What Is the Cabbage Soup Diet?
The cabbage soup diet has been around in various forms since the 1980’s. Although it has been called other names, such as the Mayo Clinic Cabbage Soup Diet and the Sacred Heart Hospital Diet, it is not associated in any way with these institutions.
The diet is low-fat and high fiber, and typically runs for 1 week at a time. Each day unlimited cabbage soup (for which there are several recipes) is paired with specific fruits, vegetables, milk or meat. A typical meal plan goes like this:
- Day 1: Fruit, except bananas
- Day 2: Vegetables like leafy greens (not starchy), but no fruit
- Day 3: Fruits and vegetables
- Day 4: Bananas and skim milk
- Day 5: Beef (or baked chicken without the skin) and tomatoes. You are allowed 10-20 oz of meat.
- Day 6: Beef and vegetables
- Day 7: Brown rice, unsweetened fruit juices, and vegetables
I could find no rationale or explanation for the order or combinations of foods recommended on different days. For the first 3 days, there is very little protein or fat and most of what you’re eating are combinations of simple and complex carbohydrates.
The protein level goes up a bit with the skim milk on Day 4 then a lot of protein is added on Days 5 and 6, returning to a combination of complex and simple carbohydrates on Day 7. None of this makes any sense to me in terms of physiology or metabolism.
Here is one recipe for the cabbage soup:
- 2 large onions
- 2 green peppers
- 2 cans of tomatoes
- 1 bunch of celery
- 1 head of cabbage
- 3 carrots
- 1 package of mushrooms
- 1–2 bouillon cubes (optional)
- 6–8 cups water or vegetable cocktail such as V8
- Chop all vegetables into cubes.
- In a large stock pot, sauté onions in a small amount of oil.
- Then add remaining vegetables and cover with water or vegetable cocktail and add bouillon cubes or other seasonings, if desired.
- Bring to a boil, then reduce to medium heat. Let simmer until vegetables are tender, about 30–45 minutes.
You may season the soup with salt, pepper, hot sauce, herbs or spices. You may also add other non-starchy vegetables, such as spinach or green beans.
The main ingredient of the soup, cabbage, belongs to the group of vegetables called cruciferous vegetables, all of which are members of the Brassica oleracea family. Other family members include broccoli, cauliflower, brussels sprouts and Chinese or Napa cabbage.
According to the United States Department of Agriculture (USDA) National Nutrient Database, 100 g of raw cabbage contains:
- Calories: 25
- Fat 0.10 g
- Carbohydrate 5.8 g
- Sugars 3.2 g
- Fiber 1.9 g
- Protein 1.3 g
- Vitamin C 36.6 mg
- Calcium 40 mg
- Potassium 170 mg
Cabbage also contains lutein (0.1mg) and zeaxanthin (27 mcg) in addition to the flavonoids kaempferol (1.2 mg), quercetin (3.9 mg), and apigenin (0.04mg).  Lutein and zeaxanthin are called carotenoid vitamins, being related to beta-carotene and vitamin A. They are the two major carotenoids found as a color pigment in the human eye (macula and retina). They are thought to function as a light filter, protecting the eye tissues from sunlight damage. Flavonoids are a group of plant metabolites thought to provide health benefits through cell signaling pathways and antioxidant effects.
Is There any Research?
A search of PubMed using the term “cabbage soup diet” brings up 8 unrelated articles, none of which actually refer to this specific diet. One of these articles by Kellingray et al  is a clinical trial the results of which suggests that increased consumption of Brassica family vegetables may be potentially beneficial to gastrointestinal health because of effects on the gut microbiome.
I was able to find another peer-reviewed publication entitled Functional Foods if fad diets: A review by Navaro et al  that discusses the Cabbage Soup Diet and the bioactive qualities of cabbage that we described in detail below.
For comparison, The Atkins Diet has 798 articles in PubMed, 115 of them labelled as “clinical trials.” There are 36 clinical trials of this diet listed in ClinicalTrials.gov.
Does Cabbage Soup Diet Aids in Weight Loss?
If you follow the cabbage soup diet as written, you will lose some weight because it dramatically limits calories. At the beginning of the diet you are eating about 1000 calories/day, increasing to about 1200 calories a day by the end of the week. The recommended number of calories for most adults is about 2000 calories/day.
At the beginning of almost any diet, the first weight loss is primarily water, along with a small amount of fat, and even some muscle. In this case, the weight loss frequently returns shortly after resuming your normal diet. In addition, because “the diet is low in complex carbohydrates, protein, vitamins and minerals,” Katherine Zeratsky R.D., L.D  says “you shouldn’t stay on it for more than a week at a time.”
