Eating well can help support your immune system and maintain strength and energy if you have HER2-negative breast cancer, which can help you get through treatments.
Although no diet can cure cancer, a healthy diet can be a tool to help you live and feel better alongside your therapies.
1. Focus on Nutrient-Dense Foods
People with breast cancer who follow a nutrient-dense diet—full of fruits, vegetables, whole grains, and lean proteins like fish and poultry—have better survival rates than those who eat a diet high in refined grains, sugar, high-fat foods, and processed meats.
Phytonutrients (plant-based compounds) are in numerous nutrient-dense plant foods. Many have anticancer properties. Polyphenols (a type of phytonutrient) also have antioxidant characteristics and anti-inflammatory properties.
People with breast cancer who had a high intake of polyphenols from plant foods had significantly reduced levels of inflammation.
Rather than focusing on any particular food, choose to eat a wide variety of these whole plant foods. This will provide you with a greater combination of nutrients for your cancer-fighting journey.
2. Incorporate Immune-Boosting Foods
Some cancer treatments negatively impact the immune system, leaving you immunocompromised (weakened or suppressed immune system). This can leave you vulnerable to other diseases, such as colds, coughs, respiratory syncytial virus (RSV), influenza, and COVID-19.
A diet rich in immune-boosting foods can help maintain the immune system and defend against harmful pathogens. Foods known for their immune-boosting properties include:
- Bell peppers
- Berries
- Citrus fruits
- Cruciferous vegetables (such as broccoli, cabbage, cauliflower, and kale)
- Fatty fish
- Garlic
- Ginger
- Green tea
- Leafy green vegetables
- Nuts and seeds
- Turmeric
- Yogurt
3. Choose Foods Rich in Calcium and Vitamin D
Individuals taking aromatase inhibitors to treat breast cancer should also increase their intake of calcium and vitamin D since bone loss is a side effect of these medications. Good calcium absorption can also help reduce bone weakening caused by certain chemotherapy medications.
Some studies have found that people assigned female at birth who have low vitamin D levels have a higher risk of breast cancer. Some research has found that calcium and vitamin D may help protect premenopausal individuals against breast cancer, but more studies are needed.
Beyond reducing risk, getting enough vitamin D and calcium may also improve your quality of life while living with HER2-negative breast cancer.
While you can meet at least some of your vitamin D needs through exposure to sunlight, some factors interfere with vitamin D synthesis from the sun, including cloud cover, melanin content in the skin, seasons, sunscreen use, and more.
Fatty fish, egg yolks, mushrooms exposed to ultraviolet (UV) light, fortified milk, and fortified cereals are among foods containing vitamin D.
Foods rich in calcium include milk, yogurt, cheese, canned sardines, salmon with bones, kale, broccoli, bok choy, fortified juices, tofu, and cereals.
4. Try Omega-3-Rich Foods
Omega-3 fatty acids are a type of heart-healthy unsaturated fat known for their anti-inflammatory properties. Some research suggests omega-3s may be beneficial when treating breast cancer and to help reduce muscle loss related to chemotherapy.
Several foods recommended in the Mediterranean diet (which emphasizes fruits, vegetables, olive oil, fish, and legumes) provide omega-3 fatty acids, including fish, nuts, and seeds. Research suggests this type of eating pattern lowers the risk of breast cancer, especially for postmenopausal people.
Foods high in omega-3 fatty acids include:
- Flaxseed
- Chia seeds
- Salmon
- Herring
- Canola oil
- Soybean oil
- Mackerel
- Trout
- Black walnuts
- Tuna
5. Add in Cruciferous Veggies
Cruciferous vegetables naturally contain high levels of certain phytonutrients called glucosinolates and isothiocyanates, which are thought to be anticarcinogenic (tending to inhibit cancer development).
Sulforaphane, a potent isothiocyanate, has been studied for its role in cancer prevention and therapy. Preclinical studies strongly support its role as a potential co-therapy for breast cancer.
Cruciferous vegetables include:
- Arugula
- Bok choy
- Broccoli
- Broccoli sprouts
- Brussels sprouts
- Cabbage
- Cauliflower
- Kale
- Watercress
6. Focus on Foods to Help Manage Your Weight
Maintaining a healthy weight can keep your body strongest during cancer treatment. Some people with breast cancer experience weight gain, while others lose weight. Either way, being outside of a healthy weight is not ideal.
Unhealthy weight gain leading to overweight or obesity can increase the risk of other diseases, such as type 2 diabetes, high blood pressure, and heart disease. On the opposite end of the spectrum, unhealthy weight loss can lead to loss of lean muscle mass. Less muscle means less stamina and strength and more fatigue, making treatment and recovery more difficult.
Foods to Help Gain Weight
Choosing foods high in protein and calories can help achieve weight gain.Tips include:
- Drink whole milk with hot or cold cereals, smoothies, or protein shakes.
- Add leftover meat or chicken to eggs, salads, pasta, and soups.
- Add beans and lentils to casseroles, soups, salads, pasta, and tacos.
- Add avocado on toast, sandwiches, eggs, salads, and quesadillas, or blend it into smoothies.
- Use olive or avocado oils to saute or roast vegetables.
