10-a-day? Here is a more realistic answer
If you are at all health conscious, you already knew that eating fruits and vegetables reduced the risk of disease. And that 5 a day was the official target.
Now researchers at from Imperial College London have conducted a meta-survey – a summary of 95 existing studies involving 2 million people. They conclude that increasing the portions of fruit and vegetables you consume from five to 10 a day could significantly reduce your risk of heart disease, stroke and cancer – and dying prematurely.
But for most people 10 a day is a daunting and seemingly unachievable aim – as was clear from the immediate reactions on social media:
“10 portions a day for a family of 5 – that’s 350 portions a week!”
“I don’t think I could even name 10 different fruits and vegetables.”
“I’d be a walking compost heap!”
So what should you do? Fortunately there are smarter ways to an ideal diet than a guilt-ridden rush to 10 a day.
The 1-minute Summary
The health effect of fruits and vegetables is due to far more than just their vitamin and mineral content – they contain compounds called carotenoids and polyphenols which have a major health benefit.
Choosing the fruits and vegetables with the highest concentration of polyphenols and carotenoids – as well as vitamins and minerals – makes more sense that struggling to reach the simple number of 10 a day.
This article lists 16 superfoods fruits and vegetables and why they are so healthy.
There are other foods to consider with health benefits that are equally vital.
A simple vitamin pill won’t help you to a 10 a day status, but a supplement that includes polyphenols and carotenoids can. Because the chemical effect of these plant derived extracts in the body is the same.
Just why are fruit and vegetables so healthy?
Fruits and vegetables certainly contain vitamins and minerals. But equally importantly they contain other nutrients known as polyphenols (including the sub-group of polyphenols called flavonoids) and carotenoids.
Polyphenols and flavonoids
Polyphenols are compounds that the plants produce to defend themselves against damage from ultraviolet light, from pathogens, and from oxidative (free radical) damage.
When we eat these plants, we absorb these same defensive properties. DNA is better protected from damage – which accounts for the reduction in cancer risk. Tissues are better protected against inflammation – which is now known to be the main driver of heart disease, stroke and diabetes.
So polyphenols are known to help:
- Lower cholesterol
- Lower blood pressure
- Improve the flexibility of arteries and blood vessels
- Prevent blood platelets from clumping together
All the above benefits reduce heart disease risk.
In addition, polyphenols reduce inflammation – which New Scientist confirms is a key driver of heart disease, stroke, diabetes, sexual dysfunction, several cancers and is strongly implicated in Alzheimer’s. Moreover certain polyphenols, especially in dark red and blue fruits, can inhibit the spread of cancer.
As Dr Paul Clayton – the former chair of the Royal Society of Medicine’s Forum on Food and Health – puts it:
“A polyphenol-rich diet ensures your blood chemistry is hostile to heart disease and cancer.”
So it’s not surprising that research shows that those people who consume the largest amounts of polyphenols were shown in one Journal of Nutrition study to have up to a 31% reduction in total mortality.
There are many polyphenols (over 8,000!) but some of the best researched with the most powerful health benefits are a group known as flavonoids, which have both anti-oxidant and anti-inflammatory properties. You’ll find them in fruits, vegetables, legumes, green tea, red wine, dark (70%) chocolate, olive oil, grapeseed extract and curcumin.
Other types of polyphenol include the tannins in coffee, wine and tea, and the anthocyanins in blueberries, cherries and blackberries. One unique type of polyphenol (diferuloylmethane), found in curcumin, has an exceptional ability to fight free radical damage and reduce inflammation. A number of plants contain more than one type of polyphenol.
Generally polyphenols and flavonoids are found most abundantly in the outer layers of plants and in the colouring. That’s why the richest sources of fruit polyphenols are found in the darker fruits like blackcurrants, blueberries and raspberries.
Flavonoids: Isoflavones and flavanols
An important sub-group of flavonoids are isoflavones, found in soy, peanuts, chick peas, alfalfa and fava beans. It is the high consumption of soy isoflavones, along with the flavanols (another flavonoid sub-group) in green tea (called catechins), that has been suggested as a reason for the lower cancer rates in Japan. The only cancer that is higher in Japan than the West is stomach cancer which is linked to their high salt intake.
