Symptoms include bloating, mood swings, food cravings, lethargy, cramping and breast tenderness. They are believed to be triggered by changes in progesterone and oestrogen levels, resulting in a relative oestrogen dominance.

Evidence suggests that almost any mooted form of prevention or cure will work for some women some of the time, so selecting the right remedy can be hit-or-miss. Nevertheless, some types of prevention have a track record of working for large numbers of women.

* What are you eating? Women with PMS tend to eat 62 per cent more refined carbohydrates, 79 per cent more dairy, 78 per cent more sodium and a whopping 275 per cent more refined sugar than other women. They also consume 53 per cent less iron, 77 per cent less manganese and 52 per cent less zinc. Sugary foods, in particular, can worsen PMS (J Reprod Med, 1991; 36: 131-6). Several studies suggest that eating a wholefood diet, which is low in fat and high in fibre, can reduce symptoms of PMS. Although PMS sufferers are often advised to eat more soya, there is no evidence to suggest it will improve symptoms.

* Check your thyroid. A large percentage of women with PMS suffer from low thyroid function (hypothyroidism) (N Engl J Med, 1986; 315: 1486-7; Am J Psychiatry, 1987; 144: 480-4). Many women with confirmed hypothyroidism, and given thyroid hormone, experience complete relief from PMS symptoms. Other methods of improving thyroid function include increasing foods rich in B vitamins and iodine.

* Protect your liver. Excess oestrogen impairs liver function by decreasing vitamin B activity. It also impairs neurotransmitters and lowers endorphin levels, resulting in PMS depression. Several aspects of lifestyle are linked to both PMS and poor liver function, including a high intake of caffeine, alcohol, smoking and ingestion of toxic substance such as pesticides. Consider detoxing your life as well as your body and using liver-supportive herbs such as milk thistle.

* Rule out depression. Symptoms can be more severe in women who already suffer from depression (Med Clin North Am, 1995; 79: 1457-72). Treating the depression can sometimes cure the PMS. Psychotherapies such as biofeedback and behavioural modification are better than antidepressants, and can significantly and permanently increase coping skills (Int J Psychosom, 1994; 41: 53-60; J Consult Clin Psychol, 1994; 62: 1026-32).

* Exercise. Women who exercise regularly rarely suffer the mood swings and physical symptoms of PMS (J Psychosom Res, 1993; 37: 127-33; Br J Clin Psychol, 1995; 34: 447-60). This may be because exercise elevates natural mood lifters - endorphins - while lowering stress hormone (cortisol) levels.

* Cut out caffeine. Tea, coffee and chocolate cravings are common with PMS, but caffeine can shorten the length of your menstrual cycle (Am J Epidemiol, 1999; 149: 550-7) and worsen PMS (Am J Public Health, 1989; 79: 67-6; Am J Public Health, 1990; 80: 1106-10).

* Chaste berry (Vitex agnus castus) balances oestrogen and progesterone levels, thereby relieving many PMS symptoms (J Women Health Gender-Based Med, 2000; 9: 315-20; BMJ, 2001; 20: 134-7). Vitex also reduces excessive levels of prolactin, which is associated with breast tenderness (Arzneim Forsch, 1993; 43: 752-6). Vitex should be taken for at least four cycles to see results.

* Reduce fat intake. Decreasing the percentage of calories from fat, particularly saturated fats, can dramatically reduce circulating oestrogen (J Clin Endocrinol Metab, 1987; 64: 1246-50; Am J Clin Nutr, 1989; 49: 1179-83) and improve PMS symptoms (Physiol Behav, 1987; 40: 483-7).

* Herbs with potential. Liquorice root (Glycyrrhiza glabra) may help balance out oestrogen dominance (Endocrinol Japon, 1967; 14: 34-8). Dong quai is typically used in combination with herbs such as peony (Paeonia officinalis) and osha (Ligusticum por-teri) for menopausal symptoms as well as for menstrual cramps (Chin Med J, 1991; 104: 776-81). Black cohosh is approved in Germany for use in women with PMS. None of these herbs, however, has been subjected to clinical trials to determine if they can prevent PMS.