- Sprinkle granola on yogurt, fruit, or pudding, mix it with nuts and dried fruit, or add it to muffin or bread batters.
- Add cheese to eggs, sandwiches, casseroles, potatoes, and other vegetables. Snack on cheese with whole wheat crackers, nuts, or apples.
- Add hard-boiled eggs to salads, casseroles, vegetables, and tuna salad, or beat eggs into mashed potatoes, pureed vegetables, and sauces.
- Add dried fruits to granola, muffins, pancakes, breads, rice, cereal, or cooked vegetables.
Foods to Help Lose Weight
If you need to lose weight, ensuring you are not losing lean muscle mass is important. Avoid going on a fad diet or other extreme eating patterns, as they likely will not provide the nourishment your body needs while living with HER2-negative breast cancer.
If you are experiencing increased appetite and weight gain, consider the following tips:
- Include high-fiber foods such as vegetables, fruits, whole grains, nuts, and seeds at each meal.
- Incorporate plant-based protein into your diet, including beans, lentils, tofu, nuts, and seeds.
- Opt for other lean proteins, such as fish, poultry with the skin removed, and lean beef and pork.
- Choose low-fat or fat-free dairy products.
- Include small amounts of heart-healthy fats, such as olive and avocado oils.
7. Go With Water Over Sweetened Beverages
Research shows a higher intake of sugar-sweetened soda is associated with increased risks of both total and breast cancer mortality among people with breast cancer.
Another study found a direct association between sugar-sweetened beverage consumption and breast cancer risk among postmenopausal women.
Examples of sugar-sweetened beverages include:
- Soda
- Sweetened tea and coffee beverages
- Fruit and punch drinks
- Sports drinks
- Energy drinks
- Flavored waters
Water is the best beverage for hydration. Staying hydrated may help decrease treatment side effects. Talk with a healthcare provider for guidance on how much water and other fluids is right for you.
8. Avoid Foods With a Higher Risk of Food Poisoning
Some cancer treatments can affect your immune system, making you more susceptible to contracting a foodborne illness. Fighting active food poisoning while immunocompromised can make getting better harder, and a serious infection may delay your treatment.
Foods with a higher risk of food poisoning include:
- Raw or undercooked meat or poultry
- Raw or partially cooked fish or seafood
- Raw shellfish and their juices
- Unpasteurized milk and foods made with it
- Unpasteurized juice
- Raw or undercooked eggs
- Raw flour in any type of dough or batter
- Unwashed fruits and vegetables
- Raw sprouts
- Cold or uncooked hot dogs, lunch meats, or deli meats
9. Reduce Processed Foods
A meta-analysis found a significant association between intake of ultra-processed foods and the risk of overall and several cancers, including breast cancer. Another review indicated that higher consumption of ultra-processed foods is slightly linked to a higher risk of breast cancer.
Many foods undergo some degree of processing. However, avoiding highly processed foods, especially while living with HER2-negative breast cancer, can help keep your body strong and provide the energy you need to undergo treatments.
Examples of ultra-processed foods include:
- Candy, cookies, cakes, and pastries
- Chips and crackers
- Fast foods
- French fries
- Frozen prepackaged meals and pizza
- Processed meats (lunch meats, bacon, hot dogs)
- Soda
Can Your Diet Slow Cancer Progression or Prevent Recurrence?
While there is no guarantee that eating a certain way will prevent HER2-negative breast cancer, diet is one of the factors that could impact it. About 18% of all cancers might be related to diet, physical activity, and other lifestyle habits.
Following a high-quality diet rich in nutrient-dense foods with minimal ultra-processed foods can benefit breast cancer prognosis. Adhering to a Mediterranean-style diet has also been linked to a decreased risk of breast cancer recurrence and improved quality of life.
When to Contact a Nutritionist
If you are experiencing any side effects of cancer, such as appetite changes, weight loss, nausea, or other eating difficulties related to your treatment, a registered dietitian who specializes in cancer nutrition can help manage your nutritional needs, including before, during, and after treatment.
Additionally, if you are struggling with knowing what to eat, need help overcoming barriers to healthy eating, or want more meal and snack ideas for living well with HER2-negative breast cancer, you could benefit from meeting with a registered dietitian nutritionist.
They can address your concerns about diet and cancer, helping you find foods that fit your lifestyle while meeting your nutritional needs while living with cancer.
Summary
Eating well can help support your immune system and maintain strength and energy if you have HER2-negative breast cancer, which can help with treatments. Although no diet can cure cancer, a healthy diet can be used alongside your therapies. Foods that may help include nutrient-rich foods such as fruit, vegetables, whole grains, lean proteins, and healthy fats.
Incorporating immune-boosting foods, choosing foods rich in calcium and vitamin D, and including omega-3-rich seafood and cruciferous vegetables in your diet while avoiding sugar-sweetened beverages and ultra-processed foods may help maintain strong bones and overall strength and stamina. Maintaining a healthy weight is also essential when living with breast cancer.
If you are suffering from nutrition-related side effects of cancer or treatments for cancer, consult a registered dietitian nutritionist for help. They can guide you on healthy food choices to help meet your nutritional needs before, during, and after your cancer journey.
