4 Harmful Supplements To Avoid If You’re At Risk For Gastrointestinal Disorders: Iron, More
March 25, 2025 by Faith Geiger
A healthy gut is one of the biggest keys to a healthy body overall. There are many great ways to nourish your gut. In addition to regularly adding probiotic-rich foods to your plate, you may turn to supplements. However, it’s always important to proceed with caution, as many supplements come with hidden risks. While certain vitamins and minerals support digestion, others can worsen gastrointestinal issues—causing bloating, constipation, or even gut inflammation. If you’re prone to digestive disorders, it’s crucial to be mindful of what you take.
We checked in with health experts to shed light on four common supplements that may negatively impact gut health, especially for those with sensitive digestive systems. They told us that calcium, magnesium, iron, and weight loss supplements should always be consumed with caution. Read on to learn about the risks of each.
1. Calcium Carbonate
One supplement to take cautiously is calcium supplements. Best known for its bone health benefits, they can also cause constipation, bloating, and gas, as they can slow down the digestive process.
Michael O. McKinney, MD from Healthy Outlook, elaborates on this and notes that "calcium is an essential element for the development of bones; however, calcium carbonate supplements produce a constipating effect and may be uncomfortable in the digestive system. This type of calcium is less soluble and may bring disturbances in the intestines, so it becomes difficult for the digestive tract to become healthy."
2. Magnesium Supplements
Magnesium supplements, especially in higher doses or specific forms like magnesium oxide, can mess up gut health by causing digestive issues such as diarrhea, cramping, and bloating. This could happen because magnesium acts as a laxative by drawing water into the intestines, leading to loose stools and dehydration if taken in excess.
"Too much consumption of magnesium can lead to a laxative effect, causing diarrhea. This can cause an imbalance in the natural gut flora and irritate the gastrointestinal tract, leading to discomfort and disrupting digestive health," says Dr. Kubanych Takyrbashev, MD, Health & Wellness Advisor at NAO.
3. Iron Supplements
Believe it or not, high doses of iron can irritate the digestive tract, leading to common side effects such as constipation, nausea, and stomach pain.
Although iron is important, McKinney says large amounts of it can "lead to an altered flora in the digestive system. Intake of large amounts of iron may promote the growth of pathogenic bacteria, thus resulting in upset stomach, constipation, bloating, and inflammation."
4. Unregulated weight loss supplements
Weight loss supplements can seem like a convenient and easy way to reach your fat loss goals, but it’s extremely important to be careful with them. These supplements promise many things but can harm your gut in several ways, particularly those containing harsh ingredients like stimulants, laxatives, or unregulated compounds.
Some weight loss supplements can cause rapid and unhealthy changes in gut function, which negatively affects nutrient absorption and leads to gut inflammation and irritation.
Another thing to consider is the lack of regulation in the supplement industry. This increases the risk of consuming harmful additives or contaminants, further compromising your gut state.
Dr. Kevin Huffman, CEO & Founder of Ambari Nutrition says, "Avoid weight loss supplements that are not regulated. A few may contain ingredients that aren’t labeled and could negatively impact gut health. Stick with the reputable brands and, due to their potency, consult your doctor before beginning any new supplement, especially if you have diabetes or are following a bariatric diet plan."
For safer weight management, it's a better idea to focus on balanced nutrition and regular exercise rather than relying on supplements.