The macrobiotic way of eating includes hojicha and kukicha (2 different kinds of teas) as a main beverage usually around meals, [so in light of your posting about tea affecting iron absorption,] is this a problem?
Are there studies as to which types of tea have high amounts of phytates or iron inhibitors?
Via the blog
The issue of phytates and tannins in tea reducing iron absorption is only problematic for people with borderline iron consumption and/or whose only sources of iron are of the non-heme variety.
After all, it is only that kind of iron --found in plants, eggs, and dairy -- which tea binds (heme iron, found in meat, actually helps absorb non-heme iron.)
If the two teas you mention are recommended as accompaniments to meals, it will certainly cause a higher reduction of iron absorption than if they are consumed between meals.
I recommend playing it safe and separating "tea time" and "meal time" by at least 45 minutes.
I want to make it clear that total tea consumption does not affect non-heme iron absorption; it is the TIMING of the consumption that matters.
Remember, too, that vitamin C aids in the absorption of non-heme iron.
So, squeezing a wedge of lemon into tea, or including potent sources of vitamin C in our meal (i.e.: tomatoes, red bell peppers, kale, and broccoli, to name a few) can help counteract some of tea's iron-blocking properties.
Although all teas contain phytates and tannins and affect non-heme iron absorption, black tea contains the highest levels of these inhibitors, while herbal varieties contain lower amounts.