- What is Letrozole (Femara)?
- How does Letrozole work?
- Side effects and risks of taking letrozole
- Foods to avoid while taking Letrozole
- Foods to eat while taking Letrozole
- Other things to avoid while taking Letrozole
- Should Letrozole be taken with food?
- What is the best time to take Letrozole?
- How to reduce the side effects of Letrozole
- Natural aromatase inhibitors
Breast cancer is estimated to be the most prevalent type of cancer, impacting millions of women worldwide each year.
Breast cancer treatment has come a long way in recent decades, which fortunately has improved the prognosis and survivability of breast cancer.
Letrozole is one of many medications used to treat breast cancer.
While it’s primarily intended to treat breast cancer, letrozole can be used for other reasons as well.
If you’ve been prescribed letrozole, you might wonder if there are any specific foods you should eat or avoid while taking it. Keep reading to learn more.
What is Letrozole (Femara)?
Letrozole is a medication in a class of drugs called nonsteroidal aromatase inhibitors. The common brand name of letrozole is Femara.
The Food and Drug Administration approved Letrozole in 1998. Per the FDA, letrozole is “indicated for first-line treatment of postmenopausal women with hormone receptor-positive or unknown, locally advanced or metastatic breast cancer.”
Letrozole might be used to help shrink breast cancer before surgically removing the tumor or before starting additional therapy like chemotherapy.
Letrozole comes in 2.5-milligram tablets, and the dosing schedule will depend on its use. The typical dosage of letrozole is one 2.5 milligram tablet daily for breast cancer. If it’s used for ovulation induction (more on that soon), the dose is usually 2.5-7.5 milligrams daily.
Letrozole works to decrease the amount of estrogen your body produces. Estrogen is the primary female sex hormone and is primarily produced by the female ovaries. The three primary types of estrogen in the female body are estrone, estradiol, and estriol.
Aromatase is an enzyme that changes non-estrogen sex hormones like testosterone into estrogen, so aromatase inhibitors block this process from occurring, thereby reducing estrogen production.
How does Letrozole work?
Letrozole is commonly prescribed to treat conditions impacted by estrogen levels, such as certain types of breast cancer. Letrozole is typically prescribed to women who have undergone menopause and who also have a specific type of “hormone-dependent” breast cancer.
Estrogen plays a large role in breast cancer. Around 75% of breast cancers are estrogen receptor-positive, meaning the hormone estrogen feeds them.
Medications like letrozole can help eliminate estrogen production, helping to slow the growth and metastasis of certain types of breast cancers.
If you don’t have estrogen-receptor-positive breast cancer, letrozole won’t be effective in treating your breast cancer. Letrozole might be used to help prevent breast cancer in certain high-risk post-menopausal women.
Letrozole is also used as a fertility treatment for women with polycystic ovary syndrome (PCOS), a hormonal imbalance that can disrupt the normal ovulation pattern.
Many women with PCOS have estrogen dominance, which can block the production of important hormones necessary for ovulation. Letrozole helps reduce estrogen levels to promote hormones that allow ovulation to occur.
Letrozole might also be used in combination with other fertility medications during a cycle of in-vitro fertilization (IVF), an infertility treatment used to attain pregnancy.
Side effects and risks of taking letrozole
There are potential side effects and risks of taking letrozole. Some of the most common side effects of taking letrozole have to do with reduced estrogen levels and include:
- Back pain
- Bone/joint pain
- Hot flashes (sudden sweating and feeling of warmth)
- Muscle pain
Other side effects that might occur less often include:
- Taste changes
- Hair thinning
- Dry skin
- Weight gain
- Increased appetite
- Mood changes
- Skin or eye redness
There may be an increased risk of osteoporosis from taking letrozole. Estrogen plays a role in bone density.
Low estradiol levels are associated with a 2.5-fold increased risk of bone fractures in older women, independent of their age or weight.
Long-term use of letrozole may negatively impact your bone density, which increases your risk of fractures.
