Tuesday, March 18, 2014

Entomophagy - dining on insects

Entomophagy is the practice of eating insects as a food source. Over 1000 species of insects are eaten around the world by traditional human societies in Africa, the Americas and Australasia. The Food and Agricultural Organisation estimated that two billion of the world’s population regularly dine on insects.

When we hear the expression hunter-gatherer we immediately think of meat, seafood, vegetables, fruits, berries, seeds and nuts. Add insects to that list. Insects are comparable to animal foods in their nutritional value. There are 14,000 year-old paintings on cave walls in Spain illustrating honey gathering and termite collection.
  
Big Five
You might head to Kenya or South Africa to see the big five. The insect world has a Big Five too, but these all played a role in our survival. The Big Five that we and other primates have enjoyed through evolution are:
1. Coleoptera (beetles)
2. Hymenoptera (ants, bees, wasps – include honey)
3. Isoptera (termites)
4. Lepidoptera (butterflies, moths – think also caterpillars)
5. Orthoptera (locusts, crickets)

Although we have eaten flies and aphids, the Big Five are usually easier to catch or appear periodically in vast numbers, such as moths, caterpillars and locusts. A good Australian example is the Bogong moth, popular with traditional Aboriginals of southern east coast. Many bees do sting, but the honey pot pay-off has made it worthwhile for both humans and chimpanzees.

Crickets tickle when they go down the throat
I know, because I enjoyed them at a cricket farm in Hoi An, in central Vietnam, recently (see pic). The crickets were raised by a three-war veteran and his son. His daughter individually de-gutted the crickets, taking them up to premium quality. Fried in oil and garlic they made a crunchy and tasty snack. You just have to first skip through that psychological checkpoint many of us have.

Entomophagy tends to include non-insects like arachnids (eg tarantulas) and myriapods (eg centipedes). Yeah, I know, I think it would take more than a psychological warm-up to send them down my gullet.

Delicious and nutritious
Insects have been analysed for their nutrient content. On average, cockroaches are 57% protein and 30% fat based on a dry weight, a similar protein and fat content to other insects such as flies (50% protein; 23% fat), ants (47%; 25%), caterpillars (45%; 28%) and crickets (61%; 13%), according to a review of 236 edible insects (Rumpold 2013).

Their protein provides all the essential amino acids needed for humans, while the fat is, in very general terms, one third saturated fats, and two thirds a mix of monounsaturated and polyunsaturated fatty acids. A decent meal of insects could give you 2100 kJs/500 Cals, which is pretty good as a food source when living off the land.

Insects are about 10% fibre, mainly in the form of chitin, suspected to help control blood cholesterol. Chitin gives insects their “crunchiness” – that’s their exoskeleton. They are also an excellent source of essential minerals like iron and zinc, along with B vitamins.

What does it all mean?
As westernised humans overcome their food prejudices and continue to explore new foods and food trends there is a good chance that you will have the opportunity to nibble on insects. Enjoy the experience. In tough times there is no doubt that many people around the globe will be relying on insect nutrition because this food source reproduces rapidly, efficiently converts feed to growth, take little space and aren’t fussy eaters.

Technically insects belong in the animal kingdom, so I wonder if insects will be popular with vegetarians?

If this topic fascinates you, and you have a spare 16 minutes, watch Marcel Dicke explain [http://www.ted.com/talks/marcel_dicke_why_not_eat_insects insects in our diet.] He claims that you are already eating 500 grams (18 oz) of insects ‘by accident’ every year. Love his T-shirt. And the chocolatier at the end.

References:
1. Rumpold BA, Schl├╝ter OK. Nutritional composition and safety aspects of edible insects. Molecular Nutrition & Food Research 2013; 57: 802-823

2. McGrew WC. The ‘other faunivory’ revisited: Insectivory in human and non-human primates and the evolution of human diet. Journal of Human Evolution 2014


3. FAO Nutritional Value of Insects for Human Consumption. This excellent, easy to read, review is here. Read this and you will have a new appreciation for insects as food (and the photos are great too).

