Table 4. Coefficient of variation (CV) for the FRAP antioxidant capacity (A), phenolic content (P) and flavonoid content (F) for 58 bottles of over the counter herbal supplements extracted with hot water and methanol.
| Water Extraction | Methanol Extraction | |||||||
|---|---|---|---|---|---|---|---|---|
| Supplier | Supplement | Bottle | A (TE)* | P (GAE) | F (CE) | A (TE) | P (GAE) | F (CE) |
| Nature’s Way | Aloe | 1 | 34.27 | 31.93 | 55.40 | 9.87 | 22.60 | 18.89 |
| Nature’s Way | Aloe | 2 | 6.29 | 4.23 | 2.67 | 11.03 | 21.01 | 13.85 |
| Nature’s Way | Astragalus | 1 | 48.62 | 23.81 | 122.55 | 6.88 | 20.67 | 44.39 |
| Nature’s Way | Astragalus | 2 | 15.00 | 13.39 | 11.93 | 66.72 | 7.85 | 11.25 |
| NOW | Astragalus | 1 | 9.37 | 38.60 | 7.23 | 12.69 | 15.35 | 9.24 |
| NOW | Astragalus | 2 | 9.34 | 27.84 | 9.94 | 18.00 | 14.53 | 18.24 |
| NOW | Biotin | 1 | 89.13 | 38.71 | 120.00 | 4.13 | 30.10 | 61.70 |
| NOW | Biotin | 2 | 22.23 | 18.81 | 0 | 161.93 | 25.24 | 0 |
| Nature’s Way | Cranberry | 1 | 44.42 | 22.15 | 68.28 | 20.64 | 39.01 | 34.59 |
| Nature’s Way | Cranberry | 2 | 9.79 | 8.39 | 10.65 | 14.22 | 26.90 | 43.47 |
| Spring Valley | Echinacea | 1 | 18.53 | 33.17 | 14.77 | 6.49 | 15.99 | 21.20 |
| Spring Valley | Echinacea | 2 | 59.95 | 14.16 | 8.21 | 7.38 | 27.26 | 8.90 |
| Sundown Naturals | Echinacea | 1 | 17.65 | 24.75 | 23.89 | 19.41 | 30.35 | 61.54 |
| Sundown Naturals | Echinacea | 2 | 7.89 | 29.93 | 25.39 | 18.06 | 187.57 | 57.86 |
| Nature’s Way | Echinacea Goldenseal | 1 | 22.63 | 22.36 | 16.03 | 9.03 | 12.89 | 5.59 |
| Nature’s Way | Echinacea Goldenseal | 2 | 9.07 | 9.59 | 9.27 | 2.53 | 47.92 | 23.05 |
| Spring Valley | Echinacea Goldenseal | 1 | 48.99 | 33.33 | 23.54 | 20.71 | 17.53 | 109.15 |
| Spring Valley | Echinacea Goldenseal | 2 | 11.57 | 25.67 | 34.89 | 11.02 | 18.91 | 78.70 |
| NOW | Ginger | 1 | 8.89 | 13.08 | 9.40 | 20.11 | 7.44 | 17.21 |
| NOW | Ginger | 2 | 9.93 | 22.92 | 14.38 | 14.37 | 9.24 | 51.64 |
| Spring Valley | Ginger | 1 | 11.56 | 40.34 | 15.49 | 9.03 | 11.37 | 18.94 |
| Spring Valley | Ginger | 2 | 31.40 | 15.15 | 12.96 | 3.08 | 33.48 | 6.07 |
| Sundown Naturals | Ginseng Xtra | 1 | 14.36 | 26.78 | 9.05 | 27.77 | 19.56 | 13.50 |
| Sundown Naturals | Ginseng Xtra | 2 | 21.23 | 39.37 | 0.00 | 22.53 | 24.74 | 300.00 |
| Spring Valley | Korean Panax Ginseng | 1 | 68.47 | 35.99 | 52.03 | 8.64 | 16.34 | 84.05 |
| Spring Valley | Korean Panax Ginseng | 2 | 0 | 169.19 | 0 | 0 | 40.26 | 0 |
| Nature’s Way | Red Raspberry Leaf | 1 | 15.12 | 6.80 | 4.18 | 4.81 | 23.30 | 4.43 |
| Nature’s Way | Red Raspberry Leaf | 2 | 19.94 | 5.26 | 8.49 | 5.46 | 11.82 | 5.95 |
| Nature’s Way | Reishi | 1 | 66.15 | 26.32 | 65.56 | 4.10 | 21.29 | 85.03 |
| Nature’s Way | Reishi | 2 | 9.08 | 15.65 | 3.33 | 49.90 | 37.46 | 16.58 |