Foods to avoid while taking Letrozole
Some foods and supplements may tend to raise estrogen levels. Eating large amounts of these types of foods might counteract the action of letrozole and reduce its effectiveness.
In general, though, there aren’t any specific foods to avoid while taking letrozole, unless otherwise indicated by your healthcare provider.
Some foods contain phytoestrogens, which are compounds from plant-based foods that resemble estrogen.
The four main types of phytoestrogens are isoflavones, stilbene, coumestan, and lignan. However, some of these phytoestrogens work to reduce estrogen levels and may be beneficial.
For instance, the use of isoflavones in adolescence is associated with a reduced risk of breast cancer. Studies conclude that the effect of phytoestrogens on hormone levels (like estrogen) is inconclusive and dependent on the stage of life and specific health conditions.
Potential foods to avoid if you’re taking letrozole for PCOS
If you’re taking letrozole to induce ovulation for PCOS, you might have insulin resistance. Improving insulin resistance can promote more stable hormone levels and might help you manage your PCOS without medications.
To help improve insulin resistance, consider reducing your intake of refined carbohydrates, including those with added sugars.
Some examples of refined carbohydrates to avoid include:
- Sweets and desserts (cake, ice cream, muffins, etc.)
- Bread products made with refined/enriched grains (white bread, white bagels, white pasta, etc.)
- White rice
- Foods with added sugar (flavored yogurt, cold cereal, certain nutrition bars)
- Sugary drinks (soda, sweetened coffee and tea, energy drinks, etc.)
Potential foods to avoid if you’ve been told to reduce your intake of phytoestrogens
While the connection between dietary phytoestrogens and estrogen levels can vary (some may lower estrogen), here are the most common phytoestrogens to be aware of if your healthcare provider wants you to avoid phytoestrogens:
- Kidney beans
- Sunflower seeds
- Wheat bran
Potential foods to avoid if you’re taking letrozole long-term
Taking letrozole long-term can result in reduced bone density. To help prevent further bone loss, consider eating fewer high-sodium foods.
High-sodium foods are generally more processed and contain much more sodium than you’d typically add to your food in the form of table salt.
A high-sodium diet can cause your body to lose calcium and promote unwanted bone loss.
Avoid high-sodium, processed foods like:
- Deli and cured meats
- Salty snacks (chips, pretzels, etc.)
- Quick-bread mixes
- Canned soups
- Frozen entrees
- Fast food like pizza, salted French fries, etc.
You may also want to limit beans and legumes if you’re at risk of osteoporosis because the phytates in beans and legumes can reduce calcium absorption. To reduce the phytate content of legumes, soak them in water for several hours before cooking them in fresh water.
Foods to eat while taking Letrozole
Eating a whole food, primarily plant-based diet can help support your health while taking letrozole. If you have breast cancer (the most common reason letrozole is prescribed), it’s important to maintain healthy lifestyle habits both during and after cancer treatment.
Eating Mediterranean-style meals and snacks might help you reduce your future cancer risk. The nutrient- and antioxidant-rich Mediterranean diet can help reduce inflammation and cancer incidence.
If you’re going to have chemotherapy after taking letrozole, it’s important to support your health as best you can in the waiting period. Chemotherapy can deplete nutrient stores, so try to build up those nutrient stores as best you can while taking letrozole.
Unless you’ve been advised to avoid a specific food by your healthcare provider, here are some generally healthy foods to eat while taking letrozole:
Fruits and vegetables
All types of fruits and vegetables are ideal to eat when taking letrozole. Aim to get a variety of colors to get different antioxidants, which help your body fight inflammation and cell damage. Some fruits and vegetables particularly high in antioxidants include:
- Berries (blueberries, blackberries, raspberries, and strawberries)
- Kidney and pinto beans
- Dark green leafy vegetables
- Orange vegetables like carrots and pumpkin
Whole grains contain more fiber, protein, and micronutrients than refined grains. In addition, studies show that people with higher fiber intakes tend to have healthier estrogen levels.
