Nutrient-dense superfoods black rice, purple corn, red palm oil

Experts agree that eating fruits and vegetables is a good idea, health-wise, though even the current recommended ‘dose’ of five-a-day – almost twice what the average UK consumer actually eats – is widely acknowledged to be sub-optimal (1).

The food industry has taken note, and it has also noted that many of us prefer processed to basic foods. Companies have capitalised on this by producing a wide range of processed foods with soft (and meaningless) fruit ‘n’ veg related claims.

Be sceptical of processed food health claims

Iced tea


Fresh green tea contains high levels of healthy protective polyphenols

Do you, for example, drink the increasingly popular bottled “iced” teas because they are ‘healthier’ than fizzy drinks? If so, you might be surprised to hear that most of them contain very few of the protective polyphenols that make green and black tea a healthy option.

Data presented at a meeting of the American Chemistry Society revealed that while green and black teas contain 50 to 150 mg polyphenols per cup, the bottled iced teas were considerably more dilute, ranging from 80 down to 3 mg per bottle, or 40 to 1 mg per cup (2). The manufacturers have cut down the polyphenols to make their drinks more palatable to a generation raised on the insipidly sweet carbonated beverages that dominate the marketplace; but they have sold our health down the river.

Pimp my potato

At the same meeting, Japanese scientists at Obihiro University in Hokkaido announced a way to enhance the nutritional qualities of the humble spud. This is interesting news; the potato is the most widely consumed vegetable, but is not currently included in 5-a-day schemes because it is mostly starch, with little phyto-nutritional value. [phyto means related to plants]

Many of the compounds we think of as phyto-nutrients are in fact phyto-alexins, which plants use to defend themselves against stressors such as infection or drought. The Japanese took this thought to its logical conclusion, stressed their potatoes by exposing them to ultra-sound or electric shocks, and found that this boosted their levels of polyphenols by up to 60% (3). Shocking potatoes might seem technically laborious, but it was easily done by throwing the tubers into salt water and then passing a small electrical current through the water!

Big potato processors will have seen this research, and some bright advertising executive is probably already dreaming up ads for ‘high antioxidant chips’.

Like ads for bottled teas, however, these will be misleading. It is true that potatoes contribute to people’s polyphenol intake (4), but this is only because we eat so much of them; they contain low levels of these valuable compounds, and an additional 60% of low is still low.

Potatoes are very far from a health food. They have a high glycemic index (ie. when eaten, they pour large amounts of glucose into the blood stream); and as a result, they have a very low nutrient density.

To make matters worse, the important compounds are almost exclusively in the skin and are lost by peeling, so that there are none at all in traditional mash, chips or French fries (5).

The sad fact is that processed foods may be value-added – to the food industry – but most of them are not health-enhanced at all. For the most part, you are better off sticking to basic fruits and vegetables.

If you want to get fancy, go for foods with a high nutrient density such as acai, blackberries, mulberries, raspberries, loganberries, arronia, coffee berries (and beans) …

And if you must eat potatoes, then choose purple sweet potatoes (or if unavailable, common orange sweet potatoes) and eat them skin and all (6, 7).

Try some unusual high-nutrient-density foods

There are some interesting newly available foods worth looking out for.

Take rice, for example. White rice is a bit like the potato: high glycemic index, low nutrient density.

Black rice

Glass bowls with different types of raw rice, close-upBlack rice, however, or ‘forbidden rice’ as it was known in ancient China, is a rich enough source of cancer-preventing anthocyanins (8) to rival blueberries and blackberries (9)! As it also contains high levels of gamma tocotrienol (a very interesting form of vitamin E), plus a substantial amount of fibre, black rice is most definitely a health food. [NB This is NOT the same as the Spanish or Italian dish arroz negro, which – while delicious – is merely white rice coloured with squid ink.]

Purple corn

Purple corn is another newly discovered health food, and an even better source of anthocyanins than black rice; in fact, it appears to contain 4 times more anthocyanins than the blueberries which used to be the benchmark for these compounds (10, 11).

purple corn on white backgroundPurple corn has been used in Peru for thousands of years in a drink called chicha moranda, which is produced by boiling purple corn with pineapple, quince, green apple, cinnamon, cloves and lime juice. This sounds interesting if astringent, but would be hard to find in Britain unless you have Peruvian friends!

