The magical kale

Healthy kale (Photo: Lodigs)

Healthy kale (Photo: Lauren)

I have long known that kale is supposed to be one of the healthiest vegetables around. I didn’t think I had tried it, but I was so wrong. The other day I looked up a translation to Swedish and for my Swedish friends in case you don’t know it is what we call grönkål. I haven’t had it often but as a southern Swedish tradition it is served as a side-dish to the Christmas ham. We have tried to find it here in Australia for Christmas but failed so we replaced it with spinach. Now I am going to renew my efforts to find kale because it is so highly spoken of.

Kale is a leafy green vegetable that belongs to the Brassica family, a group of vegetables including cabbage, cauliflower, and Brussels sprouts. Curly kale has ruffled leaves and a fibrous stalk and is usually deep green in color. It has a lively pungent flavour with delicious bitter peppery qualities. It carries more nutritional value for fewer calories than almost any other food around. Although it can be found in markets throughout the year, it is in season from the middle of winter through the beginning of spring when it has a sweeter taste and is more widely available. If you are to believe the literature it has remarkable properties.

The good side

In a previous blog we covered cholesterol and the minimal impact cholesterol-containing foods have on cholesterol blood levels. But there is more. Without going into too much detail, our own cholesterol is metabolised in the liver to bile acids, which are released into the intestine. But here most of it is reabsorbed in an essential process for the digestion and absorption of dietary fats. Now kale has been found to contain a group of resins known as bile acid sequestrants, which have been shown to lower cholesterol and decrease absorption of dietary fat. The cholesterol-lowering components do a better job of binding together with bile acids in the digestive tract when kale has been steamed. Although cholesterol is essential to the body, too much is no good as we all know.

Stir fried kale retains beneficial compounds (Photo: Mike)

Stir fried kale retains beneficial compounds (Photo: Mike)

And there are anti-cancer compounds. Kale, as with broccoli and other brassicas, contains sulforaphane (particularly when chopped or minced), a chemical with potent anti-cancer properties. Sulforaphane is an antioxidant and stimulator of natural detoxifying enzymes and, together with indole-3-carbinol, a chemical also found in kale which boosts DNA repair in cells, may reduce the risk of breast, bladder and prostate cancer. Epidemiological studies show that people who eat a lot of cruciferous vegetables have reduced incidences of cancer. In-vitro and animal studies have confirmed the anti-cancer effects and have demonstrated a reduction in frequency, size, and number of tumours. However, since boiling destroys much of the sulforaphane, steaming, microwaving, or stir frying is preferred to retain the activity of the compound.

Kale is very high in beta carotene, vitamin K, vitamin C, and rich in calcium. It is also a source of two carotenoids, lutein and zeaxanthin and a large number of flavonoids. Many of the flavonoids in kale are also now known to function not only as antioxidants, but also as anti-inflammatory compounds. It might sound too good to be true so I better stop there before I go overboard.

The bad side

There is another side of kale you should know about before rushing head on. It is among a small number of vegetables, including rhubarbs that is the most well-known, that contain measurable amounts of oxalates. When oxalates become too concentrated in body fluids, they can crystallize and cause health problems. For this reason, individuals with already existing and untreated kidney or gallbladder problems may want to avoid eating kale.

It might also pay off to buy organic kale since conventionally grown kale has been found to carry fairly high pesticide levels in some countries. However, finding organically grown kale should not be that difficult since it is a popular crop with organic farmers.

Enjoy your kale and live a long and healthy life.

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The low fat and no cholesterol diet myths

Have you been a follower of the low fat and no cholesterol diet recommendations? Have you reduced your consumption of eggs because of their high cholesterol levels? Do you always buy low fat products but you never check the total energy content? And all in the name of heart health. Well, do I have news for you. It’s all been a con! Or close to.

Our body controls cholesterol levels

Free to eat bacon and eggs again (Photo: Sean Munson)

Free to eat bacon and eggs again (Photo: Sean Munson)

Many of us have been told repeatedly that foods like red meat, eggs and bacon raise our cholesterol levels. An idea we no longer questioned since it had been ingrained in our belief system over a long time. The theory that diets high in cholesterol and saturated fat raise cholesterol blood levels came from studies in animals and humans conducted more than half a century ago. Although the results were rather dubious, persuasive argumentation helped making it a truth and a basis for diet recommendations in many countries. However, more recent results from high quality studies do not support this theory.

