For years, the neutropenic diet has been followed to help reduce the consumption of bacteria from foods. This diet has been suggested for people living with cancer, as they’re more prone to developing bacterial infections. It has also been recommended to people with weakened immune systems-specifically those with neutropenia, whose bodies produce an inadequate amount of white blood cells (neutrophils). Neutrophils are blood cells that help protect your body from infection. When lower levels of these cells are present, your immune system weakens, and your body is less able to defend itself against bacteria, viruses, and infections.
Understanding Neutropenia and the Need for Dietary Precautions
Neutropenia is a blood condition where you have fewer white blood cells, or neutrophils, which are an important part of the immune system. During cancer treatment, your care team may regularly monitor your neutrophil count. Neutropenia in cancer patients is common, affecting half of those treated with chemotherapy to some degree, in fact. That’s why it’s important to take precautions to lower your risk of infection.
Harmful bacteria can pass through the gastrointestinal tract and cause infections in people with weakened immune systems. When raw foods aren’t cleaned or prepared properly, bacteria can move from the gastrointestinal tract to other parts of the body.
Infections Associated with Weakened Immune Systems
A weakened immune system can increase susceptibility to infections, including:
- Fever
- Pneumonia
- Sinus infections
- Sore throat
- Mouth ulcers
What is Neutropenic Diet?
The neutropenic (new-tro-PEE-nik) diet is a diet designed for individuals with weakened immune systems. It is also called a sterile diet, low-microbial diet, or low-bacterial diet (LBD). The neutropenic diet restricts a person from eating foods that may contain harmful organisms, toxins, or bacteria and encourages safe preparation and handling of foods to prevent exposure to foodborne illnesses. People with weakened immune systems are more susceptible to infection from foodborne illnesses.
Read also: The Hoxsey Diet
The neutropenic diet originally was developed for patients with neutropenia, a condition in which a person has a very low number of neutrophils (white blood cells), which aid the body in fighting infection.
Historical Context and Evolution of the Diet
The neutropenic diet was first introduced in the late 1960s, when researchers identified a relationship between low neutrophils and infection risk. Neutropenic diets were once thought to be important in protecting patients from having to succumb to infection from neutropenia while undergoing chemotherapy.
Who Should Follow a Neutropenic Diet?
Doctors often prescribe the neutropenic diet to people who have medical conditions that cause weakened immune systems. These include patients with the illnesses neutropenia and HIV/AIDS; those who undergo cancer treatments, such as chemotherapy and radiation; and people who have received stem cell or organ transplants.
A doctor will run an absolute neutrophil count (ANC) blood test to determine a patient's white blood cell count. Patients who have fewer than 500 cells/mm3 usually have a decreased ability to fight off infection. These patients should use the neutropenic diet until their neutrophil count returns to average levels, which range from 1,500 cells/mm3 to 8,000 cells/mm3. Some patients start the neutropenic diet prior to medical treatments, such as chemotherapy or organ transplants, as a preventative measure to avoid illnesses before procedures. A physician will determine how long a patient needs to be on the diet.
Key Principles and Guidelines of the Neutropenic Diet
The neutropenic diet incorporates dietary changes to help prevent you from consuming harmful bacteria in foods and beverages. Neutropenic diets involve preparing, cooking and storing all foods in a specific way.
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General Tips for Safe Food Handling
In addition to following specific food guidelines, there are general tips to safely handle food and help prevent illness:
- Washing your hands before and after handling food, as well as washing all surfaces and utensils.
- Avoiding raw foods, specifically meat and undercooked eggs, along with cooking all meats thoroughly.
- Avoiding salad bars.
- Thoroughly washing fresh fruits and vegetables before eating or peeling (cooked fruits and vegetables are OK to eat).
- Avoiding unpasteurized dairy products.
- Avoiding well water if it hasn’t been filtered or boiled for at least 1 minute. Bottled water is fine if it has been distilled or filtered or undergone reverse osmosis.
- Check to make sure food is fresh.
- Keep cold foods at or below 40 degrees Fahrenheit.
The FDA developed safe food handling guidelines designed to protect people, including those with neutropenia, from infection. These guidelines include:
- Wash your hands with warm water and soap for at least 20 seconds before and after handling food.
- Use paper towels to clean kitchen surfaces.
- Use running water to rinse fresh fruits and vegetables, including those with skins and rinds you don’t eat.
- Don’t depend on color and texture as reliable indicators of safety. Instead, use a food thermometer to ensure the safe temperatures of meat, poultry, seafood and eggs.
- Cook eggs until the yolk and whites are firm.
- When cooking in a microwave, cover food, stir and rotate for even cooking.
- Refrigerate or freeze meat, poultry, eggs, seafood and other perishable foods within two hours of cooking or buying.
- Never thaw food on the countertop or at room temperature. Instead, defrost food in the refrigerator, in cold water or in the microwave.