Purple corn tortilla chips, however, are more widely available and a positive alternative to the white and yellow varieties. In fact, when consumed with home-made salsa (tomatoes, garlic, chillies, no salt), this makes up a very health-functional snack.

Red palm oil

Finally, next time you’re buying cooking oil in the supermarket, pass by the extra virgin olive oil and look instead at the ethnic section, where you could find red palm oil.

Oil palm fruit on white background

Red palm oil is made from the flesh of the palm fruit, while standard palm oil is made from the kernel.

This muddy orange oil is a rich source of carotenoids, so much so that when food scientists used it to replace 20% of the oil in chocolate, levels of carotenoids increased 20-fold, and levels of vitamin E increased 4-fold (12). These highly significant improvements in nutrient density were achieved without any trade-off in terms of taste, and point the way ahead to seriously functional confectionery.

You could wait for the new, improved chocolate bars to arrive, or you could simply start to cook with this highly nutritious new (old) oil.

Note: Palm oil sources

Standard palm oil — more appropriately termed palm kernel oil is derived from the kernel or seed of the fruit, whereas red palm oil is derived from the pulp (flesh) of the same fruit.

Therefore check the origin of red palm oil exactly as you would standard palm oil — look for sustainable sources and/or organic producers.



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See online here for delicious recipes from the Health Defence Cookbook  incorporating healthy foods featuring in a Mediterranean Diet. Combined 3 courses strip



2. American Chemical Society proceedings 2010 (1)

3. American Chemical Society proceedings 2010 (2)

4. Brat P, Georgé S, Bellamy A, Du Chaffaut L, Scalbert A, Mennen L, Arnault N, Amiot MJ. Daily polyphenol intake in France from fruit and vegetables. J Nutr. 2006 Sep;136(9):2368-73.

5. Manach C, Scalbert A, Morand C, Rémésy C, Jiménez L. Polyphenols: food sources and bioavailability. Am J Clin Nutr. 2004 May;79(5):727-47. Review

6. Park KH, Kim JR, Lee JS, Lee H, Cho KH. Ethanol and water extract of purple sweet potato exhibits anti-atherosclerotic activity and inhibits protein glycation. J Med Food. 2010 Feb;13(1):91-8.

7. Lu J, Wu DM, Zheng YL, Hu B, Zhang ZF. Purple sweet potato color alleviates D-galactose-induced brain aging in old mice by promoting survival of neurons via PI3K pathway and inhibiting cytochrome C-mediated apoptosis. Brain Pathol. 2010 May;20(3):598-612.

8. Forester SC, Waterhouse AL. Gut metabolites of anthocyanins, gallic acid, 3-O-methylgallic acid, and 2,4,6-trihydroxybenzaldehyde, inhibit cell proliferation of Caco-2 cells. J Agric Food Chem. 2010 May 12;58(9):5320-7

9. American Chemical Society proceedings 2010 (3)

10. Jing P, Noriega V, Schwartz SJ, Giusti MM. Effects of growing conditions on purple corncob (Zea mays L.) anthocyanins. J Agric Food Chem. 2007 Oct 17;55(21):8625-9

11. de Pascual-Teresa S, Santos-Buelga C, Rivas-Gonzalo J C. LC-MS analysis of anthocyanins from purple corn cob. J Sci Food Agric. 2002;82(9):1003-1006.

12. El-Hadad NNM, Youssef MM, Abd El-Aal MH, Abou-Gharbia HH. Utilisation of red palm olein in formulating functional chocolate spread. Food Chemistry, d.o.i. 1016/j.foodchem.2010.06.034

Beetroot and beet juice – in moderation

Have you seen publicity about beetroot juice? It’s good for all kinds of things, apparently. It improves failing memory, enhances stamina, reduces blood pressure and even acts as a kind of natural male potency enhancer.

Or does it?

Increased athletic performance

exercise-m+f-runners-CThe story was originally kick-started in the mainstream media a few years ago by a trio of scientific papers, all from the University of Exeter, which showed that taking dietary nitrate in the form of beetroot juice increased athletic performance (1, 2, 3).  The performance improvement was significant: the juice boosted stamina and allowed people to exercise for up to 16 per cent longer.

This was not really new work at all, as the basics had already been proven by a team at the Karolinska Institute in Stockholm back in 2007 (4).

