Trace Elements: Tiny Nutrients With Big Impacts
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Introduction
For the intricate workings of the human body to perform properly, we require more than just the carbohydrates, proteins, fats, and macrominerals that constitute the bulk components of our diets. Equally important are the micronutrients – vitamins and trace minerals – most needed only in minute and minuscule amounts. This article takes a closer look at key microminerals known as trace elements along with their vital functional roles and effects on human health and disease.
Though requisite in relatively tiny doses, these elements produce powerful ripple effects on biological pathways. Unlike fickle nutrients that come and go, trace elements take up long-term residence in the structures of enzymes, proteins and structural tissue. From this fixed position, they regulate, mediate, guard, stimulate, transmit and carry out all kinds of essential physiological duties to keep our bodies humming along. Getting too little – or too much – of these tiny nutrient powerhouses hampers delicate body processes and bears serious repercussions.
Iron – Oxygen Transporter Extraordinaire
The most familiar member of the trace mineral team, iron, accounts for the all-important task of bringing oxygen from lungs to tissues. This elemental workhorse efficiently loads oxygen onto hemoglobin molecules within developing red blood cells thanks to intricate coordination with helper molecules called porphyrins. In fact, about 70% of all iron circulating in the body gets incorporated into hemoglobin while the rest is stockpiled for future blood cell manufacture.
Upon releasing its oxygen payload to eagerly awaiting tissues, iron reclaims its post to escort carbon dioxide back to the lungs to get rid of this cellular waste product. And the devoted mineral keeps repeating this cycle almost endlessly. When iron levels run low, it’s this oxygen transport and delivery process that takes the biggest hit.
Recommended Iron Intakes:
- Infants birth to 6 months – 0.27 mg/day
- Infants 7-12 months – 11 mg/day
- Children 1-3 years – 7 mg/day
- Kids 4-8 years – 10 mg/day
- Males age 9-13 years – 8 mg/day
- Males age 14+ - 11 mg/day
- Females age 9-13 years – 8 mg/day
- Females age 14-18 – 15 mg/day
- Females age 19-50 – 18 mg/day
- Females past menopause – 8 mg/day
Top Iron-Rich Food Sources:
- Organ meats like liver or giblets
- Lean red meats
- Seafood, especially clams and oysters
- Beans, lentils and soyfoods
- Spinach, raisins and prune juice
- Fortified breakfast cereals
- Baked potato with skin
Iron deficiency develops gradually in stages over time when demands outweigh dietary supply. Symptoms escalate as deficiency worsens:
Stage 1 – Iron depletion
- No obvious symptoms – low ferritin levels
Stage 2 – Early functional iron deficiency
- Unusual fatigue/tiredness
- Poor concentration
- Frequent infections
Stage 3 – Iron deficiency anemia
- Noticeable fatigue – shortness of breath
- Fast heart rate
- Pale skin
- Brittle nails
- Headaches/dizziness
- Swollen tongue
Those at highest risk for iron deficiency include young children, menstruating women and pregnant women. Blood loss, restricted dietary intake, high grain diets that inhibit absorption, and chronic inflammation also up risk for deficiency. While iron overload from supplements can accumulate to cause toxicity issues, iron poisoning from whole food sources alone is extremely rare.
Zinc – The Metal With Multiple Protective Powers
As indispensable minerals go, zinc definitely makes the MVP list thanks to its involvement with hundreds of enzymatic reactions impacting metabolism, protein synthesis, gene expression, DNA/RNA regulation and immunity. This “jack of all trades” element – actually considered a dietary metal – gives antioxidant reinforcement to biological systems that manage oxidative stress and free radical damage.
Zinc also assists in the intestinal absorption and trafficking of other trace elements like copper and iron. Supporting cell division and growth, zinc ensures a healthy skin barrier to lock in moisture and form a protective shield against infection. Plus zinc enables proper sense of taste and smell.
