PARTS of a popular vegetable that are usually thrown away could slow the growth of lung and breast cancer cells, a study suggests.
High in fibre and antioxidants, sweet potatoes are a staple for many meals.
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The spinach-like leaves that sprout from the spuds are eaten in many parts of Asia, Africa and the Pacific.
But it’s rare to see sweet potatoes sold with their greenery in the UK.
Now, Tennessee State University researchers say compounds in the sweet spud’s leaves and stems could be used to stop the growth of cancerous cells.
The study looked into the cytotoxic effects of sweet potato greens, using purple and orange-fleshed strains grown in Tennessee State University’s Organic Research Farm.
Cytotoxic refers to a substance that kills cells, including cancerous cells.
It may stop cancer cells from dividing and growing and may cause tumours to shrink in size.
Researchers tested how effective extracts from the potatoes were against human breast and lung cancer cells, comparing them against tamoxifen – a drug that’s used to treat breast cancer.
The study – published in the journal BMC Complementary Medicine and Therapies – found that leaf extracts from purple sweet potatoes and stem and leaf extracts from orange sweet potatoes significantly inhibited the survival of lung and breast cancer cells.
The extracts were more effective against breast cancer cells rather than lung cancer cells, scientists observed.
They said the leaves’ cancer-killing properties were apparent at smaller doses when used to stop the growth of breast cancer.
At a concentration of 0.003 mg/ml, extracts from purple sweet potato leaves inhibited the growth of lung cancer cells by 37 per cent and breast cancer cells by 76 per cent.
The findings suggest that sweet potato leaf extracts may affect different cancer types in different ways.
The study also compared the effects of sweet potato extracts with tamoxifen and found that at certain levels, the leaf extracts had a similar or even stronger impact on lung cancer cells.
Extracts from the leaves and stem of orange sweet potatoes with a concentration of 0.0056 µg/µl inhibited the growth of lung cancer cells by 1 per cent more than the breast cancer drug.
Overall, the study found that the sweet potato leaf and stem compounds only had a minimal cytotoxic effect at lower concentrations but were able to slow cancer growth significantly at higher doses.
Purple sweet potato leaf extracts had the strongest effect on breast cancer cells, while orange sweet potato leaf and stem extracts were more effective against lung cancer cells, scientists said.
The root veg’s cancer-killing properties could be due to its high levels of polyphenols and anthocyanins, compounds that are known to programme the death of cancer cells.
Scientists said that further research is needed to identify particular compounds in sweet potato leaves and stems that can combat cancer progression.
Ways to reduce your risk of cancer
Not all cancers can be prevented but there are things you can do to reduce your risk.
- Stop smoking – not smoking is the best thing you can do to reduce your risk of cancer as harmful chemicals in cigarette smoke affect the entire body, not just our lungs
- Keep a healthy weight – obesity can increase your risk of up to 13 different cancer.
- Eat a healthy and balanced diet – eating lots of processed and red meat can up your risk of bowel cancer, so cutting down can reduce your risk. Have plenty of fruit and vegetables, wholegrain foods high in fibre and healthy proteins, while also cutting down on alcohol and high calorie foods and drinks.
- Enjoy the sun safely – too much UV radiation from the sun or sunbeds ups the risk of skin cancer so make sure to spend time in the shade, cover up with clothing, and use sunscreen.
- Drink less – cutting back on alcohol reduces your risk of seven types of cancer and can improve your overall health.
- Have the HPV vaccine – the jab offered for free to children aged 11-13, and some other groups. It helps protect against HPV infection, reducing the risk of some types of cancer, like cervical cancer.
Source: Cancer Research UK
But researchers suggested it may be worth incorporating the greenery in our diets.
“Incorporating these leafy greens into our diet and the bioactive compounds isolated from the plant could serve as a protective strategy against cancer,” they wrote.
“These results suggest that the leaf and stem extracts are potential natural antioxidant and anti-tumour agents that can serve as drugs or functional food ingredients.”
It comes after scientists suggested that compounds in mushrooms could help manage insulin resistance in people with type 2 diabetes.