Five foods that used to be bad for you … but now aren’t

Scott Harding, King’s College London

Nutritional guidelines and recommendations are constantly changing in the light of new research. It can be difficult to keep up with which foods are healthy and which aren’t. Here we look at five foods that have gone through the cycle of being the villains of nutritional science but are now, based on some old and some new science, apparently okay to eat again.


For a long time, eggs were thought to be bad for your heart. A large egg contains a hefty 185mg of cholesterol. Dietary cholesterol was believed to contribute to high blood cholesterol levels. But for the last 20 years, nutrition and medical research has shown repeatedly that at normal intakes dietary cholesterol has very little influence on a person’s blood cholesterol levels.

Although it’s taken a while, nutrition experts are now correcting the record for eggs and other foods that contain cholesterol (such as chicken liver and shellfish) by removing it as a nutrient of concern from dietary guidelines. Eggs are an excellent source of protein, healthy fats, and several vitamins and minerals.

No such thing.
Bob Ryskamp/flickr, CC BY

Fat spreads

The story of fat spreads, such as margarine and butter, is probably one of the most confusing stories in nutrition. The origin of margarine, which is made from vegetable fat, dates back to the mid-1800s. Since that time, margarine has replaced butter as the fat spread of choice in most developed countries. This switch was driven by the lower price of margarine compared with butter as well as recommendations from health professionals to eat less saturated fat in order to prevent coronary heart disease (CHD).

While this switch away from saturated fats began to show reduced CHD incidence in the population, researchers also identified an independent link between trans fat (a fat produced when partially hydrogenating vegetable fats to make margarines) intake and CHD. Since this link between trans fat and CHD was confirmed by multiple studies regulatory agencies around the world have sought to eliminate trans fats from the diet.

The food industry was quick to respond and has been producing trans fat-free margarine for years now. However, there is still confusion among consumers as to whether vegetable, fat-based spreads are safe to eat. The short answer is yes, as long as the food label doesn’t list “partially hydrogenated vegetable oil” as an ingredient.

Modern vegetable oil-based fat spreads are a way to replace dietary saturated fat while increasing polyunsaturated fat – a dietary change that has been shown to reduce CHD in large cohort studies.


Potatoes are one of the few vegetables considered to be unhealthy. Because they’re a high glycaemic index food they tend to get lumped in with foods made from refined carbohydrates as foods to avoid. But potatoes are a rich source of carbohydrates, vitamin C, some B vitamins and trace minerals.

How you prepare potatoes also changes the aspects of those starches that get a bad rap. Cooking and cooling potatoes increases the amount of resistant starch in the potatoes. This resistant starch then acts like dietary fibre which “resists” digestion in the gut, potentially having a positive impact on your gut bacteria.


Dairy – including milk, butter, yogurt and cheese – was once considered a staple in many people’s diet, but consumption patterns have changed, in part, due to difficult-to-interpret health messages.

Positive aspects of dairy include the high protein and calcium content. Fat content and fat type are important when choosing dairy products as some contain high amounts of fat per serving and this fat tends to be high in saturated fat.

Although it’s best to avoid a diet high in saturated fat (a risk factor for CHD), regularly consuming dairy products doesn’t need to be a concern if your overall calorie intake and fat intake is healthy. Because there are numerous studies that point toward both the healthy and unhealthy aspects of dairy it is difficult to recommend specific intakes or types of dairy foods for improving health. The recent updates to the UK Eat Well Plate still promotes dairy foods as part of a healthy diet, as long as the dairy choices are lower in fat.

Raw nuts and nut butters

Nuts also get a bad reputation for being high in fat and high in calories, leading some to suggest they should be avoided by anyone looking to lose weight. But there is mounting evidence to suggest that raw nuts are key to a healthy diet and maintaining healthy body weight. A recent study, published in the British Journal of Nutrition, showed that eating raw nuts reduces death from all causes, cardiovascular diseases, coronary heart disease and sudden cardiac death.

Although studies are still ongoing to determine what components of tree nuts are promoting these positive health outcomes, we already know the nutritional benefits. Raw nuts contain protein, healthy fats (low saturated fat and high monounsaturated and polyunsaturated fat), dietary fibre and micronutrients.

Nut butters, such as peanut butter, can also be part of a healthy diet. The fat in peanut butter has a healthy profile and peanut butter is also an excellent source of protein, fibre, vitamin B6 and magnesium. Some recent evidence has shown increased weight loss for people that replace less healthy proteins, such as processed meats, with peanut butter.

Nut and nut butter consumption can be a part of a healthy diet, but you need to be mindful of the calories.

