What Is the Gerson Therapy, and Does It Fight Cancer?

The Gerson Therapy — also called the Gerson Therapy diet — is a natural alternative treatment system that claims to “activate the body’s extraordinary ability to heal itself.”

It was developed in the early 1900s by Dr. Max B. Gerson, who used it to relieve his migraine. Later, Gerson used this therapy to treat diseases like tuberculosis and cancer.

Gerson believed that cancers and other chronic diseases are caused by changes in your metabolism that happen when toxic substances accumulate in your body. The Gerson Therapy aims to restore your health by removing toxins and increasing immunity (1).

In 1978, his daughter Charlotte Gerson established the Gerson Institute, a nonprofit organization that provides education and training in the Gerson Therapy.

Gerson practitioners are medical doctors or people with a medical, clinical, or naturopathic background who have successfully completed the Gerson practitioner training program.

The Gerson Therapy has three major components — diet, detoxification, and supplements. People on the therapy must follow an organic, plant-based diet with raw juices, use coffee enemas several times daily for detoxification, and take a wide variety of supplements (1).

Before starting the Gerson Therapy, you must apply on their website — by submitting medical records, then undergoing a case evaluation — to see if you are eligible.

Although this therapy is meant to treat a wide range of chronic diseases, the Institute mentions that certain conditions do not respond well to the Gerson Therapy. These include brain tumors, Parkinson’s disease, kidney failure, and ileostomy.

The Gerson Therapy requires a significant financial and lifestyle commitment. It can cost more than $15,000 to start and must be followed for a minimum of 2 years.

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The Gerson Therapy was invented by Dr. Max B. Gerson in the early 1900s as a nutrition-based treatment system for chronic diseases, such as cancer.

The Gerson Therapy is divided into three key components — diet, supplements, and detoxification.

Diet

The Gerson Therapy diet is entirely vegetarian and extremely low in sodium, fats, and proteins, as Dr. Gerson believed that this type of diet helps treat diseases.

Anyone on this diet is asked to consume approximately 15–20 pounds (7–9 kg) of organic produce per day. This is said to help “flood the body with nutrients.”

Most of that produce is used to make raw juices. Dieters are asked to drink up to one 8-ounce (240-ml) glass of raw juice per hour — up to 13 times per day.

Juices must be made using a Gerson-recommended juicer that first grinds the vegetables into a pulp, then extracts the juice by squeezing it under high pressure.

The Gerson Institute claims that its approved appliances provide 25–50% more juice than other juicers — and that its drinks are up to 50 times higher in certain nutrients.

However, these claims have not been validated by a third party.

Supplements

Because the diet is loaded with nutrients, its supplements are not meant to provide more nutrients. Instead, they’re intended to support your cells’ metabolic processes.

These supplements include potassium, pancreatic enzymes, Lugol’s solution (potassium iodide and iodide in water), a thyroid hormone supplement, and vitamins B3 and B12.

Potassium supplements are a key part of the Gerson Therapy. Dr. Gerson believed that diseased cells contained too much sodium and too little potassium.

Once his patients started the Gerson Therapy diet — which is high in potassium and low in sodium — their cells would reportedly shrink, which Gerson believed to be a sign of recovery (1).

Detoxification

According to the Gerson Institute, the combined effect of the diet and supplements releases toxins from your body’s tissues. Thus, your liver — which is the main organ that processes toxins — would be working harder than usual.

To support your liver, the Gerson Therapy incorporates coffee enemas that allegedly widen your liver’s bile duct so that it easily releases toxins.

The bile duct is a small tube that helps carry bile — a fluid that helps break down fatty acids and many waste products — from your liver to your intestines.

Dieters are required to do 1 coffee enema per 24 ounces (720 ml or 3 glasses) of juice consumed.

However, no scientific studies indicate that coffee enemas can widen your bile duct. What’s more, evidence is lacking that this therapy causes toxins to be released from your cells at all.

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The Gerson Therapy’s three major components are an organic, plant-based diet, detoxification, and supplements. The diet and supplements are meant to flush toxins out of your body, while detoxification is supposed to support your liver.

Although almost no scientific evidence supports the Gerson Therapy’s claims, a few case studies have examined its relationship to cancer treatment.

The Gerson Research Organization — a research group that works closely with the Gerson Institute — reported that 153 people with skin cancer on the Gerson Therapy survived much longer than patients on conventional therapy (2).

Additionally, in a case study, six people with aggressive cancers who followed the Gerson Therapy survived longer than expected from conventional treatments and experienced improved quality of life (3).

However, these studies are small and don’t provide enough information about the participants, making it hard to tell if these improvements are due to the Gerson Therapy or other reasons.

It’s also worth noting that some of these studies were conducted by the Gerson Research Organization, so there may be conflicts of interest.

