Some thoughts on zinc supplementation

My thought over the last few weeks is that men who eat a primarily vegan/vegetarian diet almost certainly need to supplement with zinc. People who eat a vegan/vegetarian diet often do not get nearly as much zinc in their diets as people who eat meat. Men need more zinc than women as it has an essential role in the male reproductive system in addition to the multitude of other functions in the body. Therefore, at the intersection of those populations zinc supplementation seems likely to be indicated.

As for myself, I took an aqueous zinc test a few weeks ago and it indicated a significant deficiency in zinc. At first I wanted to investigate getting more zinc through dietary changes and I was surprised to learn just how difficult that would be. The DRI for adult men is 11mg/day (8mg/day for adult women when not pregnant or lactating). And there are many medical professionals who suggest higher levels. In fact the US RDA has been 15mg since 1974. Here’s what Dr. Elson M. Haas, MD¬†recommends:

We probably need 15 to 30 mg of available (elemental) zinc daily for maintenance and probably about 30 to 60 mg for treatment, although more is sometimes used.

– “Staying Healthy with Nutrition” p. 214

In investigating dietary sources of zinc I was surprised to learn how little zinc was in vegetarian foods. Two important points need to be made about finding dietary sources of any nutrient. First, various food tables list the amount of a given nutrient for a food but this amount is not intrinsic to the food. While certain foods do retain higher amounts of certain nutrients it is important to note that there may be quite a range of nutrient presence in a given food due to soil conditions, fertilizers, chemicals, etc. Second, it is clear that mineral content of vegetables has declined significantly over the past century in the US. So the nutrient values of foods does not appear fixed but rather in decline.

If I wanted to get just the DRI of zinc from vegetarian foods I could eat:

  • 3 cups of raw peanuts per day
  • 4 cups of cooked black-eyed peas per day
  • 6 cups of cooked green peas, garbanzo beans, or lentils per day
  • 9 cups of cooked spinach per day
  • 22 eggs per day
  • 12 glasses of milk per day (when not lactose-intolerant)

None of those options, even in combination, is very appealing. Other options touted are cereals fortified with zinc, which is basically a poor form of supplementation, and several grains, which are naturally higher in zinc but since they cannot be consumed in their raw forms by humans one has to wonder how much zinc is in the edible forms. The only food that seems like one could reasonably consume to get more zinc are seeds. The numbers for zinc present in raw seeds is hard to come by but it seems like about two cups per day of sesame, pumpkin, squash, and/or watermelon seeds should reach the DRI.

Of course, for those who suspect, as I do, that the DRI is too low, and want to raise their intake of daily zinc to something closer to 30mg then even seeds are not going to be sufficient to reach that level. Although one should still try to eat a variety of zinc containing foods, supplementing with zinc is probably the easiest way to reach higher levels of daily zinc consumption.


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