Life is a gas, and it's healthy

Borborygmi. One of my favourite words. Borborygmi are the gurgling sounds of gas travelling along your intestines. The rumble can be most pronounced during a conversation lull at the dinner table. Hark, I hear borborygmi.

Gas inside your digestive system is normal. It comes from two main sources: 1) the air you swallow during eating or drinking; and 2) gas produced by bacterial fermentation in the large bowel, the back end of your digestive system. Smaller amounts come from CO2 production when your stomach acid is neutralised in the small intestine.

Air swallowing

One obvious way of swallowing air is through aerated drinks such as soft drink, champagne and beer. This usually comes back into the atmosphere via eructation (burping to you). Air can also be swallowed during eating, more commonly in those that eat quickly or talk a lot during the meal. If it isn’t burped out then it will pass from your stomach and into the small intestine.

Bacteria gas

Once the contents of your small intestine pass the appendix and into the large intestine, the resident bacteria feast on the fibre and small amounts of starch and protein that doesn’t get digested. When bacteria feed they produce gas. In fact, 75% of flatus is bacterial gas. As the contents move along the large intestine (aka colon) water is absorbed so the waste becomes more solid and the gas becomes entrapped in large bubbles.

Some bacterial gas is absorbed back into the blood and exhaled. This is the basis of a breath hydrogen test. If you have, say, suspected lactose intolerance your breath is tested for its hydrogen content because if lactose has reached the colon the bacteria will consume the lactose and generate far more hydrogen than normal.

Aroma

Most of flatus is oxygen, nitrogen (the two main components of air), hydrogen, methane and carbon dioxide. Some sulphur containing gases provide the head-jolting aroma. You want to know: why baked beans? The legume family have plenty of fibre and two types of carbohydrate that don’t get digested well – stachyose and raffinose – which then become bacteria food with the end product being gas.

Here’s the physics of what happens to gas down the back end. The abdominal muscles and the anal sphincter contract at the same time, thereby raising the pressure of the gas against the anal sphincter and then, at the magic moment, the pressure gradient sends out the air at high speed through a very narrow slit too small for solid waste to escape. Hopefully. The high speed gas causes the edges of the anus to vibrate. Maybe fart should be pronounced with a distinctive rolled “r”.

What does it all mean?

Gas is normal. You can reduce the amount of swallowed air by avoiding fizzy drinks and eating slower. Colonic gas is from bacteria eating undigested food ie fibre, which is exactly what the health authorities want you to eat. As one author said: “Flatulence rich in bacterial gases might be the price for the large bowel water reabsorption. It seems that little can be done to reduce flatulence.”

So if you eat plenty of fibre-containing food, you will release more methane into the air, vis-à-vis, don’t think you can solely blame global warming on the cows.

References:

Medical Hypotheses 2006; 67: 235-239

American Journal of Gastroenterology 2007; 102: 842-849

Public gas in Malawi

On the 5^th February 2011 it was reported that public farting will become an offence in the southern African country of Malawi.

“The government has a right to ensure public decency”, said George Chaponda the justice and constitutional affairs minister. “Would you like to see people farting in public anywhere? It was not there during the time of dictatorship because people were afraid of the consequences. Now because of freedom people would like to fart anywhere.”

It’s at this moment you look at the calendar. Nope, 1^st of April nearly two months away. A lost Monty Python skit? Teenage pranksters hacked into Reuters?

Apparently it is a true story (http://www.abc.net.au/news/stories/2011/02/05/3130657.htm) and this fuss is about an amendment to a current law on public farting passed in 1929. This old law says: “Any person who voluntary vitiates the atmosphere in any place as to make it noxious to health of persons in general dwelling or carrying a business in the neighbourhood or passing along a public way, shall be guilty of a misdemeanour.” (vitiate = spoil or impair the quality)

My prediction is that dog ownership will increase in Malawi (you know the rest of the story). And next time your workmate vitiates the atmosphere, remember that it is the aroma of freedom, according to George.

Cuppa tea

I’m a big fan of black tea due to my English heritage, where you weren’t supposed to leave the breakfast table if there was still tea in the pot. For one of my badges in Cubs I had to prove at the age of seven that I could brew the perfect cup of tea: pre-warm the pot, add x teaspoons of leaves (x = one teaspoon per person + one for the pot), add boiling water, stir, leave to brew for five minutes, pour into cup through tea strainer. Haven’t lost the art.

Why does tea contain caffeine?

It is quite natural for you to assume the caffeine in tea is there just to give you a lift. The tea bush in China was producing caffeine long before humans came by. Its caffeine is to dissuade bugs from nibbling on the leaves. You are drinking a form of pesticide! Don’t worry, all plant foods produce compounds to try and keep the bugs at bay. Some produce compounds to keep humans at bay. For example, chokoes, which are sometimes passed off as edible.

