Ensuring Patient Safety with Nutrient Interaction Awareness

Ensuring Patient Safety with Nutrient Interaction Awareness

Author: Georgia Nab, DC/Wednesday, February 3, 2016/Categories: May 2015

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By Georgia Nab, DC

PATIENTS HAVE REALLY GOOD INTENTIONS when they self-assess and then self-prescribe vitamins, supplements and nutrients. They Google a few health issues, and voilà, they find a singular “miracle pill.” By the time they walk through your door, they have a bagful of mismatched bottles that may make no sense whatsoever, and to top it off, they feel worse.

What I would often find, as I went through a patient’s bag of bottles, was that many times they were taking way too high amounts of some nutrients, taking unnecessary pills or not taking what they really needed. They also had no idea if taking some nutrients would interact with other nutrients or the medications they were on.

Sound familiar? I had this happen many times in my Wichita office. While these patients were often challenging, the good news was they really believed in taking dietary supplements – they knew there were many benefits. However, things they didn’t understand included what was an essential amount [Recommended Dietary Allowance (RDA) vs. what they needed] without potential overdosing; the potential for interactions; and variations in supplement quality. Along with educating patients about these key elements, I stressed to them that “Dr. Google” was NOT a good nutritional adviser.

Need to Know

Generally speaking, supplements are safe products. Concerns can arise, though, so it is important to have a basic understanding of nutrition and supplementation. For example, is the product synthetic or derived from whole food? Is it composed of a single isolate compound or a mixture of whole-food-based ingredients? What are the combined amounts of some nutrients, such as vitamin A, that could potentially become an overdose? Are there additives or food colorings in the product that could be detrimental to the patient? Has unnecessary sugar been added to the product? Reading the ingredients on a supplement bottle label with patients often helps them understand what they are really putting into their bodies.

Because every patient is unique, I highly recommend you purchase Dr. Alan Gaby’s book Nutritional Medicine as your office guide. It is a detailed guide to nutrients, including research articles on each nutrient concerning usage, interactions, adverse effects, food sources and much more. Health conditions that are often faced in practice are also discussed with recommendations – all referenced. This is a very comprehensive book with 1,358 pages and weighing in at nine pounds!

What follow are several general nutrient-nutrient interactions commonly seen in practice. We suggest that some nutrients be taken together; others we caution against combining. As the practitioner, to ensure patient safety, you should be aware of these nutrient combinations.

Vitamin A/Vitamin E/Zinc

Vitamin A, also known as retinol, is important for healthy epithelial tissues – including the skin, gastrointestinal tract, respiratory tract, genitourinary tract and more. Preformed vitamin A also functions as an antioxidant and supports the immune system.(1) You can find vitamin A in almost every multivitamin, so be familiar with the RDA/Adequate Intake (AI) for your patient (varies with age, sex and pregnancy).

According to Gaby(1), vitamin E seems to enhance the absorption and tissue uptake of vitamin A. Gaby reports that in some cases, the combination of vitamin A and E together improved clinical outcomes at lower dosages. This is important from a safety standpoint because there is less danger of exceeding the RDA/AI for the vitamins.

Another beneficial nutrient-nutrient combination is vitamin A and zinc. Zinc is important for the transport of vitamin A with low zinc levels being associated with lower levels of circulating and hepatic vitamin A. As with vitamin E, the combination of zinc with vitamin A was shown to be more effective than vitamin A alone in deficient states.(2,3)


Magnesium is essential for inhibiting platelet aggregation; it promotes the dilation of blood vessels and acts as a muscle relaxer for both skeletal and smooth muscle. Magnesium acts as a cofactor in over 300 different enzymes, influences the metabolism of many nutrients and is the second most abundant cation in the soft tissue behind potassium.(1,4) Magnesium depletion can occur in various disorders, from cardiovascular disease(5) to alcoholism(6) to medication use.(7)

Keep in mind that there are several contraindications to using magnesium supplementation, including urinary tract infection with elevated urinary phosphates, end-stage renal disease, myasthenia gravis and cerebral hemorrhage. Magnesium should also be used with caution in hyperparathyroidism and with some prescription medications.

The evidence is not clear on the interaction of calcium and magnesium. There is a possibility that large amounts of calcium increase magnesium requirements. According to Gaby, because magnesium levels are often marginal or low, it would be prudent for someone taking calcium to also take magnesium. There is no research showing an optimal ratio between calcium and magnesium, but Gaby recommends a ratio of approximately 2:1.(1)

Magnesium/Potassium/Vitamin B6

Magnesium and potassium work together, because magnesium is essential for the uptake of potassium. It is recommended that if a patient needs either magnesium or potassium, consider giving them both. Magnesium and vitamin B6 work with each other to increase absorption.(8) Often, it has been found that the combination of magnesium and vitamin B6 is more effective together than taken alone. (9) In a side note, if a patient reports feeling irritable, hyper or sensitive to sound while taking vitamin B6 alone, this would indicate the need for magnesium. Consider magnesium and thiamine when treating a thiamine case, as magnesium is required for the conversion of thiamine to its biologically active form.


