Sunday, January 27, 2013

Breastfeeding, fitness & baby's weight

A subscriber to my newsletter, Jenine wrote to me and asked if I had any nutritional advice for “athletic mothers who are breast-feeding”? Is there anything more beyond the advice to eat healthy? Breastfeeding itself certainly requires extra energy, that is, providing liquid food for someone else means you need to eat and drink more. Approximately 2900 kJs (700 Cals) are needed to produce a litre of breast milk. That has to come partly from Mum’s diet and partly from the 3-5kg of extra body fat laid down during pregnancy. Some women lose the extra body fat quickly, some slowly, but keeping active will certainly help.
Vitamin D
During the winter especially, lactating Mum’s may need some extra vitamin D as a supplement, through vitamin D fortified foods or mushrooms exposed to light. Vitamin D is needed to assist calcium absorption from the gut. Nowadays many women are assessed for vitamin D levels during pregnancy because of a rise in infant rickets in modern societies. Women who are dark skinned, indoors during the middle of the day or live further from the equator will be most at risk.

Although the baby sucks 260 mg of calcium out of Mum each day, much of it coming from Mum’s bones, taking extra calcium does not stop this bone loss, with the losses being replaced after weaning. (I didn’t know that until I just read it in a textbook). For this reason breastfeeding Mum’s don’t need to fret about taking more calcium than usual (assuming they eat calcium-rich foods like cheese, yogurt, milk, soft bones of fish, calcium-fortified soy drinks).

Most other nutrients are required in greater amounts but this is usually covered by the extra appetite from being active and producing milk.

Eat well, eat a bit more & keep active
Anyway, there is nothing unique in the advice for very active breast-feeding Mums, except to eat well and eat more. Remember that in the olden days you may have had a “day off” for the birth, then you were back out gathering and cooking so lactation was always associated with being active. If you do find weight loss after birth to be a bit too rapid, then nourishing drinks (eg Sustagen), smoothies with extra skim milk powder added or including more oil (eg olive oil) in your diet will pump up the kJs/Cals.

Breastfeeding & baby’s weight
Jenine then further asked if childhood obesity and breast-feeding were linked. She had heard that obesity can begin through mother’s milk. I assumed that she was referring to a preventative, not causative, role. My local legend, Professor Wendy Oddy, University of Western Australia, wrote a review of all the information on this very topic. In one sentence, breast-fed kids have a lower risk of being overweight as they grow up. The “why” is interesting.

1. Breast-fed kids drink until they are done. Mouth off breast signals to Mum that they have had enough (infant-regulated). Bottle-fed babies may be encouraged to finish the bottle (parent-regulated).

2. Bottle-fed babies grow at a faster rate, effecting adipokines, which in turn affect insulin sensitivity and create a chronic sub-inflammatory state playing a role in heart disease and diabetes development.

3. The Growth Acceleration Hypothesis states that rapid early weight gain may program the body for later obesity, high blood cholesterol, high blood pressure and insulin resistance (which means high blood glucose levels). Breast-fed babes seem to gain weight slower in later infancy, suggesting that breastfeeding for a year or so could protect baby from later flab and disease.

4. The Early Protein Hypothesis view is that the higher protein content of formula could be responsible for an increased infant growth rate and excessive production of permanent fat cells. Breastfeeding protects against fatness with lower blood insulin, less fat storage and preventing fat cell development.

What does it all mean?
Breast milk has all that a newborn requires and it is smart to exclusively breast feed for the first six months and continue breast feeding for the following six months while introducing solids. Baby learns to feed on demand and stop when content, normalising both appetite and growth. The pay-off seems to be a healthier and leaner child down the track. Good news. If only it could make them immune from drug dealers, charlatans, television viewing, advertising and religious fundamentalism too.

Reference: Oddy WH. Infant feeding and obesity risk in the child. Breastfeeding Review 2012; 20 (2): 7-12

Irisin: the new weight loss hormone

Fat cells

Don’t you like to be the first person in your group to use a new word? Sitting at the dining table commenting “Excuse me, you have a little bit of food on your philtrum” or “Yes, I know Sebastian, a person with exceptional proxility.” Well now, rather than saying something dull like you have been out for a walk or a game of squash you can say that you have been increasing your irisin output.

About a year ago, clever folk at Harvard University had a study published in the journal Nature. OK, it was a study done in mice, but it has really excited the research community and now we are seeing studies in humans too. In essence, it seems that when we exercise not only do we burn fat and sugar (glucose) we also produce a very interesting hormone called irisin.

Brown vs white fat cells
Irisin then travels around the body and modifies fat cells by increasing the number of brown fat cells and reducing the number of white fat cells. This is good because brown fat cells **burn** fat while white fat cells **store** fat. And the brown fat cells keep burning fat after you have finished exercise. Simply put, exercise burns fat and helps create fat burning brown fat cells, courtesy of irisin. Wait, there’s more. Irisin also help to fight insulin resistance, one key factor behind high blood glucose levels and type 2 diabetes.