Making your tea leaf

There are different ways to prepare the tea leaf. For black tea, leaves are macerated, allowing the enzyme phenolase within leaf cells to mix with polyphenolic compounds, and left for a few hours to ferment. The leaves are then heated to halt the action of phenolase (enzymes, being proteins, are denatured by heat). Voila! You have black tea, a favourite in the UK, NZ and Australia.

Green tea, an Asian favourite, and white tea (from the youngest bud and two top leaves) are heated before any fermentation occurs. Oolong tea is fermented for only 30 minutes before being heated. All four teas come from the same plant, Camellia sinensis. All four teas have flavonoids, those antioxidant compounds that have created an excited stir in the science world for the last 20 years.

The type and amount of flavonoid polyphenols in tea differ depending on the type of tea and area it is grown. Right now it is impossible to suggest that one type flavonoid had an advantage over another; they probably have multiple positive actions. Thearubigins are the main pigments in black tea. They contribute most of the colour, as well as the astringency and “body”, of the tea.

Caffeine

All four teas also contain caffeine. Love to have a nice bottle of Grange Hermitage for every time someone said to me that they take green tea because they are avoiding caffeine. The caffeine levels of each tea are similar at the leaf level, with white tea being the lowest, around 15mg per brew, because it is usually steeped for a short period. Green tea has around 40mg/cup after three minutes brewing, while a strong cup of black tea may have 60mg of caffeine.

How much caffeine will be present in your cuppa will depend on how long you brew the tea, type of tea, how much tea you brew and possibly even the region the tea was grown (Assam in north east India had the highest leaf level of caffeine in one study).

What does it all mean?

For a long time both tea and coffee unfairly had a bad name, mainly due to their caffeine content. Herbal teas were seen as a “healthy” substitute because they don’t contain caffeine. The consensus is that 300-500 mg of caffeine a day is no threat to healthy adults, although for some even 150 mg of caffeine can disrupt sleep.

Tea is the second most widely consumed drink in the world. No, Coke is not the first, it’s water. Being so popular, tea has attracted a lot of research, some of it showing that tea drinkers have less risk of heart disease, Parkinson’s Disease, type 2 diabetes and even have stronger bones. It is way too early to say that every cuppa will definitely help you to avoid disease, but the comforting thing to me is that nothing suggests that having a few cuppas a day is a problem.

You want to hear a number don’t you? OK, there is broad agreement that up to five cups a day is healthy. Just do what I do – choose big cups.

Reference: Coultate T. Food: The Chemistry of its Components, RSC Publishing 2009

Eating lessons in Kenya

Recently I popped over to Kenya to be PA for my wife, Toni, who was there as part of a Curtin University delegation. While she worked, I asked Fredie (sic) to show me the real Kenya, not the tourist stuff. We called into a roadside restaurant for nyama chomu, which is salted roast meat, in this case goat. With that we had fried potato balls with tomato sauce, mashed potato with peas and corn and a drink (see photo). They had run out of ugali, a solid corn flour dough, thankfully. I would have been the first mzungu to have been in there for weeks, maybe years, yet it was very relaxing being African.

“So where are the knives and forks Fredie?”

“Use hands.” Stupid mzungu.

“Which hand Fredie?”

“Either. And not like that, grab a handful.”

After eating a modest amount of food, having that constant visitor fear of whether I might regret this meal during the night, I expressed to Fredie that I was done.

“You have to finish the meat. You don’t leave meat in Africa.”

Sawa, sawa. So much to learn.

And I was the only one of the delegation to have polite guts for the fortnight.

Jet lag

With certainty, human beings never travelled much more than 10 km in a day throughout human evolution. Even 30 years ago, you could easily find adults who had never been in a plane in their life. Now, I have children in their early 20s who have been to more countries than I have.

In 1966 I was booted out of London and sent off to live in Adelaide, South Australia. The flight was London, Frankfurt, Athens, Cairo, Karachi, Singapore, Sydney, Melbourne, Adelaide. That’s eight legs for a flight that has two legs now and only one in 2020. I don’t recall getting jet lag, probably because the trip took so long (you disembarked and pfaffed around at each airport; no shopping malls).

Circadian disrhythmia

Travelling across time zones now is rapid and will upset your circadian rhythm (from circa diem, Latin for “about 24 hours”). More than 300 bodily functions occur with a 24 hour rhythm. These functions normally have “high” and “low' points during the 24 hour period, corresponding to a sleep-wake cycle. For example, body temperature, (which peaks at around 6 pm), heart rate, (which is higher in the afternoon), and the stomach, (which empties a little more quickly in the morning than in the evening) all have a circadian rhythm.