Wednesday, February 19, 2014

Juicing

You are not serious about your health until you juice combinations of fruits and vegetables, according to those that pray at the Church of Blended Plants. You exchange recipes online and discuss the best juicers and blenders on the market and tell the world of nature’s wonders. But will juicing elevate your health beyond the capabilities of the original ingredients?

Juicing is a relatively new concept, with the popularity growing over the last 30 years. The great thing is that you can develop your own creative formulas and in an instant you have a tasty and nutritious drink that you can down in seconds before you go to work, or sip while you check emails.
  
Don’t forget the pulp
Well-known Australian Food Coach Judy Davie has her  favourite juice. She says it is perfect for keeping her “regular”, even if she doesn’t include the pulp. Well, she probably eats lots of other fibre foods too.

Now, one criticism about juicing is that the fibrous pulp is often discarded and plant fibre is excellent for your insides. Judy reserves the pulp for using in muffins. Smart idea. Those healthy bacteria in your intestines get particularly upset if you don’t include their favourite food (they eat the fibre to produce protective compounds and nutrients in your large intestine).

Enzyme hoax
Some people will tell you that juices contain enzymes, or even “live” enzymes (do they socialise and swap orchard stories?). As an enzyme is a protein and all consumed proteins encounter protease enzymes in the small intestine, it makes no difference if they are alive or semi-conscious because they are all going to be chopped up into small chains of amino acids. It may sound like a horrible death, but that is the cruelty of nature I’m afraid. Enzymes are proteins. We eat them. They die. Then their amino acids get made into human proteins we can use and bingo!, they’ve become useful to us.

Another favourite line is that juices “detox” the body. Nope, and that’s a definite. What detoxifies your body are the lungs, liver and kidneys and they work around the clock doing a fabulous job for eight or ten decades, with luck, providing you give them good care. Detox anythings are a scam. Eating well is normal, leaving your body to do its own detoxification and “cleansing”.

Drinking vs chewing
Enjoy your homemade juice but don’t make that the only way you get two fruits and five veggies inside you. One clear benefit from eating fruit and veg the traditional way (ie chewing) is that it takes longer than drinking. Chewing food takes time, and taking time over food means that you are better able to control your appetite and less likely to overeat.

Commercial juices from the supermarket are likely to be devoid of fibre, possibly be more dilute than comes out of your juicer, and won’t contain the love and flavour of your homemade version. Fruit juices are generally 12% sugar (12g per 100mL), which is the same as a regular soft drink, so it becomes a very easy way to drink quite a few Calories as juice. Knocking back 300mL (10oz) of juice will give you 145 Cals/600 kJs, about the same as eating three medium apples. The juice won’t make much of dent in your appetite, eating three apples will.

What does it all mean?
Juices and juicing can be a neat way to get nutrients from fruit and vegetables, especially if you are in a hurry. Juicing can also be a refreshing drink that you are confident is “good for you”. Try and include the whole food where possible to avoid peeling. For example, the  peel of an apple has 60-100% of its antioxidant flavonols.

Just don’t rely on juicing to get all your fruits and vegetables, and don’t think you have moved up to a higher plane, because all those non-juicers who just chew their plant food will be equally wholesome and well.

Should you wash mushrooms ?

 I have often read that you should never wash a mushroom because it quickly absorbs water and you get squishy mushrooms. Yet there are plenty of voices out there saying that you can wash a mushroom. I write a lot as a consultant to the Australian mushroom industry, so I needed to find the “truth”.

My kitchen became a laboratory. I plonked 150g (5 oz) of whole button mushrooms in cold water and waited 5 minutes. With another lot I waited 10 minutes. After being submerged in water for the designated time I drained off the water and dried the mushrooms with a clean tea towel. Then I re-weighed the mushrooms. After 5 minutes in water there was a gain of 4 grams (2.6% gain) and 6 grams after 10 minutes (4% gain).

