People often choose multivitamins as a one stop shop to cover all their nutritional bases, so they don’t have to think about which vitamins and minerals to take. Multi-vitamins are a great option to:

• Simplify a supplement routine – especially for those who don’t like numerous pills

• Helpful for those with no current health issues

• Beneficial for general health maintenance

However, how do you know which multivitamin to choose (especially since not all multivitamins are made equal) and what about absorption?

One concern that some people have is the minerals that are included in multivitamins and whether or not they compete for absorption. The answer is, yes, minerals in multivitamins can compete for absorption in the digestive tract, mainly from shared transport pathways and chemical interactions. There are several factors that impact absorption competition, including dosage, formulation, and ratio balance.

Key examples of mineral competition are between: 1. calcium, zinc, and iron; 2. zinc and copper; and 3. iron and manganese.

1. Calcium (Ca), Zinc (Zn), and Iron (Fe)

• These minerals are divalent cations (ions with a +2 electrical charge, e.g., Ca²⁺, Zn²⁺, Fe²⁺) and share similar absorption mechanisms in the small intestine, particularly via DMT1 (Divalent Metal Transporter 1).

• High doses of one mineral (e.g. calcium) can inhibit the absorption of the others (e.g. iron or zinc) and vice versa.

• Zinc and Copper (Cu)

  • Zinc supplementation can reduce copper absorption by increasing the production of metallothionein, a protein in intestinal cells that binds copper and prevents its absorption.

  • This can potentially lead to copper deficiency with long-term high-dose zinc supplementation (higher than 40 mg/day).

1. Copper deficiency is rare, however some medications, such as thiazide diuretics, used to treat high blood pressure, can lead to zinc loss in the urine, causing deficiency. People with low copper levels might have brain and nervous system issues, including numbness and weakness in the limbs. Another common symptom is fatigue, as when copper levels are low, the body has trouble absorbing iron, which could lead to iron deficiency anemia. This can be managed by eating a copper rich diet. Other symptoms can be frequent sickness, brittle bones, problems with memory and learning.

Iron and Manganese (Mn)

• Both iron and manganese compete for absorption via DMT1. Excessive iron may impair manganese uptake.

Knowing these key interactions, what are the implications for multivitamins?

1. Formulation Matters: Some multivitamins use chelated forms of minerals (e.g. iron bisglycinate, magnesium citrate) to improve absorption and reduce competition. Chelated minerals are bound to compounds like amino or organic acids, which helps your body uptake the mineral. I find it is best to take a multivitamin that takes these conflicts into consideration.

2. Dosage Timing: Spacing out when you take conflicting minerals (e.g. take iron in the morning and calcium at dinner) can improve overall absorption.

3. Ratio Balance: Manufacturers often adjust mineral ratios to minimize interference (e.g. adding copper alongside zinc).

Here is a comparison chart of multivitamins from professional brands commonly prescribed by Naturopathic Doctors:

Mineral Interactions Breakdown

Calcium vs. Magnesium

• All products use chelated mineral forms.

• Doses (≤200 mg Ca, ≤200 mg Mg) remain low‑moderate – little competition.

Zinc-Copper-Iron Triad

• Cyto‑Matrix / Designs: no Cu or Fe → negligible Zn-related competition.

• Bioclinic / NFH: Zn and Cu included in balanced ratios; moderate potential risk but mitigated by chelation.

• Metagenics: 15 mg Zn + 1 mg Cu in citrate forms – low risk

• None include iron, eliminating iron-related competition.

Manganese & Miscellaneous Minerals

• Mn levels (0.5-5 mg) are low in all listed brands except CytoMatrix, which has a moderate amount (9 mg); and the chelated forms minimize transporter competition (e.g., via DMT1).

• Other trace minerals (selenium, chromium, molybdenum, iodine) are present in safe, low doses across formulas.

Drugstore/Grocery Store Brands Comparison

Mineral Interactions Breakdown of Drugstore/Grocery Store Brands Comparison

1. Iron-Zinc-Copper Triad

• All listed products provide iron, along with zinc and copper.

