If you were to walk the streets of Manhattan and ask 20 individuals to name all of the essential trace minerals necessary for adequate body function, how many of those individuals do you think would be able to? Could you even answer that? Unfortunately, many of us often overlook the importance of essential vitamins and minerals, and fail to understand how much of each to consume. I’ve decided to discuss the importance of trace minerals today because I’ve noticed a common theme amongst vegans. Their diets tend to lack in iron and zinc. However, it is unequivocal that if done correctly, the vegan diet can provide a plentiful amount of iron and zinc. Also, a little side note, we’re discussing trace minerals in my nutrition class this week and I’m therefore using this post as somewhat of a study tool. Let’s begin.
First things first, trace minerals are extremely important, and I did not realize this until recently. Prior to my newly acquired knowledge, I had somewhat of a sardonic attitude toward trace minerals because I took into consideration the vast majority of people who failed to consume an adequate amount of these minerals and thought well if they’re fine, then I’m probably fine too. Am I right? I was horribly wrong. Trace minerals make up only about 1% of our total body composition, yet if we neglect to consume them, problems with growth, development, various bodily functions, and overall wellness can occur. In an effort to keep this post from turning into an essay, I’m going to mainly focus on iron and zinc, and merely mention the basics of the other essential trace minerals.
Let’s begin with iron. Iron is found in a variety of foods, and can be found in two forms: heme iron (animal products), and non-heme iron (plant products). While they are different, when they are absorbed, they are essentially converted into the same thing. So whether you get your iron from plants or animals, you’re going to end up with the same Fe 2+ (iron). Because it is re-added to enriched grains during processing, enriched grain products can be a source of iron for vegans (I know no one likes the idea of consuming enriched grains these days, but I’m just letting you know it’s an option). Spinach also has a high amount of iron in it (36% daily value per 1 cup cooked spinach), however it is important to understand the following concept: Minerals from plant sources are less bioavailable than minerals from animal sources. This means that your body cannot absorb non-heme iron (iron from plant based foods) as efficiently as it can absorb heme iron (iron from animal sources). This is due to several factors. For starters, plants contain phytic acid and oxalic acid, which inhibit non-heme iron absorption because they bind to non-heme iron, and these complexes are excreted through feces. Polyphenols, found in tea and coffee also decrease heme-iron absorption. This does not mean that you cannot consume enough iron as a vegan. However, it does indicate that as a vegan, you must consume a greater quantity of iron in order to absorb an adequate amount.
Iron serves several functions in the body, therefore it is extremely important to consume enough. First, iron is a component of the proteins hemoglobin and myoglobin, which are components of blood, and muscle tissue respectively, and aid in the transport of oxygen. Iron is required for metabolism, and it is also important in the synthesis of neurotransmitters. An iron deficiency may be unnoticed at first, however it can become dangerous by eventually turning into anemia.
Have no fear veggie-heads, to increase iron absorption, increase your consumption of vitamin C. Get a blood test to make sure that you are consuming enough iron, and if you’re not, then talk to your doctor about possible options. I would stay away from supplementation, however, if it is necessary, than you may need to consider it. If you are using supplements, you must be aware that the upper limit for iron is 45mg/day. If you consume this much iron or more a day, iron poisoning may occur. Other reliable vegan sources of iron include sesame seeds (2tbsp yields approximately 22% daily value), navy beans (1 cup yields approximately 27% daily value), and most fortified cereals can provide an adequate amount of iron.
Moving onto zinc. Zinc is another essential trace mineral that vegan diets tend to lack because it is found in animal derived products (fun fact: 3oz of oysters contain 516% daily value of zinc). It is absolutely essential for proper growth and development due to its vital role in various cell functions. Unlike iron, zinc is not required to be added to fortified grains, and grain products contain high amounts of phytic acid, which as mentioned before, limit the bioavailability of trace minerals. However, active yeast increases the bioavailability of zinc up to ten times! Therefore, I recommend that vegans make sure not to skip out on baked items (I’m not saying eat cookies. I’m saying, eat baked sprouted grain or multigrain breads that were made with yeast). This is also another reason why it is a bad idea to be raw vegan.
