TABLE 2.
Circadian variations in breast-milk concentrations for thiamin, riboflavin, niacin, fat, and vitamins B-6, B-12, A, and E for days 1–31
| Vitamin or fat, % |
|||||||||||
| Time (24 h)2 | n | Thiamin | Riboflavin | Niacin | Vitamin B-6 | Vitamin B-12 | Vitamin A | Vitamin E | Fat | Vitamin Afat | Vitamin Efat |
| Day 1 | |||||||||||
| 0800–0859 | 17 | 85* | 70* | 82 | 94 | 121 | 80 | 97 | 90 | 101 | 103 |
| 0900–0959 | 3 | 95 | 39 | 42 | 126 | 34 | 119 | 98 | 117 | 101 | 91 |
| 1000–1059 | 12 | 91 | 133 | 102 | 103 | 74* | 138 | 119 | 105 | 94 | 105 |
| 1100–1159 | 10 | 101 | 83 | 122 | 106 | 146* | 98 | 101 | 96 | 81 | 116 |
| 1200–1259 | 6 | 118* | 169* | 75 | 116 | 61 | 84 | 107 | 87 | 108 | 116 |
| 1300–1359 | 11 | 100 | 96 | 79 | 94 | 117 | 107 | 112 | 114 | 108 | 83 |
| 1400–1459 | 9 | 103 | 95 | 166 | 131 | 137* | 117* | 142* | 123* | 96 | 101 |
| 1500–1559 | 8 | 115 | 101 | 73 | 106 | 119 | 120 | 105 | 133 | 82 | 89 |
| 1600–1659 | 12 | 85 | 121 | 112 | 88 | 94 | 119 | 101 | 93 | 132 | 108 |
| 1700–1759 | 9 | 108 | 102 | 99 | 107 | 75 | 71 | 87 | 108 | 82 | 93 |
| 1800–1859 | 9 | 81 | 86 | 117 | 92* | 162 | 146 | 136 | 112 | 107 | 111 |
| 1900–1959 | 7 | 107 | 153 | 125 | 136* | 146 | 90 | 105 | 96 | 185 | 109 |
| 2000–2159 | 20 | 103 | 111 | 88 | 105 | 126 | 121 | 96 | 111 | 127 | 82 |
| 2200–2359 | 12 | 124 | 131 | 93 | 113 | 105 | 126 | 82 | 89 | 122 | 90 |
| 0000–0159 | 12 | 98 | 79 | 112 | 69* | 75 | 69* | 83* | 78* | 80 | 93 |
| 0200–0359 | 11 | 96* | 79* | 50* | 67* | 59* | 69 | 82 | 80 | 81 | 90 |
| 0400–0559 | 10 | 108* | 146 | 102 | 67 | 63* | 109* | 81 | 80 | 128 | 95 |
| 0600–0759 | 9 | 76* | 61* | 80* | 71* | 108 | 87 | 84 | 90 | 92 | 108 |
| Daily median3 | 187 | 137 | 34.3 | 265 | 86.9 | 145 | 48.8 | 45.1 | 58.4 | 29.4 | 182 |
| Variance due to circadian fluctuation, % | 3.7 | 2.1 | 3.0 | 3.0 | 8.6 | 5.4 | 5.5 | 8.7 | <0.5 | <0.5 | |
| Variance due to between-subject variability, % | 81.8 | 86.3 | 73.7 | 76.8 | 54.6 | 56.7 | 48.0 | 18.7 | 67.2 | 58.4 | |
| Variance due to within-subject variability, % | 14.5 | 11.6 | 23.3 | 20.2 | 36.8 | 37.9 | 46.5 | 72.6 | 32.8 | 41.6 | |
| Day 2 | |||||||||||
| 0800–0859 | 17 | 90* | 69* | 69 | 76 | 92 | 126 | 118* | 96 | 120 | 109 |
| 0900–0959 | 7 | 100 | 159* | 116 | 105* | 55 | 98 | 123 | 111 | 88 | 90 |
| 1000–1059 | 8 | 86 | 127* | 85 | 86 | 145 | 132 | 130 | 120* | 118 | 104 |
| 1100–1159 | 10 | 107* | 167* | 97 | 127* | 54 | 119 | 113 | 100 | 112 | 118 |
| 1200–1259 | 12 | 97* | 136* | 103* | 119* | 131 | 99* | 125* | 111 | 87 | 114 |
| 1300–1359 | 4 | 117 | 220 | 155 | 128 | 172* | 210 | 93 | 106 | 203 | 68 |
| 1400–1459 | 8 | 110 | 106 | 100 | 78 | 132 | 120* | 113* | 131* | 91 | 81 |
| 1500–1559 | 10 | 112 | 113 | 115 | 128 | 85 | 146 | 103 | 104 | 129 | 98 |
| 1600–1659 | 10 | 88 | 80 | 90* | 108 | 156 | 113* | 147* | 100 | 92 | 110 |
| 1700–1759 | 10 | 110 | 95 | 115 | 93 | 118 | 119 | 99 | 104 | 134 | 78 |
| 1800–1859 | 4 | 105 | 119 | 154 | 82 | 89 | 107 | 117 | 129 | 82 | 80 |
| 1900–1959 | 8 | 76 | 68 | 67 | 91 | 123 | 101 | 116 | 79 | 155 | 112 |
| 2000–2159 | 16 | 111 | 97 | 101 | 85 | 72 | 92 | 94 | 96 | 92 | 86 |
| 2200–2359 | 17 | 93 | 100 | 109 | 103 | 100 | 101 | 79 | 103 | 102 | 119 |
| 0000–0159 | 10 | 94* | 78 | 80 | 59* | 84 | 76* | 77* | 64* | 110 | 127 |
| 0200–0359 | 10 | 82* | 62* | 66* | 111 | 89 | 69* | 87* | 76* | 84 | 113 |
| 0400–0559 | 5 | 113 | 125 | 108* | 113 | 72 | 111 | 70 | 74 | 155 | 84 |