• This combination creates the highest potential for mineral competition, especially when doses are moderate to high (e.g. 7-18 mg iron, 7-11 mg zinc, ~0.5-1 mg copper).

• Zinc and iron compete for intestinal absorption via DMT1, while zinc over-supplementation can reduce copper absorption via metallothionein induction.

2. Calcium & Magnesium

• Present in low to moderate amounts; interaction at these levels is minimal.

• Absorption of Ca and Mg is largely independent of iron/zinc/copper competition.

3. Manganese & Other Trace Minerals

• Mn (typically 2-5 mg) is low enough that any transporter competition is unlikely.

• Other trace minerals in these formulas (selenium, chromium, iodine, molybdenum) are typically at low safe levels.

4. Form of Minerals

• These drugstore brands most often use inorganic forms like oxides, carbonates, and sulfates.

• Such forms tend to have lower bioavailability and greater competition than chelated forms found in professional-grade formulas.

Practical Tips

• To reduce competition, consider separating supplemental iron and mineral-rich meals by 2-3 hours.

• Taking with food (especially with vitamin C) enhances iron absorption and reduces GI irritation.

• For those particularly concerned about absorption or competition, clinician-grade chelated formulas (like Cyto‑Matrix, Metagenics, Designs, etc.) offer lower interaction potential are recommended.

Can multivitamins move the needle?

One of Dr. Chris, ND concerns with multivitamins is that they have low doses of essential minerals which are safer for absorption competition, but they are not enough to “move the needle” on a specific health concern. Selenium supplementation, for example, is indicated for thyroid disease, both hypothyroidism and hyperthyroidism, but the trace amounts in the multivitamins would not have significant impact on disease management.

Another example is the iron content in multivitamins – they are quite low (none in professional brands, or 6- 18mg in drugstore brands) compared to heme iron supplements which tend to have much more (up to 36mg) and minimal competition if timed appropriately with other supplementation. Low iron levels are implicated in depression, anxiety and other mental health conditions, so to ensure iron supplementation is effective enough to address health concerns, we need to go beyond multivitamins.

Final Thoughts & Recommendations

The supplement world is complex and the minerals contained inside the bottles are equally complex. Multivitamins from professional brands that are recommended by naturopathic doctors are thoughtfully formulated: they all use chelated forms and do not include iron, thus significantly decreasing the risk of nutrient absorption competition. As you venture out to shop at the drugstore or online for your next multivitamin, keep the points reviewed above in mind!

1. For virtually zero mineral competition, choose Cyto‑Matrix Multi matrix

2. For well-rounded daily coverage with minimal competition, Bioclinic, NFH, Metagenics, or Designs for Health are all excellent.

3. Chelated minerals + no iron across all professional products largely avoid absorption conflicts. This is not the case for drug store brands.

4. If you ever need to take additional iron or calcium, space it apart from your multivitamin to prevent interactions

We recommend seeing a naturopathic doctor who can guide your health to taking supplements that you need for your specific health concerns. You don’t want an “off the self” and “one-size fits all” approach to your number 1 asset: your health! You want an precision approach that is customized to your individual needs. That is why choosing naturopathic medicine is the best investment you can make for your health!

References

Einhorn, V., Haase, H., Maares, M. Interaction and competition for intestinal absorption by zinc, iron, copper, and manganese at the intestinal mucus layer. Journal of Trace Elements in Medicine and Biology, 84(2024) https://doi.org/10.1016/j.jtemb.2024.127459.

Keen, C. L., & Zidenberg-Cherr, S. (1996). Manganese. In: Ziegler EE, Filer LJ, eds. Present Knowledge in Nutrition. 7th ed. Washington, DC: ILSI Press.