Another important group of plant compounds are carotenoids.
These are powerful anti-oxidants that include beta carotene found in orange plants like carrots and sweet potato – but also in dark green leafy vegetables. Beta carotene is converted by the body to vitamin A, which is essential to vision, a strong immune function and normal growth and development.
Lycopene and lutein
Perhaps even more protective is lycopene found mainly in tomatoes and linked to breast and prostate health. Lutein is another carotenoid which is also found in leafy greens like spinach and kale. Lutein is protective of eye health and is linked to a lower risk of macular degeneration.
By conferring their anti-oxidant protection to you, carotenoids deliver strong cancer-fighting properties, according to the Physicians Committee for Responsible Medicine. In addition, their anti-inflammatory and immune system properties are linked to cardiovascular disease prevention.
Fruits and vegetables are not the only plant foods that contain the health protective polyphenols and carotenoids, they are in herbs, spices, nuts and seeds too.
Because it’s not just about vitamins and minerals
Their polyphenol, flavonoid and carotenoid content are the key reason why fruits and vegetables give such impressive health benefits. And why researchers rightly point out that a simple one-a-day vitamin pill won’t deliver the same health benefits. Such supplements don’t contain either polyphenols or carotenoids.
Better fruit and vegetable nutrient absorption with healthy fats
The focus on fruits and vegetables ignores another fact if you are trying to follow the most health protective diet.
The bio-availability of polyphenols from food is not high and the nutrients are better absorbed in a diet that includes healthy fats – like Omega 3 fish oil.
There is now a strong recommendation that we should eat 2-3 portions of oily fish a week. That’s because the Omega 3 fatty acids they contain are strongly associated with healthy vision, normal brain function, reduced depression and joint health – as well as linked to a reduction in symptoms of ADHD in children with the syndrome.
So we are already beginning to see why optimum health is much more complicated than just aiming for 10 a day.
THE TOP 16 – Getting the biggest bang for your nutritional buck
Not all fruits and vegetables have the same degree of health benefit. So by focusing on the ones with the highest concentrations of vitamins, minerals, polyphenols, flavonoids and carotenoids, you don’t necessarily need to reach the 10 a day target.
Here are the top 16 foods based on a European Journal of Clinical Nutrition table and our own analysis of their combined polyphenol, carotenoid, vitamin and mineral counts – and considering their ready availability as menu ingredients.
It is not an accident that vegetables (rather than fruits) head the list as the London University study showed that vegetables were particularly strong protectors against disease.
High in a polyphenol called kaempferol, an anti-oxidant that has been shown to prevent damage to cells and inhibit the formation of cancer cells. Also includes beta carotene, vitamin K2 (cardio protective because it reduces inflammation), lutein (eye health), vitamin C (immune system and skin and connective tissue health) and manganese (healthy bones and metabolism).
Includes a range of flavonoids which have anti-cancer properties. Also includes lutein, vitamin K, vitamin C, folic acid, magnesium (heart healthy), calcium, B vitamins (essential for energy) and potassium (heart) and fibre.
This is a test.
- Broccoli, Cabbage and Brussels Sprouts
Rich in anti-oxidant polyphenols that include the anti-cancer glucosinolates and a good source of the minerals selenium (linked to lower overall cancer risk) and manganese (normal nerve function), plus folic acid (heart health) and fibre (lower bowel cancer risk).
Ideally cooked in olive oil. Why? Because tomatoes are the key source of the carotenoid lycopene but this is less bio-available in raw form. Lycopene is also important for bone health and can help lower LDL – the ‘bad form of cholesterol. Tomatoes are high in vitamin C, biotin (nervous system health), molybdenum (an important catalyst for other nutrients) and folic acid (helps prevent DNA damage).
- Blackcurrants, chokeberries, bilberries and blueberries
These all contain polyphenols called anthocyanins. These are protective plant compounds that give the fruits their deep vibrant colour. They have been shown to help inhibit both the initiation and spread of cancer cells. One study showed that a cup of mixed berries lowered blood pressure and raised HDL – the ‘good’ form of cholesterol.