| 0600–0759 | 13 | 74* | 76* | 75* | 114 | 74 | 78* | 91 | 83 | 91* | 85 |
| Daily median3 | 179 | 160 | 45.1 | 229 | 126 | 146 | 53.2 | 42.3 | 55.7 | 32.3 | 190 |
| Variance due to circadian fluctuation, % | 3.4 | 6.6 | 3.1 | 5.5 | 3.2 | 6.8 | 6.9 | 15.4 | <0.5 | <0.5 | |
| Variance due to between-subject variability, % | 85.3 | 79.6 | 79.1 | 74.5 | 49.9 | 66.1 | 51.8 | 8.4 | 67.7 | 46.9 | |
| Variance due to within-subject variability, % | 11.3 | 13.8 | 17.8 | 19.9 | 46.9 | 27.2 | 41.2 | 76.2 | 32.3 | 53.1 | |
| Day 3 | |||||||||||
| 0800–0859 | 16 | 86* | 61* | 96 | 69* | 88 | 91 | 107 | 106 | 85 | 88 |
| 0900–0959 | 7 | 99 | 167* | 97 | 83 | 61 | 107 | 135 | 119 | 100 | 113 |
| 1000–1059 | 8 | 101 | 972* | 105 | 228* | 102 | 96 | 107 | 129 | 108 | 86 |
| 1100–1159 | 10 | 107 | 476* | 88 | 134* | 82 | 76 | 90 | 89 | 93 | 111 |
| 1200–1259 | 8 | 99* | 188* | 168* | 210* | 125* | 139* | 131* | 101 | 142* | 102 |
| 1300–1359 | 11 | 132* | 288* | 78* | 283* | 84 | 114 | 118 | 106 | 115* | 93 |
| 1400–1459 | 6 | 95 | 114 | 117 | 183* | 86 | 142* | 100* | 77 | 153* | 137* |
| 1500–1559 | 14 | 118* | 133 | 140* | 107 | 118* | 125* | 111 | 117* | 101 | 107 |
| 1600–1659 | 6 | 83 | 70 | 81* | 111 | 124 | 114 | 120 | 104 | 72 | 108 |
| 1700–1759 | 7 | 116 | 151 | 103 | 102* | 131 | 190 | 89 | 101 | 188 | 97 |
| 1800–1859 | 9 | 107 | 94 | 162 | 126 | 132 | 88 | 101 | 112 | 93 | 97 |
| 1900–1959 | 6 | 121 | 121 | 123 | 117 | 101 | 123 | 71 | 93 | 97 | 76 |
| 2000–2159 | 16 | 94 | 71* | 87 | 82 | 83 | 88 | 108 | 98 | 100 | 98 |
| 2200–2359 | 17 | 89 | 62* | 126 | 80* | 113 | 88 | 97 | 97 | 89 | 105 |
| 0000–0159 | 4 | 97* | 57* | 66 | 54* | 61 | 78 | 86 | 85 | 80 | 95 |
| 0200–0359 | 9 | 98* | 86 | 108* | 77* | 61* | 75 | 80 | 97 | 104 | 83 |
| 0400–0559 | 10 | 83* | 42* | 85* | 64* | 98 | 64 | 87 | 88 | 100 | 116 |
| 0600–0759 | 9 | 80* | 41* | 92* | 94* | 126* | 71* | 83 | 70* | 72 | 126* |
| Daily median3 | 173 | 166 | 64.7 | 193 | 214 | 145 | 60.2 | 41.9 | 56.0 | 37.9 | 172 |
| Variance due to circadian fluctuation, % | 8.8 | 40.5 | 6.2 | 23.9 | 3.9 | 5.8 | 2.0 | 7.0 | <0.5 | 0.9 | |
| Variance due to between-subject variability, % | 70.0 | 30.5 | 82.4 | 59.3 | 66.9 | 59.5 | 48.1 | 23.9 | 64.3 | 59.9 | |
| Variance due to within-subject variability, % | 21.2 | 29.0 | 11.4 | 16.8 | 29.2 | 34.8 | 49.9 | 69.1 | 35.4 | 39.2 | |
Values are relative medians (%) compared with the daily median unless otherwise indicated. Relative median: for each day, medians were determined for each time interval as shown and divided by the overall daily median. Values were obtained from mean values of aliquot III (full-breast aliquot) of the milk sample collection from 18 healthy Bangladeshi mothers at 2–4 mo of lactation. Mixed-model analysis of transformed values was used to identify the most-representative sample collection time and to estimate the percentage of variance due to hourly fluctuation and subject variability. *Different from the daily median, P < 0.05. Fat, milk fat; Vitamin Afat, vitamin A adjusted for milk fat; vitamin Efat, vitamin E adjusted for milk fat.
The optimal times for collection with no significant differences of concentrations from the daily median are as follows: Day 1: 0900–0959, 1300–1359, 1500–1759, 2000–2359; Day 2: 1500–1559, 1700–2359; Day 3: 1800–1959.
Vitamin A (μg/100 mL); vitamin Afat (nmol/g milk fat); thiamin, riboflavin, niacin, and vitamin B-6 (μg/L); vitamin B-12 (ng/L); vitamin E (μg/10 mL); vitamin Efat (nmol/g milk fat); fat (g/L).