Dark chocolate’s beneficial deeds

Only dark chocolate is beneficial to health (Photo: André Karwath)

There are several different varieties of chocolate (Photo: André Karwath)

Having dealt with hazards in food during a lifetime, it is always nice to be able to look at the benefit side. We all need good news stories. However, even good news stories can be deceptive. There is much fuss made over what is called superfoods, while the overall diet is more important. And scientists test individual food components in isolation reporting highly beneficial effects in unrealistic animal experiments that have no relevance to real life. Resveratrol that can be found in red wine is supposed to be heart protective, but will require daily consumption of many bottles of wine to reach an effective dose.

But dark chocolate seems to be the real thing with normal consumption amounts sufficient to be beneficial to health.

Not all chocolates are the same

Chocolate is made from cocoa solids (cacao), mixed with fat (cocoa butter) and finely powdered sugar to produce a solid confectionery. There are several types of chocolate, dark, milk and white, classified according to the proportion of cocoa solids used in a particular formulation.

Dark chocolate, also known as “bittersweet” or “semisweet” chocolate, contains little or no added sugar, but plenty of antioxidant flavonoids that contribute to the dark colour. More flavonoids means darker chocolate.

Dark chocolate has already been hailed for its positive effects on cardiovascular health and can help lower blood pressure.

Milk chocolate is not a good antioxidant source as milk binds to antioxidants in chocolate making them unavailable.

White chocolate contains no cocoa solids at all and therefore is not a good source of antioxidants.

Let’s look at the details

Nitric oxide reduces blood pressure.

Dark chocolate increases the effect of nitric oxide in reducing blood pressure.

It is widely known that dietary nitrate leads to the substantial elevation of circulating nitrite, which is subsequently converted into bioactive nitric oxide. Bioactive nitric oxide relaxes blood vessels, increases glucose uptake and regulate muscular contraction. Dietary supplementation with nitrate rich beetroot juice has become increasingly popular in athletes and has consistently been shown to reduce oxygen demands during submaximal exercise allowing athletes to go further for longer.

Dark chocolate works a little differently. Cocoa beans contain a substance called epicatechin, a flavanol that releases vasoactive components from the endothelial cells in blood vessels increasing the bioavailability of nitric oxide. The increased bioavailability and activity of nitric oxide dilate blood vessels and increases blood flow, resulting in a reduction of blood pressure. Previous research have shown that as little as 6g per day can reduce mild hypertension, while around 40g per day can increase blood flow also in healthy patients.

Providing an edge

The previous findings have now been confirmed in a study undertaken at London’s Kingston University The scientists found that the tasty treat could help give sports enthusiasts an extra edge in their fitness training. They used a group of nine amateur cyclists. After undergoing initial fitness tests to establish a baseline for comparison, the participants were split into two groups. The first group was asked to replace one of its normal daily snacks with 40g of a dark chocolate for a fortnight, while the other participants substituted 40g of white chocolate for one of their daily snacks as a control.

The effects of the athletes’ daily chocolate consumption were then measured in a series of cycling exercise tests. The cyclists’ heart rates and oxygen consumption levels were measured during moderate exercise and in time trials. After a seven-day interval, the groups then switched chocolate types and the two-week trial and subsequent exercise tests were repeated.

After eating dark chocolate, the riders used less oxygen when cycling at a moderate pace and also covered more distance in a two-minute flat-out time trial.

All good news.

Benefits confirmed by EFSA

Only dark chocolate is beneficial to health (Photo: Simon A. Eugster)

Only dark chocolate is beneficial to health (Photo: Simon A. Eugster)

And the beneficial effects have been confirmed by the European Food Safety Authority.

The Belgian chocolate manufacturer, Barry Callebaut, has exclusive use of an existing authorised claim stating that cocoa flavanols “help maintain the elasticity of blood vessels, which contributes to normal blood flow”. The authorised conditions of use require the product label to state that 200mg of cocoa flavanols are needed for the beneficial effect. The current claim can only be used for cocoa beverages with cocoa powder or for dark chocolate which provides at least a daily intake of 200mg of cocoa flavanols.

There has been concern that authorising claims on products such as chocolate could encourage over-consumption. However, the EFSA Opinion states that the amount required for the effect can be eaten within the context of a balanced diet.

So as long as you keep within your normal calorie intake level, feel no guilt when indulging in some dark chocolate.

