The Cancer Research
Many of the phytochemicals and nutrients in winter squash are well studied in the laboratory. Winter squash also contain dietary fiber, which can act in several ways to lower cancer risk, including helping with weight control. Excess body fat increases the risk of 12 different cancers, and dietary fiber can increase the feeling of fullness.
Current Evidence: AICR/WCRF Expert Report and its Updates (CUP)
Squash is a starchy vegetable that contain fiber. After a systematic review of the global scientific literature, AICR/WCRF analyzed how these vegetables and dietary fiber affect the risk of developing cancer. This comprehensive review of decades of research concluded that there is strong – probable– evidence that:
- foods containing dietary fiber DECREASE the risk of colorectal cancer
Evidence categorized as "probable" means there is strong research showing a causal relationship to cancer – either decreasing or increasing the risk. The research must include quality human studies that meet specific criteria and biological explanations for the findings. A probable judgement is strong enough to justify recommendations.
Source: AICR/WCRF. Diet, Nutrition, Physical Activity and Cancer: A Global Perspective, 2018.
”… Supplements of beta-carotene in high-doses, especially in smokers, do not offer any cancer protection and seem to increase lung cancer risk.”
Open Areas of Investigation: Laboratory Research
Laboratory research is extensive on squash compounds such as beta-carotene and vitamin C .
- Lab research shows that vitamin C protects cells’ DNA by trapping free radicals and inhibiting formation of carcinogens.
- Alpha-carotene and beta-carotene are related carotenoids. Lab research shows that both act as antioxidants that also promote cell-to-cell communication, helping control cell growth.
- Lutein and zeaxanthin are concentrated not only in our eyes, but also in skin. A recent animal study suggests that dietary intake may decrease development of skin cancer related to sun exposure.
- Lab research shows that dietary fiber reduces cells’ exposure to cancer-causing substances and gut bacteria use it to produce short-chain fatty acids that protect colon cells.
Open Areas of Investigation: Human Studies
Human studies related to winter squash and cancer risk compare groups of people who consume relatively high and low amounts of total vegetables, squash, and/or levels of carotenoids.
Further research is underway in all the noted areas.
- Population studies that compare people with high and low amounts of beta-carotene in their diet or their blood link beta-carotene with lower risk of esophageal cancer.
- Both beta-carotene and lutein consumption are related to lower risk of renal cell cancer – a type of kidney cancer – in several large population studies.
- One study, which included almost 15,000 adults, found those with higher blood levels of alpha-carotene suffered fewer deaths from cancers of the aerodigestive tract after almost 14 years. Aerodigestive cancers include cancers of the esophagus, stomach, colon, liver, and pancreas, and larynx.