“…There are epidemiological and experimental data to substantiate various hypotheses:-
original
hygiene hypothesis: improved hygiene in early life, reduction of family size and number of siblings [4, 5, 14, 15],
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extended
hygiene hypothesis: replacement of traditional anthroposophic way of living, combining elements of conventional medicine (restrictive use of antibiotics, antipyretics and vaccination) with homeopathy and naturopathy (biodynamic diet) by modern lifestyle and new medical recommendations [6, 13, 16, 17]; reduced early exposure to infectious and microbial agents [9, 17–24]; shorter period of breast feeding with unfavourable changes in the gut flora [2, 11, 25, 26],
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first
dietary antioxidant hypothesis: antioxidant-depleted Western diet [1, 3, 11, 27–29],
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second dietary antioxidant hypothesis: increased availability of antioxidant-rich (“healthy’’) foods, especially dietary supplements such as vitamins, food preservatives or colorants and traditional Chinese or Vietnamese herbal medicine extracts [1, 30, 31],
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dietary lipid hypothesis: decreased consumption of saturated animal fat (butter, lard) and oily fish containing long chain n-3 polyunsaturated fatty acids (PUFA), increased intake of margarine, vegetable oils and fast food meals rich in n-6-PUFAs [1, 11, 27, 32, 33],
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dietary sodium hypothesis: sodium-rich Western diet [11, 24, 34],
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vitamin D deficiency hypothesis: decreased vitamin D synthesis in skin due to environmental, behavioural and intrinsic factors, in particular reduced exposure to solar radiation because of urban living, indoor occupation, pollution, skin coverage and excessive use of sunscreen for skin cancer prevention [1, 35, 36],
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vitamin D supplementation hypothesis: delayed side effect of early rickets prophylaxis with vitamin D supplements or excessive maternal concentration of 25(OH)-vitamin D in pregnancy [1, 37–40],
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maternal diet hypothesis: low maternal vitamin D, antioxidants and 3-ω-PUFAs intake in pregnancy [1, 3, 11, 25],
- parental smoking during pregnancy and postnatal exposure to environmental tobacco smoke [2, 5, 29, 41...
…”