Evening primrose oil doesn’t seem to help my PMS. Are there any other supplements?

When you were taking evening primrose oil were you taking a brand containing sufficient GLA, the “active” essential fat it contains and were you taking enough and for sufficient time? Clinical trials that suggest that this supplement has some therapeutic benefits tend to use six 500mg capsules daily of brands such as Efamol containing 10 per cent GLA over a three-to-six-month timescale.

You could also take 1,000mg of calcium daily, which may help to reduce symptoms. Lowering your salt intake may help to reduce problems with bloating, while swapping from caffeine-rich drinks to chamomile tea and taking exercise may help calm PMS-related stress.

Is it true that eating cheese after sugary foods will help to lower the risk of tooth decay?

Possibly, because eating cheese appears to reduce the acidity in our mouths. It is important to keep the pH above 5.5 as this reduces the risk of acid-forming bacteria in plaque damaging tooth enamel.

It usually takes 30 minutes for the pH of our mouths to be restored to a normal level of 7 after eating; cheese may help to restore this quickly and reduce the risk of enamel damage and tooth decay.

However, cheese is high in fat and calories and so portion control is important to avoid weight gain.

Chewing sugar-free gum containing xylitol; a sugar alcohol that has been proven to reduce the activity of acid-forming bacteria in plaque, is a more weight-friendly decay-preventing option.

Are the “posh” rock salts with big crystals any better for me than standard salt?

Pinch for pinch, you tend to be able to get hold of fewer crystals compared with fine grains of table salt. So in theory this should mean that you get less sodium by using the “posh” crystal.

However, on average we are eating 3g of salt a day more than the recommended maximum. Given that 75 per cent of this comes from processed foods, cutting back in this department will lower salt intakes much more significantly than swapping to rock salt.

My two-month old daughter has bad colic. Do any of the products on the market work?

Check with your GP that your baby’s excessive crying is definitely colic, then before turning to remedies, try feeding her in an upright position.

There is no convincing evidence that colic drops or gripe water work. Some experts believe that colic occurs when undigested milk sugar called lactose moves into the colon where bacteria feed on it and produce gas. This occurs because some babies do not produce enough of the lactose-digesting enzyme called lactase until they are around four months old. Personally, I found that putting drops of lactase (Colief) into my babies’ feeds helped.

Parents trying to cope with a baby who cries excessively can try logging on to www.cry-sis.org.uk for help and advice.

If you have a nutrition question, e-mail amanda.ursell@thetimes.co.uk