Hot potato

Not again! This time it is the simple potato that’s being demonised. This seems to never end in that scientists pick one food after another and try to find a bad apple in a complex diet. Sorry, so far there are no adverse effects reported for apples, but you just wait. Probably just a matter of time.

And the statistics used become more and more elaborate making it impossible to penetrate the reported findings. All based on dubious food frequency questionnaires in the first place.

So what’s new?

Scientists demonise potatoes.

Scientists demonise potatoes for causing hypertension.

I have to give it to them that the researchers of the new report used an impressive number of people, overall over 187,000 men and women from three large US studies covering more than 20 years of follow-up. They all belonged to a cohort of health professionals, the same groups that have been used previously to report potential public health impacts of a range of different foods.

Unfortunately, the major shortcoming of all those reports is their dependence on food frequency questionnaires to capture dietary intake details.

In this case they analysed consumption of 130 foods and beverages, including the frequency of potato consumption. This might be fine for common foods, but what about all other minor foods we eat less regularly? If they aren’t captured you have no idea of their influence. Also you need a pretty good memory to recall all you ate during the past year.

Try it yourself. How often did you consume apples or ice cream? It will be more of a guesstimate and you might not even want to admit that you ate ice cream three times a week.

And also they asked participants to self report if they had been affected by hypertension as diagnosed by a health professional since their hypothesis was that eating a lot of potatoes would lead to an increase in blood pressure.

And the findings?

The researchers predictably found that higher intakes of boiled, baked, or mashed potatoes, and French fries were associated with an increased risk of developing high blood pressure. But now it gets more confusing.

After taking account of several other risk factors for hypertension, the researchers found that four or more servings a week of baked, boiled, or mashed potatoes was associated with an increased risk of hypertension compared with less than one serving a month in women, but not in men.

But higher consumption of French fries was associated with an increased risk of hypertension in both women and men.

And even more confusing, consumption of potato crisps (chips if you’re American) was associated with no increased risk.

And finally, replacing one serving a day of baked, boiled, or mashed potatoes with one serving a day of a non-starchy vegetable was associated with a lowered risk of developing hypertension.

So what to believe?

Should potatoes be included in the vegetable group?

Should potatoes be included among other vegetables or not, who can say?

First the main rationale of the study. Potatoes are one of the world’s most commonly consumed foods – and have recently been included as vegetables in the US government healthy meals programs, due to their high potassium content. Not everyone agrees to this move. So the researchers set out to determine whether higher long term intake of potatoes could be linked to incident hypertension.

And they say their findings have potentially important public health ramifications, as they do not support a potential benefit from the inclusion of potatoes as vegetables in government food programs. Instead the findings support a harmful effect that is consistent with adverse effects of high carbohydrate intakes seen in controlled feeding studies.

But if you noticed that replacing a serving of potato with non-starchy vegetables lowered the risk of hypertension, the findings could actually be related to reduced vegetable consumption when consuming a lot of potatoes. Nitrate in vegetables is transformed to nitric oxide in the body. And nitric oxide is a vasodilator that reduce blood pressure.

Critics of the study

I am not the only critic of the study. In a linked editorial, other researchers argued that, although diet has an important part to play in prevention and early management of hypertension, dietary behaviour and patterns of consumption are complex and difficult to measure. Prospective cohort studies that examine associations between various dietary patterns and risk of disease provide more useful insights for both policy makers and practitioners than does a focus on individual foods or nutrients.

To be fair also the researchers acknowledge some study limitations and said that, as with any observational study, no firm conclusions can be drawn about cause and effect. But that didn’t deter the popular press to latch onto the findings, there are plenty of potato consumers to scare.

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Are French fries really French?

French fries are probably not French (Photo: Cyclonbill)

French fries are probably not French (Photo: Cyclonbill)

First thing to clear up is the spelling. Should it be French fries or french fries? Here it is quite clear that since the initial origin was thought to be France the fried potatoes should be spelt with an initial capital F. Even if the perceived origin might be wrong. It seems to be more likely that the origin is Belgium, and more precisely the French speaking part. Some people believe that the term “French” was introduced when British and American soldiers arrived in Belgium during World War I and tasted Belgian fries. They supposedly called them “French”, as it was the local language and official language of the Belgian Army at that time, believing they were in France.

It was thus a terrible mistake to associate the Belgian food with France. All you have to do is to walk through Brussels at lunch time and see masses of people enjoying the fried potatoes alone with only a variety of different sauces on top. Wisely the Belgians keep it neutral and only call them frites (or frieten if you are in the Dutch speaking part). Another name used for the popular dish in several countries, among them Sweden, is pommes frites. That is a good description of what the food actually is – a fried potato stick. Not always known for their diplomatic skills, in the United Kingdom people go one step further and most often call the fried potato sticks for chips. This might be just to fool the Americans who would think of thinly sliced potato, rather than a stick, that has been deep fried or baked until crunchy when talking about chips. Normal people would call them crisps.

