Functional foods: too much to swallow?

Andrew Hamilton asks whether the health benefits of some popular functional foods are as large as the manufacturers would have you believe, and makes recommendations for athletes seeking to achieve maximum health

Over the past decade and a half, a whole host of foods from spreads, to eggs and yoghurts to cereals have sprouted labels proclaiming special health benefits by virtue of novel ingredients. Dubbed ‘functional foods’ or ‘nutraceuticals’, these products claim to either boost health and well-being or offer increased protective effects over and above ‘normal’ foods. But just how true are these claims? If they are true, how much benefit do functional foods offer? And if not all of these claims are true, how can you sort the wheat from the chaff?

Stretching the truth

With the steadily growing interest in healthy eating, competition among food manufacturers is fierce. The upshot is that many manufacturers are producing food products that are not just promoted as nutritious, but actually health (and possible performance) enhancing. However, a more considered analysis shows that some of the claims made and tactics employed by the food industry are rather dubious. Here are some common examples:

  • Splashing attention-grabbing health claims across products that have been produced for years and where no new ‘active’ ingredient has been added or where the product contains all sorts of less than nutritious ingredients in addition to those about which the manufacturer is boasting – eg ‘one of your five a day’ emblazoned on tins of baked beans containing copious amounts of added sugar and salt!
  • Foods that contain active ingredients, but which also contain other ingredients that are known to be bad for health (eg live yoghurts containing probiotics but also large amounts of sugar).
  • Failing to mention that while some of these so called ‘functional foods’ may contain nutritious components, they are often already available in higher quantities in less sexy and cheaper unprocessed foods such as fruits and vegetables.
  • The cost. Is it really worth paying 300% extra for margarine that claims to reduce cholesterol or 100% more for eggs containing a higher content of essential fatty acid (omega-3) content?

In recent years, legislation and stricter food labelling have helped to banish some of the wilder health claims made by the food industry but the situation can still be very confusing for consumers. With that in mind, we’ve taken a look at some of the more common ‘functional food’ products typically found in supermarkets and put them under the microscope.

Low-fat vegetable spreads (eg low fat sunflower, low-fat spreads containing olive oil etc)

  • Health claims By lowering fat intakes and using only vegetable oils, not only can fat consumption be reduced, but cholesterol (found in butter) is eliminated, all of which may help reduce the risk of heart disease.
  • Active ingredient(s) – Water! Most low fats are made with at least 50% water, which is made to blend with the vegetable oils by using chemicals known as emulsifiers. The oil component of the spread usually comes from a mix of oils depending on the brand.
  • Evidence for benefits – Until recently, scientists believed that Western diets contain too much saturated fat, increased the risk of coronary heart disease (CHD). The latest research however suggests that naturally unprocessed saturated fats such as those found in butter, cheese and freshly cooked unprocessed meats may NOT be linked to CHD after all(1).
  • Potential drawbacks – While these spreads are lower in fat than standard spreads, the quality of the fat that remains left is questionable. Even brands that contain ‘healthy oils’ such as olive oil which proclaim the virtues of olive oil, only use a small proportion healthy oil in the product – the rest often coming from cheap hydrogenated vegetable oils, which may pose a health issue in their own right(2). And while these spreads are cholesterol-free, many nutritionists now believe that in healthy active well-nourished persons, dietary cholesterol is NOT an issue in heart disease. Many of these spreads also have plenty of added salt to disguise their watery taste.
  • Verdict – Unless you have a diagnosed high-blood cholesterol condition, the recommendation on the best evidence to date is to stick with butter. If weight loss is your goal, simply spread it more sparingly!

Cholesterol-lowering margarines (and drinks) (eg Benecol & Flora Proactive etc)

  • Health claims Eating these margarines will reduce your blood cholesterol, which in turn will lower your risk of heart disease.
  • Active ingredient(s) – Plant stannol esters, which resemble the structure of cholesterol but pass through the body unabsorbed, while inhibiting dietary cholesterol absorption.
  • Evidence for benefits – The active ingredients have undergone extensive clinical trials and produced an typical drop in blood cholesterol of around 10%(3).
  • Potential drawbacks – The clinical tests have tended to use people eating balanced diets; there’s some scepticism about the value of using these spreads in high or low-fat diets. Secondly, the amount of plant esters contained is much higher than would be typically found in diets and some nutritionists have expressed concerns about the long-term implications. Thirdly, there are many other clinically proven ways to reduce cholesterol levels, including regular exercise, a high-fibre diet and stopping smoking. Unless all of these fundamentals are already in place, you’re wasting your time and money, especially as you can expect to pay handsomely for these products.
  • Verdict – While this functional food type is one of the few to have been properly tested, these spreads are expensive and likely to be of limited value unless the rest of the diet is right. High blood cholesterol is not the only risk factor for heart disease and for most, there are other equally effective diet and lifestyle strategies, which will reduce blood cholesterol and also promote health generally. Unless you have a clinically diagnosed high blood cholesterol level, you may be better off saving your cash, and concentrating on increasing your intake of fruits, vegetables and whole grains instead.