Adjusting body clock

When travelling across time zones, some people adjust their body clocks to their destination time in the two or three days before departure. On arrival they can quickly adopt local times for eating and sleeping. This can be very effective when crossing 1-4 time zones. For example, if you are travelling east, gradually get up earlier each morning so that you are 1-2 hours “closer” to your destination time zone.

Getting sunlight early in the morning also helps this transition. Do the reverse if you are travelling west. Adjust to getting up later before you leave and expose yourself to bright sunlight in the evening if possible so that your body feels like it is closer to your destination time zone.

Anything you can do food-wise?

Yes, but it is going to sound a bit obvious. Some folk pre-order a vegetarian or low-fat dish, not because they are necessarily vego or weight conscious, it’s just that the “special meals” are often better quality. Besides, fatty meals can make you feel a bit gluggy. It’s not as if you can go for a long walk afterwards to feel more normal.

The humidity in aircraft is around 10-15%, which means that moisture is lost from your body a bit quicker than normal, estimated at an extra 20-25 mL per hour. I have read that new aircraft will have a higher humidity because anecdotal feedback has been that people experience less jet lag at a more normal humidity of 25-30%. Anyway, this is the reason you are told to “keep up your fluids” when flying. That includes tea and coffee (caffeine does not cause excessive fluid loss), water and juice.

It doesn’t include alcohol. I don’t drink alcohol on flights for two reasons: 1) it is dehydrating; and 2) my wine tastes dreadful in a dry atmosphere from a plastic cup (yeah, I know, you travel business class and get a very nice red in a glass, so it doesn’t apply). One advantage of having a beer or wine with your airline meal is that alcohol reduces platelet aggregability so blood is less sticky and you have less chance of deep vein thrombosis.

What does it all mean?

Most people jump on a plane, cross a few time zones, then cruise straight into local time. That’s probably the best you can do when crossing four or more time zones and on holidays. With three or less time zones, I like to pre-adjust my body clock in the preceding days at one hour a day, especially for easterly travel. When you arrive, immediately adopt the local time, try not to nap during the day to catch up sleep, and sleep in a cool bedroom. It can be helpful to go for a walk three hours or so before bedtime for a more restful sleep. Despite all the theories, the best cure for jet lag is still time. I think that being fit and eating sensibly helps.

Final tip – get to the airport early. The last thing you want to get is a middle seat. Sorry. Forgot. You travel business class.

Reference: Journal of Sports Sciences 2007; 25 (S1): S125-S134

Vitamin C

Vitamin C became famous the moment that Linus Pauling (pictured), a US professor of chemistry, said he thought that vitamin C could reduce the risk of the common cold. By this time, in the early 1970s, he had already pocketed two Nobel Prizes in chemistry and peace. He could have got a third when he was working hard to determine the structure of DNA before Watson and Crick beat him to it. So, Pauling was a bloke to whom you should lend an ear.

Early reports promising

Although vitamin C (ascorbic acid) wasn’t first isolated, or “discovered”, until 1928, for many years we knew of a vague compound that stopped you from getting scurvy. Only 10 mg a day will keep scurvy away, yet there has been long conjecture that a whole lot more than 10 mg was needed each day to be healthy. Not that long ago we found that people with high levels of vitamin C in their blood had a lower risk of heart disease and early death. Unfortunately, when we started giving people vitamin C supplements the results were less exciting.

You’ve heard me say this a few times - just because there is an association, we should never assume we are seeing cause and effect. High blood vitamin C is probably a “marker” of a lifestyle that includes plenty of fruit and vegetables, and of course, if you eat your veggies then there is a reasonable chance you don’t smoke or drink gallons of alcohol, and probably walk the dog too. Less heart disease was more likely due to good living than being able to pin it on a single vitamin like ascorbic acid.

Vitamin C alone not that useful

There is also a good chance that any one vitamin can’t do a lot on its own to prevent disease and needs a whole range of other nutrients and antioxidants alongside it before a benefit kicks in.

In a new review of vitamin C, published in the British Journal of Nutrition, it states that: “It should be acknowledged that in the epidemiological studies on the relationship between vitamin C concentrations and diseases there is no evidence that the relationship is due to vitamin C itself.”

Although it has long been trendy to pop 500 mg tablets of vitamin C, there is a limit to how much vitamin C our body can store. Once we have over 200 mg a day our body becomes “saturated” with vitamin C and any over this amount ends up in the loo.

And the common cold?