Remember, when it comes to food and health: all foods fit into a healthy diet. Don’t fall into the trap of believing in “superfoods” or “food villains”. Enthusiastic consumption of one particular “superfood” can be worse than consuming a so called “food villain”.

The Conversation

Scott Harding, Visiting Senior Lecturer in Nutritional Sciences, King’s College London

This article was originally published on The Conversation. Read the original article.

Posted in Uncategorized

The 2 X 500 Diet Study – Planning on Starting the 5:2 Diet? Why Not Join Our Study?

We are starting a study which is looking into how much an individuals diet changes when they initially start a fad diet like the “5:2 Diet”. If you have been thinking about starting this diet and would like to volunteer please contact us before you begin dieting.  We are looking for volunteers from the London area but are also recruiting for email/post volunteers as well. Please contact Emily Prpa ( or me if you would like more information.

.2X500 Diet Study Poster

Posted in Uncategorized

Recruiting for a Nutrition Study | BBC: Trust Me I’m A Doctor – Cholesterol Lowering Foods


BBC: Trust Me I’m A Doctor – Cholesterol Lowering Foods

We are recruiting volunteers to take part in a study investigating cholesterol lowering foods, part of which will be filmed as part of the BBC television programme Trust Me I’m A Doctor.

What is the study about?

The purpose of this study is to demonstrate to the TV audience of the BBC’s “Trust Me I’m a Doctor”, that small dietary changes can have significant impact on your blood cholesterol concentrations. Therefore, we are recruiting individuals to be randomly allocated to one of three treatment groups:

  1. low cholesterol diet
  2. three servings of oats per day
  3. 60 grams of unsalted almonds per day

If you are eligible to take part in the study you will be asked to consume your allocated treatment for 28 days (4 weeks) and visit the Metabolic Research Unit (MRU) at the start and finish of your treatment. The MRU is located on the Waterloo Campus of King’s College London in the Diabetes & Nutritional Sciences Division on the 4th floor of the Franklin-Wilkins Building. As part of this study you will likely be filmed/recorded and possibly interviewed during your visits to the MRU. Some parts of your participation may be aired as part of the programme later this year. You can still participate in the study even if you do not wish to be filmed.

What do I have to do if I participate?

You will be asked to attend 3 visits to the MRU:

  1. a screening visit to determine your blood cholesterol levels and overall health
  2. If eligible, 2 additional visits (1 at the start and 1 at the end of the study) to have fasted blood samples taken.

While you are on your treatment you will be asked to follow the instructions provided by the investigators (e.g. diet advice or treatment consumption). At any of these visits, you may also be asked to interact with the BBC presenter, producers or technical staff on-site during filming. Travel expenses will be reimbursed and you will be entered into a draw for 1 of 3 £100 retail gift vouchers.

For more information or to express interest in participating, please email

Notice regarding access to personal information: All email addresses and personal information sent to will only being used for purpose of recruitment for the study described above. No information will be shared with BBC or any other 3rd parties or used for anything other than the stated purposes.

Tagged with: , , , , ,
Posted in Healthy Eating, Nutrition

Ethics in Science Publishing – Practice that goes beyond dubious

This blog post by the editor-in-chief of the Journal of Human Nutrition and Dietetics, Professor Simon Langley-Evans from the University of Nottingham, is an eye-opener for anyone not familiar with the current practices and behaviours people will attempt in order to get scientific papers published. Blatant and shocking to say the least.

Practice that goes beyond dubious.

Posted in Education, Publishing, Science Writing

“Superfoods” – Misleading Marketing Term? BBC World Service – The Food Chain

I was interviewed by the BBC World Service – The Food Chain recently for my opinion on the term “superfoods” and my thoughts on some of the foods which have recently been labelled as “superfoods” in the media.  The show touches on foods like quinoa, teff, kale and chia from  marketing, sales, agricultural and nutritional angles.

The podcast is available here and the “On-Demand” web-stream is available here.

If you have never heard of some of these foods here is a brief description and the nutritional breakdown:

Quinoa (Chenopodium quinoa) – not actually a cereal but it is finds itself as a nice replacement for rice or barley in the diet. Cultivated originally in the areas around Bolivia by the Inca civilization. Quinoa is gluten-free and consists of 73% carbohydrates, 15% protein and 12% fat as a proportion of energy.

Teff (Eragrostis tef) – a very small grain native to Ethiopia and surrounding areas of Africa. It is a very small grain, approximately the same size as a poppy seed. It grows well in less than ideal conditions including very wet and very dry at a variety of altitudes.  Teff is high in resistant starch (up to 40%) – a type of carbohydrate similar to dietary fibre – is gluten-free and consists of 73% carbohydrate, 13% protein, 2% fat as a proportion of energy.