It is now clear that we fine-tune our own blood cholesterol levels irrespective of diet intake. The body tightly regulates the amount of cholesterol in the blood by controlling internal production. When we eat less cholesterol, the body makes more, and when we eat more cholesterol the body makes less. As a matter of fact only 25% of the cholesterol in our body comes directly from the diet while 75% is produced by our own liver on demand. Much of the cholesterol that can be found in food can’t even be absorbed by our bodies. So the theory that eating cholesterol will give you a heart attack is clearly a myth for most of us. This is also true for a few hyper-responders in which dietary cholesterol does moderately increase total cholesterol, but not the risk of heart disease.

Low-fat fad

With that out of the way we then come to the low-fat diet. In a way it makes sense to lower fat intake since fat contains about twice as much energy on a food weight basis compared to carbohydrates and proteins. But when food manufacturers lower the fat content they often replace it by sugar to improve the all important taste of their products. If you read the food label you will see that the total energy content is the same or even higher in low-fat compared to conventional products. So there is no real net gain from a weight loss point of view.

But the fat profile might be important. It’s true that some studies have shown that saturated fat intake raises blood cholesterol levels in the short term. This might not be true in the long term and some scientists even claim that the link between saturated fat and heart disease is poorly supported by scientific evidence. There is still too much controversy around this point so it might still be prudent to limit saturated fat intake if not total fat intake. Even though total fat intake varied widely, population and intervention studies have indicated that the risk of atherosclerosis can remain quite low as long as the balance between unsaturated and saturated fatty acids is favourable.  As a matter of fact new Nordic nutrition guidelines just released recommend that consumption of saturated fatty acids should be limited to 10% of total energy intake while monounsaturated fat should be 10-20% and polyunsaturated fat 5-10% of total energy intake.

New focus for diet recommendations

Added sugar in low-fat food the real culprit (Photo: jude)

Added sugar in low-fat food the real culprit (Photo: judy)

The low-fat, high-carbohydrate diet supported by medical authorities for so long might actually be an unintended culprit in the current epidemics of obesity and cardiovascular disease. Studies on low-carbohydrate diets which in turn tend to be higher in total fat suggest that they not only don’t raise blood cholesterol, but have several beneficial effects on cardiovascular disease risk markers. Low-fat diets can even be worse than low carbohydrate diets with the food industry replacing saturated fats with added sugar. There is growing evidence that added sugar may be an independent risk factor for metabolic syndrome which increases the risk of diabetes and should be the focus of new dietary recommendations.

But in reducing carbohydrate consumption do you really need to go for a high fat diet as some proponents suggest? Well, maybe not just yet. It is true that short term you might reduce your weight but long term consequences aren’t yet all that clear particularly if you include a lot of saturated fat in the diet. It will take some effort for me to drop the entrenched view that saturated fat is bad for you.

Confused by the conflicting science? Stick to the balanced diet concept and plenty of exercise and you will not go wrong.

Surprise – silicon necessary for bone health

Abundant silicon needed for bone health (Photo: Wikimedia)

Abundant silicon needed for bone health (Photo: Wikimedia)

Surprise, surprise – we might all need silicon in the diet to form healthy bones, not just to build computers. Fortunately, over 90% of the Earth’s crust is composed of silicate minerals, making silicon the second most abundant element in the Earth’s crust after oxygen. Far from eating it all,  most free silicon is used in the steel refining, aluminum-casting, and fine chemical industries. Critical is the small proportion of highly purified silicon used in semiconductor electronics forming integrated circuits in computers. But it is also used in many other applications like building materials, whiteware ceramics such as porcelain, and in traditional quartz-based soda-lime glass. Silicon is the basis for polymers called silicones that are used among other things for breast implants, but remember silicon and silicone is not the same thing.

The biological role of silicon

Forget the industrial applications, we are interested in the food aspects of silicon. And here it has been proven that it is an essential element in biology, although only tiny traces of it appear to be required. Studies of silicon deprivation in growing animals conducted in the early 1970s showed reduced growth and marked defects of bone and connective tissue. In addition, silicon supplementation of postmenopausal women with osteoporosis not only inhibited bone resorption but also increased trabecular bone volume and bone mineral density. All good things.

Thus, there are clear evidence that silicon plays a major role in bone formation, yet there has been a question mark around important dietary sources of silicon that can actually be absorbed by the body. Indeed, it has been assumed that silicon, as the bioavailable orthosilicic acid, is present only in fluids (such as drinking water and beer) but not in foods, in which it exists as polymeric or phytolithic silica.