Choose high-fiber whole grains like:
- Whole wheat bread or grains made with whole wheat flour
- Brown rice
- Whole oats
Healthy unsaturated fats can be a source of omega-3 fatty acids, which help combat inflammation.
- Oily fish (salmon, mackerel, anchovies, etc.)
Taking letrozole might increase the amount of cholesterol in your blood (hypercholesterolemia). High cholesterol levels are a risk factor for heart disease.
To help combat this effect, try to choose a protein that is lower in saturated fat, like:
- Lean cuts of red meat (pork loin, 90% lean beef, etc.)
Other things to avoid while taking Letrozole
While letrozole doesn’t negatively interact with alcohol, it might still be a good idea to abstain from it.
Estrogen levels tend to be higher in women who drink alcohol than those who don’t. Since letrozole reduces estrogen levels, you may want to limit your alcohol consumption while taking it.
Supplements with estrogen
You should avoid any supplement containing any form of estrogen while taking letrozole. Taking estrogen while on letrozole counteracts the purpose and may lessen letrozole’s effectiveness.
Xenoestrogens are a group of endocrine disruptors (things that negatively impact your hormones) that mimic estrogen.
Some sources of xenoestrogens to avoid while taking letrozole include:
- Fruits and vegetables sprayed with certain pesticides
- Certain plastics
- Certain ingredients in makeup and nail polishes
Should Letrozole be taken with food?
You can take letrozole with or without food. While nausea isn’t a common side effect of letrozole, there is still a chance you might feel sick from taking letrozole. If that happens, taking letrozole with food can help reduce the stomach upset it causes.
What is the best time to take Letrozole?
It doesn’t matter what time of day you take letrozole. The more important thing is to take it at the same time consistently from day to day. For instance, if you choose to take it in the morning, try to always take it in the morning.
How to reduce the side effects of Letrozole
- Use over-the-counter pain medications as needed for potential joint and muscle pain, such as aspirin, ibuprofen, or acetaminophen. Consider taking a warm bath to ease sore muscles. Exercise can also ease joint pain from letrozole.
- You might notice hair thinning from taking letrozole. According to a study, supplementation with vitamin C and omega-3 fatty acids may help counteract letrozole-related hair thinning.
- If you experience hot flashes from letrozole, try setting the thermostat to a cooler temperature, wear light, breathable clothing, and utilize lightweight bedding and fans to help keep you comfortable.
Natural aromatase inhibitors
Some foods have natural aromatase-inhibiting qualities, which means they may exert a weaker but similar effect as letrozole.
Flavonoids are among the most commonly tested compounds to assess their natural aromatase inhibitor properties. Flavonoids are compounds found in plant foods like fruits, vegetables, grains, tea, wine, and more.
Some of the richest flavonoid foods are:
- Red cabbage
- Red wine
- Dark chocolate
According to a study, this flavonoid is found in honey and passionflower and exhibits aromatase-inhibiting properties. Chrysin supplements are also available for a more potent dosage.
Another study found that chrysin can help slow breast cancer growth and kill breast cancer cells. The researchers concluded that chrysin might be a promising therapeutic option in addition to other breast cancer treatments or drugs.
3) White mushrooms
In a study, white mushrooms inhibit aromatase activity, making them a potential natural aromatase inhibitor.
Letrozole is a medication that blocks aromatase, an enzyme that increases estrogen levels.
Letrozole is most commonly used to treat certain types of breast cancer but is also used as a fertility drug to induce ovulation.
Studies have shown inconsistent results regarding which foods might increase estrogen levels and which can decrease estrogen levels. In general, it’s advisable to focus on eating a high-fiber diet rich in plant-based foods to support healthy hormone levels.
You may want to consider limiting alcohol while taking letrozole, as well as any other particular foods your healthcare provider recommends in your specific case.