Zinc and copper are strictly regulated in the serum. Research shows that the body’s inflammation response function or aging can have an effect on this ratio. In these circumstances, zinc is seen to decrease, whereas copper increases in serum concentrations.(10) With this, an increase in the copper-to-zinc ratio is a common feature in several age-related conditions. According to Gaby, there are cases where large dosages (100-400 mg) of zinc for long periods (more than two years) have resulted in copper deficiency. Gaby also states “Although zinc interferes with copper absorption, copper supplementation does not appear to interfere with zinc absorption, except in infants recovering from diarrhea…”(1) Research reported in a in a paper supports this statement, with the researchers concluding, “Moderately high zinc in the diet significantly reduces the apparent copper digestibility. Our results also show that moderately high copper in the diet increases copper retention, but it does not reduce zinc absorption, and moderately high zinc in the diet reduced plasma copper concentrations and ceruloplasmin activity.”(11)

Iron/Vitamin C/Calcium/ Manganese/Vitamin E

The absorption of iron is enhanced when taken with vitamin C.(12) According to Gaby, a minimum dose of 50 mg of vitamin C has been found to increase iron absorption in some studies. The effect of calcium is not clear but according to Gaby, may be dose related.(1) Reported findings in a 1995 article indicated that researchers found that a dose of 600 mg of calcium inhibited iron absorption, but a dose of 300 mg did not.(13) It may be prudent if taking large doses of calcium to avoid taking it with a high-iron meal. Manganese and iron inhibit the absorption of each other.(14) Iron also interferes with the absorption of vitamin E and with some of its biochemical effects. It is suggested by Gaby that iron and vitamin E supplements be taken at separate times to prevent iron from inactivating vitamin E.

By no means is this a complete list! The absolute best dietary advice for practitioners to give patients is to have them eat a variety of whole foods in a balanced form, keeping all food in moderation. When the patient either cannot get enough whole foods or will not eat specific whole foods, my recommendation for an ideal supplement is one with whole-food-based ingredients as close to their natural form as possible for best bioavailability and absorption. Ultimately, the bottom line is that as practitioners, it is our responsibility to understand how supplements interact in the body. I highly recommend you dive into Dr. Gaby’s book and use this as your reference guide to provide your patients with the best and safest supplement advice.


1. Gaby, Alan. Nutritional Medicine. Concord, NH. Fritz Perlberg Publishing, 2011; 51-172.

2. Christian P1, West KP Jr. Interactions between zinc and vitamin A: an update. Am J Clin Nutr. 1998 Aug;68(2 Suppl):435S-441S.

3. Adriani M, Wirjatmadi B. The effect of adding zinc to vitamin A on IGF-1, bone age and linear growth in stunted children. J Trace Elem Med Biol. 2014 Oct;28(4):431-5. doi: 10.1016/j. jtemb.2014.08.007. Epub 2014 Sep 8.

4. Kubena K, McMurray D. Nutrition and the immune system: a review of nutrient-nutrient interactions. J Am Diet Ass. 1996;96(11):1156-1164.

5. Dousdampanis P, Trigka K, Fourtounas C.Hypomagnesemia, chronic kidney disease and cardiovascular mortality: pronounced association but unproven causation. Hemodial Int. 2014 Oct;18(4):730-9. doi: 10.1111/hdi.12159. Epub 2014 Mar 18.

6. Wu C, Kenny MA. Circulating total and ionized magnesium after ethanol ingestion. Clin Chem. 1996 Apr;42(4):625-9.

7. Perazella MA. Proton pump inhibitors and hypomagnesemia: a rare but serious complication. Kidney Int. 2013 Apr;83(4):553-6. doi: 10.1038/ki.2012.462.

8. de Baaij JH, Hoenderop JG, Bindels RJ. Magnesium in man: implications for health and disease. Physiol Rev. 2015 Jan;95(1):1-46. doi: 10.1152/physrev.00012.2014.

9. Magnesium: University of Maryland Medical Center http://umm.edu/health/medical/altmed/supplement/magnesium#ixzz3VtRmxWK6

10. Malavolta M, Piacenza F, Basso A, Giacconi R, Costarelli L, Mocchegiani E. Serum copper to zinc ratio: Relationship with aging and health status. Mech Ageing Dev. 2015 Feb 7. pii: S0047-6374(15)00006-8. doi: 10.1016/j. mad.2015.01.004. [Epub ahead of print]

11. Wu X, Liu Z, Guo J, Wan C, Zhang T, Cui H, Yang F, Gao X. Influence of dietary zinc and copper on apparent mineral retention and serum biochemical indicators in your male mink. Biol Trace Elem Res. 2015.

12. Lane DJ1, Richardson DR2. The active role of vitamin C in mammalian iron metabolism: much more than just enhanced iron absorption! Free Radic Biol Med. 2014 Oct;75:69-83. doi: 10.1016/j.freeradbiomed.2014.07.007. Epub 2014 Jul 15.

13. Gleerup A, Rossander-Hulthen L, Gramatkovski E, Hallberg L. Iron absorption from the whole diet: comparison of the effect of two different distributions of daily calcium intake. Am J Clin Nutr. 1995;61:97-104. (#88 iron).

14. Rossander-Hultén L, Brune M, Sandström B, Lönnerdal B, Hallberg L. Competitive inhibition of iron absorption by manganese and zinc in humans. Am J Clin Nutr. 1991 Jul;54(1):152-6. 

DR. ALAN GABY, THE AUTHOR OF NUTRITIONAL MEDICINE (1), is an MD who has devoted his entire career to the practice of nutritional medicine. His knowledge is encyclopedic, reflective of his Yale background, and very much evidence-based. University of Western States uses his textbook in a couple of courses in the master’s program in nutrition and functional medicine. He is past-president of the American Holistic Medical Association and gave expert testimony to the White House Commission on Complementary and Alternative Medicine on the cost-effectiveness of nutritional supplements.

Dr. Georgia Nab is a chiropractor at Standard Process Inc. in Palmyra, Wisconsin. She holds a master’s degree in human nutrition and functional medicine. Prior to working for Standard Process, she owned her clinic in Wichita, Kansas, for more than a decade.

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