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The magic of blueberries

The high-bush blueberry

Blueberries highly beneficial to health

In the last post we promised to reveal the goodness of blueberries making them part of the elusive superfood category (caveat about superfoods at the bottom). So here goes.

It has long been claimed that blueberries have highly beneficial health effects, but there is a slight confusion about their naming. Let’s clarify that first. When the Americans talk about blueberries they most often refer to a species called Vaccinium corymbosum L. in Latin. It is a shrub native to North America that can reach 4 m in height and are also called northern highbush blueberries (they do also have lowbush varieties to further complicate things).

But for Europeans it is more typically a species called Vaccinium myrtillus L. in Latin and more correctly named bilberries, although naming in several local languages translates directly to “blueberry” in English.

Still confused?

Bilberries are distinct from blueberries but closely related to them. The bilberry plant is a low-growing shrub native to northern Europe producing single or paired berries on the bush instead of clusters, as the blueberry does. The fruit is smaller than that of the blueberry but with a fuller taste. Bilberries are darker in colour, and usually appear near black with a slight shade of purple. While blueberry fruit pulp is light green in colour, bilberry is red or purple.

To best distinguish the two use the colour test. If you get a heavily blue-stained tongue after eating the berries, you have just consumed bilberries.

High in antioxidants

With that out of the way, let’s focus on the high content of a range of antioxidants found in both species. Anthocyanins belong to the flavonoid family and are water soluble pigments involved in a wide range of biological activities that may be beneficial to health. Many of the biological properties of the berries are closely associated with the antioxidant activity of the anthocyanin pigments. The bilberry and blueberry fruits, besides anthocyanins, are also rich in other flavonoids (catechin, epicatechin, myrcetin, quercetin, and kempferol), phenolic acids, chlorogenic acid and ascorbic acid, which all possess antioxidant properties as well.

These compounds help to neutralise free radicals which are unstable molecules linked to the development of a number of degenerative diseases and conditions. Antioxidants may reduce the risk of coronary heart disease, inhibit platelet aggregation and protect arterial endothelial cells. In addition, these compounds could decrease the risk of cancer, reduce inflammatory damage and modulate immune response.

Quite an impressive range of beneficial effects, don’t you agree?

The magic of one daily cup of blueberries

Bilberries are as beneficial to health as blueberries (Photo: Bjørn Tennøe)

Bilberries are as beneficial to health as blueberries (Photo: Bjørn Tennøe)

Now, a new scientific report claims that just one cup of blueberries per day could be the key to reducing blood pressure and arterial stiffness, both associated with cardiovascular disease. Cardiovascular disease is a leading cause of death, with the risk increasing in menopausal women. Thus, over an eight-week period, 48 postmenopausal women with pre- and stage-1 hypertension were randomly assigned to receive either 22 g of freeze-dried blueberry powder (the equivalent to one cup of fresh blueberries) or 22 g of a placebo powder daily, while continuing their normal diet and exercise routines.

At the beginning of the study, the team measured blood pressure, arterial stiffness and select blood biomarkers. At the end of the eight weeks, participants receiving the blueberry powder on average had a 7 mmHg (5.1%) decrease in systolic blood pressure, a 5 mmHg (6.3%) reduction in diastolic blood pressure, and an average reduction of 97 cm/s (6.5%) in arterial stiffness. Nitric oxide, a blood biomarker known to be involved in the widening of blood vessels, increased by 68.5%. The rise in nitric oxide helps explain the reductions in blood pressure.

Although the results are not surprising, previous studies on blueberries included much larger amounts of blueberry powder consumption, anywhere from 50 to 250 g (equivalent to 2 to an unrealistic 11 daily cups).

So what about bilberries?

I am happy to inform you that the highest content of anthocyanins was found in bilberries compared to several blueberry varieties. However, when measuring total activity of all antioxidant compounds, some blueberry varieties beat bilberries, while others fell below the bilberry activity. So there seems to be a dead heat between the Americans and the Europeans.

One daily cup of either variety should do the deed.

Superfood caveat

And finally the superfood caveat. Angst and debate about the merits of what we eat is at an all-time high and separating fact from fiction can be difficult. In case you didn’t know, “superfoods” are so called because they supposedly have health-promoting benefits and may even help with certain medical conditions, or so the superfoods advocates claim.