| Nature’s Way | Rhodiola | 1 | 14.92 | 14.74 | 8.67 | 76.74 | 14.49 | 38.66 |
| Nature’s Way | Rhodiola | 2 | 15.54 | 11.11 | 8.88 | 39.92 | 20.68 | 23.25 |
| NOW | Rhodiola | 1 | 24.67 | 61.57 | 30.61 | 31.51 | 38.45 | 14.84 |
| NOW | Rhodiola | 2 | 28.32 | 35.93 | 25.55 | 18.20 | 20.38 | 26.13 |
| Nature’s Way | Silent Night | 1 | 10.86 | 6.76 | 12.69 | 49.61 | 6.99 | 9.37 |
| Nature’s Way | Silent Night | 2 | 23.26 | 23.57 | 30.14 | 10.54 | 17.10 | 53.23 |
| Nature’s Way | St. John’s Wort | 1 | 6.10 | 14.19 | 12.64 | 5.17 | 9.00 | 11.68 |
| Nature’s Way | St. John’s Wort | 2 | 22.68 | 36.18 | 13.53 | 23.70 | 22.51 | 8.52 |
| Spring Valley | St. John’s Wort | 1 | 29.28 | 22.40 | 26.44 | 33.89 | 10.29 | 14.67 |
| Spring Valley | St. John’s Wort | 2 | 11.91 | 10.84 | 11.15 | 18.59 | 11.85 | 8.03 |
| Sundown Naturals | St. John’s Wort | 1 | 24.80 | 20.51 | 20.13 | 14.19 | 15.51 | 11.69 |
| Sundown Naturals | St. John’s Wort | 2 | 20.72 | 9.14 | 16.58 | 13.46 | 9.42 | 9.60 |
| Sundown Naturals | Stress formula | 1 | 13.37 | 14.29 | 10.36 | 2.81 | 21.63 | 19.89 |
| Sundown Naturals | Stress formula | 2 | 18.67 | 17.96 | 17.95 | 9.91 | 84.20 | 8.70 |
| Nature’s Way | Turmeric | 2 | 15.44 | 18.38 | 0.00 | 28.72 | 28.90 | 29.30 |
| Nature’s Way | Turmeric | 1 | 19.19 | 31.13 | 0.00 | 9.99 | 13.82 | 8.85 |
| Spring Valley | Turmeric | 1 | 81.06 | 31.66 | 71.04 | 22.68 | 25.95 | 34.31 |
| Spring Valley | Turmeric | 2 | 20.81 | 21.45 | 10.13 | 15.68 | 25.50 | 25.26 |
| Sundown Naturals | Turmeric | 1 | 9.81 | 30.67 | 18.66 | 14.29 | 37.41 | 25.29 |
| Sundown Naturals | Turmeric | 2 | 16.68 | 40.59 | 45.14 | 12.25 | 13.10 | 13.48 |
| Nature’s Way | Valerian Root | 1 | 3.45 | 7.56 | 14.70 | 18.34 | 19.56 | 12.90 |
| Nature’s Way | Valerian Root | 2 | 17.96 | 9.84 | 10.37 | 36.01 | 17.17 | 22.74 |
| Spring Valley | Valerian Root | 1 | 256.21 | 15.81 | 39.06 | 5.23 | 12.28 | 54.16 |
| Spring Valley | Valerian Root | 2 | 15.71 | 41.21 | 17.44 | 11.86 | 75.11 | 12.73 |
| Sundown Naturals | Valerian Root | 1 | 7.63 | 10.20 | 12.86 | 18.19 | 23.35 | 24.48 |
| Sundown Naturals | Valerian Root | 2 | 17.96 | 31.90 | 10.20 | 22.82 | 16.68 | 16.32 |
| Nature’s Way | Yarrow | 1 | 34.58 | 38.81 | 28.12 | 12.22 | 23.18 | 21.63 |
| Nature’s Way | Yarrow | 2 | 24.06 | 39.45 | 24.53 | 5.09 | 21.86 | 7.82 |
| Rank Runs Test (p-values) | 0.114 | 0.114 | 0.993 | 0.993 | 0.008 | 0.002 | ||
* The assays include the Ferrric Reducing Antioxidant Power (FRAP) assay for antioxidant capacity expressed as Trolox equivalents per gram, the Folin-Ciocalteu method for phenolics expressed as gallic acid equivalents per gram (GAE), and the AlCl3 precipitation assay for flavonoids expressed as +-catechin equivalents per gram. The CV was based on a sample size of 10 pills from each bottle.