The NHS has issued a warning about the potential side effects of vitamins and supplements, which can cause digestive problems such as stomach pain, nausea, and diarrhoea. Many people may not realise that their daily vitamin intake could be the culprit behind these uncomfortable symptoms.
Common Supplements That Can Cause Issues
According to the Cleveland Clinic, vitamins and supplements can exacerbate digestive conditions like reflux, ulcers, gastritis, and irritable bowel syndrome (IBS). Gastroenterologist Dr Christine Lee notes that individuals with these conditions are more likely to experience side effects. However, even those without pre-existing conditions can suffer from an upset stomach, diarrhoea, nausea, or acid reflux, particularly when taking supplements containing calcium, vitamin C, or iron, which can irritate the stomach lining.
"Taking vitamins on an empty stomach can frequently upset the GI tract," Dr Lee explains, adding that it can cause many people to "experience stomach pains, nausea and even diarrhoea."
Iron Supplements
Iron is a common supplement. The NHS states that men aged 19 and over need 8.7 mg of iron daily, while women aged 19 to 49 need 14.8 mg, and women aged 50 and over need 8.7 mg. Women who still have periods after 50 may also need 14.8 mg daily. Most people obtain sufficient iron from their diet. However, taking high doses (over 20 mg) can lead to side effects including constipation, nausea, vomiting, and stomach pain. The NHS cautions: "Very high doses of iron can be fatal, particularly if taken by children, so always keep iron supplements out of the reach of children."
Vitamin C Supplements
Vitamin C is another common supplement. Adults aged 19 to 64 need 40 mg of vitamin C daily, but excessive intake can cause stomach pain, diarrhoea, and flatulence.
What to Do If Vitamins Are the Issue
Experts advise not to overdo it, as most people already get plenty of vitamins and minerals from food. Taking too many supplements can make you unwell. Here are some recommendations:
- Take vitamins with food. If you struggle to eat in the morning, try taking them with dinner. "Taking them with food enhances the body’s ability to absorb the vitamins and decreases your risk of experiencing nausea and upset stomach," Dr Lee says.
- Do not take them before exercising. "It’ll just slosh around in your stomach and induce gastric acid production," Dr Lee points out, which could worsen heartburn or reflux.
- Try easy-to-digest formats. Tablets are harder to digest due to binding agents. Dissolvable, chewable, powder, or gummy vitamins are easier on the stomach.
- Reduce your dose size. Taking a smaller dose daily is better than a large dose weekly. If you take several vitamins, try half with breakfast and half with dinner.
- Eat a diet rich in vitamins. Dr Lee advises getting vitamins naturally through food. Sardines, dairy, and leafy greens are great for calcium; shellfish, legumes, red meat, and pumpkin seeds provide iron. Real food sources are always preferred over supplements.
Always read the label and consult your doctor before taking vitamins, as some may interfere with medications or may not be suitable for you. Arrange an appointment with your GP if you have concerns.
