy inflammatory response.
3.2. Utrzymanie prawidłowego funkcjonowania mięśni (ID 155)
The evidence provided by consensus opinions/reports from authoritative bodies and reviews shows that there is consensus on the role of vitamin D in normal muscle function (Norman and Henry, 2007; Cotler et al., 2008).
Muscle weakness is a feature of the clinical syndrome of vitamin D deficiency. Clinical symptoms of vitamin D deficiency myopathy include proximal muscle weakness, diffuse muscle pain, and gait impairments such as waddling way of walking (Schott and Wills, 1976; Ceglia, 2008).
The vitamin D receptor is expressed in human muscle tissue, and its activation may promote de novo protein synthesis in muscle (Sorensen et al., 1979).
The Panel considers that a cause and effect relationship has been established between the dietary intake of vitamin D and maintenance of normal muscle function.
3.3. Utrzymanie prawidłowego funkcjonowania układu sercowo-naczyniowego (ID 159)
Ten references were provided to substantiate the claimed effect – three legislative texts (CEDAP,1997; NHPD 2009; ODAOIOUs, 1995), one guideline for the control of health claims (NFA, 2002), one consensus opinion (JHCI, 2003), one opinion from the authoritative body (SNF, 2004), three human studies (Armas et al., 2004; Patel at al., 2007; Shoji et al., 2004), and one in vitro study (Cohen-Lahav et al., 2007).
In the opinions from JHCI (2003) and SNF (2004) the relationship between dietary intake of vitamin D and function of circulatory system is not mentioned.
Shoji et al. (2004) evaluated the effect of vitamin D3 analogue supplementation on the risk of cardiovascular mortality in haemodialysis patients with end-stage renal disease. The Panel considers that in this study the effect of vitamin D analogue given for medical purposes was assessed and no evidence was provided that haemodialysis patients are representative of the target population with regard to vitamin D status.
The association between serum 25(OH)D level and chosen clinical and laboratory markers of disease activity in patients with early inflammatory polyarthritis was studied by Patel at al. (2007). Armas et al. (2004) compared the effect of the same single dose of vitamin D2 and D3 (50.000 IU taken orally) on serum 25(OH)D concentration. In an in vitro study, the mechanism of inhibition of 1,25(OH)2D3 and 1,24(OH)2D2 on TNFα expression in macrophages was investigated (Cohen-Lahav et al., 2007). The Panel notes that the endpoints studied did not relate to the claimed effect and therefore no conclusions can be drawn from these studies for the scientific substantiation of the claimed effect.
The Panel concludes that a cause and effect relationship has not been established between the dietary intake of vitamin D and maintenance of normal cardiovascular function.