Recommended Zinc Intakes:
- Infants birth to 6 months – 2 mg per day
- Infants 7-12 months – 3 mg/day
- Children 1-3 years – 3 mg/day
- Kids 4-8 years – 5 mg/day
- Males and females ages 9-13 – 8 mg/day
- Males age 14+ - 11 mg/day
- Females ages 14+ - 9 mg/day
Top Zinc-Rich Foods:
- Oysters
- Red meats (beef, lamb)
- Poultry (dark meat chicken, turkey)
- Baked beans
- Pumpkin, squash and watermelon seeds
- Nuts like cashews and almonds
- Peanut butter
- Milk and yogurt
- Baked whole grain bread
Deficiency Signs and Symptoms:
- Poor wound healing
- Frequent infections
- Hair loss
- Diminished appetite
- Alterations in sense of taste or smell
- Skin rashes or acne breakouts
Those at greatest risk for zinc deficiency include vegetarians/vegans, alcoholics, and anyone with digestive disorders like Crohn’s disease that impair nutrient absorption. The mineral copper directly competes with zinc for absorption, so over-consumption of copper supplements potentially leads to zinc deficiency over time.
Copper – The Bone Builder
Aiding enzymes that form and stabilize collagen’s connective framework, copper lends critical assistance with building and maintaining bone matrix structure. This handy trace mineral also expedites the conversion of iron to its usable heme state so it can bind to hemoglobin for oxygen transport. Neurotransmitter production in the brain relies on copper-containing enzymes as does the metabolism of cholesterol and glucose.
As part of antioxidant enzyme superoxide dismutase (SOD), copper neutralizes dangerous free radical molecules that trigger oxidative damage and inflammation. Like zinc, this mineral supports proper immune system responses as certain white blood cells store and release copper as needed in cases of wounds or infection.
Recommended Copper Intakes:
- Infants birth to 6 months – 0.2 mg/day
- Infants 7-12 months – 0.22 mg/day
- Children 1-3 years – 0.7 mg/day
- Kids 4-8 years – 0.9 mg/day
- Males and females ages 9-13 – 0.9 mg/day
- Males ages 14+ - 0.9 mg/day
- Females ages 14-18 – 0.9 mg/day
- Females age 19+ - 0.9 mg/day
Top Copper-Rich Foods:
- Organ meats like liver
- Seafood including oysters, lobster
- Leafy green vegetables
- Mushrooms
- Avocado
- Soy products
- Nuts like cashews and almonds
- Beans, lentils, tofu
Deficiency Signs and Symptoms:
- Bone abnormalities
- Frequent bone fractures later in life
- Loss of hair pigment
- Neurological issues like numbness/tingling
- Impaired iron transport
- Weakened immunity
- Irregular heartbeat
Those consuming high levels of zinc supplements sometimes present with copper deficiency as excess zinc impairs absorption of copper. Deficiency risk also rises with high intake of high fructose corn syrup, ongoing diarrhea, celiac disease and certain surgeries that remove part of the stomach.
Manganese Makes Connections
As just a “trace” mineral, manganese plays big roles in bone mineralization, blood clotting factors, reproductive hormones, key enzymes, antioxidants like SOD, and cartilage/collagen production. This hard-working element aids proper brain and nerve functioning as manganese gets actively transported along neural pathways. Within mitochondria, manganese helps convert nutrients to energy as this mineral activates numerous metabolic enzymes.
By assisting with collagen matrix formation, manganese lends structural support and strength to skin and skeletal systems. As part of glycosaminoglycans (GAGs), the building blocks of bone, manganese binds to proteoglycan complexes which give cartilage its tough, resilient nature able withstand compressive joint forces.
Recommended Manganese Intakes:
- Infants birth to 6 months - 0.003 mg/day
- Infants 7-12 months – 0.6 mg/day
- Children ages 1-3 years – 1.2 mg/day
- Children ages 4-8 years – 1.5 mg/day
- Males/females ages 9-13 years – 1.9 mg/day
- Males age 14+ - 2.2 mg/day
- Females age 14+ - 1.6 mg/day
Top Manganese-Rich Food Sources:
- Mussels
- Brown rice
- Spinach
- Pineapple
- Mixed nuts and seeds
- Beans (white beans, soybeans)
- Instant oatmeal
- Sweet potatoes/yams
Deficiency Sign Signs & Symptoms:
- Bone malformations
- Joint pain
- Seizures
- Hearing loss
- Infertility
- Birth defects with restricted intake during pregnancy
Those with alcoholism and pancreatic insufficiency/poor fat absorption run higher risk for manganese deficits as do post-menopausal women and vegetarians. Overexposure to manganese particles with occupations like mining/welding may damage the brain's dopamine system resulting in poor coordination, mood changes and difficulty speaking.
