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”.


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

Is Coke responsible for Santa wearing red?

Yes, if you read the convincing argument by Mark Pendergrast in his book For God, Country & Coca-Cola (Phoenix 1994, p181). In an effort to sell more Coke in the colder months around Christmas in the northern winter, artist Haddon Sundblom created the classic Santa in the winter of 1931. Previously Santa dressed in blue, yellow or green and was often portrayed as tall and lean. After Sundblom had drawn him as part of the Coca Cola adverts he was forever portly, red, jolly and booted and appeared in promotions every subsequent Christmas to be “repositioned” as red.

As 1931 is before many of us can remember, we happily accept as plausible a story that fits our view of the world. As with many myths, they evolve over time and we actually can’t pinpoint a set moment when Santa became red, jolly, booted and larger than life. According to a [ very good article] at myth-busting central, aka, the classic Santa was around well before Sundblom got his crayons out. Even Coca Cola agree that Santa was red before they dressed him up. As you know, we humans much prefer a simple fib than an ephemeral truth.

Sunday, November 17, 2013


OK, are you up for some biochemistry? Simple biochemistry, I mean. It will help explain why vegetables are good for your blood pressure and why beetroot juice has become the new sports performance darling. The magic of nitrates in your diet seem to be part of the solution, working beyond the benefits of just being fit and training hard if you are an athlete.

Nitrates – the new training tool
It is only been in the last five years or so that nitrates have gained recognition as compounds that benefit our physiology. A series of studies have now shown that one very good source of nitrates, beetroot juice, has dramatically reduced times in running trials. One study showed a 30 second improvement in time over 5km in fit female runners, and you can’t complain about that. Another study in men revealed that less oxygen was required to exercise at a set level and they could cycle 12-14% longer before exhaustion.

However, it seems that you need to take beetroot juice for six days rather than expect a result from just a single dose. It has even improved exercise capability in people with peripheral artery disease (poor blood flow to the extremities of the body).

Beyond exercise performance, nitrates also help keep blood pressure down and arteries healthy, as we shall see.

How does nitrate work?
Let me take you on a weird journey. Let’s say you eat nitrate-containing foods. They go through the stomach and into the small intestine where the nitrate is absorbed into the blood. The nitrate then circulates and becomes concentrated in the saliva which is released into the mouth. Now oral bacteria convert the nitrate (NO3) in your saliva to nitrite (NO2). These bacteria are not the ones that cause tooth decay. Then you swallow the saliva. In the stomach the nitrites are converted to nitric oxide, the wonder molecule that dilates your blood vessels making blood flow easier, lowering blood pressure and slicing a chunk of time off your personal best.

If you’ve read that and it seems that nitrates go around the body twice, first as nitrate, then as nitrite before becoming nitric oxide, then you have pretty well got the idea. Saliva? Who would have thought it was good for blood pressure and endurance?

Where do I find nitrate?
It is primarily in vegetables, especially the leaves, stems and roots of green vegetables. Foods high in nitrates are spinach, silverbeet, kale, parsley, celery, lettuce, rocket, beetroot and radish. Modest amounts are in banana, broccoli, cabbage, leek, capsicum/peppers, cucumber, pumpkin, strawberries and, get this, potato crisps and salami where the nitrate is added as a preservative. Nitrates and nitrites got a bad name by association because they are added to cured meats to stop bacterial spoilage.

There is not a lot of nitrate in other vegetables and fruits, but they can’t be dismissed because they provide polyphenols and vitamin C, critical in nitric oxide production in the stomach. Nitrate levels in food vary depending upon fertilisers (more nitrate), soil type and light exposure (less nitrate). Nevertheless, by far the majority of nitrate in the diet comes from vegetables with vegetables and fruit combined providing 90% of dietary nitrates. About 2% comes from processed meats and another 4% from pizza and savoury snacks.

Nitric oxide (NO)

Why the fascination with nitric oxide? As I have mentioned, NO helps relax blood vessel walls so that more blood flows through and with great ease. In addition, it stops platelets from clumping together to form blood clots, and also stops them from adhering to the sides of your arteries to slowly block them. You have all heard of Viagra. That famous tablet elevates NO levels to increase blood flow, but only in one part of the body. Just don’t expect the same effect from a bowl of salad.

Beetroot juice
OK, now you want to know how much beetroot juice you need to give you a PB in your next run, cycle, or triathlon. Simply put, the volume that will give you 300 mg nitrate. The nitrate amount will be on the label (0.3g = 300 mg). The research studies use about 500 mL (17 fl oz) but you can now buy beetroot juice concentrate. Quaff it about two hours before you get active. For more detail read the excellent fact sheet from the Australian Institute of Sport on beetroot juice and sport.

What does it all mean?
We are now looking at nitrates in a different light and appreciating their health value. Eat your vegetables. They are helping keep your blood pressure healthy while helping your endurance and getting you through the day. Simple enough. Not suggesting that you eat more pizza, crisps and salami for nitrates and you should know why because you are smart. But that spinach salad should be looking more attractive.

If you enjoy sport, and especially if you are involved in endurance sport, then also eat your vegetables. In addition, vegetable juice (home-made, without the added salt might be best) and beetroot juice taken a couple of hours before exercise could make it a more beautiful experience.

If you go the beetroot juice route note three things:
1)  I haven’t met anyone who says it has a wonderful taste, especially the concentrate. Expect the spinal shivver when consuming;
2) Your pee may turn pink for a while. It’s OK. It’s your favourite colour anyway;
3) Don’t use antibacterial mouthwash before taking beetroot juice because you will kill the very bacteria that produce the nitrites needed to form nitric oxide.

As we find out more about the bacteria in your mouth keeping you healthy, I wonder what will happen to the sales of those mouthwashes? Yes, you still need to clean and floss your teeth. No residual food in the mouth means no decay. But should you continue with that mouth wash?

For those who love 75 page reports here is one on nitrates and nitrites in the Australian diet.