Li, Y., Cheng, Y., & Tang, N. (2024). Unraveling the Intricate Interplay: Iron and Zinc’s Regulatory Mechanisms on Calcium Bioavailability During Intestinal Absorption. Food Reviews International, 41(2), 345-372. https://doi.org/10.1080/87559129.2024.2401431

Raman, R. (2020, May 20). Chelated minerals: Types, benefits, and recommendation. Healthline. https://www.healthline.com/nutrition/chelated-minerals

Rolić, T., Yazdani, M., Mandić, S. et al. Iron Metabolism, Calcium, Magnesium and Trace Elements: A Review. Biol Trace Elem Res 203, 2216-2225 (2025). https://doi.org/10.1007/s12011-024-04289-z

Sandström, B. (2001). Micronutrient interactions: effects on absorption and bioavailability. British Journal of Nutrition, 85(S2), S181-S185. https://doi.org/10.1079/BJN2000312

Turnlund, J. R. (1998). Human whole-body copper metabolism. The American Journal of Clinical Nutrition, 67(5), 960S-964S. https://doi.org/10.1093/ajcn/67.5.960S

U.S. Department of Health and Human Services. (n.d.). Office of dietary supplements – manganese. NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Manganese-HealthProfessional/

https://www.mayoclinic.org/drugs-supplements-zinc/art-20366112

https://www.healthline.com/nutrition/copper-deficiency-symptoms#TOC_TITLE_HDR_2

https://pmc.ncbi.nlm.nih.gov/articles/PMC5307254/

https://pmc.ncbi.nlm.nih.gov/articles/PMC10788288/#:~:text=We%20hypothesize%20that%20young%20adult,thereby%20reducing%20risk%20for%20depression.

Once you have selected which breakfast you would like, add that shopping list to the following list.

· Filtered or spring water

· Lemon (6)

· Organic Celery Stalks (6 Organic)

· Organic Cucumbers (10 small)

· Organic carrots (6 small)

· Organic tomatoes (3 medium)

· Organic zucchini (4 medium)

· Green string beans (1 cup)

· Avocado (3 ripe)

· Organic sprouts, preferably alfalfa, watercress, or sunflower sprouts (3 handfuls)

· Garlic cloves (3 cloves)

· Ginger (3 knobs)

· Fresh organic cilantro, finely chopped (3 handfuls)

· Dried thyme, rosemary, oregano, or other French Provence herbs (2 teaspoons)

· Fresh organic parsley (1 large bunch)

· Ground cinnamon (1 tsp)

· Nori sheets (3)

· Tamari or soy sauce (3 tablespoon)

· Organic miso paste (1 tablespoon) or Unrefined sea salt (2 teaspoons)

· Raw almonds (you can use almonds or a mixture of macadamia nuts, pecans, hazelnuts, Brazil nuts, pine nuts, pumpkin seeds or sunflower seeds) (3 handfuls)

· Toasted sesame seeds (3 tablespoons)

· Unrefined sea salt (1 teaspoon)

· Raw honey or maple syrup (1 tbsp)

· Chia seeds (4 tbsp)

· Use store bought almond or hemp milk or make yourself with Raw almonds (1.5 cup) & Honey or rice syrup (3 tbsp)

· Chamomile Tea / Dried Chamomile Flowers

People experience a wide range of emotions during this period. It can be helpful to remember that each person’s journey through the holidays is unique. For those that need to hear this – it’s okay not to feel joyful and merry. Your feelings are valid, and taking care of your emotional well-being is paramount.

A teacher for me has been “Radical Forgiveness” by Colin Tipping – the following is an excerpt from this book:

What are the Adrenal Glands?

• The adrenal glands are part of the endocrine system, which is a collection of glands and organs in the body that release important hormones.
• These hormones travel through the blood and body fluids to act on other organs, tissues and cells in your body.
• The adrenals are located on top of both kidneys.
• The hormones that the adrenals secrete are responsible for a number of normal body functions and are necessary for life.