Chromium - The Great Blood Sugar Stabilizer
By enhancing insulin efficiency and signaling, the trace mineral chromium helps transport sugar from the bloodstream into cells where it gets used for energy production. Chromium is concentrated more in muscle compared to other tissues as it amplifies insulin’s effects on proteins involved in carbohydrate/fat metabolism and energy utilization. Research confirms chromium supplementation improves glycemic control and blood lipid profiles in type 2 diabetics.
Chromium is better absorbed from nutritional yeast sources compared to mass produced supplements. Grains, certain seasonings, meats, eggs, cheese and fish supply varying amounts of bioavailable chromium as well. The essential mineral binds tightly to iron transport proteins which likely explains why iron-deficient individuals often have concurrent chromium deficits resulting in blood sugar dysregulation.
Recommended Chromium Intakes:
- Infants birth to 6 months – 0.2 mcg/day
- Infants 7-12 months – 5.5 mcg/day
- Children ages 1-3 years – 11 mcg/day
- Kids ages 4-8 years – 15 mcg/day
- Males/females ages 9-13 years - 25 mcg/day
- Males ages 14-50 years – 35 mcg/day
- Males age 50+ years – 30 mcg/day
- Females ages 14-18 years – 24 mcg/day
- Females ages 19-50 years – 25 mcg/day
- Females age 50+ years – 20 mcg/day
Top Chromium-Rich Foods:
- Nutritional yeast
- Broccoli
- Grape juice
- Whole grain products
- Turkey/chicken breast
- Eggs, cheddar cheese
- Potatoes
Deficiency Signs and Symptoms:
- Elevated blood glucose levels
- Nerve damage
- High cholesterol/triglycerides
- Fatigue/weakness
- Impaired growth rate
Those with diabetes or metabolic syndrome face higher risk for suboptimal chromium status as do pregnant women. Strict vegetarian diets may provide insufficient chromium compared to meat-containing diets. Getting too much chromium from supplements can negatively impact kidney health over time.
Iodine – The Thyroid’s Partner
The trace mineral iodine centers upon healthy thyroid status as this gland concentrated in the neck requires iodine to produce critical hormones T3 and T4 which regulate metabolism, growth, temperature regulation, protein production and much more. Iodine constitutes 65% of T4 (thyroxine) thyroid hormone’s molecular weight. Deficits during pregnancy adversely affect neurological development.
While iodized salt helps prevent deficiencies, over-consumption of salty foods to dangerously high levels should be avoided. Sea vegetables and seafood contain variable levels of iodine as well. After absorption, this mineral accumulates in the thyroid and mammary glands more than other bodily tissues.
Recommended Iodine Intakes:
- Infants birth to 6 months – 110 mcg/day
- Infants 7-12 months – 130 mcg/day
- Children 1-8 years – 90-120 mcg/day
- Males/females ages 9-13 years – 120 mcg/day
- Males/females ages 14+ years - 150 mcg/day
- Pregnant females – 220 mcg/day
- Breastfeeding females – 290 mcg/day
Top Iodine-Rich Foods:
- Iodized salt
- Seafood
- Yogurt
- Milk
- Eggs
- Prunes
Deficiency Signs and Symptoms:
- Thyroid enlargement (goiter)
- Hypothyroidism
- Impaired growth
- Learning disabilities
- Gestational problems
Vegans/vegetarians run higher risk for iodine deficiency without seaweed or iodine-fortified foods. Excessive iodine intake should be avoided as well, especially in those with autoimmune thyroid conditions. Like other trace minerals, iodine gets concentrated more in certain tissues like the thyroid gland and mammary glands compared to whole body status.
