I’ve been confused about zinc. It’s true, despite years in the nutrition biz. How can this be? I’m not confused about the fact that zinc is a nutrient, critical for immune function, gene expression, hormone regulation, protein structures, eye health (especially related to Age Related Macular Degeneration), nerve transmission and wound healing. I’m confused about whether older women can get enough from diet. And I’m confused about whether or not plenty of us are walking around with insufficient zinc status.
Adult women are supposed to consume 8 mg zinc per day. “Adult woman” is described as anyone 19 years or older. The assumption is that there’s no difference between the metabolic needs of a 19 year old and a 69 year old. Right.
The NIH Fact Sheet for Health Professionals about zinc describes all kinds of potential problems for zinc status:
- Vegetarian/vegan diets: animal-sourced foods are the best source of zinc. If you’re eating fewer of those, or none because you’re focused on a plant-based diet, your zinc intake will suffer. Consider this:
- 3 oz of beef has 7 mg of zinc, close to the daily recommendation. But what if you don’t eat beef? How about milk/yogurt? One 8-ounce cup of milk has 1 mg, so you’d need to drink 7 glasses of milk to get the same amount. Are you going to do that everyday? If you avoid dairy, it gets worse. One-half cup of kidney beans has 0.9 mg. You’d need to eat 4 cups of kidney beans per day. Everyday.
- Then there’s the added problem of phytates, substances in plant foods like whole wheat or kidney beans, that interfere with zinc absorption. Zinc recommendations for vegans are 50% higher than the standard; in other words, 12 mg/day, or 6-7 cups of kidney beans per day.
- Medications: numerous medications commonly taken by older adults can interfere with zinc absorption: antibiotics, drugs for rheumatoid arthritis, diuretics. Know anyone taking those?
- Calcium also interferes with zinc absorption. And older women are told to boost calcium intake for bone strength.
- Less food in general as we age. Do you eat the same amount of food you ate at age 19?
- Malabsorption due to digestive disturbances or chronic diarrhea, which could be caused by infections, illness, other medications, chemotherapy or other nutrient deficiencies. All more common for older adults.
Zinc deficiency is typically described as rare in the US. This statement is usually followed by a list of deficiency symptoms, including:
- loss of appetite
- loss of sense of smell
- irritability and depression
- rough dry skin
- hair loss
- slow wound healing
- Type 2 diabetes
- vision changes, especially related to the retina
- poor immune function
Hmm, know any older women or men with some of those problems?
Things that make me go “Hmmmm…”
We’re supposedly getting enough zinc from our diets, yet we’re at risk for not consuming or absorbing enough for several reasons specifically related to age. And there are lots of symptoms of zinc insufficiency that are also common in old age. All of which got me thinking about zinc more seriously.
The official government mantra is that healthy diets should provide enough zinc (that’s the official government mantra about pretty much all nutrients). To which I would add “However, read that paragraph above.” The Linus Pauling Institute list of groups at risk of zinc deficiency includes: adults 65 years and older, people who use medications that interfere with absorption and vegans/vegetarians. Declining zinc status could be a side-effect of the current focus on plant-based diets.
What to do?
Here’s one thing we can’t do: get tested for zinc status. There are no reliable blood tests that measure zinc. At best, you can add up any risk factors you might have for poor intake or poor absorption, such as avoiding meat, or taking certain medications.
You can read through the list of potential zinc insufficiency symptoms and identify the ones that that relate to you. The danger in this sort of self-diagnosis is that your symptoms could be due to something else, and taking zinc won’t be helpful. In fact, taking too much supplemental zinc can be harmful. Excessive prolonged zinc intake (ex: 60 mg/day for several weeks) can cause copper deficiency symptoms, and interfere with medications.
Multiples, particularly those for seniors, usually have adequate zinc, so if you take a multiple on a regular basis, you’re already supplementing zinc intake at a reasonable dose.
Unfortunately I haven’t found any single zinc supplements that provide just the recommended daily amount of 8 mg. Most have 2 to 3 times that amount. It’s very annoying, particularly given the risk for excess intake. If you buy one of those, you could take it 2 or 3 times/week. Or break pills in half, even taking half every other day. Zinc is a mineral; you don’t suddenly become deficient overnight if your intake was lower on one day.
I’m not confused about zinc anymore. Rather I’m concerned that
- older adults are at increased risk for insufficiency
- many common health problems of aging are linked to zinc insufficiency
- there’s no reliable test for zinc status
If you want to get most of your zinc from food, meat is the best source. Here are some examples:
6 medium oysters 27-50 mg 3 oz cooked beef 5-9 mg 3 oz dark meat turkey or chicken 2-3 mg 3 oz cooked pork 3 mg 6 oz plain yogurt 1.1 mg 8 oz milk 1 mg