A major study of the role of diet in our risk of doença cardíaca and other conditions was published last year. It looked at both avoidable deaths and 'Disability Adjusted Life Years', or DALYs - a measure of health among people who are still alive. Here are their conclusions of the impact of food on our health worldwide.

Five+ a day confirmed

In third place - low intake of fruits accounts for 2 million deaths and 65 million DALYs. Of course, veg is also important, and the more variety of fruta e vegetais you eat the better. Fresh, frozen and canned all count towards your 5 a day, and in an ideal world you'd be better off looking at 7 a day - 5 portions of veg and 2 of fruit.

Standard advice is to 'eat a rainbow' - green leafy veg, red tomatoes, oranges, red soft fruit and purple aubergines are an example. Different coloured fruit and veg contain different vitamins and minerals.

Many of my patients bemoan the cost of fresh fruit and vegetables, convinced that veg-rich diets are only for the wealthy. Yet the humble (and versatile) tinned tomato offers an extraordinary range of benefits for a remarkably modest cost. They are rich in antioxidants - a group of vitamins, carotenoids, phenolic compounds, and phenolic acid that can neutralise free radicals. Since free radicals are unstable molecules linked to the development of a number of degenerative diseases and conditions, the benefits are obvious.

Importantly, while many fruits and vegetables lose some of their health benefits (including much of their water-soluble vitamin C) unless raw or only lightly cooked, the process of cooking actually increases the levels of the powerful antioxidant lycopene in tomatoes.

In second place - low intake of whole grains is estimated to cause 3 million deaths and 82 million DALYs. Whole grain and wholemeal food is an important source of roughage - insoluble fibra which is good for your bowels. But it also helps keep your weight down, helping improve cholesterol and blood pressure and reduce the risk of diabetes tipo 2. And 'soluble fibre', found in many fruits as well as in oats and veg, is particularly effective at controlling cholesterol and blood sugar.

For some people, particularly those with type 2 diabetes, a low-carb diet can result in significant improvements in blood sugar - in many cases, enough to put type 2 diabetes into remission. But there is a world of difference in terms of health harm between the deadly white stuff and other forms of starchy carbohydrates.

Switching refined carbs (sugar, white flour products) for unrefined (wholemeal and whole grain) is an easy way to help your heart. Pulses and lentils are a great way to boost your protein and fibre intake - add them to stews or soups.

The winner - excess sal in our diet is thought, worldwide, to lead to up to a staggering 1-5 million deaths and 70 million DALYs. The extraordinary thing here is the main effect of high salt intake is on just one risk factor - pressão alta. On average as a country we eat about 8 grams of salt a day, 25% more than the recommended 6 grams (about a teaspoon). The Department of Health has worked out that if we all cut our salt intake by just one gram a day, we could prevent well over 4,000 early deaths a year in the UK. In pounds, shillings and pence, this tiny change would save the NHS £288 million a year.

Three quarters of the salt in our diet comes from processed foods - often hidden in sauces, soups and pickles, as well as the more obvious salty snacks, bacon and salamis. Cooking from scratch allows you much more control over the ingredients - flavouring with herbs, spices and lemon juice instead of salt. In the long term, a gradual reduction in the levels of salt in your diet can help retrain your palate so you don't miss it. But if you want the flavour of salt, consider a reduced sodium alternative such as LoSalt.

The Portfolio diet, which can reduce cholesterol over the long term by 20%, follows many of these principles. As well as lots of fruit, veg and pulses, they recommend upping your soya intake - tofu, soya drinks or yoghurts and soya beans all count. Another of their secret weapons is a daily dose of plant sterol or stanol - Flora ProActiv, Benecol etc. Another still is nuts (in their case almonds) which provide 'good' oils to improve your cholesterol.

Finally, the dieta mediterrânea is associated with long life for a reason. Fruit, veg, whole grain foods and unsaturated fats (olive or rapeseed oil) all feature here - along with low intake of saturated fats (from fatty meat and processed cakes, pastries etc) and regular oily fish. Importantly, refined sugar intake is also low in the Mediterranean diet.

Dr Sarah Jarvis has acted as a medical advisor for LoSalt.