Summary of Interactions with Vitamins, Herbs, & Foods
Replenish Depleted Nutrients
Reduce Side Effects
In controlled studies, the addition of 300 IU per day of vitamin D3 (cholecalciferol) did not improve the bone-preserving or fracture-preventing effects of hormone replacement with estradiol plus a progestin (a synthetic form of progesterone) in postmenopausal women without osteoporosis. However, in a controlled study of osteoporotic women, only those receiving both hormone replacement and vitamin D had increases in bone density of the hip; no improvement occurred in the hip with hormones alone. More research is needed to determine conclusively when vitamin D is important to add to hormone replacement.
Potential Negative Interaction
In a group of 37 postmenopausal women treated with conjugated estrogens and medroxyprogesterone for 12 months, urinary zinc and magnesium loss was reduced in those women who began the study with signs of osteoporosis and elevated zinc and magnesium excretion. The clinical significance of this interaction remains unclear.
In a small, controlled study of women with surgically removed ovaries, estradiol levels in the blood were significantly higher after estradiol was taken with grapefruit juice than when estradiol was taken alone. These results have been independently confirmed, suggesting that women taking oral estradiol should probably avoid grapefruit altogether.The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Pomegranate juice has been shown to inhibit the same enzyme that is inhibited by grapefruit juice. The degree of inhibition is about the same for each of these juices. Therefore, it would be reasonable to expect that pomegranate juice might interact with estradiol in the same way that grapefruit juice does.The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
Studies have shown that grapefruit juice significantly increases estradiol levels in the blood. One of the flavonoids found in grapefruit juice is quercetin. In a test tube study, quercetin was found to change estrogen metabolism in human liver cells in a way that increases estradiol levels and reduces other forms of estrogen. This effect is likely to increase estrogen activity in the body. However, the levels of quercetin used to alter estrogen metabolism in the test tube were much higher than levels found in the body after supplementing with quercetin.
There is evidence from test tube studies that another flavonoid in grapefruit juice, naringenin, also has estrogenic activity. It has yet to be shown that dietary or supplemental levels of quercetin (or naringenin) could create a significant problem.The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.
Last Review: 03-24-2015
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