Now, I imagine if you did wash your mushrooms to clean off any residual ‘dirt’ you can do it in less than 5 minutes with 0% gain. The mushrooms were then cooked and their brief swim didn’t affect the eating quality.

Then, I read that Robert Wolke, Professor of Chemistry at the University of Pittsburgh had done the very same experiment about a decade ago and found a 2.7% weight gain after soaking mushrooms for 5 minutes. How’s that for brilliant, reproducible kitchen science?

I should warn you that I did the very same experiment with sliced mushrooms. Oh dear! They gained 27% of their weight in water within 5 minutes. Still edible after cooking, but not so good. Why the difference? The sliced mushroom have their inside flesh exposed and this is the part that absorbs water quickly. The “skin” of the whole mushroom is essentially impervious to water as you would expect from a food designed to grow in rain, fog and dew. In fact, the extra weight gained with the whole mushroom might be because I didn’t dry off all the external water.

Of course, you could just brush any visible dirt from a mushroom. I wasn’t suggesting that you need to wash them. Anyway, now you know the truth too. You can give your mushrooms a quick rinse before cooking. Trust us. Quote us. Robert and I are scientists.

Reference:
Wolke RL. What Einstein Told His Cook. WW Norton & Co. 2002 (p268)

Tuesday, January 14, 2014

Multivitamin supplements

Give a talk on any aspect of nutrition and there is a good chance that you will be asked “Should I take a vitamin supplement?” A realistic answer would be: “If you are here at a presentation on nutrition, then there is a good chance that you eat well and are least likely to need any supplement.” But that’s not what people want to hear, because a supplement is seen as taking control of your own health.

Literature review
A review of all the literature published from 2005-2012 on vitamin and mineral supplements has looked at their ability to influence heart disease and cancer, either of which conditions are likely to be on your death certificate if you live a long and fruitful life, remembering that you can’t die of birthdays, wisdom and experience (formerly known as old age). They looked at virtually all the vitamins, along with the minerals calcium, iron, magnesium and selenium.
  
No effect on heart disease
Multivitamins don’t appear to have any effect on the risk of heart disease, although there might be a slightly lower risk of cancer but that was a borderline result. However, there was no overall effect on mortality from all causes over the period of each study. Even when looking at combinations of nutrients the results were very inconsistent. One selenium study showed a lower risk of cancer while another didn’t, and as there were only two good studies on selenium, which result do you want to believe?

Beta-carotene kills smokers quicker
Six trials on beta-carotene showed no effect on the risk of heart disease or cancer, unless you are a smoker or asbestos worker, then beta-carotene supplements increase your risk of lung cancer. This result has received lots of attention in the past as it appears that beta-carotene accelerates the proliferation of existing lung cancer cells.

What might be better than a multivitamin?
This is not the first review that has concluded that there is no consistent evidence that vitamin and mineral supplements do not lower the risk of cancer or heart disease, nor reduces the risk of early death. It follows at least 10 others, including some on antioxidant supplements, with the same conclusion. Thankfully, there was no evidence of harm either.

The authors state that one reason for the disappointing effect of multivitamins might be that: “physiologic systems affected by vitamins and other antioxidant supplements are so complex that the effects of supplementing with only 1 or 2 components is generally ineffective or actually does harm.”

My biased take on this is that there may be a lot more than vitamins and minerals helping to reduce disease risk, like the many thousands of other bioactive compounds found in food, so eat good quality food. Well, someone had to say it.

Of course supplements do have their place, such as folate taken before and during pregnancy to lower the risk of having a child with spinal deformities.

What does it all mean?
These studies were done in people who were otherwise well, in other words they may not have got the kind of benefit from a supplement as someone who was sick, ate poorly or sleeping under a bridge each night. So, the studies didn’t include people who were nutrient deficient (eg iron deficiency anaemia) who would clearly benefit from a suitable supplement.

Virtually all the studies were run over 10 years or less, and very few included women. As you know, studying humans is expensive so we rarely see studies over 3-4 decades. Maybe there is a long-term benefit for taking supplements over half a century, who knows?

