The fact that we have finally been treated to some sunshine is likely to enhance our appetite for salads. Few would doubt that salads offer a good deal from a nutritional perspective. However, where flavour is concerned, I reckon that what turns a good salad into a really great one is the dressing.

Unfortunately, conventional wisdom dictates that the oily nature of traditional dressings does not bode well for our waistlines or weight, and such fat-phobia has spawned an ever-expanding number of low-fat and even 'fat-free' dressings. However, as I explained in a previous column, review studies have found that long-term low-fat eating is quite ineffective for the purposes of weight loss. Research has also revealed that fat can actually enhance the nutritional value of the food we eat.

Specifically, studies have shown that fat aids and abets our ability to extract and absorb carotenoid nutrients such as betacarotene (found in many green, yellow and orange fruits and vegetables) and lycopene (found primarily in tomatoes). The role that fat plays in the extraction of carotenoids from food was most recently assessed in a study published this month in the American Journal of Clinical Nutrition.

Researchers measured the levels of three carotenoids (betacarotene, alphacarotene and lycopene) before and after the consumption of a mixed salad accompanied by either a fat-free, reduced-fat or full-fat dressing. Researchers found that eating salad with a fat-free dressing did not lead to a significant rise in the levels of any of the carotenoids measured.

However, when the salad was eaten with a reduced-fat dressing, there were appreciable rises in the levels of all three nutrients. What is more, the full-fat dressing boosted carotenoid levels significantly higher than the fat-reduced variety. The reason for this is not known for certain, though it has been suggested that fat assists the release of carotenoids from food and eases their passage through the gut wall into the bloodstream.

Whatever the precise mechanism, the effect undoubtedly promises significant benefits to our health: carotenoids have been found to offer an array of beneficial biochemical actions for the body, and a mass of evidence now exists which suggests that they have considerable cancer-protective properties.

When it comes to choosing an oil for a dressing, I prefer cold-pressed extra-virgin olive oil. Olive oil is rich in monounsaturated fat, which can bring benefits for the heart and circulation. The oil is extracted with minimal processing and with no application of heat - factors that are believed to help preserve its innate healthy properties.

Nutrition news
Atherosclerosis is the name given to the process in which cholesterol-like substances deposit themselves on the inside of the body's arteries. Atherosclerosis in the vessels supplying blood to the brain (the carotid arteries) increases the risk of problems such as stroke and dementia. In a recent study, researchers assessed the effects of drinking pomegranate juice in a group of people with confirmed carotid atherosclerosis. The pomegranate fruit contains a variety of 'antioxidant' compounds (including phenolic substances, tannins and anthocyanins), one effect of which is to protect cholesterol from oxidation, thereby reducing its tendency to be deposited on the inside of the arteries. Individuals drinking 50mls of pomegranate juice each day enjoyed an average 35 per cent reduction in the extent of their carotid atherosclerosis over the course of a year.

In comparison, those not having pomegranate juice (the control group) saw an average increase in the extent of their carotid atherosclerosis of 9 per cent. This study suggests that regular consumption of pomegranate may stimulate important anti-atherosclerotic actions within the body.