Nutrition scientists are quick to dispute such claims, saying that the word “superfoods” is simply a marketing tool used by their advocates. To rely solely on superfoods would be dangerous as they cannot substitute for a generally healthy and balanced diet.

BPA opinion is nigh

BPA can be found in cans and plastic bottles

BPA can be found in cans and plastic bottles contributing to oral exposure.

Bisphenol A (BPA) is a chemical used in plastic bottles and inner coating of beverage cans, and its exposure is almost ubiquitous. The European Food Safety Authority (EFSA) has previously reviewed the use of BPA in food contact materials four times. It has now reviewed BPA for the fifth time and has at last settled on a final version of the new BPA opinion. But we don’t yet know what the EFSA Panel has decided since the opinion is undergoing final editorial work and will not be published until sometime in January 2015.

From the initial draft we know that EFSA believes that exposure to BPA is likely to adversely affect the kidney, liver and mammary glands and possibly also the reproductive, nervous, immune, metabolic and cardiovascular systems. It might also pose a risk for development of cancer.

Quite a list of negative effects you would think. But only at very high exposure levels, EFSA said.

Reduced tolerable levels proposed

To be brave EFSA proposes that the tolerable daily intake of BPA should be reduced to 5 µg/kg bodyweight from previously 50 µg/kg bodyweight. This allows EFSA to claim that the health risk for any population group is low. It is because the highest estimates for combined oral and non-oral exposure to BPA now would be 3-5 times lower than the proposed limit, depending on the age group.

Not everyone agreed with the EFSA view as evidenced by stakeholders submitting almost 500 comments during online public consultations of the draft opinion. Comments were received from a broad range of interested parties including NGOs, members of the public, academia, national food safety agencies and the food industry ranging from positive to negative. Predictably, industry thought that the draft opinion went too far, while some NGOs wanted an outright ban.

So a good compromise you would think. Not so sure.

The Americans and the French at opposing ends

The Americans are relaxed as usual. Just days before the adoption of the EFSA opinion, the Food and Drug Administration issued a statement saying that BPA is safe at current levels. The FDA said its verdict was based on a four-year review of more than 300 scientific studies. However, it mentioned three ongoing safety assessments and said that the agency might revise its conclusions pending their findings. A bit of hedging there.

But what about the food-loving French? Well, the French are not so sure that EFSA is right and has actually banned BPA from all packaging, containers, and utensils intended to be used in direct contact with food from 1 January 2015. Health issues potentially caused by BPA are thus taken much more seriously by the French Government. However, reasonably, there seems to be an allowance exempting packages introduced onto the market before this date to remain until stock is exhausted.

So what is a simple soul to believe? Just following the literature introduces further doubts.

Thermal receipts can contain high levels of BPA.

Thermal receipts can contain high levels of BPA contributing to dermal exposure.

New research findings

It is well-known that BPA is applied to the outer layer of thermal receipt paper as a print developer and can be present in very high quantities of around 20 mg BPA/g paper. Although EFSA’s assessment indeed did include exposure from thermal receipts, a recently published study showed that using hand sanitisers or other skin care products often containing mixtures of dermal penetration enhancing chemicals, can increase by up to 100-fold the dermal absorption of BPA. Significant free BPA was also transferred from hands to French fries leading to a rapid and dramatic increase in BPA exposure from the two sources.

There are some previous indications that BPA might be associated with hypertension and decreased heart rate variability. Now, a just published new study confirm without doubt that BPA can acutely increase blood pressure at normal exposure levels. In a randomised crossover trial, 60 non-institutionalised adults aged 60 years and over visited a study site three times, and were provided with the same beverage in two glass bottles, two cans, or one can and one glass bottle at a time. The researchers found that after consuming two canned beverages the systolic blood pressure increased by a statistically significant 4.5 mm Hg compared to consuming two glass bottled beverages and the urinary BPA concentration increased  by more than 1,600 per cent.

Don’t expect revolution

Of course those two late studies are not included in the EFSA review, but if they were would they change the conclusions? Not so sure. It seems overwhelming evidence is needed for the scientific experts to change their view. Thus don’t hold your breath, it is unlikely that the final opinion, when published, will change much from the earlier draft.

Ordinary salt a killer, or not!

