Please note that the information in this blog is not intended as medical advice. Please consult your doctor before taking supplements. The recommended intakes are general recommendations for adults; children, pregnant women and people with some medical conditions may have different needs to those listed below.
Minerals are key players in the body’s immune responses, metabolism (energy), hormones and normal functioning throughout life, and deficiencies can lead to chronic inflammatory and fibrotic diseases and a large range of symptoms including fatigue, difficulty concentrating and poor memory.
Minerals are fundamental to many aspects of human biology, and to remain healthy we must be obtain sufficient amounts from what we consume. Minerals are key players in the body’s immune responses, metabolism (energy), hormones and normal functioning throughout life, and deficiencies can lead to chronic inflammatory and fibrotic diseases and a large range of symptoms including fatigue, difficulty concentrating and poor memory. Some minerals are micronutrients that we only need in trace (tiny) amounts, while others are needed in relatively large amounts.
Although minerals are obtained from our diet, and most healthy people don’t need supplements, mineral deficiencies are common. Chronic inflammation can increase requirements and gender often has an influence on the recommended daily intake. For example, women frequently have low levels of iron, and often need iron supplements. People with diarrhoea and those taking antacids such as proton pump inhibitors for stomach problems can have mineral deficiencies.
If you’re taking more than one mineral supplement it’s a good idea to take them several hours apart.
So, it’s good to have an understanding of the Recommended Dietary Intakes (RDI) and have the necessary tests to check if your body has adequate levels of minerals. Note that the RDI is the amount obtained overall, including from food. As with many aspects of health, balance is important. Consuming more of any particular mineral (or vitamin) is not necessarily better and can sometimes be dangerous if it’s above the Tolerable Upper Intake Level (TUI). So it’s a good idea to check supplements you may be taking, particularly multivitamins, to make sure that the TUI isn’t exceeded.
The form that minerals are taken in is also important. Some forms in supplements are not easily absorbed and can cause digestive problems – for example, magnesium oxide, the most commonly sold form of magnesium, is poorly absorbed and may cause diarrhoea. In addition, minerals can interact with the absorption of other minerals if they’re taken together, and can interact with some medications. So, if you’re taking more than one mineral supplement it’s a good idea to take them several hours apart. For example, calcium and magnesium can reduce each other’s absorption.
Magnesium deficiencies are common in western countries, with only about half of adults in the US obtaining sufficient amounts of magnesium from their diet.
The majority of this information is from the National Institutes of Health with additional information from ConsumerLab and published research. Please note that I haven’t attempted to list all of the minerals needed for good health, or all of the possible interactions with medications or health conditions in this blog.
Magnesium
Recommended Dietary Intake
• Women 320 mg/day
• Men 420 mg/day
Tolerable Upper Intake Level
The NIH recommends no more than 350 mg/day taken as a supplement (not including dietary forms). Higher doses can cause diarrhoea and nausea.
Importance
Magnesium is necessary for energy production, protein synthesis, muscle and nerve function, blood glucose control, blood pressure regulation and bone health. Less than 1% of the magnesium in our bodies is in the blood, with the rest occurring inside cells and bones, so blood tests are not accurate methods for detecting deficiency. Urinary magnesium is sometimes measured after magnesium dosing to see how much the body needs to hold onto due to a deficiency.
Forms
Water soluble forms like magnesium citrate, lactate and bisglycinate are better absorbed and generally better tolerated. Magnesium oxide, carbonate, chloride, sulphate can cause diarrhoea. Note that magnesium oxide is used in laxatives to treat people who are constipated.
Interactions
Very high doses of zinc from supplements (142 mg/day) can reduce magnesium absorption. Some diuretics can increase magnesium absorption, others can reduce it. Magnesium can interfere with some antibiotics.
Magnesium deficiency
Adequate amounts of magnesium can often be obtained from eating a healthy diet. However, magnesium deficiencies are common in western countries, with only about half of adults in the US obtaining sufficient amounts of magnesium from their diet [1]. If people consistently consume less magnesium than needed this can increase the risk of illnesses including high blood pressure, cardiovascular diseases (heart disease and stroke), type 2 diabetes, gout and migraines. When magnesium supplements are needed, around 150 to 200 mg daily should be enough. Be aware that many supplements contain magnesium (sometimes well in excess of the recommended amounts), for example, calcium supplements, so always check the label. Magnesium supplements may help to treat dementia.
Food containing magnesium
• Almonds
• Spinach
• Cashews
• Legumes
• Seeds
• Peanuts
• Cereal
• Rice, brown
• Yoghurt
• Beans
• Bananas
Zinc
Recommended Dietary Intake
• Women 8 mg/day
• Men 11 mg/day
Tolerable Upper Intake Level
40 mg. Doses of 50 mg zinc or more can interfere with copper absorption (which can cause low copper status), reduce immune function, and lower good cholesterol levels. High zinc from supplements can cause diarrhoea, headaches, reduce immune function, nausea etc.