Raspberries and strawberries will give you the same sort of health benefit but at a slightly lower potency.
Cocoa is one of the very highest polyphenol-rich foods, and those polyphenols (the flavonoid sub-group flavonols) are cardio-protective. They reduce inflammation in artery walls that otherwise leads to atherosclerosis and the risk of heart attack. So much so that certain pharmaceutical companies are trying to create drugs from them! Prefer cocoa powder but dark chocolate is a good and tasty source.
- Onions, leeks and garlic
Onions and leeks are allium vegetables that contain a different class of anti-oxidant polyphenols. These particular polyphenols have been shown to improve the flexibility of artery walls and hence reduce blood pressure. Garlic contains similar polyphenols to onions, but at higher concentrations, and garlic polyphenols can help block the formation of blood clot platelets. So their combined effect is to reduce heart disease risk. Garlic can also enhance your immunity due to its antibacterial and antifungal properties.
- Spices and seasonings
If you want the highest level of polyphenols per gram weight, several spices and seasonings come at the very top. However, you don’t eat many grams of spices, so the amount of polyphenols you consume is not high.
Nevertheless, cooking with cloves, basil, oregano, celery seed, sage, thyme, turmeric, ginger and rosemary will boost your polyphenol intake. In fact researchers of one of the famous ‘blue zones’ (geographical areas with the highest percentage of fit and healthy centenarians) lists their liberal use of rosemary as one of the reasons for their longevity. See article on blue zones here.
Curcumin – derived from turmeric – is an especially potent anti-oxidant and anti-inflammatory nutrient with substantial research to support its use in cooking and as a supplement.
- Nuts and seeds
Data from the US National Institutes of Health confirms that “nuts are high in polyphenol antioxidants which would inhibit the oxidative (free radical) processes that lead to atherosclerosis”. They do this by improving the flexibility of arterial walls and reducing inflammation. The nuts and seeds with the highest polyphenol count are celery seeds, flaxseeds, chestnuts, hazelnuts, pecans, roasted soy beans, almonds and walnuts.
- Plums and prunes (which are dried plums)
Everyone knows that prunes have a laxative effect. Less well known is the fact that they are high in a class of polyphenols that have been shown to help prevent carcinogens binding with DNA and causing mutations – and that they help lower LDL cholesterol.
- Peppers – Sweet and Chili
Green, red, orange, yellow sweet peppers and chili peppers are twice as high in vitamin C as oranges. They contain folic acid and are high in the anti-oxidant magnesium and in iron. The brain has a high fatty acid content and is therefore vulnerable to oxidation or free radical damage – rather as fat left out oxidises or goes rancid! The particular polyphenols in peppers (capsicum) have been shown to protect against oxidative damage of both the brain and liver.
Grape seeds, grape skins and grape juice all contain several types of polyphenols – resveratrol, phenolic acids, anthocyanins, and flavonoids. An article in the International Journal of Molecular Sciences confirms that: “The dietary consumption of grape and its products is associated with a lower incidence of degenerative diseases such as cardiovascular disease and certain types of cancers.” There is a high concentration of polyphenols in both the seeds (which is why it is a useful supplement) and the skin, which accounts for the positive effect of red wine – in moderate amounts!
Go for olives, black or green that are preserved in oil rather than salt/brine, because salt preservation reduces their polyphenol content.
They contain 4 types of polyphenol. So does an apple a day really keep the doctor away? Well, research indicates it may keep the grim reaper at bay – as several animal studies suggest these polyphenols may switch on genes associated with improved longevity. And the polyphenols in apples are linked to lower heart attack rates.
- Citrus fruits including oranges, tangerines and lemons
These are high in vitamin C which works synergistically with vitamin E to be cardio-protective. Interestingly, a study (referenced below) shows that over 80% of the anti-oxidant potency of citrus fruits is due to their polyphenol, rather than vitamin C content.
This vegetable contains an unusual polyphenol (neobetanin) that has been shown to help reduce blood sugar levels and improve insulin response. So it should help lower the risk, and improve the symptoms of, diabetes. Beetroot also contains a nutrient called betaine. Betaine, a quasi B vitamin, is proving to be an effective supplement for heart health as – in conjunction with other B vitamins – it reduces the levels of a blood protein called homocysteine. And people with high homocysteine levels are at significant risk of heart disease.