Selenium – The Immunity Mineral
While classified as a trace element, selenium is technically considered a mineral-like element since it resembles sulfur in its biological activities. Selenium protects cell membranes from destructive oxidation processes while stimulating immune processes like antibody formation and white blood cell production. As selenoproteins, antioxidant enzymes (glutathione peroxidases) combat inflammation, regulate thyroid hormones and neutralize DNA-damaging reactive oxygen species and free radicals.
Convincing research confirms selenium inadequacy significantly raises risk for viral mutations and impaired host immunity against unfamiliar pathogens. This explains why low selenium status predisposes certain populations to more aggressive mutated strains of influenza and coronaviruses compared to selenium replete groups exposed to the same viral strains.
Recommended Selenium Intakes:
- Infants birth to 6 months – 15 mcg/day
- Infants 7-12 months – 20 mcg/day
- Children 1-3 years – 20 mcg/day
- Children ages 4-8 years - 30 mcg/day
- Males/females ages 9-13 years – 40 mcg/day
- Males/females ages 14-18 years - 55 mcg/day
- Males/females ages 19+ years - 55 mcg/day
Top Selenium-Rich Food Sources:
- Brazil nuts
- Seafood (tuna, halibut, sardines, shrimp)
- Meat (beef, turkey, chicken, lamb)
- Eggs
- Spinach
- Mushrooms
Deficiency Signs & Symptoms:
- Muscle weakness
- Cardiomyopathy
- Joint pain
- Poor immune function
- Cognitive decline
- Thyroid dysfunction
Those following vegan or very low meat diets run higher risk for selenium deficiency as do those with severe gastrointestinal disorders that impair mineral absorption from foods. Getting high dose selenium supplements over long time periods is not recommended and may elicit toxicity effects like hair/nail brittleness and neurologic dysfunction.
Fluorine/Fluoride: Decay Fighter
The mineral-like trace element fluorine – present as fluoride when bonded to other molecules – promotes oral health by strengthening tooth enamel against acidic decay. Topical fluoride applications prove most effective for protecting teeth rather than fluoride from drinking water sources or toothpaste.
Fluoride does not seem to prevent cavities by any systemic biological mechanism, but rather topical contact with teeth during critical windows of development. Excess accumulation over years, however, causes dental fluorosis and bone fragility. Seafood, teas, and drinking water provide much of the fluoride in western diets – along with intentional fluoridation of municipal water supplies.
Besides protecting enamel, fluoride assists metabolic enzyme functions related to collagen synthesis and energy release from glucose. Low fluoride intakes show little indication of adverse effects provided other nutrients like calcium and vitamins C, D and K are adequately supplied.
Recommended Fluoride Intakes:
- Infants birth to 6 months – 0.01 mg/day
- Infants 6-12 months – 0.5 mg/day
- Children 1-3 years – 0.7 mg/day
- Children 4-8 years - 1 mg/day
- Males/females ages 9-13 years – 2 mg/day
- Males/females ages 14+ years – 3 to 4 mg/day
Dietary Fluoride Sources:
- Fluoridated drinking water
- Seafood
- Black/green teas
- Grape juice
- Baked whole grains
- Almonds, pistachios
- Dried fruits
Toxicity Symptoms:
- Dental fluorosis
- Skeletal fluorosis
- Joint pain, limited mobility
- Gastrointestinal distress
Infants should not receive fluoride toothpaste or strong fluoridated dental treatments as excessive early life exposure causes permanent tooth enamel mottling (fluorosis). Standard fluoridation of drinking water optimizes protective effects while minimizing fluorosis risk. Those with kidney disease or osteoporosis face greater risk from accumulating excessive fluoride levels.
While just “trace” amounts are needed, minerals like iron, zinc, copper, manganese, chromium, iodine and selenium wield incredible influence on growth, development, appetite, cognition, metabolism, immunity, thyroid status and more. As with most nutrients, excessive intakes from supplements hold greater risks for toxicity while reasonable doses from normal diets confer benefits – assuming no preexisting conditions or medication interactions exist. Attaining proper balance and ratios of synergistic trace minerals proves just as vital as adequate intakes. Deficiency or excess of any given mineral over time bears negative health consequences. But when kept within appropriate ranges, these tiny nutrients produce huge protective payoffs.
Author
Dr. Maajid Mohi Ud Din Malik (M.Sc. Ph. D.)