Health Experts
Nutritionist
Q&As with our nutritionist
Dr Pamela Mason answers online readers' queries regarding saturated fat, the nutritional value of roasted nuts and jam, plus, whether dietary changes can help chronic kidney disease
RDA for fat
Q: When seeking to reduce intake of saturated fat is it still necessary to have one's RDA? If not, why is there a recommended daily allowance?
A: There is no RDA for saturated fat in the UK. The guidance is that no more than 10% of your calories should come from saturated fat, but you don't need to have that much. However, the majority of people in the UK find it hard to achieve an intake of saturated fat as low as that. You do need some fat, but the essential requirement is for linoleic acid (a polyunsaturated fat of the n-6 family, found in seeds, nuts and oils and spreads made from them) and alpha-linolenic acid (a polyunsaturated fat of the n-3 family found in seeds, nuts, oils and green vegetables). LA and ALA are the essential fats and should constitute 1-2% of your calorie intake. There are separate recommendations for the long chain omega-3 fats found in oily fish, but the basic advice from the Food Standards Agency is to consume one portion of oily fish each week.
Nutritional value of processed nuts and fruit
Q: Is there any nutritional value left in nuts once they have been roasted, and in fruit once it has been made into jam, please?
A: Yes, there is some nutritional value in both these foods. Roasted nuts remain a good source of essential fatty acids and starchy carbohydrates, vitamins (particularly E and the B group) and minerals such as iron. The vitamin E content will fall with heating, but it does not disappear. However, if the roasted nuts also contain salt as many do, this is not beneficial. Personally I find I have got used to the taste of plain nuts of all kinds and now enjoy them much more than the salted, roasted peanuts I used to like.
In relation to jam, this contains carbohydrate in the form of the fruit and also in the sugar or fruit juice or whatever is used to sweeten the fruit in the jam recipe. However, while fresh fruit is a good source of vitamin C, the level falls when the fruit is made into jam. For example, one study looking at guavas found that guava jam contained 35.6mg of vitamin C per 100g of fruit in the jam (not per 100g of jam) while the average vitamin C content of guava juice was 76.2mg per 100g of fruit used in the juice. Storage of jam also resulted in a further fall in vitamin C content. So, there is some vitamin C in jam, but it is significantly less than that in the fruit juice or the whole fruit.
Chronic kidney disease
Q: I am now 64 and have been treated with medication for essential hypertension for many years. After recent blood tests, my GP diagnosed chronic kidney disease and changed my medications. From internet research, I understand that diet is also key in slowing down CKD but no advice has been given to me on that subject. Should I see a dietician who understands CKD with a view to changing my eating habits?
A: Yes, it would be a good idea to see a dietician about your kidney disease. I suggest you ask your GP for a referral. I cannot advise you specifically as I don't know what stage your kidney disease is at - and this does make a difference to nutritional recommendations.
Information on this site is for interest only and is not a substitute for professional medical advice. You should consult your own doctor about any specific health concerns.