Excess sodium can cause heart disease (Photo: Wolf Soul)

Excess sodium can cause cardiovascular disease (Photo: Wolf Soul)

Some simple facts:

  • Cardiovascular disease is the number one cause of death in the world
  • Excess sodium intake raises blood pressure
  • High blood pressure is one of the major contributors to the development of cardiovascular disease

Research just published modelling populations across 187 countries attributed more than 1.6 million cardiovascular-related deaths per year to sodium consumption above the World Health Organization’s recommendation of a maximum of 2.0 g per day.

The details of the study

The researchers collected and analysed existing data from 205 surveys of sodium intake in countries representing nearly three-quarters of the world’s adult population, in combination with other global nutrition data, to calculate sodium intakes worldwide by country, age, and sex.

The researchers found the average level of global sodium consumption in 2010 to be 3.95 g per day, nearly double the 2.0 g recommended by the World Health Organization. All regions of the world were above recommended levels, with regional averages ranging from 2.2 g per day in sub-Saharan Africa to 5.5 g per day in Central Asia.

The proportion of deaths from heart attacks and strokes attributable to sodium ranged quite a bit. In Canada, the United States, Australia and New Zealand, about 10% of cardiovascular deaths were linked to high salt intake. But in a wide band stretching from Eastern Europe all the way across into Central Asia and East Asia, the percentage of cardiovascular deaths attributed to sodium consumption jumped up to 20 to 25%. This happens to be the Old Silk Road, where people traveled vast distances on trade missions and needed salt to preserve their food. This tradition of eating salt-preserved foods has survived to our days.

The researchers found that reduced sodium intake lowered blood pressure in all adults, with the largest effects identified among older individuals, blacks, and those with pre-existing high blood pressure. They stated that because the study focused on cardiovascular deaths, the findings may not reflect the full health impact of sodium intake, which is also linked to higher risk of nonfatal cardiovascular diseases, kidney disease and stomach cancer, the second most-deadly cancer worldwide.

So that’s settled then, is it? Doom and gloom, since limiting salt consumption is difficult given that 80% of a person’s daily salt intake comes from the foods they eat, rather than the salt shaker.

Not so fast!

On the contrary, another recent study suggests that many dietary guidelines for sodium intake are unrealistic, and that the low recommended level of sodium could be associated with a higher risk of cardiac disease and mortality.

Although it has long been the view that eating too much salt will raise your blood pressure, a comprehensive global study now says that too little salt in your diet also can harm your heart health. There appears to be a “sweet spot” for daily sodium intake between 3 and 6 g (equal to 7.5 to 15 g of salt) associated with a lower risk of death and heart disease than either more or less.

The study included more than 100,000 adults from the general populations of 17 countries, providing a broad sample of people that varied greatly in socioeconomic, geographic and demographic makeup. The study found that those who consumed more than 6 g of sodium daily had higher blood pressures than those who consumed less sodium. Within this group, blood pressure increased with higher sodium intakes. The effect of dietary sodium intake on blood pressure was less dramatic for those in the medium (3 to 6 g) range of sodium intake and none for those in the low range of sodium intake (less than 3 g). However, sodium intake of less than 3 g per day was tied to a 27 percent increased risk of death and heart disease, according to their findings.

The study thus provided evidence that both high and low levels of sodium intake may be associated with an increased risk of death and cardiovascular disease and that healthy people probably can eat about twice the amount of salt compared to what is currently recommended — or about as much as most people consume anyway. Since only one in 20 people in the world currently eat what is recommended, it’s not a very practical recommendation.

The good news

Potassium in bananas can counter effects of sodium (Photo: Branko Collin)

Potassium in bananas can counter effects of sodium (Photo: Branko Collin)

But there is more. Before you start to worry too much about a futile effort of counting your exact intake of sodium think potassium. The study provided new evidence about the association of sodium and potassium intake with blood pressure, death and major cardiovascular events. It showed that consuming larger amounts of potassium counterbalanced the adverse effect of high sodium excretion on blood pressure. Potassium is a nutrient found in fruits, vegetables and beans. Rather than focusing on sodium, maybe it is better to focus on eating an overall healthy diet and pursuing healthy lifestyle changes.

It is probably safe to say that if you don’t already have high blood pressure and you’re not over 60 or eating way too much salt, salt won’t have much impact on your blood pressure.

But this is controversial news that could potentially undercut current public health messages about salt. It will take some further time before scientists can agree on the way forward.

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