Common nutrient deficiencies in IBD and why they happen

If you live with Crohn’s disease or ulcerative colitis, you may already know that fatigue, low energy, or slow healing can be linked to more than just the condition itself. People with inflammatory bowel disease (IBD) are at higher risk of vitamin and mineral deficiencies. This happens even when eating a healthy diet, because IBD affects the way nutrients are absorbed and used by the body.

Understanding the most common IBD nutrient deficiencies can help you work with your healthcare team, adjust your diet, and consider supplements if needed.

Why nutrient deficiencies are common in Crohn’s and colitis

There are several reasons why people with IBD are more likely to have low vitamin and mineral levels:

• Malabsorption: inflammation in the gut makes it harder to absorb nutrients.

• Surgery: resections, especially in the ileum, reduce absorption of vitamin B12 and bile acids.

• Diarrhoea: frequent bowel movements flush out minerals like zinc and magnesium.

• Restricted diet: avoiding foods due to symptoms can limit nutrient intake.

• Medications: steroids, methotrexate, sulfasalazine and other IBD drugs can deplete certain vitamins.

The most common vitamin and mineral deficiencies in IBD

Vitamin D

Often low due to malabsorption and reduced sun exposure. Supports immune health and bone strength.
Food sources: oily fish, eggs, fortified plant milks, mushrooms.

Vitamin B12

Low when the ileum is affected by Crohn’s disease or removed surgically. Essential for energy and nerve function.
Food sources: fish, dairy, eggs, fortified plant milks, nutritional yeast.

Folate (Vitamin B9)

Reduced by certain IBD medications and poor absorption. Important for red blood cell production.
Food sources: leafy greens, beans and pulses, avocado, asparagus.

Iron

Depleted by blood loss, poor absorption, and inflammation. Low levels cause anaemia and fatigue.
Food sources: lentils, beans, spinach, pumpkin seeds, red meat.

Zinc

Lost through diarrhoea and poor absorption. Needed for immunity and wound healing.
Food sources: pumpkin seeds, chickpeas, cashews, whole grains.

Magnesium

Low with diarrhoea and malabsorption. Supports muscles, energy, and relaxation.
Food sources: nuts, seeds, leafy greens, dark chocolate.

Calcium

Often low if dairy is avoided or from long-term steroid use. Vital for bones and muscle function.
Food sources: dairy, fortified plant milks, tahini, almonds.

Selenium

Sometimes low due to malabsorption and soil depletion. Needed for antioxidant protection.
Food sources: Brazil nuts, fish, eggs, whole grains.

Omega-3 fatty acids

Frequently low because of diet imbalances. Help reduce inflammation and support brain health.
Food sources: oily fish, flaxseeds, chia seeds, walnuts, algae oil.

Vitamin K

Can be depleted with fat malabsorption. Supports blood clotting and bone health.
Food sources: leafy greens, broccoli, Brussels sprouts.

How to manage IBD deficiencies

• Ask for blood tests: the only way to know your nutrient status is to get tested.

• Prioritise whole foods: build meals around nutrient-dense foods that are tolerated.

• Consider supplementation: in some cases, diet alone is not enough, and targeted supplements are required.

• Work with a professional: a nutritional therapist like me who is familiar with IBD can guide you safely.

Free chart: IBD nutrient deficiencies and food sources

I have created a free one-page chart that shows the most common vitamin and mineral deficiencies in Crohn’s and ulcerative colitis, why they occur, and which foods support healthy levels. It is simple, visual, and easy to save or print.

👉 Click here: Free download of nutrient chart for IBD

Key takeaway: Vitamin and mineral deficiencies are common in Crohn’s disease and ulcerative colitis, but they can be managed. By understanding why they occur and focusing on supportive foods and supplements, you can reduce risks and give your body the best chance to heal.