Herb & supplement monograph

Blood Type Diet Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by ·Updated June 2026
What is this page for?

First and foremost: how Blood Type Diet interacts with medications. The heart of this page is the interaction list — every drug Blood Type Diet is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Blood Type Diet is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Interaction report

Drugs that interact with Blood Type Diet

0 medications have a known interaction with Blood Type Diet, graded by severity. Select any drug for the full evidence-based detail.

We don’t currently list any known drug interactions for Blood Type Diet. This doesn’t guarantee none exist — always confirm with your pharmacist before combining supplements with your medications.

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

  • Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
  • Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
  • Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
  • No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

  • Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
  • Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
  • Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

  • Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
  • Each drug listed above links to the full report for that exact Blood Type Diet combination — clinical detail, likelihood, evidence level, and citations.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
Monograph

Blood Type Diet: Uses, Safety & Side Effects

Medically reviewed by · Reviewed June 2026 ·
The bottom line

The Blood Type Diet claims that eating foods matched to your ABO blood type improves health and weight, but good-quality studies have not shown that blood type determines who benefits from a given diet. Any health improvements people see are more likely from simply eating more whole, unprocessed foods. Talk to a pharmacist or doctor before making big changes, especially if you have a health condition.

Common forms
Eating plan (whole-food diet based on ABO blood type)
People commonly use it for
  • Weight loss
  • General wellness
  • Heart health
  • Digestive health
  • Reducing inflammation

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance
OverallUse caution

The diet itself is generally food-based, but restricting whole food groups may lead to nutrient gaps.

PregnancyInsufficient reliable information

Insufficient reliable information available; avoiding using.

Read the full pregnancy detail
BreastfeedingInsufficient reliable information

Insufficient reliable information available; avoiding using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

The Blood Type Diet is an eating plan popularized in the 1990s by naturopath Dr. Peter D'Adamo in his book Eat Right 4 Your Type. It is not an herb, plant, or supplement — it is a dietary approach.

The main idea is that your ABO blood type (A, B, AB, or O) should decide which foods you eat. For example, type O is told to eat more meat and fewer grains, while type A is steered toward a mostly plant-based diet. Each blood type also gets lists of foods to avoid.

People follow the diet hoping to lose weight, feel more energetic, or improve overall health.

How it works

The diet's creator proposed that each blood type evolved at a different time in human history and is suited to certain foods. He also suggested that proteins called lectins in some foods react differently with each blood type, causing problems like clumping of blood cells or inflammation.

This lectin theory has not been confirmed by solid scientific research in people. Most of the supporting ideas come from theory rather than well-designed human studies.

Any real benefits people experience are best explained by the diet pushing them toward more vegetables, fruits, and whole foods and away from processed foods and added sugar — changes that help almost anyone.

Effectiveness

Does Blood Type Diet work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by .

Evidence overview · 1 use evaluated
1 Insufficient evidence
How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.
2Likely EffectiveGood evidence, though not yet conclusive.
3Possibly EffectiveSome evidence suggests a benefit.
4Possibly IneffectiveSome evidence it may not help.
5Likely IneffectiveFairly strong evidence it doesn’t help.
6IneffectiveStrong evidence it doesn’t work.
7Insufficient Reliable Evidence to RateToo little research to say either way.

For Blood Type Diet, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 1 condition — evidence insufficient to rate
Insufficient Reliable Evidence To Rate Obesity
Rating & evidence shown verbatim from Natural Medicines

The blood type diet postulates that individuals with blood type A will experience cardiometabolic improvements from a plant-based diet, while individuals with blood type O will not. However, a secondary analysis of a clinical trial in obese patients has found that following a low-fat vegan diet for 16 weeks is associated with comparable improvements in weight, lipid levels, and glycemic control in all patients, regardless of blood type.

