If you’ve been reading my blog for a while, you already understand how important Zinc is to our health and well-being. Zinc is an essential trace-mineral, without which we could not develop and grow properly. Increasing our consumption of zinc-rich foods can help to prevent birth defects, keep our hormones and neurotransmitters in check, and help us maintain our natural beauty. Zinc can even prevent and reverse hair loss and infertility.
Even if you’re not a vegan, you’ve probably noticed that most of the zinc-rich foods promoted in the media are sourced from animals, despite the fact that most fruits and many vegetables contain zinc as well. And a few plants contain more zinc per serving than many animal sources. Below, I’ve listed the ten best plant sources for zinc, as well as the amounts per serving size.
Top 10 Zinc-Rich Plant Foods
- Watermelon seeds, 100 grams – 10mg/serving
- Dark chocolate, 100 grams – 9.6mg/serving
- Napa Cabbage, 1 cup – 4mg/serving
- Flax seeds, ½ cup whole seeds – 3.65mg/serving
- Sesame seeds, ¼ cup – 2.79mg/serving
- Pumpkin seeds, ¼ cup – 2.52mg/serving
- Green peas, 1 cup – 1.8mg/serving
- Lima beans, 1 cup cooked – 1.79mg/serving
- Cashews, 1 ounce dry roasted – 1.6mg/serving
- Spinach, cooked, 1 cup – 1.37mg/serving
- Chickpeas, ½ cup cooked – 1.3mg/serving
- Brown rice, 1 cup cooked – 1.21mg/serving
- Oatmeal, 1 packet instant, plain, prepared with water – 1.1mg/serving
- Peanuts, 1 ounce – 1mg/serving
- Shiitake mushrooms, ½ cup – 0.96mg/serving
- Kidney beans, 1 cup cooked – 0.9mg/serving
- Avocado, 1 cup – 0.9mg/serving
- Blackberries, 1 cup – 0.8mg/serving
- Asparagus, 1 cup – 0.7mg/serving
- Corn, 1 cup cooked – 0.7mg/serving
- Peas, ½ cup cooked – 0.5mg/serving
- Raspberries, 1 cup – 0.5mg/serving
- Loganberries, 1 cup – 0.5mg/serving
- Brussels sprouts, 1 cup – 0.4mg/serving
- Pumpkin, 1 cup – 0.4mg/serving
- Garlic, 1 ounce – 0.3mg/serving
- Dates, one whole pitted – 0.1mg/each
Most fruits, seeds, and many vegetables contain zinc, but the top 10 contain above average amounts and are easy to find in most North American grocery stores. The top 2 zinc-rich plant foods contain more zinc per serving than most animal sources.
How Much Zinc Do We Need?
Our zinc requirements depend mostly on age, but also gender and state of maternity. In the case of infants 0-6 months, there is no true RDA (recommended daily allowance), only an AI (adequate intake) amount, which is 2mg.
Adequate intake is the level that is assumed to ensure nutritional adequacy. It is established when evidence is insufficient to develop an RDA. The RDA is only slightly above adequate intake levels, in most cases. This is especially true for trace-minerals, like zinc. Below, is the NIH (National Institutes of Health) Recommended Dietary Allowance table for Zinc. Keep in mind, all amounts are per day.
Recommended Dietary Allowance for Zinc
How Much Zinc Is Too Much?
As Zinc is a trace mineral, we don’t need much at all to stay healthy. And it takes more than 4 times the highest RDA for adults (and over a fairly long period of time) before zinc becomes harmful. The highest level of nutrient intake we can consume without suffering potentially dangerous side effects is called the Tolerable Upper Intake Level (UL). Below, is the NIH’s UL table for Zinc. Again, all amounts are per day.
Tolerable Upper Intake Level for Zinc
Symptoms of Zinc Overdose
The symptoms of a zinc overdose (also known as “zinc toxicity”) include, but are not limited to…
- abdominal cramping
- severe headaches
- nerve damage
- decreased appetite
- copper deficiency
- flu-like symptoms
- frequent infections
One of the more concerning side effects of consuming excessive amounts of zinc is a copper deficiency. Copper and zinc balance each other out, and excessive amounts of zinc will decrease your supply of copper. The National Institutes of Health Office of Dietary Supplements has stated that taking 150-450 mg of zinc has not only been linked to copper deficiency but also lowered immune system function and a decrease in HDL “good” cholesterol levels.
It would be very difficult, if not impossible, to reach these excessive levels of zinc through diet, especially since most of the foods that contain zinc also contain copper. FYI, an excessive intake of copper will, in turn, lead to a zinc deficiency, with many of the same and even more alarming symptoms.
The possibility of excess is one important reason why we should all strive to get most, if not all, of our zinc (and copper) from the foods we eat. We must also be aware that it’s not just supplements that we must be cautious of.
Non-Dietary Zinc Sources
Several years ago, it was discovered that a number of nerve damage cases, with no obvious cause, were the result of two commonplace personal care products for denture wearers: PoligripTM and FixodentTM. They both contained zinc – at that time – and users were absorbing excess amounts from these products in addition to what they were getting from their diets.
The extremely low levels of copper caused by the excess zinc, in addition to the toxic effects of the zinc itself, lead to bone marrow suppression and degeneration of the spinal cord, resulting in crippling nerve damage to some users of these products. The condition is commonly known as ‘human swayback disease’.
Some of those affected by these products ended up in wheelchairs and at least one died. The manufacturer of PoligripTM promptly removed the zinc from their denture adhesive and settled with complainants. FixodentTM was not so quick to do either, and at least one lawsuit against the manufacturer was dismissed for lack of “valid scientific evidence”.1
One crucial lesson we can take away from that unfortunate denture adhesive fiasco is the importance of investigating the ingredients in our personal care products, particularly those that are used in the mouth.
If you have any questions or comments on the topic of zinc-rich foods or want to share your list of zinc-containing products to avoid, post them below or tweet me on Twitter.
1 L. Pearle, J. Hill, C. Vlasto and C. Andreadis. “Fixodent: Can Excessive Use of Popular Denture Cream Cause Nerve Damage?” ABC News, February 8, 2011. Web. August 2018
Hanks, Heather, MS. CAM. “26 Foods High in Zinc for Overall Good Health”. Health Wholeness, n.d. Web. August 2018
“Zinc – Fact Sheet for Health Professionals”. National Institutes of Health (NIH), March 2, 2018. Web. August 2018
Meixner, Makayla, RD. “7 Signs and Symptoms of Zinc Overdose”. Healthline, June 16, 2018. Web. August 2018
DeNoon, Daniel J. “Zinc Poisoning Linked to Popular Denture Creams.” WebMD, February 15, 2011. Web. August 2018