The sugar-carb-fat wars - who's right?

We have quite recently seen banner headlines about how saturated fat had been the victim of a systematic witch hunt by the establishment for decades. Instead, they suggest, all the time we should have been focussing on sugar as the bad guy. In fact, their view is that fry-ups should be back on the menu for good health.

I'm not convinced. It's not that I believe sugar is blameless - anything but. Sugar is worse than just completely empty calories - it is actively damaging to our health, and has undoubtedly played a huge part in our current worldwide epidemics of obesity and type 2 diabetes. In fact, there is emerging evidence that even low calorie sugar substitutes might not be the guilt-free alternatives we have all believed for so long.

But the evidence against saturated fat is damning. In 2016, the World Health Organization published a 72-page report examining reams of evidence (and including evidence from 84 studies) of the effect of saturated fat on cholesterol levels. It concluded that replacing saturated fats with unsaturated (particularly PUFA, or polyunsaturated fats) improved total cholesterol, 'bad' LDL cholesterol and triglyceride levels. Replacing sat fats with PUFAs was more effective at reducing lipids than replacing them with a mixture of carbohydrates. This includes refined carbohydrates, of which sugar and white flour are the most commonly eaten examples.

Thousands of studies on millions of patients have shown a clear link between cholesterol levels and risk of heart attack and stroke. But getting studies that show definitively that any one food causes heart attacks and strokes is challenging. For a start, the 'gold standard' for a clinical trial is a double blind trial - where two options are compared, and neither the patient nor the investigators know what group the patient is in. Most people would realise if they were randomly assigned to the Full English or the porridge-and-nuts group. Secondly, it takes weeks or months for your cholesterol to change - but decades before enough people have heart attacks for a difference to show.

That's where so-called 'observational studies' come in. 2015 saw the publication of study which followed 127,000 men and women over 24-30 years. It showed replacing 5% of saturated fat in the diet with the same calorie equivalent of PUFAs was associated with a 25% lower risk of heart disease. For wholegrain carbohydrates, the figure was 9% - but substituting refined carbohydrates for saturated fat didn't reduce the risk of heart attack and stroke at all. A further analysis looked at the individual sources of saturated fat (lauric, palmitic, stearic, myristic acids) and showed a similar picture. It also showed that the benefits don't just apply to unsaturated fats and wholegrain carbohydrates - replacing sat fats with plant proteins also cut the risk of heart disease.

And that's what makes this study so interesting to me. It's not about what you cut out, it's about what you replace it with - and it's about the bigger picture diet-wise. We really should have learnt that by now. As the editorial that accompanies the paper points out, "no single observational study can tell us whether or not a single nutrient is 'harmful'".

Where do carbs fit in?

The 'eatwell' plate, which gives guidance on the ideal proportions of food in a balanced diet, says we should bulk out our diets with carbohydrates, but some dieters believe 'carbs' are the great enemy.

In fact, the guidance hasn't changed that much at all recently - it's just been tweaked. However, the tweaks are of key importance. New guidelines still recommend half our energy from carbohydrates, but stress that we should be upping our intake of wholegrain and wholemeal 'unrefined' carbohydrates. To balance this, we should be cutting down on refined carbs - white processed food and particularly added sugars. Increasing the fibre in our diets in this way has been shown to cut the risk of bowel cancer, type 2 diabetes, high blood pressure, heart attack and stroke, as well as painful piles. As for fats, the balance of evidence still tells us that saturated animal fats and fried foods are bad for our hearts - and our waistlines. Keep up your efforts to eat more fish and white meat rather than red (especially fatty) or processed meats.

Where does the Mediterranean Diet fit in?

We do know enough about a combination of foods that our Southern European colleagues have espoused for years. The Mediterranean Diet, with its strong evidence for heart protection, isn't about one food. It's about a combination of lower dairy products, red meat, processed meats, and sweets and higher veg (including tomatoes, garlic and onions)/fruit/unrefined carbohydrate/fish/nuts/olive oil. It ticks all the boxes in today's study - unsaturated fats, plant protein and unrefined carbohydrates - and it works.

Sugar - beware the hidden culprits

In our drive to cut out fat, many of us have turned to 'low-fat' processed foods which often contain added sugar. This, it turns out, can be as bad for your heart and your weight as a high-fat diet. The new guidelines highlight the dangers of 'free sugars' - honey, syrups and even unsweetened fruit juices are included, along with 'normal' white or brown sugar. Sugary drinks have been specially condemned.

Artificial sweeteners, on the other hand, have been extensively studied and declared safe by the European Food Standards Agency in moderation. Added to hot drinks or foods, they can reduce calorie intake by a bit - but small amounts add up in the long term. Some sweeteners can be substituted for sugar in cooking - and while doctors don't recommend cookies and cakes on a regular basis, there's little doubt that they're less bad for your health if they're made with alternatives to sugar

Fruit and veg - 5, 7, 10?

For years, the message has been to eat 5-a-day - that's five helpings of about 80g of unprocessed fruit or veg, or about a heaped tablespoon of dried. A dessert bowl of salad, 1 banana/orange/apple or three to four heaped tablespoons of most veg (potatoes don't count) each count as a portion. But now we're getting new advice - seven portions a day would be good and some enthusiasts even recommend 10. They have a multitude of health benefits - apart from vitamins and micronutrients, they're high in fibre and people who have a Mediterranean diet with lots of fruit and veg have lower rates of heart disease.

Frozen, dried and canned veg and fruit all count - but beware fruit in syrup, which is high in sugar. Try and eat a rainbow - different coloured fruit and veg have different vitamin levels. And limit fruit juice and smoothies - a glass a day with a meal is fine but the fruit, the whole fruit and nothing but the fruit is even better!

The exceptions that prove the rule

Some oils can be actively good - especially omega 3s, found in oily fish (although beware, this kind of fat is still high in calories). And some fruits, like cranberry, may have added health benefits - a daily glass or two of 27% cranberry juice drink (read the label) could cut the chance of cystitis, but ongoing research is showing promise in heart health and diabetes too. However, they're impossible to eat unsweetened - drink sugar-free versions to avoid offsetting the benefits.

Alcohol addition? No way

Every so often a headline pops up to tell us that alcohol cuts heart disease - but that hasn't changed the rules one bit. For men over 40 and women past the menopause, one or two units a day may protect your heart, but above that level other risks quickly outweigh any gains. What's more, the risk of several cancers increases rapidly with increasing alcohol intake. So the current guidelines (not more than 14 units a week for men and women, spread over several days and with at least two alcohol-free days a week) are here to stay.

Fibre foods!

New recommendations suggest increasing fibre intake to 30g a day - more than double the amount the average Briton eats. Wholemeal and wholegrain foods, pulses and lentils and high-fibre cereals all help.

So let's stop focussing on only sugar or only saturated fat as the bad guys. Let's accept we should be viewing them both with caution, and looking at what we do eat as well as what we don't. We owe it to our hearts.

With thanks to 'My Weekly' where sections of this article were originally published.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Egton Medical Information Systems Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.