More research coming
There will now be a flux of research on irisin. One paper published in December 2012 showed that obese people had high levels of irisin, suggesting that more is being produced to help combat high blood glucose levels common in obesity.

Irisin is not the only protein being secreted by the muscles. Active muscles produce hundreds of proteins, some doubtless acting as hormones, so irisin may be only one of a family of “secretory peptides” that act to keep us lean and healthy. They are part of the explanation why fit people live longer than those who watch endless hours of mind altering, light emitting machinery.

What does it all mean?
Be active. Be fit. Don’t wait for irisin tablets or injections. We have been disappointed in the past with weight loss “breakthroughs”. Early research like this just helps us to marvel and understand the human body. Once a few more studies are done then expect, about March 2014 I’d say, the charlatans to spruik potions that “boost your irisin”. Just roll your eyes and go for a walk and boost your own for free while getting some vitamin D and a mental refresher at the same time.

Boström P et al. Nature; 481 (7382): 463-468. doi:10.1038/nature10777 2012

Tuesday, January 1, 2013

The first vitamin

How long have vitamins been around? For millions of years, you rightly declare, because soon after we had life, we had biochemistry and therefore vitamins to help those biochemical pathways function. But how long have we known about vitamins? Not long at all. The very first vitamin was isolated in 1912. It wasn’t vitamin A as you would predict. It was what we now call vitamin B1 or thiamin.

The man responsible was a Polish scientist called Casimir Funk, working at the Lister Institute in England. He found that a diet lacking thiamin lead to the severe condition beri-beri, and providing an adequate amount of thiamin meant avoidance of the condition. Pretty exciting stuff in 1912.

Thiamin used to be spelled thiamine (with the e) to emphasise that it was a chemical with an “amine” group. Indeed, Funk originally thought that there were many “vital amines” in nature so coined the term “vitamines”. When it became clear that not all “vitamines” were amines, the “e” was dropped, leaving us with the word vitamin.

Vital Amines
To be fair, Funk wasn’t convinced of his own argument. He wrote: I must admit that, when I chose the name, “vitamine”, I was well aware that these substances might later prove not to be of an amine nature.” Funk wrote a stunning 500 page book, published in 1922 with nearly 1600 references, discussing all the science behind this very new avenue in nutrition.

Even in 1922 we only knew of vitamin B (not yet realising it was a group of vitamins, not just one vitamin), vitamin C, vitamin A (not knowing that beta-carotene was a precursor) and an unnamed anti-rickets vitamin (later proved to be vitamin D). Only the chemical structure of thiamin was known.

Disappearing Vitamin C
Not everyone understands why vitamins exist. After I had given a presentation in England, a lady confronted me with the view that “oranges today do not have vitamin C” and therefore we needed her vitamin C supplements. Supplement representatives often parrot the company line and, having no scientific background, do not even think to ask for some proof. As Funk wrote “We already know that vitamine (sic) C is generated on the germination of seeds”, that is, oranges have vitamin C for the health and growth of the oranges. No vitamin C = no orange. They do not produce vitamins for humans, they produce vitamins for themselves. That goes for all plant foods – all those nutrients are for the plants health; you just happen to benefit too when you dine on them.

Fresh is best?
Just a reminder for those that are concerned about the nutrient content of their fresh produce. Foods like fruits and vegetables will have a reasonable amount of vitamins if they look and feel fresh. Prepare and eat them soon after buying, which means it is smart to shop three times a week for fresh produce. Frozen fruit and vegetables also have a high vitamin content.

In Australia only 7% of the adult population eat enough fruit and vegetables for good nutrition. Now, as that is self-reported information, and humans are great fibbers, the number is closer to 12. Not 12%, just 12 people total. So, we would be better off eating more fruit and veg before worrying about issues like conventional vs organically grown.

What does it all mean?
Nutrition is a relatively young science, compared to mathematics, physics and astronomy. There is a lot to learn, but we humans tend to let ourselves speculate way ahead of knowledge. Will a vitamin supplement improve your health? Very likely, if your home is a park bench or under a bridge. Otherwise, I doubt it.

It is more useful to concentrate on things that have a much higher likelihood of extending your life – work hard, be fit and active, eat wholesome food, be social, volunteer, challenge your mind, be resilient when life ain’t pretty and be comfortable in your own skin. (Read  The Longevity Project if you want evidence that there is more to a long life than eating vegetables).

Yes, additional vitamins can be very helpful in certain situations and conditions eg the full range of vitamins in cystic fibrosis, folate pre-pregnancy and the first trimester, vitamin D in the winter if you live far from the equator. Folate and vitamin D were hardly mentioned 30 years ago and now we appreciate the potential benefits of supplements to some people. So, (I note to myself), expect to be further surprised by vitamins over the coming decades, but don’t expect them to be a single, or simple, solution to a long and healthy life.