Importance
Zinc is essential for many functions including proper immune function, wound healing, cell signalling and DNA synthesis. It’s required for hundreds of enzymes.
Forms
Around 60 % of zinc citrate and zinc gluconate are absorbed. Only 50% of zinc oxide is absorbed.
Interactions
Large doses of zinc can reduce copper absorption and lead to copper deficiency. Zinc absorption can be reduced by larger doses of iron in supplements (but not in food). Zinc can interact with some antibiotics and diuretics.
Zinc deficiency
Most people obtain sufficient amounts of zinc from their diets. However, in the US 15% of adults have zinc intakes below the Estimated Average Requirement (RDI). Zinc deficiencies increase with age, with 20% or more of people over the age of 50 being deficient in the US [1]. A deficiency can cause problems with skin, bones, digestion, nerves and ability to fight infections. Zinc deficiencies can also cause a lack of taste and smell. Zinc supplements may help people with age-related macular degeneration, respiratory infections, and type 2 diabetes.
Blood tests are used to access zinc status, but levels in blood fluctuate during the day, and levels decrease during infections and illness. People with gastrointestinal disorders, type 2 diabetes, vegetarians and people with alcohol use disorders are more likely to have a zinc deficiency. People with thyroid conditions (a common cause of hair loss), can have an acquired zinc deficiency [2].
Foods containing zinc
• Meat
• Fish
• Seafood
• Eggs
• Milk
• Beans
• Nuts
• Wholegrains
Iron
Recommended Dietary Intake
• Women 18 mg/day. Over the age of 50: 8 mg/day
• Men 8 mg/day
Note: vegetarians who don’t eat seafood need around twice as much iron, since the nonheme iron from plants is not readily absorbed.
Tolerable Upper Intake Level
45 mg/day unless prescribed by a doctor to treat a deficiency. Too much iron can create inflammation, organ fibrosis and a range of symptoms. In extreme cases iron overdoses can cause death.
Importance
Iron is well known for its role in red blood cells and the transport oxygen and in some hormones. Iron is also essential for almost every aspect of cell functioning, muscle function, nerve function and healthy connective tissue. Although most people obtain enough iron from their diet, it’s an often overlooked fact that many people with acute or chronic inflammation have anaemia. Iron is crucial for a host of biochemical pathways, including the production of energy, DNA and hormones. Therefore, iron deficiency and anaemia are serious health problems that should be corrected [3].
Forms
Supplements are often in the form of ferrous sulphate, ferrous gluconate, ferric citrate, or ferric sulphate.
Interactions
Calcium reduces iron absorption. Taking iron with tea or with other minerals can reduce iron absorption. Taking iron supplements with thyroid medications can reduce the efficacy of the medication. Many purified plant-derived polyphenols form insoluble precipitates with iron and prevent absorption [4].
Iron deficiency
Many healthy women have an iron deficiency, often without anaemia. Iron deficiency and anaemia are prevalent in aging, people with chronic low-level inflammation and in many medical conditions. Pre and post-operative anaemia increases the risk of adverse surgical outcomes [5]. Of interest, iron deficiency promotes a Th-2 immune response with associated pro-fibrotic cytokines (proteins the body makes), and is linked to allergies [4]. A decrease in the ability of blood to transport oxygen can create hypoxic (oxygen deficient) conditions together with the production of pro-fibrotic cytokines [4].
If you’re planning surgery, or have recently had surgery, you should have your iron levels checked, and people with long-term arthrofibrosis should also have regular blood tests to check iron levels.
Food containing iron
• Red meat, seafood, and poultry
• Iron-fortified breakfast cereals and breads
• Beans, lentils, spinach, and peas.
• Nuts
Iodine
Recommended Dietary Intake
• 150 μg, up to 500 μg (men and women)
Tolerable Upper Intake Level
1 100 μg. Long-term intakes above this amount increases the risk of adverse health effects.
Importance
Iodine is essential for human life and appears to play an important role in immune responses [6], the nervous system and disease prevention [7]. Iodine is a core component of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). Thyroid hormones regulate many important biochemical reactions including metabolism, protein synthesis and thermoregulation.
Forms
Iodine in food and iodized salt is present in several chemical forms including sodium and potassium salts and inorganic iodine.
Interactions
There can be interactions between iodine in supplements and anti-thyroid medications, angiotensin-converting enzyme (ACE) inhibitors such as benazepril and potassium-sparing diuretics, such as spironolactone.
