How superfoods can be BAD for your health

| Mail Online

Foods hailed for their health benefits could actually be detrimental, say US researchers. They've found a Mediterranean diet could put heart attack victims at greater risk of cardiac problems. Here, we reveal the other 'superfoods' that should come with a health warning...

GRAPEFRUIT
Grapefruit: Should come with a warning

Grapefruit: Should come with a warning

Grapefruit contains naringenin, known to balance blood sugar levels and help prevent metabolic syndrome - a precursor to diabetes - by encouraging the liver to burn up excess fat.

But grapefruit can boost levels of oestrogen; older women who consume a quarter of a grapefruit daily could raise their chances of developing breast cancer by 30 per cent, according to u.S. research.

'But grapefruits are still a great source of vitamin C, fibre and other phytonutrients,' says Helen Stracey, of the British Dietetic association.

As long as you're given the green light by your GP, half a grapefruit, or 250ml of grapefruit juice, daily will have real health benefits - but anything over a litre of juice or two grapefruit a day should be avoided.'

TURMERIC

As well as relieving IBS, protecting the liver and improving the digestion of fats, curcumin, an active component in turmeric, has been shown to have anti-tumour effects. Having two curries a week helps prevent Alzheimer's, U.S. research has shown.

But while moderate amounts are fine, consuming more than 100mg of the spice daily can lead to stomach ulcers. Turmeric can also thin the blood, so avoid large amounts if you have a bleeding disorder, are about to undergo surgery or are taking blood-thinning drugs.

High doses can reduce blood sugar levels, so are not advised for diabetics. Limit your intake to around a teaspoon a week, says Catherine Collins, chief dietician at St George's Hospital, London.


SOYA

This is found in 60 per cent of processed foods. The beans are also used to make products such as tofu, soy sauce and soya milk.

'With less saturated fat than meat and containing high levels of omega3 fatty acids for heart health, the unrefined soya bean also contains all seven essential amino acids needed to maintain and repair all your body's tissues from muscles to hair,' says Catherine Collins.


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On the flip side, soya also contains large quantities of chemicals that may hamper protein digestion, block the absorption of minerals and affect metabolism. It also contains high levels of the chemicals genistein and daidzein, which mimic the hormone oestrogen and may affect fertility.

And while soya may slightly lower the risk of breast cancer, one U.S. study found soya supplements could be risky for breast cancer survivors, as these contain higher amounts of oestrogenlike isoflavones that 'coax breast tumour cells to divide and multiply'.

The British Nutrition foundation recommends sticking to one portion of unprocessed soy products a day.


CHILLI

Capsaicin, the chemical in chilli-based spices such as cayenne and paprika, provides pain relief and improves blood circulation, and has been proven to reduce cancerous tumours.

Chilli is also good for dieters - overweight women who added a quarter of a teaspoon of chilli pepper to main meals lost 5lb a month. it stimulates 'diet-induced thermogenesis' - when some of the food gets converted to heat rather than stored as fat.

But people who ate one hot chilli pepper a day had a 15 per cent higher risk of stomach cancer, according to study from Yale university. It can also aggravate i BS symptoms.

Chilli is believed to reduce the stomach's protective barriers, which can lead to ulcers and may cause acid reflux, indigestion or heartburn.

'Stick to a maximum of three small chillies a week, eaten with other foods which form a balenced diet, for maximum benefits,' says Collins.
Oily fish: Full of vitamins but can also increase risk of diabetes

Oily fish: Full of vitamins but can also increase risk of diabetes


OILY FISH

Salmon, mackerel and sardines are packed with omega3s, which prevent heart disease and boost brain health. they're also rich in vitamin a and vitamin D.

'Oily fish is one of the few foods that contain vitamin D, which we usually produce by being exposed to sunlight,' says Collins. 'This boosts the mood-boosting hormone, serotonin.'

But oily fish could increase the risk of diabetes. pesticides found in the sea and which accumulate in fatty tissue may play a role in the development of the disease by limiting our ability to produce insulin.

'Animal studies have shown these types of toxins in the womb may cause obesity in later life,' says Dr Robert Lustig, an obesity expert from the university of California.

'Everyone should aim for one 140g portion a week - women of childbearing age and children should eat no more than two portions; others can have four,' says Collins.