Q: I have heard that some foods are good to eat if they are related to your blood group. For example I am A positive and it is said that I should not eat too many Brazil nuts as my system does not agree with them nor oranges… Do you agree with this form of belief? That some food should be eaten according to your blood group?

A: The blood type diet was introduced by Peter D’Adamo who suggested that because the cells in our bodies have certain distinct chains of polysaccharides which put us into one of four blood types, O, A, AB or B then we should eat a diet that is right for whichever blood type we are.

The blood type theory is founded on anthropology because it is reasoned that as type O was the first blood type to evolve, then people with this blood type should eat like our hunter-gatherer ancestors. The theory is based on the action of lectins, which are proteins found on the surface of certain foods. So when you eat a food containing lectins that are not compatible with your blood type then the lectins can cause health problems.

I have a problem with the thinking that we can all just be slotted into four groups, according to the four blood types. And in fact there are more than four because with each group there are sub-groups (e.g. rhesus positive and negative) and these differences are not taken into account. The other major problem is the lack of evidence. There has not been any scientific evidence to show that an interaction between blood type and diet has an impact on health. Biochemical research has also found no differences in how lectins react with each different blood type. Even D’Adamo adds a warning to say that even within each blood type there are individual variations so don’t expect all the recommendations to apply to you. The difficulty would then be knowing which ones apply and which ones don’t and then the blood typing theory starts to fall down.

Q: I have not had sexual intercourse for 17 months as I split up with my boyfriend and went through a long depression about it. I am now completely recovered and have met a new boyfriend. However, during sexual intercourse, it is quite painful, in a particular position (missionary), and not in others.

I am 49, I stopped my periods about 3 years ago and I am following your vitamin supplement advice to the letter. This is new to me. I know that you recommend the Sylk lubricant but I am wondering if there is anything I should have checked and if you could explain why the pain is there and what you would suggest to do to improve the situation, as this is a cause of concern as you can imagine.

A: As with any pain you should get it checked out and your doctor may do it or refer you to a gynaecologist. It is interesting that you were probably using the same position (missionary) with your ex-boyfriend and yet you had already gone through the menopause three years ago.

Also, that you are not getting pain with intercourse in every position. For some women, pain in certain positions is caused by a retroverted uterus (where the womb naturally tilts backwards instead of forwards) but you would have experienced the discomfort with previous boyfriends. Fibroids are also associated with pain or discomfort during intercourse and these are very common for women around the menopause and could give pain on intercourse in certain positions and not others depending on where the fibroids are situated.

Other problems like ovarian cysts, prolapsed womb, infections and endometriosis are also known to cause painful sex (medically known as dyspareunia) so that is why you should get it checked in order to rule out any problems. If you are given the all clear then my suggestion is to use the Sylk lubricant and avoid any positions which may be uncomfortable.

Q: I’m trying for my second baby and my doctor has suggested I lose some of the weight I gained during my last pregnancy first. Is it worth it as I’m going to gain weight anyway when I’m pregnancy?

A: It most certainly is. Mothers who pile on the pounds after their first baby could be putting their next baby at risk. On the other hand, losing too much weight quickly after a pregnancy could be just as dangerous. Any rapid weight changes between pregnancy can increase the risk of babies suffering high blood pressure along with premature or stillbirth.

There is growing evidence that sudden and dramatic changes in weight put a huge strain and can harm babies. One study from Sweden published in 2006 which examined 207, 5000 women between 1992 and 2001 highlighted the dangers of weight gain. It found a rise in a woman’s body mass index (BMI) by just one or two points between her first and second pregnancy increased the risk of diabetes and pre-eclampsia. A second study published last year in the American Journal of Obstetrics and Gynaecology examined the risks of losing weight. It found that women whose BMI fell by five or more units between pregnancies had a higher risk of premature birth than those whose weight remained stable. Although apparently contradictory these studies show how important it is to attain and maintain a healthy weight before, during and after pregnancy so my advice to you is not to try and diet to lose weight but to make sure you eat healthily and get regular exercise (see my tips on healthy eating and my fertility boosting tips in this issue). That way you’ll be getting all the metabolism (fat burning) benefits of a healthy diet and you’ll also be giving yourself the best possible chance of a healthy pregnancy and birth.

You may also be worried about gaining weight once you are pregnant. Under no circumstances should you diet during pregnancy. If you crash diet you will deprive yourself and the baby of valuable nutrients. Your body may also start to detoxify (losing toxins stored in fat throughout your body) and these toxins will pass though the baby before they are excreted.

If you eat a good, nutritious diet, you will lose any unnecessary weight naturally. The way to lose weight during pregnancy is to eat healthier and any excess weight will come off. A healthy weight gain during pregnancy is considered to be not more than 15 kg (33lb) and also not less than 5kg (11lb). If you find that you are well above or below this range, talk to you doctor.

The most important thing you can do to maintain a healthy weight is to ensure that your blood sugar is balanced by eating regularly. If you miss meals in an attempt to restrict calories, you may end up craving sweets and chocolates because your blood sugar has dropped too low.

Reduce your intake of concentrated fruit juices, even unsweetened brands. These juices may have some nutritional value, but they lack fibre and many women have found that they can cause weight gain because they cause the blood sugar to fluctuate. Juice should always be diluted (half and half) with water.

Eat slowly and chew well. It takes 20 minutes for your brain to register that you are full, so if you eat slowly you can avoid overeating before you get that message.