Foods Allowed on the Neutropenic Diet
Foods you’re allowed to eat on the neutropenic diet include:
- Dairy: all pasteurized milk and dairy products, such as cheese, yogurt, ice cream, and sour cream
- Starches: all breads, cooked pastas, chips, French toast, pancakes, cereal, cooked sweet potatoes, beans, corn, peas, whole grains, and fries
- Vegetables: all cooked or frozen vegetables
- Fruits: all canned and frozen fruit and fruit juices, along with thoroughly washed and peeled thick-skinned fruits like bananas, oranges, and grapefruit
- Protein: thoroughly cooked (well-done) meats and canned meats, as well as hard-cooked or boiled eggs and pasteurized egg substitutes
- Beverages: all tap, bottled, or distilled water, as well as canned or bottled drinks, individually canned sodas, and instant or brewed tea and coffee
Patients on this diet can eat well-cooked foods. They can consume canned or frozen fruits, vegetables, and juices. They can eat roasted nuts or ones cooked or baked in other foods.
Foods to Avoid on the Neutropenic Diet
Foods you should eliminate while following the neutropenic diet include:
Read also: Weight Loss with Low-FODMAP
- Dairy: unpasteurized milk and yogurt, yogurt made with live or active cultures, soft cheeses (Brie, feta, sharp Cheddar), cheeses with mold (Gorgonzola, blue cheese), aged cheeses, cheeses with uncooked vegetables, and Mexican-style cheeses like queso
- Raw starches: bread with raw nuts, uncooked pasta, raw oats, and raw grains
- Vegetables: raw vegetables, salads, uncooked herbs and spices, and fresh sauerkraut
- Fruits: unwashed raw fruits, unpasteurized fruit juices, and dried fruits
- Protein: raw or undercooked meat, deli meats, sushi, cold meat, and undercooked eggs with runny yolk
- Beverages: sun tea, cold brewed tea, eggnog made with raw eggs, fresh apple cider, and homemade lemonade
Generally, the diet prohibits raw fruits and vegetables, freshly squeezed fruit and vegetable juices, dried fruits, fresh herbs and spices, deli meat, raw honey, raw nuts, and unpasteurized dairy products. Patients are advised to avoid eating yogurt with live and active cultures and aged or soft mold-ripened cheeses. They also should not consume any products past the expiration date.
Food Preparation Guidelines
Food preparation is very important. Patients are advised to wash their hands before handling or preparing any foods. They must sanitize all food surfaces, utensils, cookware, serving ware, and cutting boards with hot water prior to and after use. They should ensure that they are cooking all meats, seafood, and eggs until they are well done to destroy any bacteria the foods may contain. People should avoid eating any products made with raw foods. In addition, hot and cold foods must be kept at the correct temperatures.
Patients should not drink unpasteurized beverages. They may consume tap water and bottled water but should avoid spring water and well water unless boiled prior to consumption.
Current Research and Scientific Evidence
Though some institutions incorporate this diet into medical treatment plans, more research is needed to demonstrate its effectiveness. Traditional treatment methods shouldn’t be ignored. Also, there are no published guidelines on how to use this diet.
The usefulness of a neutropenic diet has never been scientifically proven. However, neutropenic diets remain in place in many institutions even though their usefulness is controversial. There really should not be a debate about the use of neutropenic diet for cancer patients. Its usefulness has never been scientifically proven. However, neutropenic diets remain in place in many institutions even though their usefulness is controversial. Although food may contain harmful organisms and research has shown that bacterial translocation is possible, recent studies have been unable to obtain significant differences between placebo and intervention groups.
Based on the current findings, there’s not enough evidence to prove that the neutropenic diet prevents infection. Neither the National Comprehensive Cancer Network (NCCN) nor the Oncology Nursing Society Cancer Chemotherapy guidelines recommend the neutropenic diet.
Studies and Meta-Analyses
One 2006 study examined the infection rate between two preventive diet plans. A group of 19 pediatric chemotherapy patients was either put on the neutropenic diet or a Food and Drug Administration (FDA)-approved food safety guidelines diet. Results from this study were inconclusive, showing no statistically significant differences between the two test groups. A 2019 systematic review came to a similar conclusion. The authors of this meta-analysis did not find any evidence to support the use of a neutropenic diet for patients with cancer.
In a more recent study by Moody et al. [15], 19 pediatric patients receiving myelosuppressive chemotherapy were randomized to a neutropenic diet or to the Food and Drug Administration-approved (FDA-approved) food safety guidelines diet [16]. Patients randomized to the neutropenic diet were given dietary restrictions that included not eating raw fruits (except for those that could be peeled by hand), raw vegetables, aged cheeses, cold meat cuts, fast food, and takeout food. For the most part, all patients on the food safety guideline diet adhered to the diet while adherence was 94% for the neutropenic diet. There were no statistically significant differences between the two groups with respect to the degree and duration of neutropenia (absolute neutrophil count <1,000 mm−3), median number of cycles of chemotherapy, use of postchemotherapy filgastrim, and comorbidities.
