(12) Premenstrual syndrome
Premenstrual syndrome (PMS) is a condition which affects
many women for up to two weeks before their period starts. Symptoms may
be physical (eg, headache, backache, weight gain, abdominal swelling,
breast tenderness) or mental (eg, lethargy, marked mood changes, food
craving, lack of concentration). The number and type of symptoms varies
between women and can be different each month. Many women wish to try
nutritional methods to manage their symptoms, and there is evidence that
a healthy diet that is low in fat and high in fibre can help to relieve
PMS.
- Women who suffer from PMS should take particular care to consume a
diet low in fat, sugar and salt, and high in fibre and starch.
- Low blood sugar levels may exacerbate symptoms. It is therefore important
that sufferers do not skip meals. Long gaps (ie, more than three hours)
between meals and snacks should be avoided. This can be achieved by
having three small meals and three small snacks each day. Food portions
should be small because of the risk of weight gain. This pattern of
eating seems to be particularly important in the luteal phase, when
PMS is most likely to occur.
- All meals and snacks should contain a source of starch (eg, bread,
potatoes, breakfast cereal, pasta, rice, scones, crispbread). There
is evidence that this may help to reduce some PMS symptoms (eg, sugar
craving, mood swings) by providing a steady supply of energy and not
allowing blood sugar levels to fall too low. Starchy foods are also
thought to increase the secretion of serotonin, and this may help to
improve mood.
- Excessive caffeine intake should be avoided. This means no more than
five cups/glasses of coffee, tea, chocolate and cola a day. Decaffeinated
coffee, decaffeinated cola, herbal tea and water are better choices.
- Alcohol can lower blood sugar levels. No more than one to two units
a day should be consumed, and it is best to drink with a meal or snack
rather than on an empty stomach.
- Gamma-linolenic acid (GLA) supplements (eg, evening primrose oil,
starflower oil) may help some women who suffer from PMS. However, consistent
benefit in clinical trials has been found only for premenstrual breast
pain. A dose of 120-160mg twice a day of GLA (equivalent to three to
four 500mg capsules of evening primrose oil) may be tried.
- Vitamin B6 has been claimed to help reduce the symptoms
of PMS. The evidence is controversial, but a recent systematic review
of nine published trials representing 940 patients with PMS suggested
that doses of vitamin B6 up to 100mg daily are likely to
be of benefit in treating premenstrual symptoms and premenstrual depression.
If there is no improvement in symptoms after four months, or if tingling
in the hands and feet is experienced, the supplement should be stopped.
High doses of vitamin B6 taken over a prolonged period may
cause nerve toxicity, but this is unlikely at doses up to 100mg daily.
- Evidence for the effect of other supplements (eg, zinc, vitamin E)
is sparse. Magnesium levels have been found to be low in some women
with PMS, although further research is needed. Some clinics recommend
a magnesium supplement of 250mg daily, and this may be effective in
a number of women.
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This series of “dietary advice tips” is intended
to be a reminder of the main points to be made by pharmacists when giving
nutritional information to the public. The conditions included in the
series are those where diet is a well recognised risk factor, those in
which diet contributes to the management of the condition, and others
for which patients may welcome sound dietary advice.
Written by Dr Pamela Mason (a pharmacist with a postgraduate qualification
in nutrition)
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