What’s more, reviews by organizations like the U.S. National Cancer Institute have found no evidence that the Gerson Therapy is useful in treating cancers (4).

In fact, a study in people with pancreatic cancer found that those who received traditional chemotherapy survived 3 times longer — 14 months compared to 4.3 — than those on a diet similar to the Gerson Therapy (4, 5).

High-quality studies are lacking to determine whether the Gerson Therapy combats cancer. Thus, the claims made by the Gerson Institute cannot be backed up.

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The claim that the Gerson Therapy treats cancer is lacking in scientific evidence. Few high-quality studies have been done.

The Gerson Therapy bans foods that are high in protein, sodium, and fat. Additionally, you cannot eat foods with certain compounds that the Institute claims interfere with the healing process.

Here is a list of foods you cannot eat on the Gerson Therapy:

• Meats and seafood: all meats, eggs, seafood, and other animal proteins
• Protein supplements: all protein powders, including dairy and vegan formulas
• Dairy: all dairy products, including milks and cheeses — but excluding plain, organic, non-fat yogurt, which is allowed after 6–8 weeks on the diet
• Soybeans and soy products: all soy products, such as tofu, miso, and soy milk
• Certain vegetables: mushrooms, hot peppers, carrot greens, radish greens, mustard greens, and raw spinach (cooked spinach is fine)
• Dried beans and legumes: dried beans and legumes — but lentils are allowed at six months if you’re in good health
• Certain fruits: pineapples, berries, cucumbers, and avocados
• Sprouted alfalfa and other bean or seed sprouts: completely banned — unless advised by an experienced Gerson practitioner
• Nuts and seeds: all nuts and seeds
• Oils and fats: all oils, fats, and naturally high-fat foods, such as coconuts, nuts, and avocados — except flaxseed oil, to be used only if prescribed
• Salt and sodium: all salt or sodium, including table salt and Epsom salts
• Spices: black pepper, paprika, basil, oregano, and others
• Beverages: water (see below), commercial juices, sodas, coffee and coffee substitute (with or without caffeine), black tea and non-herbal teas that contain caffeine
• Alcohol: all alcoholic beverages
• Condiments: soy sauce, tamari, liquid aminos, mustard, and others
• Baked foods and sweets: all cakes, muffins, pastries, candies, and sweets
• Baking powder and baking soda: completely banned
• Other prohibited items: toothpaste, mouthwash, hair dyes, permanents, cosmetics, underarm deodorants, lipstick, and lotions

Spices and fruit — such as pineapples and berries — are prohibited because they contain aromatic acids, a plant compound. Dr. Gerson believed that aromatic acids interfered with the healing process.

As most personal hygiene products are banned, the Institute provides a list of alternative hygiene products that contain permitted ingredients.

Notably, you’re discouraged from drinking water while on the diet. Gerson believed that water would dilute your stomach acid and not allow enough room for fresh foods and juices.

Instead, you’re encouraged to drink up to 13 glasses of freshly pressed juice or herbal tea per day.

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The Gerson Therapy is highly restrictive, banning meat, sweets, fats/oils, many common hygiene products, and even drinking water. Keep in mind that avoiding water may be dangerous.

The Gerson Therapy mandates an organic, plant-based diet. You’re encouraged to consume:

• Fruits: all fresh fruits except berries and pineapple, which harbor aromatic acids
• Dried fruits (stewed or pre-soaked only): peaches, dates, figs, apricots, prunes, and raisins — all unsulphured
• Vegetables: all except mushrooms, hot peppers, carrot greens, radish greens, mustard greens, and raw spinach (cooked spinach is fine)
• Lentils: allowed only at the six-month mark if you’re in good health
• Grains: rye bread (unsalted, non-fat), brown rice (if prescribed), and oatmeal
• Dairy: only non-fat, plain, organic yogurt — and only after six weeks
• Spices (in small amounts): allspice, anise, bay leaves, coriander, dill, fennel, mace, marjoram, rosemary, sage, saffron, sorrel, summer savory, thyme, and tarragon
• Condiments: vinegar — either wine or apple cider
• Fats: flaxseed oil — only if prescribed
• Beverages: freshly pressed juices (as prescribed), caffeine-free herbal teas

In addition to the above foods, certain items are permitted occasionally:

• Bananas: half a banana per week
• Breads: only whole-wheat rye (unsalted, non-fat) — 1–2 slices per day
• Quinoa: once a week
• Yams and sweet potatoes: once a week (regular potatoes are unrestricted)
• Popcorn: air-popped, as a holiday treat only — a few times per year
• Sweeteners: maple syrup (grade A dark color — formerly grade B), honey, brown sugar or unrefined blackstrap molasses — 1–2 teaspoons (15–30 ml) of any per day, maximum

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The Gerson Therapy is a plant-based diet that relies heavily on fruits, vegetables, and certain grains. You’re required to eat entirely organic foods.