Deficiency
Iodine deficiency is well known to cause a wide spectrum of diseases, including hypothyroidism [8]. Since the 1920’s, iodine has been added (as potassium iodide) to iodised table salt and bread in many countries in order to prevent the once widespread, devastating effects of severe iodine deficiency. Although the efforts to reduce severe iodine deficiency have been very successful, mild deficiencies remain a problem golbally [7], in part due to the increasing popularity of boutique specialty salt (for example, Himalayan pink salt) and organic breads which are typically not iodised.
Levels of iodine are tested in urine. A 24-hour collection of urine is needed for an accurate determination of iodine status.
Most people have adequate intakes of iodine. The people who are most at risk of iodine deficiency include those with chronic inflammation and fibrosis, because inflammatory cytokines and TGF-β1 (the main fibrotic cytokine) inhibit the uptake of iodine [7]. Others include:
• People on a low salt diet for example, who have high blood pressure
• Postmenopausal women who have reduced milk intake [9]. (Please note that this does not necessarily mean that milk consumption is good for you)
• People who avoid milk and other dairy products [9]. Plant based milk replacement products contain very little iodine9
• People with high consumption of alcohol
• Vegans and vegetarians
Fibrocystic breast disease is a benign fibrotic condition characterized by lumpy, painful breasts and palpable fibrosis. It commonly affects women of reproductive age, but it can also occur during menopause. Some research suggests that iodine supplementation might be helpful for fibrocystic breast disease [10, 11].
Food containing iodine
Oceans contain most of the world’s iodine, and some is taken in by breathing when you’re near the ocean [7]. Saltwater fish and seafood are natural sources of iodine.
• Bread made with iodate dough conditioner (most commercially sold bread doesn’t contain iodine)
• Cod
• Seaweed (amount varies with type of seaweed)
• Oysters
• Greek yoghurt
• Iodised salt
• Milk (sometimes) – levels in milk and dairy products varies greatly, and amounts have reduced
References
U.S. Department of Agriculture. Usual Nutrient Intake from Food and Beverages, by Gender and Age, What We Eat in America, NHANES 2013-2016. (2019). <http://www.ars.usda.gov/nea/bhnrc/fsrg>.
Betsy, A., Binitha, M. & Sarita, S. Zinc deficiency associated with hypothyroidism: an overlooked cause of severe alopecia. Int J Trichology 5, 40-42 (2013). https://doi.org/10.4103/0974-7753.114714
Lanser, L., Fuchs, D., Kurz, K. & Weiss, G. Physiology and Inflammation Driven Pathophysiology of Iron Homeostasis-Mechanistic Insights into Anemia of Inflammation and Its Treatment. Nutrients 13 (2021). https://doi.org/10.3390/nu13113732
Roth-Walter, F., Pacios, L. F., Bianchini, R. & Jensen-Jarolim, E. Linking iron-deficiency with allergy: role of molecular allergens and the microbiome. Metallomics 9, 1676-1692 (2017). https://doi.org/10.1039/c7mt00241f
Kaufner, L. et al. Erythropoietin plus iron versus control treatment including placebo or iron for preoperative anaemic adults undergoing non-cardiac surgery. Cochrane Database Syst Rev 8, CD012451 (2020). https://doi.org/10.1002/14651858.CD012451.pub2
Mendieta, I. et al. Molecular iodine exerts antineoplastic effects by diminishing proliferation and invasive potential and activating the immune response in mammary cancer xenografts. BMC Cancer 19, 261 (2019). https://doi.org/10.1186/s12885-019-5437-3
Waugh, D. T. Fluoride Exposure Induces Inhibition of Sodium/Iodide Symporter (NIS) Contributing to Impaired Iodine Absorption and Iodine Deficiency: Molecular Mechanisms of Inhibition and Implications for Public Health. Int J Environ Res Public Health 16 (2019). https://doi.org/10.3390/ijerph16061086
Pearce, E. N. & Zimmermann, M. B. The Prevention of Iodine Deficiency: A History. Thyroid 33, 143-149 (2023). https://doi.org/10.1089/thy.2022.0454
Mathiaparanam, S. et al. The Prevalence and Risk Factors Associated with Iodine Deficiency in Canadian Adults. Nutrients 14, 2570 (2022).
Ghent, W. R., Eskin, B. A., Low, D. A. & Hill, L. P. Iodine replacement in fibrocystic disease of the breast. Can J Surg 36, 453-460 (1993).
Kessler, J. H. The effect of supraphysiologic levels of iodine on patients with cyclic mastalgia. Breast J 10, 328-336 (2004). https://doi.org/10.1111/j.1075-122X.2004.21341.x