Chia (Salvia hispanica) – an oil seed – not a cereal – which is rich in alpha-linolenic acid (plant based omega-3) and when eaten whole is a good source of dietary fibre.  Also native to the areas of central and southern America this seed consists of 15% carbohydrates, 17% protein and 67% fat as a proportion of energy.

Kale – a leafy green vegetable similar to broccoli, cauliflower and brussels sprouts. Like most dark green leafy vegetables it is high in beta-carotene which can be converted to vitamin A in the body, vitamin C and high in vitamin K. These dark green leafy vegetables are also good plant sources of iron.

Posted in Education, Healthy Eating, Nutrition

Phytosterols, Blood Fat and Blood Pressure

Does phytosterol consumption reduce postprandial

serum triglycerides and blood pressure?


Hand and plant sterol drink - new text copy

Who are we looking for?

We are recruiting male and female individuals between the ages 25-55, who are slightly-to-moderately overweight.

What will you have to do? 

  • Stage 1: A screening visit at the KCL Metabolic Research Unit (MRU). At this visit we will ask you some health questions and take a small blood sample to determine if you meet the criteria for the study.
  • Stage 2: If you meet the study requirements you will be asked to come to the MRU for two further visits.  At each you will have blood samples taken and will be asked to consume a specially prepared breakfast and lunch meal. There will be a 28 day period between visit 1 and 2 during which you will be asked to consume a small yoghurt drink daily for a month (e.g.Proactive which is commonly used to lower cholesterol in the blood).

What do you get?

Upon completing the trial you will receive £100 plus your travel expenses. You will receive results from your health tests, including information about your blood fats and cholesterol levels.

What to do next? 

If you are interested in participating please contact us to receive a more detail study information package and schedule your screening visit to the MRU.

Contact Information:  Dr Scott Harding: or 020 7848 4349

Tagged with: ,
Posted in Lipids and Lipid Metabolism, Nutrition, Supplements

Preventing Disease – Not Treating – Should Be Your Goal with Your Health

I was asked by the staff at King’s In Touch Magazine to turn my recent presentation at the Pint of Science 2014 festival in to a “King’s Recommends” style article which has a five items list.  Here is the pre-print version of the magazine article.  If you want to see the slides, you can check them out here at

Preventing Disease – Not Treating – Should Be Your Goal with Your Health

Like many of you I struggle to find the right balance of diet, exercise and other lifestyle habits that keep me at the right body weight and level of fitness.  As someone who researches and teaches in the area of diet, lifestyle and chronic disease I understand all too well the consequences of not prioritizing these aspects of life.  I know I need to find this balance if I want to stay healthy as I age.  The alternative is to slide into a routine of worrying about my health until later in life.  Unfortunately, putting off a focus on health has some very nasty consequences.  Research has clearly shown that by not managing my weight and fitness I will be more likely to develop type 2 diabetes and cardiovascular diseases, which means that I will die at a younger age – meaning less time with my family and friends.  Sadly, I generally fall short of my lifestyle goals and based on the most recent UK health statistics so do the 2 out of every 3 people in the UK who are classed as overweight or obese.   Here are my suggestions of what to prioritize in your life so you can stay healthy and live longer.


  1. Your Weight. While it might seem obvious and a bit of a no brainer, most people who need to lose weight do not.  Find the strategy that works for you and stick to it.  If it gets boring, find something new to challenge you!
  2. Your Waist-line. There is overwhelming evidence showing that having high abdominal fat – easily determined by your waist circumference – means you are 3-5 times more likely to have a heart attack or stroke.  By losing weight you should see your waist-line shrink as well.
  3. Your Physical Activity. Do you know the recommended physical activity requirements for the average UK adult?  Don’t worry if you don’t, when surveyed most people in the UK did not know either.  What is most worrying is that many people never achieve the weekly minimum.  You need at least  150 minutes per week of physical activity that gets your heart rate up and the sweat running down your brow – now you know!  Remember this target is the low hanging fruit NOT the bar you should be setting for yourself.
  4. Your Inactivity. Many people equate increasing physical activity with decreasing inactivity but they are very different things. Think about the body positions you spend most of your day in – if it does not involve high levels of walking, stretching, jumping, running, twisting and climbing then you are too inactive.  Today many occupations and home related activities require very little use of muscles and require very low levels of energy – both of which contribute to decreased fitness and increased body fat.  You need to move more and sit less.
  5. Your Other Bad Habits. Quit smoking, drink less alcohol and get more sleep.  Smoking, moderate to excessive alcohol consumption and lack of sleep just compound the risk of developing lifestyle related diseases like type 2 diabetes and coronary heart disease.
Posted in Healthy Eating, Nutrition, Obesity, Overweight and Obesity
Dr Scott Harding

%d bloggers like this: