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.

Cramps (mainly in sport)

We have all experienced that excruciating knot of painful involuntary muscle spasm that can stop us dead in your tracks. About two out of three fit and active people have experienced the cramp. It commonly occurs in the calf, thigh or foot. It can happen in both cool and warm environments.

What triggers a cramp?

Nobody knows for sure. Surprisingly, this topic is poorly covered in most sports medicine books and is not well researched. It has long been suspected that the most common causes in athletes are dehydration, heavy salt losses or, more recently, just plain muscle fatigue leading to a loss of muscle control.

Heavy sweating can cause significant sodium (salt) losses from the body, and this may trigger a cramp if the sodium isn’t replaced during the activity. To combat the threat of cramp, athletes add some extra salt to their meals and take a sports drink throughout training and competition. One study of a tennis player who regularly got cramps revealed that he lost more sodium through sweat than he ate in his diet. By taking a sports drink and increasing the sodium in his diet, he was able to reduce the cramps to rare occurrences.

More recently, studies have shown there are no differences in blood sodium levels or levels of hydration in crampers compared to non-crampers leading to the view that cramping is due to a tired muscle losing coordination of its contractions. If low levels of salt in the body are the cause of cramp it does not explain why only certain muscles get cramp or why rest or stretching the afflicted muscle often “cures” the cramp. The best explanation to date is that muscle cramp is due to a tiring muscle losing its ability to control its contractions and going into involuntary spasms.

The best advice we have

The truth is that we don’t fully understand muscle cramp, nor know the best advice to help avoid the cramp. You may have your own solutions that work for your body. Until we know more, the sensible advice is:

1. Drink plenty of fluids during activity to avoid dehydration. A dehydrated body seems to be more prone to cramping.

2. If you lose a lot of sweat during exercise, especially over an hour or more, try a sports drink to help replace the lost sodium.

3. Be fit. Cramps are less common in fit people.

4. Eat well. Cut the saturated fats that clogs arteries. Cramps can occur in muscles that have a reduced blood supply due toas a result of narrowed arteries.

5. Stretch before and after exercise. If you suffer night cramps, stretch before going to bed.

6. Be untrendy and wear loose, comfortable clothes. Tight -fitting clothes can reduce blood flow to muscles, making them more susceptible to cramps.

7. Acclimatise to the environment in which you perform, especially when moving from cool to warm climates.

Stretch the point

If you do get a cramp, stretching the cramped muscle is the best way to reduce the pain. If it happens in the calf, grab the toes and ball of your foot and pull them towards the kneecap, or get someone to do it for you as shown in the pic. This helps the muscle to relax. Applying ice can also stop the spasm and reduce the pain.

What does it all mean?

If you have access to millions then please start the International Research Unit for Cramp and Stitch. We need it because we know stuff-all about the nuisance pain we all experience. Because humans evolved in a warm environment, it is often said that salt depletion is unlikely to be the cause of cramp in most people, but there have been reported cases of “whole body” cramps in athletes where salt depletion is a more likely cause. Otherwise, it seems that looking after yourself may be your best bet against cramp. If you would like a bit more on the topic, here is a lengthy discussion [http://www.medicinenet.com/muscle_cramps/article.htm].

References: British Journal of Sports Medicine 2009; 43: 401-408

Night cramps

Mollie wrote: “I’m hanging out for cramps info. I am getting terrible ones, especially at night and on waking, especially with sudden movements of legs, and even hands and fingers. Can it be just because I’m getting old? Wearing different, not so comfortable shoes for a day of training seems to exacerbate them.”

Well Mollie, cramps do tend to occur more frequently with age. Lot’s of people do suffer night cramps, so you would think that there would be a whole lot more on the topic.

The Mayo Clinic can describe night cramps [http://www.mayoclinic.com/health/night-leg-cramps/MY00410] but offer no solution, and a British site [http://www.patient.co.uk/health/Cramps-in-the-Leg.htm] gives some tips to reduce night cramps. Oh yes, and stick to comfy shoes.

Food and Zits

About a year ago I wrote about the link between chocolate and pimples and found the evidence poor. Since then there have been a couple of reviews of the diet data so I thought I would share them with you.

Good parent, bad teenager

Parents have long handed out dietary advice to reduce pimple production, seemingly based more on socially accepted dogma (avoid sugar, soft drinks and confectionery) rather than any good quality research. No doubt, it suited the good parent/bad teenager model of family life. Since the turn of the century there has been some, but not many, well designed studies to try and determine whether our diet does influence acne.

Glycaemic Load

I took a look at a couple of review papers and both agree that the best evidence is that a low Glycaemic Load diet has the greatest ability to control pimples, that is, a diet that has the least effect on blood glucose levels. For example, it means less rice crackers and crispbreads, cornflakes, crumpets, one-minute oats and more fruit, legumes, nuts, vegetables and dairy foods.

Of course, many people are adamant that certain foods trigger their acne, and there is no argument from me. It is plausible that for some folk specific foods or greasy takeaways can be manifest on their face the next morning. Trying to give general anti-acne diet advice to all is the tricky bit.

Other theories

There have been other theories of late, such as a diet rich in omega-3 fats from fish helps protect against acne, but there is no clear link between other aspects of the diet and pimples. There has been conjecture that dairy foods, like skim milk, increases the risk of acne by increasing Insulin-like Growth Factor (IGF-1) production, a hormone that elevates the sex hormones that cause acne. The jury is out on that one. The most convincing evidence remains for the high Glycaemic Load diet.

What does it all mean?

For a start, there doesn’t seem much point in trying to scare those with acne into thinking that avoiding jelly beans and soft drink is a solution. Avoiding the occasional treat is hardly going rid the skin of pimples.

What is clear is that it has been particularly difficult to isolate one aspect of the diet that promotes or defends against acne, meaning that other factors are unavoidable, with adolescent hormones being an obvious one. For example, when you lower the Glycaemic Load of the diet (ie get people to eat better), people of ample size often lose weight and one wonders if the weight loss is equally helpful as low Glycaemic Index (GI) foods in reducing the incidence of zits.

On the other hand, eating well seems to be the most effective way to put diet in your corner for the acne battle. Choosing low GI foods is helpful, except GI is such a difficult physiological concept to get across, so maybe just telling people to eat mainly minimally processed foods will help. Getting them to do so is not so easy.

References:

Journal of the American Academy of Dermatology 2010; 63: 124-141

Clinics in Dermatology 2010; 28: 12-16

Vinegar and your Blood Glucose

When you eat well you limit the excursions in your blood glucose levels, generally making it easier to control your weight, your pimples and your diabetes, should they be problems. It has been known for some time that adding a tablespoon of vinegar to a meal (eg vinegar in your salad dressing) can reduce the blood glucose response to the meal by 30%.

The theory is that adding vinegar to a meal slows down the rate at which food empties from the stomach and enters the small intestine for digestion, therefore slowing the absorption of glucose.

A recent paper (Eur J Clinical Nutrition 2010; 64: 727-732) indicates that the vinegar effect is more pronounced after high GI meals and not the low GI meals we suggest for good health (and less zits). They used a wine vinegar. I assume the effect is still present with a flavoursome 4-clover leaf balsamic.

Low joule sweeteners & appetite

Sweetening agents in food or as a powder or tablet have been around for many years. I have already told you that my folks used saccharin during the sugar restrictions of the 2^nd World War. Much misinformation on sweeteners circulates the internet because the world loves to hate stuff they don’t understand.

One thought has been that sweeteners like aspartame (Nutrasweet) at best didn’t make you eat less kilojoules and at worst, made you overeat, countering the close-to-zero calories they offer.

Sugar vs sweeteners

Sugar has been thought as a culprit in weight gain since the 1960s, so replacing sugar with a sweet substitute that provided very few calories was always seen as part of the remedy and would help weight loss. To test whether people compensated for the “missing kilojoules” when consuming low joule sweeteners, researchers first gave test subjects a “pre-load” meal that had either sucrose (cane sugar), or the low joule sweeteners aspartame or stevia (a sweet extract from the leaf of Stevia rebaudiana). They were blind as to which pre-load snack they got.

The participants had a controlled breakfast. Later in the day they were given one of the three pre-load snacks, followed 20 minutes later by a regular lunch. In the evening they were given another of the three pre-loads (with either sucrose, aspartame or stevia) followed by a dinner to their liking.

Appetite not affected

The pre-load snack had an extra 200 Cals (835 kJ) when the sugar was added, compared to the sweetener. If the low joule sweeteners aspartame or stevia had no effect on appetite, then the subjects should have made up the difference in kilojoules by the end of the day, such that they ate the same number of kilojoules independent of whether the pre-load meal had sugar or sweetener.

At the end of the day, when the pre-load snack had a low joule sweetener, the people ate around 300 Cals (1255 kJ) less food than those who had sugar included. Conclusion: low joule sweeteners helped lower the amount of Cals/kJs eaten over 24 hours.

Caveats

The pre-load snacks were solid (crackers and cream cheese sweetened with sugar, stevia or aspartame). The results may have been different if the choice was regular or diet soft drink. The people chosen did not have psychological problems with their food. Had they been aware of the kilojoule content of their snacks (or knew they were drinking diet soft drink) they may have made psychological adjustments to what they chose at lunch or dinner. The study was over 24 hours and a compensatory calorie catch-up may have occurred on subsequent days. All the same, this research is consistent with other research suggesting that “diet” food and drinks can help weight control in many people.

What does it all mean?

When I fly I usually have a water, Diet Coke or Pepsi Max (I’m one of those who can’t really tell the difference) to counter the dry atmosphere in an aircraft. The occasional diet soft drink or food with a low kilojoule sweetener can play its part in stopping overeating. As always, controlling your weight is about eating well and being fit. Low joule sweetened foods can help in a small way.

Reference: Appetite 2010; 55: 37-43

Hash brown content of Harley Davidson's

While reading Martin Lindstrom’s book Buyology (http://www.martinlindstrom.com) he mentioned that Harley Davidson had tried to trade mark its engine sound when Japanese bike manufacturers tried to mimic that engine rumble. He described it as the signature fast “potato-potato-potato” sound. I hadn’t heard the sound described that way before. You probably have, and so have many others (put Harley and potato into your search engine).

Ok, nothing to do with food. I just liked the analogy, but not around my house after 10pm please (because the sound wedges into my consciousness and fries my sleep. Hey, I know it’s not funny, but I didn’t think you would read this far). The photo was taken at the Elvis Festival, Parkes, NSW in January 2008. From memory, Kelvin the owner, paid $35,000 for it. And yes, he has the complete Elvis outfit and wig.