Sources Ref 104095

Source & disclaimer. Effectiveness ratings and evidence summaries are provided by Natural Medicines (Therapeutic Research Center) and shown as licensed. Where Natural Medicines hasn’t rated a use, HelloPharmacist’s pharmacists may add their own reviewed rating and evidence (each such entry is labeled). This is educational information, not medical advice — talk with your pharmacist or doctor before starting, stopping, or changing a supplement.

Safety & precautions

Because the Blood Type Diet is built around real foods, it is not dangerous for most healthy adults in the short term. However, some versions cut out entire food groups, such as grains, dairy, or many proteins. Over time this can lead to nutrient gaps (for example, calcium, fiber, or certain vitamins).

People with diabetes, kidney disease, heart disease, eating disorders, or other medical conditions should be especially careful and talk to a doctor or dietitian before starting.

For pregnancy and breastfeeding, use caution. Restrictive diets may not provide enough calories or nutrients for you and your baby. It is safest to avoid strict versions and work with your healthcare provider on a balanced plan.

Side effects

The diet itself does not cause classic "side effects" like a drug would. Problems usually come from being too restrictive.

These can include low energy, constipation or digestive changes, unwanted weight loss, or missing nutrients if major food groups are dropped. Cutting out dairy without a replacement, for instance, may lower calcium and vitamin D intake.

If you feel weak, dizzy, or notice you are losing weight quickly or unintentionally, stop and check with a healthcare professional.

Dosing

There is no "dose" for the Blood Type Diet — it is an eating pattern, not a pill. Followers are given food lists for their blood type and adjust meals accordingly.

If you want to try it, focus on the healthy parts (more whole foods, fewer processed foods) and make sure you still get a full range of nutrients. A pharmacist, doctor, or registered dietitian can help you plan a balanced version and decide whether any supplement, such as a multivitamin, is needed.

Pregnancy & Breastfeeding

Blood Type Diet & Pregnancy

Insufficient reliable information

Insufficient reliable information available; avoiding using.

Blood Type Diet & Breastfeeding

Insufficient reliable information

Insufficient reliable information available; avoiding using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

© 2026 Therapeutic Research Center

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

The 1 references that drive our Blood Type Diet monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Barnard ND, Rembert E, Freeman A, Bradshaw M, Holubkov R, Kahleova H. Blood Type Is Not Associated with Changes in Cardiometabolic Outcomes in Response to a Plant-Based Dietary Intervention. J Acad Nutr Diet. 2020;S2212-2672(20)31197-7. PubMed
Keep reading

This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Pharmacist Counseling Corner

Blood Type Diet: Common Questions

What is Blood Type Diet used for, and does it work?
People use Blood Type Diet for a range of reasons, but according to the Natural Medicines database the current clinical evidence is insufficient to confirm it works for the specific conditions it has been studied for. See the graded list on this page, and talk to your pharmacist or doctor before relying on it for any condition.
Does Blood Type Diet interact with prescription medications?
We do not currently list any known drug interactions for Blood Type Diet. This does not guarantee that none exist, so always confirm with your pharmacist before combining it with your medications.
How are Blood Type Diet interactions rated?
Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.
Is it safe to take Blood Type Diet with my medications?
It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.
Where does this Blood Type Diet interaction information come from?
Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.
Does the Blood Type Diet really work?
Research has not shown that matching food to your blood type improves health. Any benefits people see usually come from eating more whole, unprocessed foods rather than from their blood type.
Is the Blood Type Diet safe?
For most healthy adults it is generally safe short term because it is food-based, but very restrictive versions can cause nutrient gaps over time. Talk to a healthcare provider if you have a medical condition.
Can I follow the Blood Type Diet while pregnant or breastfeeding?
Use caution. Restrictive eating plans may not provide enough calories or nutrients during pregnancy and breastfeeding, so check with your doctor before starting.
Do I need to know my blood type to eat healthy?
No. A balanced diet rich in vegetables, fruits, whole grains, and lean proteins benefits people of all blood types. You do not need your blood type to eat well.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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