Gardner et al. [17] studied 153 newly diagnosed acute myelocytic leukemia (AML) patients who were admitted to a high-efficiency particulate air-filtered room to receive induction therapy. With use of their early risk of mortality (ERM) score for stratification, patients were randomly assigned to a diet with (uncooked n = 75) or without (cooked n = 78) fresh fruits and vegetables. Prophylaxis with both antibacterial and antifungal was used for all patients. No differences were found between the groups for age, ERM score, chemotherapy received, or days at risk. The study outcomes showed no significant difference for time to major infection (p = .44) or survival (p = .36). The proportion of those who developed a major infection was 29% for those in the group without fresh fruits and vegetables and 35% for those allowed to have fresh fruits and vegetables (p = .60).
DeMille et al. [8] sought to determine whether the use of the neutropenic diet (no fresh fruits and vegetables) in an outpatient setting influenced the number of febrile admissions and positive blood cultures. Twenty-three patients aged 33-67 years completed a 12-week program in which they were instructed on the neutropenic diet prior to chemotherapy. Study personnel used phone calls to assess adherence at 6 and 12 weeks and reviewed hospital charts at the end of the study. Sixteen patients were deemed compliant while seven were noncompliant.
In a study by van Tiel et al. [18], 20 adult patients with acute leukemia (acute lymphoblastic leukemia [ALL] and AML) receiving remission-induction chemotherapy were randomized into two groups: one group to receive antimicrobial prophylaxis (Cipro) and a LBD, and the other group to receive the same antibacterial prophylaxis and a normal hospital diet. During chemotherapy cycles, fecal samples were collected daily to detect gram-negative bacilli or Candida species. There were no differences in the two groups with respect to mean age, mean weight, total number of chemotherapy cycles, and total number of days within chemotherapy cycles.
Limitations of Existing Research
There are major limitations of most of these studies. These include the following: (a) small sample size; (b) the absence of documentation and/or measurement of other variables that determine the incidence of neutropenic infection including the degree and duration of neutropenia, exposure to viruses, use of granulocyte colony-stimulating factors, hematologic versus solid tumors, and extent of mucositis; and (c) potential study bias due to awareness of the neutropenic diet by patients assigned to the regular diet arm, resulting in their reluctance to eat fresh fruits or vegetables. Larger randomized studies powered adequately to compare infection rates between a normal diet and neutropenic diet are needed.
Because there is an absence of evidenced-based studies supporting the use of the neutropenic diet, there are no official published guidelines on its use.
Expert Opinions and Guidelines
The National Comprehensive Cancer Network (NCCN) 2009 guidelines [20] on prevention and treatment of infectious complications do not mention the use of the neutropenic diet. The Oncology Nursing Society (ONS) Cancer Chemotherapy guidelines and Recommendations for Practice [21] state that “no recent studies have linked dietary restrictions with a lower risk of infection for neutropenic patients with cancer; however, basic principles, such as avoiding uncooked meats, seafood, eggs, and unwashed fruits and vegetables, may be prudent.”
Alternative Approaches and Considerations
The Importance of Food Safety Guidelines
The United States Department of Agriculture (USDA) recommendations for food safety for people with cancer [22] include the following: (a) consumption only of pasteurized juices and dairy products; (b) washing hands in warm soapy water before handling, preparing, and eating food; (b) consuming food that has not passed the expiration date; and (d) storing raw meat, fish, and chicken carefully in wrapped containers to avoid spillage of juice onto other foods.
Each year, roughly 48 million cases of foodborne illness are reported in the United States-meaning they sicken about one in six Americans a year. Although most healthy people recover from foodborne illnesses relatively quickly, some develop chronic or severe health problems. Certain people are also at a higher risk of developing foodborne illnesses.
Quality of Life Considerations
The dietetic challenges neutropenic patients struggle with include decreased quality of life, malnutrition, gastrointestinal side effects, food aversion, and impaired cell-mediated immunity from vitamin deficiency. Several studies have emphasized the importance of food in patients' quality of life [10, 15]. Patients receiving chemotherapy undergo many stressors including body image changes and an uncertain future [8].
“As much as possible, we want cancer patients to eat as much as they want, whenever they want,” Sonntag says.
Consulting with Healthcare Professionals
Prior to starting the neutropenic diet, discuss your dietary changes and health needs with your doctor to prevent interfering with any treatment plans.
Future Research Directions
Further research needs to be conducted to better evaluate the use of neutropenic diet. Research questions to consider might include the following: (a) Which food choices and food-preparation techniques would best improve patient compliance? (b) Is there a specific oncology population who benefits most from the use of neutropenic diet? (c) Is there a role for the neutropenic diet in neutropenic chemotherapy patients independent of other interventions (i.e., antibiotics, growth factors, and use of private room) used to prevent infection?
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