Is bacon dangerous? The science behind food trends

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Is fat really bad for you? Should we devour less salt? And whats wrong with gluten, anyway? A science writer and a consultant cardiologist separate fact from fiction

The great diet food con

Have you ever wondered why people on diets seem to be on and off them forever? Or why its genuinely merely people who struggle with their weight who have extra low-fat mayonnaise in their fridge? Most processed foods branded as diet, low-fat, light or lighter arent what theyre cracked up to be. And if you look at their lengthy ingredients lists, youll realise that theyre not even very good for you.

Take low-fat mayonnaise. When you strip out the fat you have to reinject flavor with sweetness. So an emulsion of eggs and petroleum has become a emulsion of water, maize starch, extra sugar and glucose syrup. Or to put another way: water, sugar, sugar and sugar. Thats an awful plenty of sugar, and because the traffic lights on packets of food dont flash red until a whopping 27 g of sugar is in each 100 g portion thats simply under seven teaspoons a busy shopper wont think twice about selecting this healthy option.

Other culprits are microwaveable low-fat snacks. The high glycaemic index, carbohydrates and sugars aside, producers are so busy bending backwards to limbo under the threshold for each of the other traffic-light categories that they often leave out plenty of healthy foods such as positive fats, fruits, vegetables and fibers. Its why theyre often so tasteless and dont leave you feeling full for long.

The diet food industry is a headless beast driven by marketplace forces: it stimulates good business sense to make low-quality food with effective branding. The only way we can bring it to its knees and stop this totalitarianism of tiny, tasteless snacks is to become savvy both consumers and stop buying them. If you feel yourself being seduced by an alluringly presented diet food and dont have time to interrogate its ingredients, a good rule of thumb is to just say no.

Are calories important ?

We love to ascribe value to things. It helps us make decisions about a jumble of information, like the way we use calories to help us manage what we eat.

The concept entered public consciousness during the first world war when the state used it to make sure people didnt overeat during food dearth. The calorie the unit of energy needed to heat one cm 3 of water by 1C has since became the backbone of our understanding of healthy eating, but at what cost?

In a perfect world it stimulates perfect sense. If you devour more energy than your body needs, then according to the central tenet of Einsteins most famous equation itll be turned into mass a wibbly-wobbly type of mass around your belly and thighs.

The problem is that our bodies dont burn energy with the consistency of a Bunsen burner. We do not assimilate all the nutrients from some foods, says Pete Wilde, a prof at the Institute of Food Research in Norwich. By chewing and eating whole almonds, for instance, we assimilate merely around two-thirds of the energy listed on the label. The calcium in milk and dairy products reacts with fatty acids and again reduces the energy absorbed.

The different rates of digestion of different foods can also affect your appetite and assess the extent to which you end up eating. The more slowly our food is digested the less hungry well feel for longer, Wilde adds. The calories absorbed by two different foods could be the same, but if one food is digested more slowly, itll make us less hungry and less likely to snack.

In how your body its utilization and stores energy, 140 calories of cola is not the same as 140 calories of broccoli. If you want to lose weight by starving yourself, then a calorie-restricted diet is the way to go. Though youll likely bounce back once you start to eat normally. If youre after a sustainable way to be healthy its best to believe a little more about the constituents of your food.

A healthy diet is not about restriction but inclusion of diverse and protective foods. Opting food on the basis of merely calorie content is like selecting their own lives partner on how quickly they can run 100 metres: it might be useful in extreme circumstances, but for your day-to-day life and general wellbeing, its pretty much useless.

Salt

Look out for the mountains of salt used to make low-quality processed foods more palatable. Photograph: Jean-Christophe Riou/ Riou/ SoFood/ Corbis

Should I lower my salt uptake ?

Whether your salt has been coaxed from a cave by a Tibetan monk or extracted from brine by a human called Gary, its always precisely the same thing sodium chloride. Because its the sodium in salt thats associated with high blood pressure( the only health concern with salt) if anyone tells you fancy salts like sel gris, fleur de sel, Hawaiian ocean salt or pink Himalayan salt are any healthier than the ordinary table stuff theyre wrong.

The matter of whether or not you should lower your salts intake is less cut and dried. Some peoples blood pressure is more sensitive to salt than others. Even scientists are divided about how to construe the evidence on an individual level, but to get bogged down with the scientific disputes would be to miss the point: salt stimulates food taste good.

The first thing that MasterChef magistrate Michel Roux Jr remarks on is a dishs seasoning. Poor Rick Stein must live in constant fear of finally being caught by the salt police he mentions so regularly. Nobody has in the past won a Michelin star with a salt-free menu.

