Mrs. L, a 72-year-old woman with type 2 diabetes, had been taking metformin for the past 8 years to control her blood sugar. Recently, she began experiencing persistent fatigue and a tingling sensation in her hands and feet. She wondered if this was due to aging, but her pharmacist suspected more.

Do you know that some commonly prescribed medications may gradually deplete your body of essential nutrients? Micronutrients (https://www.ncbi.nlm.nih.gov/books/NBK597352/), such as vitamins and minerals, are critical for producing energy to support body functions, or to maintain overall health. When micronutrient levels fall below the minimum recommended thresholds, these deficiencies may impact well-being, making people feel unwell. Symptoms of certain micronutrient deficiencies may include bone pain, weakness, tiredness, slow healing wounds, skin discoloration or itchiness, etc. For a full list of the recommended amounts of micronutrients, please visit Health Canada (https://webprod.hc-sc.gc.ca/nhpid-bdipsn/atReq?atid=multi_vitmin_suppl&lang=eng) for its multi-vitamin/mineral supplements monograph website.

How Medications Can Cause Micronutrient Deficiencies 

Certain medications can contribute to micronutrient deficiencies in various ways. This includes decreasing micronutrients absorption in the stomach or gut, changing their breakdown process in the body, or increasing their excretion through the kidneys. Some medications can also change the stomach’s natural acidity, damage the gut lining, or compete with micronutrients for absorption. Additionally, certain drugs may speed up nutrients breakdown or interfere with the pathways that are involved in processing or utilizing the micronutrients. Table 1 includes some examples of medications, what and how micronutrient(s) may be affected by them. This is not a comprehensive list. However, readers are encouraged to refer to another reference for further information (https://journals.sagepub.com/doi/10.1177/8755122518780742), e.g., Medications and Micronutrients: Identifying Clinically Relevant Interactions and Addressing Nutritional Needs (published in the Journal of Pharmacy Technology in 2018).

Recognizing and understanding these effects is important when using multiple medications, especially for individuals with chronic medical conditions. Long-term use of some of these medications may increase the risk and severity of micronutrient depletion over time. This can be worsened further if mis-identified as being a normal part of ageing or disease progression (like our patient, Mrs. L, see above).

Table 1. Examples of medications that may cause micronutrient deficiencies (Note: This is not a comprehensive list.)

How Pharmacists Can Help 

Pharmacists play an important role in educating patients about the importance of maintaining a balanced, nutrient-rich diet. While the body generally requires small amounts of vitamins and minerals, when dietary intake is insufficient, or if medication use interferes with their absorption, targeted supplementation may be necessary. Identification of at-risk patients through routine blood work, follow-up medication therapy management and monitoring are key. Interventions for micronutrient deficiencies that pharmacists could recommend include suggesting the right vitamin or mineral supplements, giving advice on foods that could boost micronutrient levels, and checking whether medications may be affecting or lowering micronutrient absorption/excretion. 

In Mrs. L’s case, a Vitamin B12 test (recommended and/or ordered by her pharmacist or primary care provider) revealed a micronutrient deficiency that contributed to her symptoms of tingling feet and hands. With appropriate supplementation and ongoing monitoring, her condition improved – highlighting the critical role that pharmacists can play in detecting and managing medication-induced micronutrient deficiencies. Overall, pharmacists play a vital role in helping patients optimize their medications while ensuring patients can maintain sufficient micronutrient levels. This helps keep medication therapy both safe and effective.

Sheena Ye, Christie Poon, and Laura Brady are PharmD Students at the Leslie Dan Faculty of Pharmacy, University of Toronto; and Certina Ho is an Assistant Professor, Teaching Stream, at the Leslie Dan Faculty of Pharmacy and Department of Psychiatry, University of Toronto.