Zinc has been getting a lot of publicity lately, thanks to our understandable obsession with immune function. The human immune system is extremely complex, but one thing is clear: immune function depends on several key nutrients, one of which is zinc. When your immune system is fighting off an infection or repairing an injury, zinc is mobilized and used up, so a steady supply is essential.
Good food sources of zinc include:
- Mussels and clams
You can see the theme: meat and fish, particularly shell fish, are great sources. Whole grains, nuts and beans are frequently promoted as good zinc sources, but there’s a catch. The zinc in those foods isn’t always absorbed very well because the fiber in those foods interferes with absorption. This is particularly true for whole grain foods. Fermentation of the food can change the fiber effect and improve absorption.
Let’s do some nutrition math. The recommended daily intake of zinc is 8 mg for an adult woman. By the way, this recommendation is the same for a 20 year old and a 70 year old, despite the fact that age has a negative impact on digestion and absorption of many nutrients from food. Plus as we age, we tend to eat fewer high zinc foods, like meat, for a variety of reasons: cost, preparation, chewing, appetite, etc.
Here are some examples of zinc sources, and how much of each food you’d need to eat every day to get the minimum daily recommended intake:
|zinc per serving||Servings/day = 8 mg|
|Oysters, raw||14 mg per 3 oz||1 medium oyster|
|Milk, low fat||1 mg per 8 oz cup||8 cups/day|
|Beef, cooked burger||5.4 mg/3 oz cooked||4 oz cooked burger|
|Chickpeas, cooked||1.2 mg/half cup cooked||3-1/3 cups cooked|
|Tofu cubes||1.8 mg per 4 oz portion||17 oz|
|Cheese, cheddar||1 mg/1 oz portion||8 oz cheese|
|Almonds||0.9 mg/ 1 oz almonds (about 23 whole)||1-3/4 cup whole almonds (about 200)|
|egg||0.65 mg/ large egg||12 eggs|
One oyster a day keeps the doctor away? Well, if you like oysters and can afford them and have a good source for fresh oysters, maybe you can go that route for zinc. Four ounces of cooked hamburger isn’t a stretch either. But 8 oz of cheese?? 12 eggs?? 3-1/3 cups chickpeas (garbanzo beans)??? 200 almonds (there goes your daily calorie allowance) !!
Intake vs. Absorption
A few years ago, a well-known nutrition researcher was discussing immune-critical nutrients. She was well-versed in nutrition, and noted that she was confident she was consuming the recommended zinc intake daily. BUT… when she actually tested her blood zinc level, she was deficient. She seemed shocked by this. I was not. Intake is one thing, but it’s meaningless if you aren absorbing the nutrients. They have to get into your system to be of any use.
One way to improve your chances of absorbing sufficient zinc is to take a supplement. Should you do that? There are several considerations, one of which is out of our control: knowing your blood level. No doctor I know of would ever order a blood zinc test. No insurance would pay for that on a routine basis. Maybe they should. Zinc levels will impact immune function, along with many other many other metabolic systems (skin integrity, wound healing and eye health are 3 examples). So supplementing with zinc is a shot in the dark. Maybe a good idea; maybe unnecessary. Without a blood test there’s no way to tell.
[Side Note: If you’re facing surgery, ask your surgeon to refer you for a pre-op nutrition assessment. Recovery depends on an adequate supply of key nutrients, zinc being one of them.]
The other problem with zinc supplements is the dose level. I cannot find any zinc supplements with less than 40/50 mg per tablet. This is well above the 8 mg recommendation. And there can be problems with long term use of higher doses of zinc. There’s evidence that long term supplementation with high doses of zinc could interfere with copper metabolism. The tolerable upper intake is set at 40 mg/day.
What to do? First, find the lowest dose supplement you can, which will probably be around 40-50 mg. My approach is to break the tablets in half. In fact, taking half a tablet just every other day would be a decent supplement to the zinc you also get from food.
Diet is key
Which brings up the other key point: you should include some meat, fish or poultry in your diet for the zinc content (also for the high quality protein). It’s one reason I recommend a “sometimes” vegetarian diet. Meat and fish are the best zinc sources. Dairy foods and eggs have some, but as you can see from the chart above, you’d have to eat very large amounts of dairy foods every day to get the minimum zinc intake. It’s doubtful that an older adult could stomach 8 ounces of cheese, 12 eggs or 2 quarts of milk every single day.
I know, I’m exaggerating a bit for effect. You could get 8 mg of zinc by eating 2 oz cheese, 3 eggs, 2 cups of milk and 50 almonds every day.
Many plant foods contain zinc, but not in high amounts, and as noted, the fiber in these foods can interfere with absorption. Which isn’t saying you shouldn’t still eat beans, nuts and whole grains. They have many other nutrients and health benefits.
Everyone’s diet and food preferences are different. Unless you’re a big fan of oysters, you need to pick good zinc sources. Easy to do if you eat red meats. You don’t need huge portions. But if you truly eat little or no red meat, you might consider a small supplement as discussed above. If you regularly take a multiple vitamin/mineral, you might already be taking zinc. Check the label. The amount of zinc in a multiple will likely be closer to the 8 mg/day recommendation.
Until someone in the health/medical field wakes up and pushes for routine zinc testing, we’re stuck with this guessing game. At least with a sometimes vegetarian diet, you will be consuming some high zinc foods on a regular basis.
Zinc and Migraines?
Thanks to a newly published study, you might be hearing about zinc and migraine headaches. This study used food intake data from the ongoing U.S. National Health and Nutrition Examination Survey (NHANES), using food records from more than 11,000 people. The researchers (strangely, this study was done in Beijing using U.S. data) compared zinc intake from food and supplements to reported migraine incidence. They concluded that higher zinc intakes were linked to less risk for migraines.
That’s nice. Does that mean Cause-And-Effect? No, not necessarily. People with higher zinc intake would be eating more meat or fish, so also eating more protein and more of the nutrients unique to animal foods (B12 comes to mind). As one reviewer noted, plenty of other nutrients, such as vitamin D, have been linked to migraines. So don’t rush out and buy zinc supplements thinking you’ll prevent migaines.