Q I’ve heard a lot recently about syndrome X, but I don’t really understand what it is. Can you please explain what the symptoms are, who is likely to develop it and how it can be treated? – AJ, Plymouth
A There is a close association between so-called syndrome X and PCOS. Syndrome X, also known as metabolic syndrome or insulin-resistance syndrome, was a term first coined in 1988 by Dr Gerald Reaven, professor of medicine at Stanford University.
It is characterised by a combination of insulin resistance or diabetes, dyslipidaemia (a disorder of lipoprotein metabolism), hypertension and obesity, especially around the abdomen. The principal difference from PCOS is that both men and women can develop syndrome X.
Essentially, syndrome X refers to a cluster of abnormalities in glucose and lipid (fat) metabolism that can lead to heart problems. Despite this loose definition – or perhaps because of it – syndrome X is calculated to affect 47 million people in the US and around five million in the UK (Am J Cardiol, 2003; 92: 35-42).
One major study, involving 2906 men, revealed that a heart attack was far more likely in patients who had high blood pressure, high triglyceride and low HDL (good)-cholesterol levels, a combination considered to be typical of syndrome X. Indeed, it was this combination of factors, rather than high blood pressure on its own, that posed the true risk for heart disease (Hypertension, 2000; 36: 226-32).
Researchers at Duke University in Durham, North Carolina, agreed with the general definition of syndrome X after studying a group of 53 male and female heart patients (Arch Intern Med, 2003; 163: 1889-95).
Researchers in Japan, after studying 46 heart patients, also agreed that high insulin and glucose levels, accompanied by dyslipidaemia, were all cofactors in syndrome X. However, they then decided to call their discovery ‘cardiac syndrome X’, adding a further complication to an already confusing situation (Anadolu Kardiyol Derg, 2003; 3: 222-6).
The position taken by the Japanese scientists highlights a fundamental problem. As substantial uncertainties remain in terms of a clinical definition of the syndrome, how certain is it that these constellations of risk factors indicate a discrete disorder at all? Or will syndrome X ‘prove to be a distracting detour on the route to encouraging more widespread application of evidence-based practices to prevent diabetes and cardiovascular disease?’ asks James Meigs, assistant professor of medicine at Harvard Medical School (BMJ, 2003; 327: 61-2).
But even if the syndrome is merely a convenient hook on which to hang a number of disorders, there does appear to be a magnifying effect in symptoms when all of the cofactors are present (Arch Intern Med, 1999; 159: 1104-9).
If there is one unifying feature in syndrome X, it’s likely to be insulin resistance (J Clin Invest, 1997; 100: 1166-73). This is consistently seen in type II diabetes, although its association with cardiovascular disease is less certain (Am J Epidemiol, 2000; 152: 908-11). Unfortunately, assessing insulin levels is still a complicated – and unpleasant – process, according to George Howard, professor of epidemiology at Bowman Gray School of Medicine in Winston-Salem, North Carolina, and the technology to easily monitor insulin is still years away.
Yet, if syndrome X shadows PCOS, perhaps the major factor is obesity – which is, at least, easier to assess. But, again, obesity by itself is not necessarily an indicator of insulin resistance – although it may well, in time, lead to it (J Clin Invest, 1997; 100: 1166-73).
Syndrome X may merely highlight the complexity of heart disease, and that it is the synergistic combination of various disorders that ultimately leads to a serious heart condition. And whether or not it even exists or should be taken seriously, syndrome X has at least ‘sexed-up’ the interest in heart care and general health.
Sethu Reddy, from the department of endocrinology at the Cleveland Civic Foundation, has detailed the factors that are recognised as syndrome X, and each one in itself is a useful marker of your general health and wellbeing.
So, to qualify as a candidate for syndrome X, a patient must have:
* a waist size more than 40 inches (102 cm) in men, and 35 inches (89 cm) in women
* high levels of triglycerides (fats) and LDL cholesterol (the ‘bad’ one)
* low levels of HDL cholesterol (the ‘good’ form)
* high blood pressure (greater than 130/85 mmHg)
* high levels of glucose
* insulin resistance.
As such, it is reasonably easy to rectify some of these danger signals, and without resorting to a regime of pharmaceuticals. As Dr Reddy points out, even small decreases in weight can result in significant improvements in dyslipidaemia, and high blood pressure and glucose levels.
It may be that syndrome X equates to the risk factors associated with type II diabetes, and treating this will also treat syndrome X. Indeed, researchers have found that exercise and weight-loss programmes have been sufficient to take patients out of the syndrome X category. The Duke University study mentioned earlier found that a regime that combined aerobic exercise with weight loss was more effective than one that involved only exercise.
Dr Reaven, who coined the syndrome’s name, believes that it can be managed by a diet that comprises 15 per cent protein, 40 per cent fats (mostly monounsaturated) and 45 per cent carbohydrates. Such a diet should prevent triglyceride levels from rising and HDL cholesterol from falling, he says. Reaven also believes that diet is more effective in preventing heart attacks than drugs that lower blood pressure.
Following up on Dr Reaven’s dietary recommendation, one drug company has created a nutritional snack bar for patients with syndrome X (the ‘SynX Bar’) that provides his 15:40:45 nutritional ratio. The company, Shaman Pharmaceuticals, also claims to have added ‘safe and natural ingredients from our library of more than 2600 plants from the rainforest’ to the product.
Alternatively, it may be enough for you to adopt a low-carbohydrate diet that also eliminates all refined carbohydrates such as biscuits, cakes and snack foods.
However, until syndrome X is given the status of a genuine condition, its treatment will remain in the arena of lifestyle changes rather than something that will launch a thousand prescription drugs.