Key Adrenal Gland Hormones:
• Cortisol:
○ Provides your body tissues with energy to combat the effects of stress, keeps you alert and awake in the daytime, it decreases at night to allow you to sleep, it is a natural anti-inflammatory, and it stimulates the immune system.
• DHEA:
○ A natural anti-inflammatory hormone, it is used to convert into other hormones that your body may need, may be responsible for female libido, is a source of estrogen after menopause.
• Aldosterone:
○ Involved in the balance of salt and water in your body, therefore affects your blood pressure.
• Adrenaline (epinephrine):
○ Gives that well-known “adrenaline rush” sensation and is part of the “fight or flight” reaction of extreme or sudden stress.

Stress and the Adrenals:
• When you are under elevated acute stress (e.g. Studying for final exams, meeting a deadline, skipping a meal) your adrenals respond by producing more cortisol to help you deal with that stress.
• This adrenal response can be helpful and harmless in getting you through the stress in the SHORT TERM.
• However, if the stressful situations continue for too long and the cortisol levels remain chronically elevated and the adrenal glands may eventually burn out ►ADRENAL FATIGUE.
• The cortisol levels will drop as the adrenals begin to fail to keep up with the person’s need for stress hormones.

Symptoms of Adrenal Fatigue:
• Fatigue, lethargy
• Light-headedness (including dizziness and fainting) when rising from a sitting position or laying-down position
• Lowered blood pressure and blood sugar
• Difficulty concentrating or remembering (brain fog)
• Consistently feeling unwell or difficulty recovering from infections
• craving either salty or sugary foods to give them energy
• Unexplained hair loss
• Nausea
• Alternating constipation and diarrhea
• Mild depression
• Decrease sex drive
• Sleep difficulties
• Unexplained pain in the upper back or neck
• Increased symptoms of PMS for women
• Tendency to gain weight and inability to lose it – especially around the waist
• High frequency of getting the flu and other respiratory diseases – plus a tendency for them to last longer than usual.

Prevalence of Adrenal Fatigue:
• Up to 80% of people at some point in their lives!

How do we Diagnose Adrenal Fatigue?
• Based on the above symptoms
• Pupil dilation exam
• Orthostatic blood pressure
• Hormone testing (blood, salivary)- e.g. Cortisol, DHEA

Treatment Strategies:
• Get enough sleep
• Reduce stress
• Exercise regularly
• Eat a healthy diet
• Vitamins and supplements
Copyright 2014 Natural Terrain Naturopathic Clinic.

Stress can undermine your health. The connection between stress and high blood pressure, heart disease and many digestive problems is well-established in medical research. Stress creates hormonal and blood sugar changes, causes the body to excrete nutrients and adversely affects the immune system.

The adrenal glands are directly affected by stress. They are responsible for the “fight or flight” response. Hans Selye, MD, conducted experiments creating stress in rats. The rats were made to tread water with their legs tied until they became exhausted and died. Dr. Selye analyzed the rats at various stages of the experiment and dissected their adrenal glands. He found that the adrenal glands responded to stress in three distinct stages. In the initial stage, the adrenal glands enlarged and the blood supply to them increased. As the stress continued, the glands began to shrink. Eventually, if the stress continued long enough, the glands reached the third stage of adrenal exhaustion. The adrenal glands produce certain hormones in response to stress. In a stressful situation, they raise blood pressure, transfer blood from the intestines to the extremities, increase the heart rate, suppress the immune system and increase the blood’s clotting ability.

This response is meant to be short-lived. When primitive man walked through the forest, he’d see a wild animal. His heart rate would increase, his pupils would dilate, his blood would go out of his digestive system and into his arms and legs, his blood clotting ability would improve, he would become more aware and his blood pressure would rise. At that point he’d either pick up a stick and try to fight the animal or run. The physiological changes brought on by the adrenal glands would make the body more efficient at doing either of those things. This is called the fight or flight response. If he survived the ordeal, chances are it would be a while before such a strain was put on the adrenal glands and the rest of the body again. He would have an opportunity to relax, eat nuts and berries (and a little meat from the wild animal, if he was lucky). His adrenal glands would have a chance to recover.