Whether you should take a multivitamin supplement or not is your choice. Just don’t expect too much from them, certainly not the benefits you will get from eating well, being fit, hugging the kids, donating to charity, reading a good book and (insert your favourite safe, inexpensive, endorphin-liberating and legal past-time here).


Reference:

Fortmann SP et al. Annals of Internal Medicine 2013; 159 (12): 824-834

Monday, December 9, 2013

The "discovery" of vitamin A

It is easy to think that one person discovered a vitamin on a Thursday just before lunch. It makes history so much easier to re-tell. In the case of vitamin A, the process of discovery spanned 130 years, starting in 1816 when a French physiologist Francois Magendie fed dogs a poor diet and found they died in a similar fashion as malnourished infants, and ending with its manufacture in 1946.

Milk gave the clue
Through a series of experiments in the late 19th century it was clear that milk contained something that was important to life. Giving animals the separate components of milk – lactose, protein, fat and salts – could not sustain life, yet whole milk could.

This was the time when the dogma dictated that life needed only protein, fats and carbohydrates, and some minerals like iron, so finding there was more to nutrition and life was surprising. What was this mystical component in milk?
  
Dietetic factors
Biochemist Frederick Hopkins in 1906 proposed that there were “unsuspected dietetic factors” in food that accounted for conditions such as scurvy and rickets. We now know they were caused by a lack of vitamins C and D respectively.

At this time it was also assumed that all fats were the same, yet different fats had a different ability to support life. If animals were given the fat extracted from eggs or milk, or simply as butter, they lived but if the fat came only from lard or olive oil they died. The fat-soluble substance in butter and egg yolk actually contained vitamins A, D and E, all of which were yet to be identified.

Then things began to fall into place and clever people started finding a range of vitamins. Hopkins was awarded the Nobel prize in 1929 (along with Christiaan Eijkman) for “the discovery of the vitamins”, and in his acceptance speech he acknowledged the work of those who went before.

Scientists behaving badly
Then the bunfight began. Elmer McCollum from the University of Wisconsin claimed that he had discovered vitamin A in 1913 because he had worked out it was a fat-soluble compound, despite others having determined that fact in the preceding 20 years.

McCollum would continue to claim that he was the one to find vitamin A, yet was unable to get any backers. He attacked rivals, sabotaged research, stole colleagues research notebooks, so it was no surprise that he wasn’t nominated for a Nobel Prize.

It took until 1937 before we knew the structure of vitamin A and until 1946 before it was first manufactured, completing the process of discovery.

Vitamin A not the first vitamin
You would assume that vitamin A was the first vitamin found, then isolated in a laboratory and declared to the world. Not so. That was vitamin B, now known as vitamin B1 or thiamine, first isolated in 1912 by Casimir Funk who said that thiamine was a “vital amine” and coined the term “vitamine”. Now both vitamine and thiamine have lost that last “e”. As long time readers will know, Popeye consumed spinach for its vitamin A content, not for its iron. Well, for the beta-carotene content really, but back in 1932 we didn’t know that beta-carotene became vitamin A in the body.

During the second half of the 20th century, vitamins were given almost god-like status, with most of the claims and beliefs being disproven. We were swallowing mountains of vitamin C in the hope it stopped the common cold (it didn’t), and we hoped a multivitamin would reduce stress and perk us up (not that easy, sorry). OK, the B vitamin folate as a supplement for expectant Mums can help reduce the risk of spinal deformities in the foetus, so it wasn’t all bad news.

What does it all mean?
The science of vitamins is a very young science and there is much more to discover. Although small amounts of vitamins are needed to avoid disease, we are not clear on the amount needed to prolong life or prevent a disease. One genuine concern is that although vitamins are considered “natural” we love to take them in amounts not found in nature. Could years of taking vitamin supplements become a health problem in the future? There is some evidence that says “Yes” and other evidence that says “No problem”.


Reference:

Semba RD. On the ‘discovery’ of vitamin A. Annals of Nutrition & Metabolism 2012; 61: 192-198