The stories were accurate enough, however. Drinking beetroot juice provides a large enough dose of nitrate to alter blood flow and oxygen metabolism in a way that genuinely does enhance physical performance, and many athletes are now bulk-buying this vegetable juice and using it as a form of natural doping!

An arterial relaxant

Beet juice may also have medical applications. Nitrate is metabolised in the body to nitric oxide (NO), a powerful messenger compound with multiple effects in the body including the relaxation of arteries. The changes in arterial behaviour which occur when nitrates are ingested would be expected to reduce the symptoms of intermittent claudication, a painful cramping of the calf muscles that is a consequence of peripheral vascular disease and often diabetes.

Nitrates would also be predicted to reduce blood pressure, which makes beetroot juice a potential treatment for hypertension. I am not aware of any studies yet on intermittent claudication, but at least two reports find that beetroot juice (5) and inorganic nitrate (6) do indeed lower blood pressure. These two studies were both in healthy volunteers but they certainly suggest that beetroot juice could be an alternative or adjunct to anti-hypertensive drugs.

There are no scientific reports of the use of beet juice as a sexual enhancer, but as its mechanism of action on blood flow is in some ways similar to that of Viagra, there has been a lot of speculation (fuelled, no doubt, by the companies that make beet juice), that this fashionable new drink could be a kind of sex aid.

Brain food?

To add to the media hysteria, a trial also demonstrated that beetroot juice increases blood flow in certain key areas of the brain (7).  A major feature of nitrate’s ability to increase blood flow is that it acts preferentially in conditions of low oxygen, allowing nitrate to increase blood flow precisely in the areas where it is needed most.

In this study, the high nitrate diet did not alter total cerebral blood flow, but did lead to increased regional blood flow in the frontal lobe white matter – the areas of the brain commonly associated with degeneration that leads to dementia and other cognitive problems. The scientists who did this study at North Carolina’s Wake Forest University claimed that this improvement in blood flow might improve mental function in the elderly.


Enjoy beetroot in Health Defence Cookbook recipe “Roasted vegetables with cracked wheat salad”

But danger of too much nitrate

So should we all be drinking daily beet juice for breakfast? I’m afraid that the answer is almost certainly NO. This is because in the longer term, too much nitrate is not good for us.

You’ll know that nitrates are often added to processed meats like bacon, ham, sausages and hot dogs, as they add a pink colour and function as preservatives to help prevent the growth of harmful bacteria. Unfortunately these processed meats are strongly linked to increased cancer risk of the digestive tract.

Moreover, despite the above research suggesting that nitrates could be used to help the ageing brain, there is a good deal of evidence that high dietary nitrate levels will increase the risk of developing Alzheimer’s.

High levels of dietary nitrate lead to raised levels of nitric oxide synthesis, and this, if sustained, causes a condition known as nitrosative stress. This has been strongly implicated as a cause of protein malfolding, a form of protein denaturation that occurs in the brains of Alzheimer’s patients (8, 9, 10). In fact, compounds that block nitrosative stress in the brain have been shown to slow and reverse the damage caused by Alzheimer’s in pre-clinical models (11).

Moderation in all things

The lesson of all this is moderation in all things, including natural things.

That includes l-arginine, a natural amino acid used by some to treat the vascular problem intermittent claudication (mentioned above), and to enhance male sexual function. As this compound is another potent source of nitric oxide, it also increases nitrosative stress (12), and will therefore, like beet juice, increase the risk of Alzheimer’s if used heavily.

Just as worryingly, l-arginine is widely used to treat the symptoms of vascular disease yet it has been implicated in increased death rates after heart attacks (13). The counter-arguments made by arginine sales-persons are not convincing, and certainly not enough to ignore the principle of due diligence.

By all means eat more beetroot in your healthy Mediterranean-style diet, but beware of too much concentrated beet juice.

Indeed, beware of ANY high-dose single-nutrient concentrates or supplements. As with foods, a wide range of nutrient supplements in moderate amounts is hugely preferable to an excessive intake of just one.


If you enjoyed this article, please share it with family and friends (see buttons below).

CTA Register NewsletterAnd register now for a free e-newsletter on the latest in nutrition and health research.

You can follow us on or for daily headline health tweets.

Dr Paul Clayton designed NutriShield as a comprehensive healthbutton-2 supplement with OPTIMUM levels of essential nutrients. See more detail elsewhere on this site or click on the button.