Two studies by Műller et al [5, 6] show that adaptive thermogenesis (AT) works against weight loss in calorie-restrictive diets. Adaptive thermogenesis is a term that describes how your body responds to calorie restriction. To maintain a stable environment your body reacts to changes in energy balance by changing the rate of your metabolism (i.e. the conversion of food to energy). Lean body tissue (which is primarily muscle tissue) is the most metabolically active body tissue.
A decrease in lean body mass would lead to a decrease in your metabolism. AT refers to a slowing of metabolism that’s greater than expected based on your lean body mass. It involves interaction between a number of hormones including hormones that control your appetite, like leptin, insulin, thyroid hormone and stress hormones like cortisol, norepinephrine and epinephrine.
The Cabbage Soup Diet causes weight loss by dramatically limiting calories. Weight loss is primarily water weight and returns quickly when discontinued. As it is not a nutritionally balanced diet, it is not recommended for use for more than one week at a time. The limited number of foods in the diet makes it easy to become quickly bored with it.
Does Cabbage Soup Diet Support Satiety and Regularity?
The argument that the cabbage soup diet supports satiety and regularity is based on the assumption that it contains high fiber foods. Fiber, the nondigestible component of plant food, is touted by most health professionals as being helping in maintaining stool regularity.
Soluble fiber allows more water to remain in your stool, making it softer, larger, and easier to pass through your intestines. Insoluble fiber adds bulk to your fecal material, which quickens its passage through your intestines and prevents that constipation. ChooseMyPlate.gov recommends that women ages 19 to 50 get at least 25 grams of fiber in their daily diets, and men in the same age group get 38 grams. Women age 50 or older are recommended to get 21 grams of fiber, while their male counterparts are encouraged to eat 30 grams.
Satiety, the state of feeling full, is also associated with increased dietary fiber. However, according to a study by Wander et al , not all fiber is created equal. Wander says that “fibres characterized as being more viscous (e.g. pectins, β‐glucans and guar gum) reduced appetite more often than those less viscous fibres (59% vs. 14%), which also applied to acute energy intake (69% vs. 30%).” A 2013 systematic review by Slavin and Clark  designed to determine the short-term effects of fiber consumption on satiety and food intake in healthy adults.
This review consisted of 107 individual treatments (or individual studies within studies) measuring satiety and 55 individual treatments measuring food intake within 44 published articles. Most treatments showed no effect. Only 39% of the treatments reduced subjective satiety ratings, and 22% of the treatments reduced food or energy intake compared with the control groups.
Of the 38 fiber types studied for satiety effects, only whole grain rye, rye bran, beta-glucan from oats and barley, lupin-kernel fiber, and a mixed diet of specific fiber-containing foods demonstrated a benefit in most or all treatments.
The cabbage soup diet does contain a number of high fiber foods that may contribute to regularity and satiety, but the effect may not be as great as it is touted to be.
Does Cabbage Soup Diet Help Fight Diseases?
“Fighting diseases” is a rather nebulous expression. There are plenty of studies done on individual food components used in the cabbage soup diet. Jiang et al  looks at the effect of cruciferous vegetables on markers of inflammation.
Verhoeven et al  did an epidemiological study on brassica vegetable and cancer risk. Masuzaki et al  looks at the effect of brown rice in diabetes. But for a diet that shouldn’t be used for more than one week is not likely to result in any long-term health benefits or disease prevention.
According to Navaro et al  the only relevant pilot study done in humans compared the effect on lipid profile of a commercially available vegetable juice which contained cabbage extract vs. a specially prepared fruit/vegetable drink with Brassica rapa (napa cabbage/bok choy)  The specialized drink was reported as being superior to the commercial beverage in normalizing lipid profiles.
A later reanalysis of the data by Allison, Antoine and George  finds that the an incorrect statistical method led to “unsubstantiated conclusions.”
Although the cabbage soup diet contains some healthy ingredients, there is no scientific evidence to support that using these ingredients, in this combination and amounts, for a one week period will result in any lasting health benefits.
Does Cabbage Soup Diet Promote Detoxification?
Usually when asked about whether a food or supplement promotes detoxification, I struggle to keep my eyes from rolling before I launch into my “lecture” about how detox or cleansing programs are unnecessary. As Peter Pressman, MD, an internal medicine specialist at Cedars-Sinai Medical Center in Los Angeles says: “The body already has multiple systems in place — including the liver, kidneys, and gastrointestinal tract — that do a perfectly good job of eliminating toxins from the body within hours of consumption.”