The frying oil contributes to energy consumption (Photo: Wikimedia)

The frying oil contributes to energy consumption (Photo: Wikimedia)

With all that out of the way let’s move on to the more important part of this blog, the nutrition information. Actually, in the UK they might be on to a good thing since their chips are cut thicker and thus absorb a little less fat during frying. Because fat is one of the problems. The potato sticks are normally fried in beef tallow, lard, or other animal fats, adding saturated fat to the diet. Replacing animal fats with palm oil simply substitutes one saturated fat for another. Replacing animal fats with partially hydrogenated oil adds trans fat, which has been shown to both raise LDL cholesterol and lower HDL cholesterol. Definitely a bad thing. Canola/rapeseed oil, sunflower-seed oil, or mixes of vegetable oils are also used, but beef tallow is generally more popular, especially amongst fast-food outlets.

The final fries contain a lot of energy from carbohydrates in the form of starch and from the fat absorbed during the frying process. A large serving of 150 g of fries provides close to 500 kcal from the 60 g of carbohydrates and the 25 g of fat, plus 350 mg of sodium. To spend that amount of energy you would need to run for an hour or walk for more than two hours.

So the lesson? Call them pommes frites or chips and you don’t have to worry about the spelling and eat them sparingly unless you walk for two hours a day. And blame the Belgians and not the French for inventing the little tempting devils (although the French chefs seem to want to share in the blame).

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Acrylamide – nothing seems to help

French fries a large contributor to acrylamide exposure (Photo: freephotouk)

Acrylamide is a chemical compound that typically forms in starchy foods during frying, baking, roasting and grilling. It is linked to the browning of food during the so called Maillard reactions. The darker the food the more acrylamide seems to be formed. It was found in food by coincidence in 2002 when examining a leak of the industrial chemical polyacrylamide from a tunnelling project in the south of Sweden. It was first thought to be an environmental contaminant. It has since been shown to actually be a process contaminant formed in food during dry heating, but not boiling.

Acrylamide received a lot of attention among scientists and the popular press over the first years of its discovery. Industry started programs to attempt to reduce its formation and household cooking instructions were issued. The toxicity of the compound was explored in more detail.

Toxic properties

The toxic effects of acrylamide in industrial exposure and in smokers have been known for some time and include damage to the nervous system and to male fertility. However, looking at potential food exposure, the Food and Agriculture Organization of the United Nations and the World Health Organization concluded that the levels required to observe such effects was 500 to 2,000 times higher than the average dietary exposure of acrylamide. From this, they concluded that acrylamide levels in food were safe in terms of neuropathy and infertility, but raised concerns over human carcinogenicity based on known carcinogenicity in laboratory animals.

Checking your consumption patterns (Photo: mikeandanna)

Attempts to confirm a cause and effect relationship in humans between acrylamide exposure and cancer is on-going. A number of epidemiological studies have looked at the correlation between acrylamide intake through food frequency questionnaires and a range of different cancers. Many studies proved negative, but there were indications that dietary acrylamide could be associated with the formation of myeloma, head-neck cancer, oesophageal cancer, endometrial cancer and ovarian cancer.

Now there is documentation of a further effect. A new report published on 23 October 2012 described maternal exposure to acrylamide and birth weight of children. A team led by Marie Pedersen from the Centre for Research in Environmental Epidemiology (CREAL), Spain, measured blood levels of acrylamide and its common metabolite glycidamide and found that dietary exposure to acrylamide while pregnant resulted in reduced birth weight and head circumference in the off-spring. The authors pointed to a potentially substantial public-health implication of their findings since reduced birth head circumference has been associated with delayed neurodevelopment.

Attempts to reduce acrylamide formation

Acrylamide forms from sugars and an amino acid (asparagine) during high-temperature processing of plant foods in particular such as potato crisps, French fries, bread, biscuits and coffee. In a report published by the European Food Safety Authority (EFSA) in 2011, fried potatoes (including French fries), roasted coffee and soft bread were identified as the major contributors to acrylamide exposure in adults, while fried potatoes, potato crisps, biscuits and soft bread were identified as the major contributors to exposure in adolescents and children. The exposure estimates for these different age groups in Europe were comparable to those previously reported in scientific literature and in risk assessments carried out by the Joint FAO/WHO Expert Committee on Food Additives (JECFA).

The food industry has been exploring ways of reducing acrylamide levels in foods without reducing desirability and taste, including using lower cooking temperatures and adding enzymes to reduce the amount of acrylamide that forms during cooking. The industry in Europe developed a “tool box” containing advice on how to reduce acrylamide formation.  Many of the recommendations should have been adopted by now. It seems the process changes have had limited success. An EFSA report published on 23 October 2012 showed only very limited changes in acrylamide levels between 2007 and 2010 in most food groups. With some good will slightly reduced acrylamide levels could be seen in some cereal-based foods for children and non-potato savoury snacks but on the contrary  acrylamide seemed to increase in coffee and coffee substitutes, crisp bread and some types of French fries.

What is the consumer to do?

Coffee – to drink or not to drink? (Photo: arimoore)

If the industry is mainly failing in their attempts to reduce acrylamide levels in food what is the consumer to do? We could of course just give up. A more sensible approach would be to be a bit more careful when heating food since acrylamide formation increases with increased heat. If toasting bread, make it only golden brown. Equally be careful with the French fries. Although coffee might delay the development of Alzheimer’s disease, it is also a major contributor to acrylamide exposure. Not an easy choice.