Health Defence bookDr Paul Clayton’s best-selling book Health Defence is available from most good bookstores. See the website for excerpts and links to buy direct from the publisher.

See online here for delicious recipes from the Health Defence Cookbook  incorporating healthy foods featuring in a Mediterranean Diet. Combined 3 courses strip


1. Bailey SJ, Winyard P, Vanhatalo A, Blackwell JR, Dimenna FJ, Wilkerson DP, Tarr J, Benjamin N, Jones AM. Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans. J Appl Physiol. 2009 Oct;107(4):1144-55

2. Bailey SJ, Fulford J, Vanhatalo A, Winyard PG, Blackwell JR, DiMenna FJ, Wilkerson DP, Benjamin N, Jones AM. Dietary nitrate supplementation enhances muscle contractile efficiency during knee-extensor exercise in humans. J Appl Physiol. 2010 Jul;109(1):135-48.

3. Vanhatalo A, Bailey SJ, Blackwell JR, DiMenna FJ, Pavey TG, Wilkerson DP, Benjamin N, Winyard PG, Jones AM. Acute and chronic effects of dietary nitrate supplementation on blood pressure and the physiological responses to moderate-intensity and incremental exercise. Am J Physiol Regul Integr Comp Physiol. 2010 Oct;299(4):R1121-31

4. Larsen FJ, Weitzberg E, Lundberg JO, Ekblom B. Effects of dietary nitrate on oxygen cost during exercise. Acta Physiol (Oxf). 2007 Sep;191(1):59-66.

5. Webb AJ, Patel N, Loukogeorgakis S, Okorie M, Aboud Z, Misra S, Rashid R, Miall P, Deanfield J, Benjamin N, MacAllister R, Hobbs AJ, Ahluwalia A. Acute blood pressure lowering, vasoprotective, and antiplatelet properties of dietary nitrate via bioconversion to nitrite. Hypertension. 2008 Mar;51(3):784-90.

6. Kapil V, Milsom AB, Okorie M, Maleki-Toyserkani S, Akram F, Rehman F, Arghandawi S, Pearl V, Benjamin N, Loukogeorgakis S, Macallister R, Hobbs AJ, Webb AJ, Ahluwalia A. Inorganic nitrate supplementation lowers blood pressure in humans: role for nitrite-derived NO. Hypertension. 2010 Aug;56(2):274-81.

7. Presley TD, Morgan AR, Bechtold E, Clodfelter W, Dove RW, Jennings JM, et al. Acute effect of a high nitrate diet on brain perfusion in older adults. Nitric Oxide 2010 Oct 15, Published online ahead of print

8. Dildar K, Sinem F, Gökhan E, Orhan Y, Filiz M. Serum nitrosative stress levels are increased in Alzheimer disease but not in vascular dementia. Alzheimer Dis Assoc Disord. 2010 Apr-Jun;24(2):194-7.

9. Gu Z, Nakamura T, Lipton SA. Redox reactions induced by nitrosative stress mediate protein misfolding and mitochondrial dysfunction in neurodegenerative diseases. Mol Neurobiol. 2010 Jun;41(2-3):55-72. Epub 2010 Mar 25. Review

10. Nakamura T, Lipton SA. S-Nitrosylation of Critical Protein Thiols Mediates Protein Misfolding and Mitochondrial Dysfunction in Neurodegenerative Diseases. Antioxid Redox Signal. 2010 Sep 2. Epublished ahead of print.

11. Dumont M, Wille E, Calingasan NY, Nathan C, Flint Beal M, Lin MT. N-iminoethyl-L-lysine improves memory and reduces amyloid pathology in a transgenic mouse model of amyloid deposition. Neurochem Int. 2010 Jan;56(2):345-51.

12. Huang H-S, Ma M-C, Chen J. Chronic L-arginine administration increases oxidative and nitrosative stress in rat hyperoxaluric kidneys and excessive crystal deposition. Am J Physiol Renal Physiol 295: F388-F396, 2008

13. Schulman SP, Becker LC, Kass DA, Champion HC, Terrin ML, Forman S, Ernst KV, Kelemen MD, Townsend SN, Capriotti A, Hare JM, Gerstenblith G. L-arginine therapy in acute myocardial infarction: the Vascular Interaction With Age in Myocardial Infarction (VINTAGE MI) randomized clinical trial. JAMA 2006 Jan 4;295(1):58-64.