The benefits of beer

High silicon levels in beer (Photo: cizauskas)

High silicon levels in beer (Photo: cizauskas)

Beer appears to be a major contributor to silicon intake. Researchers have published findings from a study of commercial beer production looking at the relationship between beer production methods and the resulting silicon content. The study examined a wide range of beer styles for their silicon content and also looked at the impact of raw materials and the brewing process on the quantities of silicon that enter wort and beer.

A previous study had shown that silicon in beer is readily bioavailable because it is solubilised during the mashing process of beer making. The new research noticed little change in the silicon content of barley during the subsequent malting. The majority of the silicon in barley can be found in the husk, which wasn’t affected much by the malting process. Samples of hops showed surprisingly high levels of silicon with as much as four times more silicon than is found in malt. However, hops are normally used in a much smaller quantities than barley. But if you want to optimise silicon intake you should go for beers produced using a higher hops content since the final beer proved to contain higher silicon levels. Testing of commercial beers showed that the silicon content in the final product could vary between 6.4 to 56.5 mg per litre, close to a ten times difference.

Based on these findings, some studies suggest moderate beer consumption may help fight osteoporosis, a disease of the skeletal system characterised by low bone mass and deterioration of bone tissue. It has also been shown that men have a higher silicon intake than women, mainly due to a higher beer consumption contributing to 45% of their total silicon intake. Good news for beer drinkers you might think.

All is not lost if you don’t drink beer

The high silicon levels in bananas is not bioavailable (Photo: robin_24)

The silicon in bananas is unfortunately not bioavailable (Photo: robin_24)

But what about if you don’t drink beer? Not to worry. It has been shown that the silicon in solid foods can be hydrolysed to bioavailable orthosilicic acid in the gastrointestinal tract. A study of different food sources found that silicon in grains and grain products (rice, breakfast cereals, breads, and pasta) was readily absorbed. However, except for green beans and raisins, the silicon in vegetables and fruit was less readily absorbed. Surprisingly, silicon absorption was low from bananas, which are high in silicon and could have replaced beer as the number one source.

Before you get concerned about your silicon intake, it should be clear that silicon deficiency has not been observed in humans. Such a fact doesn’t discourage food supplement manufacturers. There are a range of silicon supplements on the market with claims like:

  • improving cell metabolism and stimulating cell formation;
  • inhibiting the ageing process by supplementing tissue silica that rapidly decreases with age;
  • strengthen weak connective tissue by improving its structure and function;
  • increasing the elasticity and firmness of blood vessels, making them less likely to develop atherosclerosis;
  • enhancing the appearance of hair and nails as well as skin.

Such food supplements might not do much damage since toxicity of silicon is very low. However, it will be a waste of your money since the normal diet should provide sufficient silicon anyway. Your call, but a glass of beer now and then might be cheaper.

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Uproar in margarine industry

The margarine industry is upset (Photo: BMK, Germany)

The margarine industry is upset (Photo: BMK, Germany)

The margarine industry is up in arms and blaming everyone else. This is due to the report published by the European Food Safety Authority (EFSA) pinpointing margarine as the highest contributor to 3-MCPD exposure and reviewed here in a previous blog. This process contaminant as you might recall is particularly toxic to the kidney. What is making the situation problematic is that according to EFSA’s calculations some sections of the European population exceed the safe limit for this possible carcinogen. These include children, toddlers, the elderly and the very elderly, so a broad spectrum of the population. Margarine and similar products accounted for up to 70% of exposure to 3-MCPD in several population groups.

Now we hear that representatives for the margarine industry point the finger at the oil refining industry. They state that 3-MCPD is formed during the refining of oils and not during margarine production. This might of course be right but you would expect the manufacturers of margarine to take responsibility for the product they sell. The findings of 3-MCPD esters in margarine should not have caught manufacturers unaware since you expect vigilance in relation to the presence of toxic chemicals in their own product and raw material inputs. There is no real surprise that 3-MCPD can be found in refined oils since it is known that it can be formed when heating fat-based and fat containing foods.

The margarine industry further try to shift blame to other parts of the food industry claiming that 3-MCPD esters occur in all food products containing refined vegetable oils and fats such as confectionary, cakes, biscuits, soups, ready meals and also margarines. There are some mitigating factors in that levels of 3-MCPD esters can only be determined accurately in vegetable oils and fats, while there are no validated methods yet to analyse the levels in final food products. EFSA thus recommends that standard analytical methods should be further developed and established to analyse 3-MCPD in different foods. So there might still be surprises to come.

In the meantime it might be safer to use butter for your sandwich or why not a few drops of cold-pressed olive oil to better comply with a healthy Mediterranean diet.

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