Omega-3 rich eggs

  • Health claims These eggs contain a significantly higher level of essential omega-3 fatty acids and lower levels of saturated fats, as well as being rich in protein, vitamins and minerals. Boosting omega-3 fat intake by eating these eggs may help immunity, skin and hair condition and may reduce the risk of heart disease and cancer in later life.
  • Active ingredient(s) – The active compound is 18:3w3 alpha-linolenic acid, one of the two essential fatty acids in the diet. The increased omega-3 fat content is obtained by feeding hens a more varied vegetarian diet, which is rich in a variety of seeds and green vegetation.
  • Evidence for benefits – These eggs do have higher levels of omega-3 fatty acids and nutritionists agree that many Western diets are increasingly deficient in these essential fats. This is particularly the case as the intake of omega-6 fats (found in oils frequently added to processed foods such as sunflower) is rising, which disrupts the ideal omega-3/omega-6 ratio(4). An accumulating body of evidence also shows unequivocally that increased omega-3 intakes can produce a number of health benefits(5).
  • Potential drawbacks – *Cost – these eggs are around 50% dearer than free range eggs and more than double the cost of standard eggs. *Welfare – although the hens are fed a healthier diet, they are not necessarily reared in free range conditions, so (like all non-organic eggs) the eggs may still contain pesticide residues. *Quantity – each egg contains only around 0.6 grams of omega-3 fat. While this makes a useful contribution to the diet, you’d need to eat at least 14 eggs per week to meet the very modest COMA recommendations on omega-3 intake and considerably more for optimum intakes. While many nutritionists believe the role of dietary cholesterol in heart disease has been greatly exaggerated (at least in health people), prudence suggests egg consumption should not exceed 10-12 per week on a regular basis.
  • Verdict – If you enjoy eggs, eat them regularly, and don’t mind paying extra, these eggs could make a useful contribution to your dietary omega-3 intake. Don’t forget though that there are alternatives. Fatty fish such as mackerel, herrings and sardines are tasty free-range, organic and much richer in omega-3 than ‘omega-3’ rich eggs. Nuts such as walnuts and seeds such as pumpkin are also nutritious and good sources of omega-3 oils.

Bio-active yoghurts & yoghurt drinks


  • Health claims Probiotic yoghurts and drinks contain beneficial bacteria that help maintain a healthy colon and digestive tract. They help replace the body’s natural and protective intestinal bacteria and by doing so can boost immunity and also help with constipation, gut infections, irritable bowel syndrome, excess gas production and offer general protection to the gut.
  • Active ingredient(s) – Most of these yoghurts and yoghurt drinks contain one or both types of two bacteria – lactobacillus acidophilus and bifidus. Others, such as ‘Yakult’ contain L-casei. Some products also contain ‘prebiotics’, which are generally in the form of gummy fibres upon which these beneficial bacteria can feed and proliferate.
  • Evidence for benefits – Early studies suggested that while probiotics may help those with compromised digestive system function, or after courses of antibiotics, there was little evidence to suggest that healthy individuals, with no GI problems and who ate a good diet stood to benefit from probiotics. In the last decade however, a large amount of research has been carried out revealing the huge importance of the gut biota in for human health. In particular, research suggests that optimising gut flora may help improve immune function, and play a role in the prevention of degenerative diseases, such as obesity, diabetes, cancer, cardiovascular diseases, malignancy, liver disease, and inflammatory bowel disease(6).
  • Potential drawbacks – Very few really. Apart from the cost, the main drawback is that (like many other yoghurts), probiotic yoghurts and drink often come loaded with a good dollop of sugar, which supplies empty fattening calories – read labels carefully!
  • Verdict – If you like yoghurt and can find low-sugar or plain, natural versions of these probiotic yoghurts, you have nothing to lose except perhaps a few extra pennies on your shopping bill. The recent research on probiotics and immunity also suggests that that regular probiotic use could be a good investment through the winter months in other to keep coughs, colds and flu at bay(7). However, while there may be benefits in those with certain health conditions, be aware that otherwise healthy individuals should not expect to experience great gains in health.

