Make sure you know your numbers

Your nutrition numbers, as the name suggests, are the numbers health professionals monitor to gauge whether a range of key health indicators - salt, fats, cholesterol, sugar - are flashing in a good or bad way.

Understanding these numbers can enable you to better understand the links between poor diet and poor health (including, to come full circle, conditions such as hypertension) and, from there, do something about it.

One number to watch for is elevated salt levels in your diet, often from processed or unhealthy foods, which can raise blood pressure.

Salt levels can be checked via a blood or urine test and anything above 146 mmol/L (millimoles per litre) will be a red flag. The NHS recommends an adult should have no more than 6g of salt a day (around one level teaspoon) in their diet.

The NHS also has healthy food factsheets with useful advice on how to reduce salt in your diet. This includes cutting out salty snacks, sauces, high-salt soups and sandwich fillings, and removing any salt cellar from the table.

Another nutrition number to watch out for is elevated cholesterol. While there are 'good' and 'bad' types of cholesterol, the NHS recommends a healthy total cholesterol level is below 5 mmol/L, with anything above 5.5 borderline high.

You can get your cholesterol checked through your GP or via an over-the-counter finger prick test through a pharmacy.

Lowering your cholesterol is all about a combination of eating less fatty foods (for example butters, cakes and processed meats) and switching to a more 'Mediterranean' diet of oily fish, olive oil, brown rice, fruits, nuts and seeds. Doing more exercise and quitting smoking will also help.

As the NHS makes clear, a small amount of fat is a vital part of a healthy, balanced diet. Fat is a source of essential fatty acids, which the body cannot make itself.

The issue here therefore is about 'saturated' fats, which are found in many foods, both sweet and savoury, including meat, butter, cream, cheese, chocolate – all the good stuff, essentially.

The government recommends that men should not eat more than 30g of saturated fat a day, and women no more than 20g a day. There are also trans fats, un-, mono- and poly-saturated fats.

You don't need to know everything about all these numbers, which can be complex – that's what nutritionists are for.

The key takeaway here, again, is that as part of a healthy diet you should try to cut down on foods and drinks that are high in saturated fats and trans fats and replace some of them at least with unsaturated fats.

Blood-sugar levels are critical to managing conditions such as diabetes, where hyperglycaemia (too high blood-sugar levels) and hypoglycaemia (too low) can both be life-threatening if not treated rapidly.

Blood-sugar levels are important for all of us, however, as, over time, overly high blood-sugar levels can damage blood vessels, leading to health problems such as coronary heart disease, kidney disease and diabetic eye disease.

You can get your blood-sugar level tested through a blood test via your GP, and, as the British Heart Foundation points out, 'normal' should be between 4.0 to 5.4 mmol/L when fasting or up to 7.8 mmol/L two hours after eating.

Eating too much sugar generally, most of us will well know by now, can make you gain weight and can cause tooth decay.

The government recommends that 'free sugars' - in other words, sugars added to food or drinks, and sugars found naturally in products such as honey and unsweetened fruit – should not make up more than 5% of the energy (calories) you get from food and drink each day.

Adults, the NHS argues, should have no more than 30g of free sugars a day, (roughly equivalent to seven sugar cubes).