The Cochrane Database [http://www.ncbi.nlm.nih.gov/pubmed/17636648 Systematic Review] in 2007 said: “The failure of vitamin C supplementation to reduce the incidence of colds in the normal population indicates that routine mega-dose prophylaxis is not rationally justified for community use.”

And when the most powerful database in the universe says that, you better take notice. Hey, Linus was a legend and even legends are allowed to speculate and not get it right sometimes. Remember, his first crack at the DNA structure was wrong too. A brilliant human, but still a human.

What does it all mean?

The daily vitamin C recommendations in Australia and New Zealand are 45 mg; 75-90 mg in the US; and 40 mg in the UK. If you can eat an orange (70mg), a small salad (100 mg), a serve of broccoli (30mg if you don’t boil it to a fraction from mush), or a banana (12 mg) you can see that it is pretty easy to meet your C needs with normal good eating. If you have a very low vitamin C status (more likely in smokers) then you might benefit from a supplement (100 mg, not 500 mg or 1000 mg), but as I, and many others in the nutrition game, will tell you, a vitamin supplement ain’t no substitute for getting decent feed into you.

Reference: British Journal of Nutrition 2010; 103: 1251-1259

Vitamin D

Just like there are trends in TV, fashion and music, there are trends in nutrition. If you have been around for a while then you would have seen a few – fat, fibre, calcium, vitamin C, antioxidants, organic, and the favourite of the last five years has been vitamin D. Getting insufficient vitamin D (primarily through too little sun exposure) has been linked to an increase in an ever-expanding list of medical problems such as heart disease, types 1 and 2 diabetes, multiple sclerosis, depression, colon cancer as well as the well-known problem of osteoporosis (brittle bones).

Institute of Medicine report

Three weeks ago the Institute of Medicine released a new report [http://www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D.aspx] on both calcium and vitamin D. The report re-affirmed that too little vitamin D, along with too little calcium, caused osteoporosis.

The report did increase the recommended daily amounts of vitamin D to Americans and Canadians (previously they were the same levels as Australia) and that increase met with support from academics. However, the report was less enthusiastic about the link with lower levels of vitamin D and common medical problems.

How much vitamin D?

Theoretically you can get all your vitamin D through sun exposure, but many are reluctant to do that for fear of skin cancer. Yet, you don’t need much sun exposure – about 5-8 minutes during the middle of the day (approx 10am – 3pm) in summer, and about 30 minutes in winter for light-skinned people living in temperate zones. In other words, not enough sun to burn, or even get red. Otherwise, you need to get from your diet:

19-50 year olds: 5 mcg (200 IU) in Australia/NZ; 15 mcg (600 IU) in US/Canada; it is assumed you will get adequate sunlight in the UK (insert own gag here).

51-70 year olds: 10 mcg (400 IU) in Australia/NZ; 15 mcg (600 IU) in US/Canada; 10 mcg (400 IU) in the UK

71+ year olds: 15 mcg (600 IU) in Australia/NZ; 20 mcg (800 IU) in US/Canada; 10 mcg (400 IU) in the UK

mcg = microgram;

IU = International Units;

1 mcg = 40 IU

Now, the problem here is that it is virtually impossible to get all your vitamin D needs through healthy eating. Our main sources of vitamin D are margarine (1 mcg in 2 teaspoons), oily fish (about 1-3 mcg per 100g), egg yolk (0.5 mcg per egg) and hard cheese (0.3 mcg in 30g). Some milks are fortified with vitamin D (eg Anlene). You can see you will need to scoff quite a bit of salmon, eggs and margarine to get your D needs. (In the US and Canada there are light-exposed mushrooms that provide 15 mcg/600 IU or more in a single serve. I am working with the mushroom industry in Australia to get high vitamin D mushrooms on the market in 2011).

Blood test

One of the most common blood tests requested is for vitamin D, because so many people appear to be low. How low is low? Mmmm. Tricky question. Last century we thought that a blood level of 25 nmol/L (10 ng/mL) was fine because that seemed to stop rickets and osteoporosis. Now experts like Professor Rebecca Mason from Sydney University say that 50 nmol/L (20 ng/mL) is a better goal for overall health. My pathology test form came back stating that a “healthy” level was 75-120 nmol/L (30-48 ng/mL). There is no universal agreement for the ideal blood levels of vitamin D.

What does it all mean?

Those who get very little sunlight, have dark skin, shield their body from sunlight, are in long term care, or are elderly are likely to have low levels of vitamin D. As diet very probably won’t make up the difference in vitamin D, then daily vitamin D supplements of 25-50 mcg (1000-2000 IU) will need to be taken. Get your blood level tested. If it is clearly at the lower level, get some judicious sunlight, eat wisely, and depending upon where you live, track down some vitamin D mushrooms.