New Study Finds Intermittent Fasting Increases Cancer Risk?

Intermittent fasting has been trending for some time, with many people going on a schedule of eating only between restricted hours in the day to provide overall digestive, immune and metabolic restoration. For example, on an intermittent fasting diet, one eats every day, but only between 12 and 6pm, to obtain a full 18 hours of GI rest. This is considered an extreme version of this diet, and one could extend the window of eating, or even restrict it in the case of cancer patients. Whatever window you use, it is the long resting period that provides deep healing that otherwise would not have been possible. This is because the digestive system needs to rest for a long enough period to begin intricate repair processes. Many find benefits from a 3-5 day fast in repairing GI issues, restoring immune function, increasing detoxification, and improving sleep. 

New Study Shows Intermittent Fasting Increases Cancer Risks, But All Headlines Leave Out the Important Part...

A recent study published in the journal "Nature" examined whether intermittent fasting (IF) may elevate cancer risks in mice and found that it did in special circumstances, particularly the re-feeding stage. They focused on the fact that stem cells were thought to regenerate under fasting conditions, but found that regeneration was supressed during fasting, but increases rapidly after breaking the fast with food. The researchers decided to see what happened if they broke the fast of mice with mutagenic substances. When the carcinogenic substances caused damage, because that damag was done to already-rapidly producing stem cells, cancerous changes were amplified. The researchers acknowledged that most studies on fasting do not include the re-feeding phase. Their research shows that the refeeding stage is critical, and that exposing oneself to toxic food after fasting can be more harmful than eating the same food without prior fasting. This has been common knowledge in the nutritional hygiene movement and among those promoting intermittent fasting. How you break the fast determines to what extent your body makes the most of it. 

Worst Foods To Break a Fast

• Cooked meat
• Cooked grains
• Overcooked vegetables
• Processed food
• Simple carbohydrates, like Russet potatoes
• Dense proteins, like unsprouted nuts and beans
• Alcohol containing foods and beverages
• High sugar beverages

Best Foods To Break a Fast

• Raw low-sugar fruits
• Salads with diverse greens
• Kim chi and fermented vegetables
• Green drinks
• Carrot juice
• Celery Juice
• Raw Milk or Kefir 
• Low sugar smoothies 

Critique of Study

The major problem with this study was that it actually found that intermittent fasting was beneficial up to the point the individual consumed something highly carcinogenic and mutagenic, like heterocyclic amines from charred meat. We would expect similar results with other toxins ingested after fasting, like the toxic metabolites created from heated carbohydrates like advanced glycation end products like acrylamide.

To improve the study, and to show they weren’t just trying to give bad press to the intermittent fasting diet, they could have had two experimental groups in addition to the control, with one being fed the carcinogenic diet, and one fed an all raw fruit diet, to see what kinds of differences there were. As the study has made the rounds of the internet, the headlines have usually been misleading. The one exception was in Nature itself, where the article was entitled: "The Surprising Cause of Fasting's Regenerative Powers", which does justice to the significance of the study's findings. As the author concisely states: "Breaking a fast carries more health benefits than the fasting itself, a study in mice shows.". 

Instead of spining the article negativly towards intermittent fasting, objective analysis confirms how important it is to break a fast correctly. This study provides evidence to support fasting as a regenerative process that makes the endothelial lining suceptible to damage, as rapidly self-replicating but regenerated stem cells are in danger of mutagenesis when exposed to carcinogens after fasting.  In general, previous studies have found that fasting improves endothelial function and the gut-vascular barrier. 

Different Types of Intermittent Fasting 

All intermittent fasting schedules allow at least 12 hours of rest before eating. One of the most common is to eat for an 8 hour window, providing 16 hours of rest, which is optimal for most people seeking to repair and detox. Even more intense fasting periods though are easily accomplished, and reccomended for cancer paitents and intense detoxing, such as eating only a 4 hour window, or eating only every other day. 

Benefits of Intermittent Fasting

A growing body of research underscores its positive impact on brain health, immune function, digestive health, heart health, cholesterol levels, and nutrient absorption.

Among its many advantages, brain health stands out prominently; studies, such as those by Patterson and Sears (2017), indicate that intermittent fasting can enhance cognitive function and protect against neurodegenerative diseases. This is attributed to the stimulation of autophagy, a process that clears damaged cells, and the promotion of neuronal health through increased production of brain-derived neurotrophic factor (BDNF). Additionally, intermittent fasting bolsters immune function by reducing inflammation and oxidative stress, as highlighted by Mattson, Longo, and Harvie (2017). These effects can lead to a lower risk of chronic diseases and improved overall immune response. Digestive health also benefits substantially from intermittent fasting. The practice allows the digestive system to rest and repair, which can enhance the gut microbiome's diversity and function, thereby improving nutrient absorption and reducing gastrointestinal disorders.

Cardiometabolic health sees a marked improvement with intermittent fasting as well. Research by Varady et al. (2021) demonstrates that fasting can lead to significant reductions in LDL cholesterol and triglycerides, lowering the risk of cardiovascular disease. The regulation of blood sugar levels and improvements in insulin sensitivity further contribute to heart health. Intermittent fasting also promotes better nutrient absorption by optimizing digestion and metabolic processes. Studies have shown that fasting periods can lead to enhancements in the efficiency of nutrient uptake, ensuring that the body utilizes consumed nutrients more effectively. This holistic approach to eating not only aids in maintaining a balanced diet but also supports the body's overall metabolic health. In conclusion, the comprehensive benefits of intermittent fasting—ranging from enhanced brain function and immune health to improved digestion, heart health, and nutrient absorption—are well-documented in scientific literature, making it a compelling practice for nutrition-conscious individuals seeking to optimize their well-being.

Reccomended Supplements 

It is generally recommended to take a multivitamin, preferably from a pure source, like Dr. Clark's multivitamin called Cranials. Another critical addition would be probiotics, for helping restablish gut microorganisms. Kefir is one of the best sources of probiotics, as it helps repopulate long lost endogenous species and repair the entire digestional tract. Other common supplement for this diet is coconut oil, which helps the body product energy while in ketosis, while also having antimicrobial and healing benefits. Finally, if you are on a high nutrient diet, with considerable detoxing, you may experience benefits from digestive and protelytic enzymes, which help the body clear damaged, misfolded proteins, remove biolfilms, and improve overall digestive and bowel function. 

References

• Imada, S., Khawaled, S., Shin, H. et al. Short-term post-fast refeeding enhances intestinal stemness via polyamines. Nature (2024). https://doi.org/10.1038/s41586-024-07840-https://www.nature.com/articles/s41586-024-07840-z
• Patterson, R. E., & Sears, D. D. (2017). Metabolic effects of intermittent fasting. Annual review of nutrition, 37(1), 371-393.
• Mattson, M. P., Longo, V. D., & Harvie, M. (2017). Impact of intermittent fasting on health and disease processes. Ageing research reviews, 39, 46-58.
• Varady, K. A., Cienfuegos, S., Ezpeleta, M., & Gabel, K. (2021). Cardiometabolic benefits of intermittent fasting. Annual review of nutrition, 41(1), 333-361.
• Santos, H. O., Genario, R., Tinsley, G. M., Ribeiro, P., Carteri, R. B., de Faria Coelho-Ravagnani, C., & Mota, J. F. (2022). A scoping review of intermittent fasting, chronobiology, and metabolism. The American journal of clinical nutrition, 115(4), 991-1004.
• Varady, K. A., Cienfuegos, S., Ezpeleta, M., & Gabel, K. (2021). Cardiometabolic benefits of intermittent fasting. Annual review of nutrition, 41(1), 333-361.