# Nutrition and diets in primary immunodeficiencies
Nutritional choices play a supportive role in severe immunodeficiencies. Because the immune system does not function properly, infections can develop more easily and last longer. Certain dietary patterns are being investigated or recommended as a complement to medical treatment, particularly because malnutrition or specific deficiencies can further weaken the immune system.
Below you will find an overview of dietary approaches associated with this condition in practice and science.
Protein-rich nutrition
ResearchediPositive results in clinical studies, not yet standard treatment
This dietary pattern emphasizes regular intake of complete proteins (for example from meat, fish, eggs, dairy, legumes). Proteins are essential for the production of immune cells and antibodies.
In severe immunodeficiencies, especially those accompanied by diarrhea or malnutrition, protein losses in the intestine can occur. A 2026 study on primary intestinal lymphangiectasia as a cause of secondary immunodeficiency and another study on protein-losing enteropathy (2026) show that protein loss via the intestine is a serious problem. Adequate protein intake helps compensate for these losses.
Research from the literature (2026) shows that in children with non-cystic fibrosis bronchiectasis and malnutrition, the immune system responds more weakly to infections. This suggests that adequate protein supply is important for immune function, although direct evidence specific to primary deficiencies is limited.
**Risks:** In certain immunodeficiencies with gastrointestinal symptoms, diarrhea can impede protein digestion. This may require adapted forms (for example ground or liquid protein sources) that place less strain on the gastrointestinal tract.
Nutrition rich in micronutrients (vitamins and minerals)
ResearchediPositive results in clinical studies, not yet standard treatment
This pattern focuses on adequate intake of vitamins (especially A, C, D, E) and minerals (zinc, iron, selenium) that are known to be important for immune function.
Research from 2026 on Ataxia-Telangiectasia, a form of primary immunodeficiency, shows that vitamin D deficiency is common in these patients and is associated with more severe inflammatory responses. This suggests that vitamin status is relevant to the course of immune disorders.
Zinc plays a crucial role in the development of T cells and immune response. Malnutrition is often accompanied by zinc and iron deficiency, both of which impair immune function.
**Risks:** Overdosing of certain vitamins (for example excessive vitamin A) can in some contexts adversely affect immune function. This requires caution and guidance from the medical team or dietitian.
Probiotic supplementation
ResearchediPositive results in clinical studies, not yet standard treatment
Probiotic foods and supplements contain live bacteria (for example Lactobacillus, Bifidobacterium) that can support the intestinal flora.
A randomized controlled trial from 2026 showed that probiotic supplementation in infants improved respiratory health, gastrointestinal health, immune balance and gut microbiota composition. This suggests possible benefit also for children with defective immune systems who are affected by infections and diarrhea.
However, the mechanisms are not fully understood, and effects can vary greatly depending on disease type and individual.
**Risks:** For very severely immunocompromised patients (for example with certain forms of combined immunodeficiency), live bacterial cultures can theoretically cause infections themselves. This requires careful selection and medical approval.
Periodic fasting or time-restricted eating
UnproveniNo scientific evidence that it works
This pattern restricts the eating window to certain hours of the day or involves regular fasting periods.
For primary immunodeficiencies, no direct research on periodic fasting is known. In patients with malnutrition — which is common in severe immunodeficiencies with diarrhea or malabsorption — fasting could potentially be harmful as it may cause further nutritional deficits.
Research from 2026 on protein-losing enteropathy and intestinal gland weakness shows that continuous, adequate nutritional intake is crucial to prevent deficits. Fasting would work against this.
**Why unproven:** There are no studies on the effects of periodic fasting in primary immunodeficiencies. Until evidence is available, this pattern cannot be recommended and may even be risky.
Diet low in specific components (for example, low FODMAP)
ResearchediPositive results in clinical studies, not yet standard treatment
This pattern limits intake of difficult-to-digest carbohydrates (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) to relieve gastrointestinal symptoms (bloating, diarrhea).
In immunodeficiencies with severe diarrhea — as reported in research from 2026 on selective IgA deficiency (with chronic enteropathy), primary intestinal gland weakness and protein-losing enteropathy — dietary adjustment may be necessary.
A low-FODMAP pattern can help with symptom management, although this is usually done under the guidance of a dietitian. It is not immunodeficiency-specific, but aimed at intestinal comfort and absorption.
**Risks:** Inappropriate dietary restriction can lead to further malnutrition. This requires expert advice to ensure nutrition remains adequate.
Diet with stabilized glutamine or arginine
ExperimentaliOngoing in study setting, outcome still unknown
Glutamine and arginine are amino acids involved in intestinal function and immune response. Nutritional supplements of these are sometimes studied in contexts of intestinal damage and immunosuppression.
For primary immunodeficiencies, direct research is limited. The research from 2026 on intestinal gland weakness and protein-losing enteropathy as complications of immunodeficiencies suggests that intestinal barrier support may be relevant, but specific amino acid supplementation is not well established.
**Why experimental:** There are still insufficient clinical trials in primary deficiencies. It may have theoretical benefit, but has not been demonstrated as a standard approach.
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**Nutritional choices in primary immunodeficiencies are always individualized.** Because the underlying condition and associated intestinal, absorption and infection problems can vary greatly, nutritional guidance should be part of your medical team: your clinician, or — better yet — a dietitian with experience in immunodeficiencies. They can determine which nutritional choices are safe and meaningful for your or your child's specific situation.
_This information never replaces a doctor's judgment. Always discuss your situation with your own healthcare provider._