Why is cabbage not good for blood type O?

Why Cabbage Might Not Be Ideal for Blood Type O

If you follow the blood type diet, you may have heard that people with blood type O should limit or avoid cabbage. While this idea stems from the popular blood type eating theory by Dr. Peter D’Adamo, it’s worth understanding the reasoning behind it—even if science hasn’t fully backed it yet.

According to this theory, individuals with blood type O, often described as descendants of ancient hunters, thrive on high-protein diets and may struggle with certain grains, legumes, and specific vegetables—particularly those in the Brassica family, which includes cabbage, cauliflower, broccoli, and Brussels sprouts. The concern lies in compounds called goitrogens, naturally present in these vegetables, which can interfere with thyroid function by inhibiting iodine uptake.

For type Os, who are said to be more sensitive to dietary stressors, excessive goitrogenic foods like raw cabbage may contribute to sluggish thyroid activity over time—potentially leading to fatigue, weight gain, or hormonal imbalances. While cooking can reduce goitrogen levels significantly, proponents of the blood type diet still recommend moderation.

It’s important to note that mainstream science hasn’t confirmed the blood type diet’s claims. Many people, regardless of blood type, consume cabbage without issue, and the vegetable is rich in fiber, vitamin C, and antioxidants. But if you're type O and notice digestive discomfort or low energy with heavy cruciferous vegetable intake, it might be worth exploring whether portion or preparation makes a difference.

As always, individual responses vary. While cabbage isn't inherently "bad" for blood type O, understanding your body’s signals matters more than any rigid rule.