According to the USDA, the RDA for zinc is 11mg/day for men and 8mg/day for women. The average American diet contains an sufficient amount of zinc because most Americans consume an ample amount of animal protein. Vegans need to monitor zinc intake more carefully. Vegan sources of zinc include oats, wheat bran, nutritional yeast, nuts and seeds.
Other essential minerals include Copper, Manganese, Iodine, Selenium, Chromium, and Fluoride. Molybdenum is an essential ultra trace mineral that is also vital for proper health. These minerals are listed below along with their RDA’s or AI’s, their vegan food sources, and their basic functions.
Copper: Copper is an important component or various enzymes in the body. Remember, enzymes help carry out various chemical reactions in the body, and are necessary for proper bodily function. The RDA for copper is 900μg (micrograms)/day, and Americans on average consume more than needed. Copper can be found in vegan foods such as walnuts, pecans, kidney beans, and are extremely plentiful in lentils.
Manganese: Vegans tend to consume a ton of manganese because it is primarily derived from foods such as cereals, nuts, left greens, and tea. Dairy and meat products provide very little manganese to the diet. The RDA for manganese is 1.8mg/day for women and 2.3mg/day for men. This is an AI or adequate intake value because there currently isn’t enough data to determine exactly how much is needed in the diet. Manganese, like other trace minerals is an essential component of various enzymes, and is particularly important in carbohydrate metabolism and collagen formation (collagen is the interconenctive tissue that basically supports all of your bones and muscles and such). Too much manganese can cause nerve damage and that is why the upper level is set at 11mg/day.
Iodine: The hands down best source of iodine is iodized salt. In just one teaspoon, you receive 266% of the recommended daily value. Other vegan sources of iodine include seaweed, and some bread. It is important to remember that although something may be high in sodium, it does not necessarily mean it contains iodized salt. Processed foods usually contain non-iodized salt. The RDA for iodine is 150μg (micrograms)/day. Note that the absorption of iodine is inhibited by goitrogens. These compounds limit the thyroids ability to use iodine, and they are found in foods such as raw fruits and vegetables including broccoli, peaches, strawberries, soy, peanuts and potatoes. It is important for vegans to take this into consideration because Iodine is necessary for proper function of the thyroid gland. Iodine is necessary for the regulation of metabolism via the thyroid gland.
Selenium: The greatest sources of selenium are in seafood and meat based products, however, vegans can acquire selenium from grains and cereals. The amount of selenium in a grain is dependent on how much selenium was present in the soil which the grain was grown. The RDA for selenium is 55μg (micrograms)/day. Selenium is important in 25 different enzymes and is works as part of the antioxidant defense system in the body. It may decrease risk of prostate and lung cancer.
Chromium: While not a whole lot is known about chromium, we do know that it is essential in glucose uptake and it helps normalize blood sugar levels. If one id deficient in chromium several symptoms can occur including weight loss, nerve damage, and glucose intolerance. The AI (adequate intake) for chromium according to the USDA is 35μg (micrograms)/day for men and 25μg (micrograms)/day for women. Chromium can be found in mushrooms, broccoli, dried beans, nuts, and dark chocolate.
Fluoride: This nutrient is actually debatably essential, meaning of course that normal bodily functions can occur without it. However, it does help in preventing cavities and those ugly brown spots that sometimes develop on the teeth due to lack of care. The AI for Fluoride is 3mg/day for women and 4mg/day for men, which is determined based on the amount that can prevent cavities. The best sources of fluoride are seaweed, tea, and water. Seafood also contains fluoride, but that’s not vegan.
Molybdenum: Last, but not least we have the ultra trace mineral Molybdenum. Being that it is ultra trace does not sully its significance. Molybdenum is an essential component of several enzymes that carryout various functions in the body. The AI for Molybdenum is 45μg (micrograms)/day for adults. It can be found in foods such as grains, nuts and legumes.
All of the information above is from two different sources.
- Byrd-Bredbenner, C., Moe, G., Beshgetoor, D., & Berning, J. (2013). Wardlaw’s Perspectives In Nutrition (9th ed.). New York, NY: McGraw-Hill.