Chromium: what the research does and doesn't show

The evidence doesn't support constipation or weight gain as documented chromium side effects, and it doesn't support a tested, established dose for pregnancy or breastfeeding — the digestive complaints reported in trials run the other way (loose stools, not constipation), the weight data leans toward a small loss rather than a gain, and no trial in this literature enrolled pregnant or breastfeeding participants.

What the evidence doesn't support

It doesn't support constipation as a chromium side effect: the largest safety-relevant reviews describe loose or watery stools among reported gastrointestinal complaints, not constipation, and we didn't find a trial reporting constipation specifically. It doesn't support weight gain: the trial data on chromium and body weight found a small average weight loss against placebo, not a gain. And it doesn't support a specific safe or effective dose for pregnancy or breastfeeding — those groups have their own, separate Adequate Intake figures, but no clinical trial of chromium supplementation in pregnant or breastfeeding people appears in this literature, so nothing here is evidence for or against supplementing in either situation.

What the trials found

A 2013 meta-analysis of 11 randomized trials in overweight and obese adults reported gastrointestinal and other adverse events including watery stools, vertigo, headaches and hives among people taking chromium versus placebo — headache and loose stools were the most GI-specific complaints, not constipation. A 2014 meta-analysis of 25 randomized trials in people with diabetes reported that adverse events overall did not differ meaningfully between chromium and placebo groups at the doses those trials used. Across both reviews, the same body of research found a small average weight loss with chromium (about 0.5 kg versus placebo in the 2013 analysis), not weight gain.

On pregnancy and breastfeeding specifically: the Food and Nutrition Board's dietary reference intake report sets a slightly higher Adequate Intake for these groups than for other adults — around 29-30 mcg/day in pregnancy and 44-45 mcg/day while breastfeeding, depending on age — reflecting increased need, not a tested supplemental dose. No randomized trial in the chromium literature reviewed here enrolled pregnant or breastfeeding participants, so there's no trial-based safety or efficacy data specific to either group beyond that reference intake figure.

Questions people ask

Can chromium cause constipation?

We didn't find a trial reporting constipation as a chromium side effect. The gastrointestinal complaints that have been reported are loose or watery stools, the opposite issue.

Can chromium picolinate cause diarrhea?

Loose or watery stools have been reported as an adverse event in at least one meta-analysis of chromium trials, though rates weren't broken out in enough detail to give a percentage.

Can chromium picolinate cause weight gain?

No — the trial evidence points the other way. A meta-analysis of 11 randomized trials found chromium associated with a small average weight loss compared with placebo, not a gain.

Can chromium cause headaches?

Headache has been listed as a reported adverse event in chromium trials, alongside other mild complaints like dizziness and loose stools, generally at rates the largest reviews describe as not clearly different from placebo.

Is chromium safe during pregnancy?

No clinical trial of chromium supplementation in pregnant people appears in this literature, so there's no trial-based answer either way. Pregnancy has its own, slightly higher Adequate Intake figure, but that's a nutrient-need estimate, not a tested supplement dose — talk to your doctor before adding a chromium supplement during pregnancy.

Is chromium safe while breastfeeding?

Same gap: no trial of chromium supplementation in breastfeeding people was found in this review. Talk to your doctor before adding a chromium supplement while breastfeeding rather than using a general adult dose.

What is chromium and magnesium good for, together?

There's no dedicated trial of chromium and magnesium taken together — each has its own separate research base at its own dose. See chromium and magnesium: what's the difference for how the two compare as nutrients and food sources.

When to talk to a doctor

Talk to a doctor before taking chromium if you're pregnant or breastfeeding, or before giving it to a child — this page and the broader literature don't cover dosing for children at all. See who should not take chromium and chromium side effects for the fuller picture on tolerability at ordinary doses.