Cruciferous vegetables - like kale, cabbage and broccoli
These members of the ‘brassica’ family of vegetables (like broccoli) are rich in antioxidants and nutrients which are believed to help protect our health.
So in theory they should be good for us. But does research confirm this?
Can they help prevent cancer?
In 2012 the US National Cancer Institute reported a mixed picture when it came to cancer prevention. Most studies didn't show a protective effect but a few did, particularly for women rather than men. The most positive recent study was also in women. A study of 547 female lung cancer patients in Shanghai, published in 2015, concluded that higher cruciferous vegetable intake was associated with statistically significant better lung cancer survival. Meanwhile, an analysis of nine previous studies into cruciferous vegetables and pancreatic cancer risk, also published in 2015, found a significantly decreased risk associated with a higher intake of cruciferous vegetables - although the researchers concluded that more research was still needed here.
Why the mixed results?
The American Institute for Cancer Research notes that recent studies have produced mixed results and explains this could be due to genetic factors. Scientists recently found that about half of us don’t carry a specific gene which helps determine how long the body retains and uses the protective elements in cruciferous vegetables. Another possible factor is that our gut microbiota (the mix of bacteria in our gut, which varies from person to person, partly due to what we eat) may influence the extent to which our bodies are able to make use of these protective elements.
So cruciferous vegetables are likely to help protect some of us against a number of cancers – but not everyone.
What else do we know about them?
- Cruciferous vegetables may also help protect against cardiovascular disease and stroke. An analysis of 8 studies, published in 2016, found that an increased intake of green leafy and cruciferous vegetables appeared to reduce the incidence of cardiovascular disease (which includes heart disease, heart attack and stroke).
- The protective elements in cruciferous vegetables tend to be higher when they are raw or steamed (for 3 - 4 minutes) compared with longer cooking or boiling.
- According to a systematic review cruciferous plants are believed to be safe in humans with the exception of allergies.
- However, people with IBS (Irritable Bowel Syndrome) may wish to limit their intake to avoid bloating and gastric distress.
Pulses (lentils, beans and chickpeas)
Pulses are a cheap source of protein, vitamins, minerals and fibre. They are rich in essential fatty acids (‘good’ fat) but low in (‘bad’) saturated fat. They also have a low glycemic index, so are helpful for people with diabetes.
Can they help prevent and manage type 2 diabetes?
They also have a low glycemic index, so are helpful for preventing or managing diabetes, as found, for instance, in a study involving over 3,000 people published in 2012 - and they are recommended by Diabetes UK.
Might eating pulses also help lower cholesterol and blood pressure?
A review of the available evidence, published in 2014, concluded that eating pulses appears to significantly reduce LDL ('Bad') cholesterol levels - although it went on to say that more research is needed to verify these results. The British Heart Foundation agrees that pulses help lower cholesterol levels. Pulses may also lower blood pressure. That was the conclusion from a review of the available evidence in 2014 (although the researchers indictaed that more research was needed on this).
Can pulses help you control your weight?
It has been suggested that pulses can help you feel fuller quicker and so help control weight. A review of the evidence, published in 2016, found that overall there was a statistically significant reduction in body weight when following a diet containing pulses, even when compared with a non-pulse diet containing the same number of calories.
Berries (Blueberries, Goji berries and Strawberries)
Various berries have been suggested as potential ‘superfoods’, often on the basis of their high level of antioxidants. What does research suggest?
Goji berries - no reliable evidence?
As regards Goji berries the NHS advises that when it comes to immunity, cardiovascular disease and life expectancy there is no reliable evidence to support the suggested health benefits. The NHS also advises there is no convincing evidence, as yet, that these berries protect against cancer.
Blueberries - mixed results?
It isn’t convinced by the claims for blueberries either, although it does accept there is some research suggesting possible health benefit. It notes that a 2012 study of 93,000 women found those who ate three or more portions of blueberries and strawberries a week had a 32% lower risk of a heart attack compared with those who ate berries once a month or less. However, it notes that the study could not prove that these fruits definitely caused the lower risk. Evidence for possible protection against cancer appears to be based on laboratory studies on cells and animals rather than trials in humans. A more recent review of the evidence from clinical trials, published in 2016, was more positive in one respect. It concluded that berry consumption might help prevent and control cardiovascular disease by lowering risk factors such as LDL ('Bad') cholesterol, blood pressure and BMI (Body Mass Index)
There is some evidence that including berries in your diet can lead to cognitive benefits, especially improvements in memory.
Not 'superfoods' but good as part of your five a day?
BUPA advises that individual berries are unlikely to be ‘superfoods.’ However it observes that what we do know is that eating plenty of fruit and vegetables can help reduce our risk of certain illnesses, including some cancers. They suggest it may be that the beneficial effects of fruit and vegetables are due to a combination of things, rather than one specific component. Rather than opting for alleged 'superfoods', they recommend eating at least five portions of a variety of fruit and vegetables a day.
- Cruciferous vegetables (like kale, cabbage and broccoli) appear to reduce the risk of certain cancers for some people - although, probably for genetic reasons, not everyone. They are generally safe to eat and may also protect against heart attack and stroke.
- Pulses (lentils, chickpeas and beans) appear to help reduce blood pressure and ‘bad’ cholesterol. Their low glycemic index makes them suitable for preventing and managing diabetes – and they can help you control your weight.
- Berries are unlikely to be ‘superfoods.’ However, they may help reduce the risk of cardiovascular disease, including heart attack, and protect the memory. Their main value is probably as part of the target of five portions of fruit and vegetables a day – as this wider combination appears to reduce the risk of illness.
Reviewed and updated by Viktoria Sekamov, November 2017. Next review date October 2021.