However, imagine my surprise when looking up cruciferous vegetables, I came across several studies that examined the effect of Brassica species (mostly broccoli, but some mention cabbage) on liver enzymes responsible for detoxification!
But first, a brief primer on Toxin (Xenobiotic) Metabolism
Xenobiotic metabolism (from the Greek xenos “stranger” and biotic “related to living beings”) is the set of metabolic pathways that modify the chemical structure of drugs, poisons and other substances from our environments that are foreign to an organism’s normal biochemistry. In animals, including humans, these metabolic pathways operate primarily in the liver.
Drug or xenobiotic metabolism is divided into three phases. In phase I, enzymes such as cytochrome P450 oxidases introduce reactive or polar groups into xenobiotics. These modified compounds are then conjugated to polar compounds in phase II reactions. These reactions are catalyzed by transferase enzymes such as glutathione S-transferases.
Finally, in phase III, the conjugated xenobiotics may be further processed, before being recognized by efflux transporters and pumped out of cells. Drug metabolism often converts lipophilic (fat soluble) compounds into hydrophilic (water soluble) products that are more readily excreted by the kidneys.
Nho and Jefferey  look at sulfur-based metabolites in cruciferous vegetables called glucosinolates. Their studies, done in rats, showed that glucosinolates were able to boost the activities of two detoxification enzymes: quinone reductase (QR) and glutathione S-transferase (GST).
A study by Houghton, Fassett and Coombs  looked at a specific group of glucosinolate metabolites called sulforaphanes. They found that these phytochemicals (from broccoli) induced phase II antioxidant and detoxification enzymes. They propose developing broccoli hybrids that contain higher amounts of sulforaphanes for commercial use.
A review article by James et al  examined the scientific investigations done as of 2015 on sulforaphane and other nutrigenomic activators of a gene called Nrf2 (nuclear factor erythroid 2-related factor). Nrf2 is considered a “master regulator” of cell defense, countering many harmful environmental toxins and carcinogens. Sulforaphane has been shown to activate Nrf2 as well as Phase II enzymes more effectively than other widely used phytochemical-based supplements like curcumin, silymarin and resveratrol.
Foods that are high in sulforaphane, such as cabbage and broccoli, may indeed aid the biochemistry of detoxification in the liver.
Is the Cabbage Soup Diet Safe?
Overall, the cabbage soup diet is relatively safe, as long as it is only used for a one-week period. Long-term use is not recommended as it is low in protein, healthy fats and other key nutrients. Because you are not getting proper nutrition, you may feel weak or tired while you are on the diet. Large amounts of cabbage can also make you prone to flatulence and bloating.
Depending on the recipe (and the broth in particular) for the cabbage soup, the soup may be high in sodium. This may be a problem for those with high blood pressure or those following a low-sodium diet. Those with diabetes may have difficulty managing their sugar levels while on the diet.
Because the diet is lax on specifying portion size, overeating bananas can cause high potassium levels, leading to electrolyte imbalances. Cabbage is also very high in vitamin K, which may interfere with blood thinners such as warfarin.
There are a few anecdotal reports of gallstones and gallbladder blockages in people who used the cabbage soup diet for long periods. This can be a unintended consequence of any rapid weight loss, low-fat diet. With a normal diet, fatty foods cause the gallbladder to release digestive juices. If fat intake is very low, not much digestive juice is released and what is in the gallbladder turns into a thick sludge, or even into a gallstone.
A study by Wytiaz et al reports that cabbage is one of several foods that can aggravate the symptoms of gastroparesis (slow emptying of the stomach).
The cabbage soup diet may be safe for most people if used only for a very short period. Longer use can lead to nutritional deficiencies due to its low protein, fat, and lack of other key vitamins and minerals. Care should be taken by individuals with health problems such as high blood pressure, diabetes, or other illnesses as noted above.
Overall the cabbage soup diet is relatively easy to follow. It tells you what you can and can’t eat on specific days. Other than making a large pot of cabbage soup, there is not a lot of meal preparation required. However, the lack of variety in the diet makes it easy to get bored with it – one of the key reasons people quit the diet.
Weight loss may be significant for the first week but will quickly return when you resume your normal diet.
If you want to try this diet to fit into your clothes before a special event, it might be OK. But as a long-term solution to achieving and maintaining a healthy weight, it just isn’t going to do the job.
However, cruciferous vegetables do contain several beneficial phytonutrients and should be included in a healthy diet.
So, go ahead, make cabbage soup- just don’t make it the main ingredient of your diet.