Green tea and green tea blends

  • Health claims Tea, especially green tea is very rich in antioxidants; increasing antioxidant intake helps protect the body against harmful free radicals, which scientists believe play an important role in the process of ageing, and development of degenerative disease. Consuming products such as green tea can boost our antioxidant defence system and reduce the risk of degenerative diseases such as heart disease and some cancers.
  • Active ingredient(s) – Phytochemical polyphenolic compounds such as catechins. The strongest known catechin in terms of antioxidant activity is epigallocatechin gallate (EGCG), which is said to be 200X more active than vitamin E, one of the main antioxidant nutrients in the diet. While black tea also contains some catechins, the levels in unfermented green tea are significantly higher.
  • Evidence for benefits – There’s very solid evidence from a number of long-term studies that those who regularly consume tea (black or green) derive a number of health benefits and experience a reduced risk of a number of chronic diseases(8,9).
  • Potential drawbacks – Pure green tea tastes quite bitter. Also, there are a huge number of different antioxidants in fruits and vegetables. Research indicates that these compounds and nutrients work synergistically, so you should try to consume the widest range of fresh fruits and vegetables for effective protection. Don’t delude yourself that simply washing down a staple diet of pasta and cheese with a mug of green tea blend will sort out all your antioxidant requirements!
  • Verdict – If you like a cup of tea, you’ve nothing to lose (and possibly much to gain), especially as the price premium is reasonably modest. If pure green tea is not to your taste, try a black/green tea blend, which still offers plenty of benefits.

Fortified’ breakfast cereals


  • Health claims By adding extra vitamins and minerals to the cereals (eg Cornflakes etc.), the nutritional value of the cereal is enhanced, which is good for our health.
  • Active ingredient(s) – Normally added are vitamins B1, B2, B3, B6, folic acid, B12 and the mineral iron.
  • Evidence for benefits – It is true that these nutrients are frequently short in processed diets and that increasing our intakes can help improve health and vitality but…..
  • Potential drawbacks – Many of these cereals are refined, with the germ and husk of the grain removed. This strips the grain of at least 30 different nutrients of which only 7 are added back. Most of these cereals have also been stripped of valuable dietary fibre and many contain high levels of sugar and salt, both of which are eaten to excess in Western diets.
  • Verdict – If someone came up to you in the street with a knife, stole your watch, jewellery, credit cards, money and clothes, then gave you back your underpants and the bus fare home, would you feel fortified? Avoid any processed cereals that claim to have been fortified. Instead, stick to whole grain unrefined cereals like Shredded Wheat, whole porridge oats, Weetabix and sugar-free muesli, which are rich in fibre, have not been stripped of goodness and do not need fortifying!

High-fibre cereals (eg oat bran and wheat bran products)

  • Health claims By replacing some of the fibre missing from processed diets, we can promote more regular bowel movement, reduce cholesterol uptake from the intestine (especially oat bran) and help reduce the risk of bowel and colon diseases.
  • Active ingredient(s) – Most commonly wheat bran or oat bran, which is especially rich in gummy fibres that can help bind cholesterol in the gut, rendering it less absorbable.
  • Evidence for benefits – There’s good evidence that diets naturally high in fibre reduce the risk of heart disease and bowel cancer. There’s also moderate (but not overwhelming) levels of evidence that oat bran is particularly effective at helping reduce cholesterol uptake from the gut, and creating a more ‘gentle’ release of energy into the bloodstream(10).
  • Potential drawbacks – The cholesterol-lowering effects are mainly confined to the soluble cereal fibres – ie from oats. Secondly, too much ‘neat’ fibre can bind any minerals present strongly, making them less available to the body, which can reduce your mineral uptake. Thirdly, many high-fibre cereals are ‘glued together’ with sugar and salt, neither of which are desirable. Finally, high intakes of raw bran can aggravate those who suffer from intestinal problems such as irritable bowel syndrome.
  • Verdict – For those with heart health problems or high blood cholesterol, some oat bran produce might be useful. For everyone else, get your fibre as Nature intended (ie from unrefined whole grains, wholemeal bread, fruits, vegetables, beans, nuts and seeds) and (unless you tend to have problems in that department) you shouldn’t have to bother with bran cereals, some of which are nutritionally very poor indeed.


  1. BMJ. 2015 Aug 11;351:h3978. doi: 10.1136/bmj.h3978.
  2. Bratisl Lek Listy. 2016;117(5):251-3.
  3. Int J Clin Pharmacol Ther. 2006 Jun;44(6):247-50.
  4. Curr Sports Med Rep. 2007 Jul;6(4):230-6.
  5. Food Funct. 2018 Jun 15. doi: 10.1039/c8fo00348c. [Epub ahead of print]
  6. Biomed Res Int. 2018 May 8;2018:9478630. doi: 10.1155/2018/9478630. eCollection 2018.
  7. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-17487-8
  8. Biomed Pharmacother. 2018 Apr;100:521-531. doi: 10.1016/j.biopha.2018.02.048. Epub 2018 Feb 23.
  9. Biomed Pharmacother. 2017 Nov;95:1260-1275. doi: 10.1016/j.biopha.2017.09.024. Epub 2017 Oct 6.
  10. Br J Nutr. 2014 Oct;112 Suppl 2:S19-30. doi: 10.1017/S0007114514002281.

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