Kirkham AA, Ford KL, Topolnyski J, et al. Time-restricted eating to reduce cardiovascular risk among older breast cancer survivors: a single-arm feasibility study. JACC: CardioOncology. 2022;4(2):276-278.
To assess the efficacy of time-restricted eating in reducing cardiovascular risk in breast cancer survivors
Weekday fasting for 16 hours per day may reduce cardiovascular risk in breast cancer patients.
Single-arm feasibility study
There were 22 breast cancer survivors (mean age: 66 years ± 5 years), with an average body mass index (BMI) of 31.5 kg/m2, who had undergone anthracycline chemotherapy within the past 1 to 6 years (mean: 3 years ± 1 year). Most participants (68%; n=15) either had metabolic syndrome or were eligible for pharmacological intervention to reduce cardiovascular risk. Fifty percent of participants had received left-sided radiation, and 91% were taking tamoxifen with or without an aromatase inhibitor.
Participants fasted Monday through Friday for 16 hours per day and ate only between 12 pm and 8 pm for 2 months. This time-restricted eating schedule is abbreviated TRE 16:8.
Study Parameters Assessed
Investigators assessed Framingham scores, metabolic syndrome, age, smoker/nonsmoker status, and hypertension treatment status for cardiovascular disease risk factors.
They assessed the following lab values postovernight fasting after 1 of the days of the week during which the participant followed the time-restricted eating protocol: glucose, total cholesterol, and high-density lipoprotein (HDL) levels.
Physical exams assessed blood pressure levels and waist circumference measurements. Investigators analyzed visceral adipose tissue using magnetic resonance imaging (MRI). They used 8-point bioimpedance to assess fat and fat-free mass in participants.
Cardiovascular disease risk, metabolic syndrome, visceral adipose tissue, fat mass, and fat-free mass
After 2 months of time-restricted eating, the median Framingham cardiovascular disease risk significantly decreased from 10.9% to 8.6% (P=0.037). There were significantly reduced levels of visceral adipose tissue (P=0.009), whole-body fat mass (P=0.046), and median body mass (P=0.025).
There were no significantly improved results in total cholesterol, HDL levels, systolic blood pressure, and mean BMI levels.
Out of the 15 breast cancer survivors who either had metabolic syndrome or were eligible for pharmacological intervention to reduce cardiovascular risk at the beginning of this study, after 2 months of time-restricted eating, only 7 participants still remained in this category.
Study funding sources for this study are implied, though not explicitly stated, and the authors stated all disclosures.
Practice Implications & Limitations
This preliminary study presented some potential clinical benefits of time-restricted eating (TRE) for breast cancer survivors who already have increased cardiovascular disease risk. With breast cancer survivors at higher risk of mortality due to cardiovascular disease, increasing accessible integrative interventions for treatment is very important.
Not only may time-restricted eating reduce cardiovascular disease risk in breast cancer survivors, but there are a number of studies that suggest that those who practice TRE intentionally or inadvertently may improve their breast cancer prognosis as well.1-6 In a study of more than 2,000 people with breast cancer, those who fasted for more than 13 hours per night (TRE 13:11) had significantly reduced breast cancer recurrence risk, though there were no significant differences in mortality rates.1 This study showed that for each additional 2 hours of fasting per day, there were significantly improved HbA1c levels as well as significantly increased sleep length.1 Although there are conflicting data on the relationship between breast cancer prognosis and HbA1c,7,8 it is clear that improved sleep can significantly reduce inflammatory biomarkers in breast cancer patients undergoing chemotherapy.9
For example, in a study of 97 people with advanced breast cancer, improved sleep significantly reduced overall mortality.10 Regular eating and sleeping times are requisites for a healthy circadian rhythm, which has been linked to reduced risk of cancers and cardiovascular diseases.11
More studies should be done to differentiate whether it is the regular eating times or the fasting aspects of time-restricted eating that are the most beneficial, or if it is the combination of the 2.
The study under review here touched upon possible untoward symptoms, such as headaches and irritability.
Systemic inflammation has been implicated in cancer and its recurrence. The readily measurable inflammatory marker C-reactive protein (CRP) has been linked to poor breast cancer prognosis.12 Results from the 2009–2010 National Health and Nutritional Examination suggest that longer fasting intervals in people with breast cancer were associated with significantly reduced CRP levels.2 For breast cancer patients with high CRP levels, TRE may be an intervention to consider to improve their prognosis and reduce inflammation.
Studies on TRE in breast cancer patients are suggesting that we may be able to stratify who is most likely to derive benefit as we gather more data. In a study of almost 2,000 Chinese women, the results showed that TRE may be more clinically relevant for reducing breast cancer risk for those who had formerly been eating past 10 pm for long durations (eg, over 20 years), those who regularly ate between 12 am to 2 am, those who ate foods other than fruit and vegetables late at night, and those with a BMI less than 25.4
Although TRE is a low-risk and low-cost option, there are potential adverse side effects to consider. The study under review here touched upon possible untoward symptoms, such as headaches and irritability. Other studies have found similar symptoms as well.13 Rarer side effects from TRE are vomiting, diarrhea, nausea, constipation, dizziness, increased thirst, and fatigue.13 Studies have shown that these side effects generally reduce over time.13
As with any integrative nutritional protocol, it is of the utmost importance to assess each patient individually and provide each patient with the risks and benefits of a particular TRE protocol so they can make an informed decision about whether to go forward with time-restricted eating.