The relationship between salt intake and blood pressure is complicated, says Anthony Heagerty, prof of medicine at the University of Manchester. Lowering salt is advisable on its own population level because many people will respond favourably to an overall lower salt uptake, he says, but teasing out the effect on an individual is harder. An unhealthy diet, excess weight and alcohol play a large its participation in an individuals hazard of hypertension, so if youre worried about blood pressure you can lower your salt, but its perhaps more important to focus on your overall food and alcohol intake.

Fruit and veg rich in potassium, such as mushrooms, spinach and bananas, can help lower blood pressure. Appear out for the mountains of salt used to make low-quality processed foods and snacks more palatable. Employing salt in a sensible way can make the food you cook at home taste better, and, importantly, give you a better manage on what youre putting in your body.

The complicated history of fats

It started in the 1950 s with a suit of mistaken identity. Saturated fats, researchers said, were the main cause of heart disease. The smoking gun? Fatty deposits in patients arteries and studies showing that people in Mediterranean countries where people tend to eat more unsaturated fats like olive oil than saturated fats like butter had a lower hazard of disease.

By the 1970 s the food industry responded. Their answer was trans fatty acids, or trans fats: unsaturated fats transformed by hydrogenation to fit convenient criteria. Once hydrogenated, for example, cotton or vegetable oils would be solid at room temperature to make margarine. Fats could be chemically tweaked to increase the shelf life of cookies and cakes, or to avoid them from breaking down during the repeated reheating done in chip shops and restaurants.

That these trans fats were made from unsaturated ones, the thinking went, entail they were healthier than saturated fats. It was a fallacy supported by the medical community; and one which proved to be deadly.

The increased consumption of trans fats contributed to a peak of heart attacks and strokes during the 1980 s and 90 s. Eating them, it turns out, can also increase your risk of type-2 diabetes, so theres little wonder that producers, at the behest of governments, have been reducing the amount of trans fats in their products.

Theres still no legal requirement for companies to label trans fats as such, cautions Chloe Miles, of the British Dietetics Association. Its important to check the ingredients lists. Appear out for anything with partially hydrogenated oils or fats. The usual suspects are takeaways, tarts, pies, fried foods, cakes, cookies and hard margarines.

Ding dong, pseudoscience nutritionists proclaimed at the jaunt of trans fats, the witch is dead! But they fell into a dangerous trap: they started saying that saturated fats such as butter and coconut petroleum are good for you. This is by no means true. Though angelic compared with trans fats, eating too much saturated fat will damage your health by displacing healthier foods. Trying to replace saturated fats completely with low-fat alternatives, though, means youll be eating more sugar and refined carbohydrates, which will do you worse, so saturated fats should be used wisely to make some healthy foods more satisfying.

The heroes are unsaturated fats from whole food sources. Olive petroleum, seeds, nuts, oily fish and avocados, if prioritised over saturated fats, can help you lose weight and avoid heart disease. And they may even protect against neurological disorders such as depression. The health benefits of these fats is a simple message that should not get lost in a complicated history.

Sausage

People who feed excessive sums of processed meats can also have unhealthy lifestyles. Photograph: Norman Hollands/ Getty Images

Should I feed processed meat ?

Bacon sandwiches are one of lifes little pleasures. The only problem is that the World Health Organisation has classified bacon, along with all other processed meats, as a group-1 carcinogen up there with cigarettes, plutonium, asbestos and uranium.

But the picture is a little more nuanced. Traditionally we lumped red and processed meats together in these scientific analyses. Merely recently have the two been separated out, showing that for cancer, as well as cardiovascular disease, a sensible amount of red meat is probably fine processed meat, it seems, had been the most powerful contributor to disease and had been tip-off the balance. But, in terms of hazard, is a 30% meat sausage genuinely the same as a cured, air-dried Iberico ham? The truth is that nobody knows.

There are some mechanistic explanations for why processed meats might cause colorectal or bowel cancer, says Louis Levy, head of nutrition science at Public Health England( PHE ), such as something carcinogenic that happens during the cook process or something used to preserve them.

Given the incomplete picture, PHE advises a limit of 70 g of red or processed meat a day. The reason for 70 g? Its to ensure that the people who feed meat will still get the iron benefits of nutrient-dense red meats. But this seemingly sensible guideline falls pollute of a familiar problem it lumps all red and processed meats together.

Another possibility for the link between processed meat and disease, Levy says, is confounding: analyses have shown that people who feed excessive sums of processed meats have otherwise poor diets and unhealthy lifestyles which increase their likelihood of disease; given the severity of the potential consequences, merely a buffoon would be flippant about the risk.