Of course other fruits and vegetables are also definitely valuable, but neither their polyphenol nor carotenoid content is as high as the listed foods.
The above analysis helps us understand why the authors of the Imperial meta-survey were able to claim that:
“Fruit and vegetables have been shown to reduce cholesterol levels, blood pressure, and to boost the health of our blood vessels and immune system.
“This may be due to the complex network of nutrients they hold… For instance they contain many antioxidants, which may reduce DNA damage, and lead to a reduction in cancer risk.”
Many of the polyphenols and carotenoids we have mentioned exert their health benefits through what is called gene expression. They have the ability to switch on ‘good’ genes and switch off genes that can lead to negative health.
The recommendation of more than 5 a day is not new – and is it realistic?
Although the advice has stirred a lot of comment, it’s not actually new. For over 4 years the American Cancer Society has been recommending 9 portions a day.
But we – along with leading health researchers – have mixed feelings about the call for 10 a day. It may well just demotivate people by being seen as unrealistic. Moreover for less well-off families it would be financially challenging.
Here’s our final recommendation:
Emphasise the fruits and vegetables in your diet with the highest overall nutritional values – not simply looking at vitamins and minerals but at polyphenol and carotenoid content. Use the TOP 16 as much as possible and double, triple or quadruple your intake by combining different fruits and vegetables in smoothies, stir-fries, soups and fruit salads. See simple healthy ideas devised by TV cook Portia Spooner in collaboration with Dr Paul Clayton in the Health Defence Cookbook here online.
Consider a supplement that includes polyphenols and carotenoids alongside simple vitamins and minerals.
Why health experts are now recommending some supplements – because less food means less nutrition
A few years ago Dr Paul Clayton, who is the former Chair of the Forum on Health at the Royal Society of Medicine, published a series of articles in the Journal of the Royal Society of Medicine.
In these articles he identified a fundamental fact which most researchers overlook.
Over the last 50 years – and due to our sedentary, low energy burning lifestyle – the average person has had to cut their calorie intake by almost 1,000 calories a day.
Less food means less nutrition. That’s compounded by the fact that the nutritional quality of some fruits and vegetables has measurably declined, and by the fact that urban pollution and the stresses of modern life have simultaneously increased our demand for those nutrients that confer protection to tissues and cells.
Dr Clayton agrees with other health experts that the priority in creating an ideal ‘health defensive’ diet is fresh fruit and vegetables. That’s because they contain such a wide range of polyphenols and carotenoids, some of which we have yet to identify.
But he is also adamant that a well-designed nutritional supplement can have an important part to play in enabling people to get the level and type of nutrients they need for a genuinely protective diet.
The science has moved on. It is now possible to isolate carotenoids like lycopene or lutein. And it’s possible to extract polyphenols from plants in the form of extracts of green tea, grapeseed and curcumin.
These individual polyphenols and carotenoids work in exactly the same way and have the same health benefits as they do in the original plant. Indeed in some cases they may even be better absorbed in supplement form.
A ‘well-designed’ supplement does not mean a simple a-z vitamin and mineral pill at just RDA levels. That will not make much difference. It should include polyphenols and carotenoids.
It should also deliver vitamins and minerals at an optimum level. Because the intake of some nutrients – like vitamins C, D and E, the B vitamins, which are critical for energy, and the minerals selenium and chromium – all need to be several times the minimum RDA levels before they deliver the maximum health benefits.
That ‘ideal’ supplement should also include Omega 3 fish oil, because we are now advised to eat 2-3 portions of oily fish a week – but like the 10-a-day recommendation, for most people this is also unrealistic.
Dr Clayton is not a theoretical scientist. He has used his 35 years of research on health and nutrition to advise on a supplement that includes a range of polyphenols, carotenoids, vitamins, minerals, Omega 3 and even CoQ10. It’s called Nutrishield – www.nutrishield.com and its aim has been to combine the nutrients found in the diets of the healthiest people.
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See online here for delicious recipes from the Health Defence Cookbook incorporating healthy foods featuring in a Mediterranean Diet.
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