Here is a sample meal plan for one day on the Gerson Therapy:

Breakfast

• a bowl of oatmeal with half of a sliced apple and 1 teaspoon (15 ml) of honey
• 8 ounces (240 ml) of fresh-squeezed orange juice

Snack

• 2 pieces of fruit of your choice
• 8 ounces (240 ml) of carrot juice

Lunch

• fresh salad (vegetables of your choice)
• 1 baked potato
• 1 cup (240 ml) of warm vegetable soup of your choice with a slice of rye bread
• 8 ounces (240 ml) glass of carrot-apple juice

Snack

• 2 pieces of fruit of your choice
• 8 ounces of grapefruit juice

Dinner

• Mixed greens (kale, collards, and Swiss chard) cooked with onions and garlic
• 1 cup (240 ml) of Hippocrates soup — celery root, potatoes, onion, leek, tomatoes, garlic, and parsley, simmered in water for 1.5–2 hours until soft, then blended
• 1 baked potato
• 8 ounces (240 ml) of green juice — lettuces, escarole, beet tops, watercress, red cabbage, green bell peppers, swiss chard, and green apple processed in an approved juicer

Snack

• 8-ounce (240-ml) glass of green juice

On top of this, the average participant would drink 7 additional 8-ounce (240 ml) glasses of fresh-squeezed juice per day.

Supplements

Your specific supplement regimen depends on what you’re prescribed by your Gerson Therapy practitioner.

That said, most people take potassium, pancreatic enzymes, Lugol’s solution (potassium iodide and iodide in water), a thyroid hormone supplement, and vitamins B3 and B12.

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A typical day on the Gerson Therapy includes plenty of fresh-squeezed juice, supplements, and vegetables.

Although no comprehensive studies exist on the health attributes of the Gerson Therapy, it may provide some benefits — largely thanks to its nutrient-rich, plant-based diet.

Here are some potential benefits of the Gerson Therapy:

• Higher in many nutrients. Plant-based diets tend to provide more fiber, antioxidants, vitamins, and minerals than typical Western diets high in processed foods (6, 7, 8).
• May reduce your risk of heart disease. Diets high in fruits, vegetables, and fiber have been linked to a reduced risk of heart disease (9, 10, 11).
• May improve kidney function. Plant-based diets may protect against kidney disease and kidney stones (12, 13, 14).
• May reduce arthritis pain. Plant-based diets have also been linked to reduced arthritis symptoms, such as joint pain, swelling, and morning stiffness (15, 16, 17).
• May help relieve constipation. The Gerson Therapy and other plant-based diets are high in fiber, which may help relieve constipation and keep your digestive system healthy (18, 19).

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While insufficient research has been conducted on the Gerson Therapy, its nutrient-rich, plant-based diet may provide several health benefits — including a reduced risk of heart disease and healthier digestion.

The Gerson Therapy has several serious risks and downsides.

For starters, coffee enemas — which are done four to five times daily — can be dangerous. Self-administered enemas may damage the area around the anus and cause severe electrolyte imbalances, especially if done more than once per day.

What’s more, they may cause serious bacterial infections, rectal burns, and even death (20, 21).

Severe electrolyte imbalance has been linked to heart failure and can be fatal (22, 23).

Furthermore, plant-based diets like the Gerson Therapy may not contain sufficient iron, increasing your risk of iron deficiency. Some signs of iron deficiency include low energy, shortness of breath, and anemia (24).

Because the diet is so restrictive, social events and travel can be difficult unless you bring your own food.

What’s more, the Gerson Therapy restricts many protein-rich foods, such as poultry, soy, and eggs. As cancer often elevates your needs for dietary protein, a protein-restricted diet can be problematic, leading to fatigue and malnutrition in some people (25, 26).

Additionally, since the diet discourages drinking plain water, dehydration may occur if you don’t closely follow the recommendations to consume 15–20 pounds (7–9 kg) of organic produce per day and drink raw juice every hour.

People with cancer are often at a greater risk of dehydration due to both disease symptoms — such as nausea and diarrhea — and treatments like chemotherapy (27).

It’s advisable to discuss proper treatment with your healthcare provider before committing to this diet. Using unapproved alternative treatment methods can lead to dangerous side effects and may worsen your health.

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The Gerson Therapy has several health risks, such as low protein intake and an increased risk of mineral deficiencies. Its coffee enemas are particularly dangerous, as they may cause death.

The Gerson Therapy is an organic, plant-based diet that claims to treat chronic diseases like cancer through supplements and detoxification.

However, no high-quality studies support its benefits. What’s more, it may pose serious health risks, leading most health experts to discourage the Gerson Therapy — especially for treating cancer.

It’s best to stick to a well-rounded, nutritious diet and follow treatment guidelines laid out by your healthcare provider.