Try to favour red meat over processed meat and choose quality over sum because there are other benefits to cutting back on meat. Your shopping will be cheaper. Youll be able to eat more oily fish, vegetables, nuts and fiber. And, given the enormous amount of carbon the meat industry pumps into the air, if you go veggie for a few days a week youll be doing your bit for the planet.

The gluten-free con

Food packaging that screams about what is not in it and merely whispers about what is should always be a red flag. This is nowhere more true than with gluten-free foods.

About 1 % of the population have coeliac disease. They are allergic to gluten, a mix of proteins may be in grains, and must adhere to a strict, lifelong diet if they want to live without belly pains, diarrhoea, vomiting, anaemia and fatigue.

Then there are people who are gluten intolerant. Its tricky to define but it probably affects about another 1 % of the population who have the milder symptoms of coeliac( it cant be medically diagnosed) without lasting damage to their gut.

Interesting, then, that about one in five of us or 20% vs the 2% who would actually benefit buys or has bought gluten-free food. Merely people with coeliac disease are likely to benefit from a gluten-free diet, says Dalvinder Mandair, a consultant gastroenterologist in the NHS. For the others theres no physiological mechanism by which not eating gluten will help them, but because gluten intolerance is such a subjective thing it can be open to persuasion.

That 18 in every 20 customers are buying gluten-free products because of a perceived but non-existent health benefit is certainly good marketing. But thats no reason to do down peoples attempts to feel healthy as long as their decisions are well-informed. Its at this point that things start to break down for gluten-free foods.

Theyre often more expensive than their gluten-containing counterparts, and to compensate for the elasticity gluten gives to things like cakes and bread, producers spoon in more sugar, E-numbers and additives. Its a long way from the healthy, natural image they like to invoke.

If you keep avoiding food with gluten in it youll not be eating much fiber, and a diet lacking in fiber can increase your risk of lower-bowel cancer and cardiovascular disease.

If youve not got coeliac disease, you should ask yourself whether its really worth going gluten-free.

Broccoli

In how your body uses energy, 140 calories of cola is not the same as 140 calories of broccoli. Photograph: Tastyart Ltd Rob White/ Getty Images

Understand cholesterol and control it with diet

Cholesterol is another incorrectly maligned component of our diet. Because its a waxy substance it cant dissolve in our blood, so its packaged into little ferries along with fat and protein to be transported to where it is needed for things like making hormones. Its cholesterols inclusion in these transportation ferries where the misunderstanding about its role in ill-health comes from.

Low-density lipoprotein, or LDL, cholesterol ferries are known as bad cholesterol. These are the packages of cholesterol, fats and proteins constructed in the liver and sent off around the body. On the way, and under specific conditions, they can get trapped in the lining of your arteries and leave fatty deposits that can lead to cardiovascular disease.

Then theres good cholesterol, or high-density lipoprotein( HDL) cholesterol ferries. On their way back to the liver to be unpacked and excreted, these ferries help to pick up the fatty deposits and thus lower your risk of disease. Whether your total cholesterol, therefore, is high or low is an oversimplification its the balance of good and bad cholesterol ferries thats important.

Think of this balance, known as your lipid profile, as a gauge of your general health. The canary down the proverbial coalmine is a bad profile: high levels of bad LDL cholesterol, high levels of trigylcerides( another type of fat in your blood) and low levels of good HDL cholesterol. The good news is that many people can reverse a bad profile by changing their diet and lifestyle rather than by popping more pills.

Counter to what you might have heard, cholesterol in your diet from things such as eggs and prawns is virtually irrelevant. Instead, watch out for excess sugar and refined, low-fibre carbohydrates( both cause spikes in your blood sugars, your liver responds to the upsurge by packaging the sugar into triglycerides and bad cholesterol and sending them out into the body ). Avoid trans fats, eating more saturated fats than unsaturated fats from whole food sources, and drinking too much alcohol.

To improve your profile you can actively introduce foods with lots of soluble fiber: pectin in gummy fruits and beta-glucan in porridge protect the rest of the food youve eat from digestive enzymes, meaning its digested more slowly and you get fewer sugar spikes. Prioritising unsaturated fats from whole foods such as nuts and oily fish will reduce your bad cholesterol and increase your good cholesterol. And in case you thought you could feed your way along a delicious route to a healthy heart: exert is key, so get those walking shoes on and earn that brunch.

Dr Ali Khavandi is a consultant interventional cardiologist at Royal United Hospital NHS Foundation Trust Bath

Read more: www.theguardian.com

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