Many people in modern society do not have the luxury of a recovery period for their overworked adrenal glands. The changes caused by the overproduction of adrenal hormones stay with them. The stimulation of the adrenal glands compromises immune function, so people under constant stress will tend to catch colds and have other immune system problems, like allergies. Stress causes many digestive problems such as indigestion, colitis and irritable bowel syndrome. Blood flow to the digestive tract is decreased because adrenal hormones also cause an increase in the blood clotting ability, so prolonged stress can lead to the formation of arterial plaque and heart disease.

Worrying makes the adrenal glands work. Relaxing and thinking peaceful thoughts enables them to rest and heal. That is why yoga and meditation are so good for you. You go a long way in preserving your health and energy if you do not fret about things over which you have no control. It’s the amount of worry and not necessarily the size of the problem that stresses your adrenal glands. If you worry a lot about little problems, you do as much damage to your adrenal glands as someone who really has a lot of stress. If you can control your worrying when under stress, you minimize the damage stress does to your health. A wise man once said, “worry is interest paid in advance on money you haven’t borrowed yet.”

Dr. Selye described the progression of stress on the adrenal glands as General Adaptation Syndrome. The first stage is called the alarm reaction. This is when someone (with healthy adrenal glands) can perform amazingly well when the need arises. The primitive man, seeing the saber tooth tiger, was able to run faster than he ever dreamed possible during the alarm reaction. If the stress continues, the body moves into the resistance stage, during which the adrenal glands become enlarged. In this stage, a person can feel anxious, have cold, clammy hands; a rapid pulse, and a decreased appetite, but hasn’t begun to feel any of the more serious symptoms of the exhaustion stage. During the exhaustion stage the adrenal glands begin to fail to meet the demands placed upon them. During this stage, the individual begins to have a variety of symptoms including fatigue, digestive problems, obesity, depression, dizziness, fainting, allergies and many other problems.

People with weak adrenal glands frequently crave coffee and sugar, as well as salt. Sugar and caffeine stimulate the adrenal glands. It’s as if your adrenal glands are two horses towing a wagon load of bricks up a mountain and sugar, or caffeine, act as the whip you use to get the horses to keep trying. What they need to get to the top of the mountain is nourishment and a rest period.

To effectively treat the adrenal glands, you must eliminate as much stress from your life as possible. Emotional stress is the kind of stress most people think of when stress is mentioned, but there are many different kinds of stress. Thermal stress results from being exposed to extremes of temperature; physical stress from heavy physical work, poor posture, structural misalignments, lack of sleep and being overweight; and chemical stress from ingestion of food additives, exposure to pollutants and consumption of sugar and alcohol. Changes in blood sugar are also a form of chemical stress. Eating frequent, small meals is often very helpful, since people suffering from adrenal fatigue are often hypoglycemic (having low blood sugar).

Situations are not always controllable, but stress and how you react to the situation is. Stress is cumulative. Emotional, structural, and chemical stress all affect the body the same way. Your adrenal glands do not know the difference between failing an exam, treading water, or excessive sugar consumption. Furthermore, if you consume excess sugar because you failed an exam, it will add to the level of stress you experience.

If you reduce the stress that you can control and change how you respond, stressful situations will not have as much of a physical effect on you. For instance, eating frequent meals and avoiding sugar will reduce stress on the adrenal glands. So, even if you can’t do anything about your in-laws coming to spend the summer, you can reduce your stress by controlling your diet. Also, how you think of the stress will make a difference in the health of your adrenal glands. Your mother-in-law’s handy tips on how you should raise your kids, clean your house, or her penchant for eating everything that isn’t nailed down (without offering to pay for groceries), won’t stress your adrenal glands if you don’t focus on it.

If you can’t change your work situation, then improve your diet and get plenty of rest. Change how you think about your job situation. Focus on the positive; you do have a job, you do eat regular meals when most of the world doesn’t. Just do the best you can and think of the things you can’t control in positive terms.

As Naturopathic Doctors, we are always concerned about the health of your adrenal glands. We will do our best to support you with lifestyle suggestions, nutritional advice and various remedies so you can feel your best!!

Copyright 2014 Natural Terrain Naturopathic Clinic.