Tag Archives: nutrition

Does beetroot juice work for you?

Drinking beetroot juice before a race has become very popular, as it can make you go faster. However, a new study suggests that beetroot juice will not help you if you are already very fit.2631746551_ba1338f5b7

Studies have shown that a single intake or a short term (3-6 days) supplementation of beetroot juice shortens your time on a time-trial event and allows you to tolerate high intensity exercise much better. This is because beetroot contains nitrates (NO3-).

Your body absorbs NO3- and secretes it into your saliva, where your mouth bacteria transform it into NO2-, which is then taken up by your stomach as you swallow. (That is why beetroot has no effect if you use antibacterial mouthwashes.) NO2- becomes NO in tissues which are in need of oxygen, such as working muscles.

NO dilates blood vessels and makes your body more efficient at using oxygen to produce energy. It also improves the contractibility of your muscle fibres.
This is great news, not only for athletes, but also for the elderly who have a reduced aerobic capacity, and for people suffering from hypertension as it will lower their blood pressure.
However, there is a problem. Most studies showing a benefit have been done on sedentary or moderately fit people. Studies on elite athletes on the other hand, are rather disappointing.

To try to understand this better, Simone Porcelli and her colleagues have studied the effect of beetroot juice on 21 young men of different aerobic fitness levels. The VO2 max values of the participants ranged from 28.2 ml/kg/min (sedentary people) to 81.7 ml/kg/min (elite level).
The researchers tested their fitness by a run to exhaustion, a series of 6-min sub-maximal runs on the treadmill, and a 3 km time trial. All the participants performed the tests twice, once after taking 500 ml/day beetroot juice for 6 days and once after drinking the same amount of a placebo for the same time.

There was an inverse relationship between the VO2max of the participants and the benefits of taking beetroot juice. In other words: the participants with the highest VO2max showed the least benefits, while those with the lowest VO2max benefitted most. The researchers also measured the blood levels of NO3- and NO2- of the participants, and noted that the fitter ones showed a smaller increase after drinking beetroot juice.

These results are not easy to explain, and Simone Porcelli and her colleagues have come up with 3 possibilities:

1) NO2- is mainly transformed into NO when tissues need oxygen. Elite athletes will have more blood vessels in their muscles due to many years of training, and it is therefore possible that the right conditions to form NO happen only rarely.

2) Athletes might take in much more nitrates with their normal diets, as they are likely to eat more than sedentary people. In this case the supplements would not matter anymore, and could just end up in their urine. Unfortunately, the researchers did not check the urine levels.

3) Our bodies can also make NO via a completely different pathway, without the need of any dietary NO3-. It is possible that many years of training have optimised this system and fine-tuned the athletes’ metabolism, making nitrate supplements superfluous.

The researchers noticed a higher NO3- and NO2- blood level in the fittest participants before taking any juice, which makes one of the two last possibilities (or both) more likely than the first one.

Whatever the reasons, if beetroot juice does not work for you, you should be happy!

photo credit: <a href=”http://www.flickr.com/photos/24987280@N00/2631746551″>Beetroot</a&gt; via <a href=”http://photopin.com”>photopin</a&gt; <a href=”https://creativecommons.org/licenses/by-sa/2.0/”>(license)</a&gt;

 

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Do we snack because we are bored?

Several studies have shown that television watching makes you snack more, which is very dangerous for your waistline, while others have found no effect. Could this discrepancy be due to the content of the programmes? If so, choosing your programs wisely would help you to keep your weight under control.

© Kmitu | Dreamstime Stock Photos
© Kmitu | Dreamstime Stock Photos

It is possible that your mood, in particular your level of boredom, could influence how much you are eating. To check this out, Colin Chapman and his colleagues compared how much 18 normal-weight women snacked when watching an engaging comedy program, with what they ate looking at a boring lecture or reading a boring text. The snacks consisted of grapes and M&M chocolates.

The women snacked significantly less during the engaging television program than during the boring one or while reading the boring text. There was no real difference between the amount snacked while reading or watching something boring.

Previous studies have already shown that obese people tend to eat more when bored, but now more and more researchers think that everybody does so. Moreover, if Colin Chapman is right it would mean that being bored by other means than television watching (in this experiment: reading) is just as bad.

The researchers also noted that when bored the women snacked more on grapes than on chocolates. When captivated however, they had relatively more chocolate. They suppose that when the women had more time to choose, they went for the healthy option. Even so, they took in more calories than when they were captivated.

Of course, this experiment was conducted in a lab and the women might behave otherwise when at home. The researchers did not check what the women ate after the experiment and we therefore do not know if there was any effect on the size of their meal.

We do not know either what the women were used to do. Habits are powerful, and if you are used to snack while watching television or if you associate snacking with having a good time, you will find it harder to control it.

Even so, if you want to keep your snacking under control, you should avoid boring stuff… Alternatively, you could make sure that there are no snacks available when you have boring things to do, which is probably a more realistic solution.

References

CD Chapman, VC Nilsson, HA Thune et al. Watching TV and food intake: the role of content. PLoSOne. 2014; 9(7): e100602. doi: 10.1371/journal.pone.0100602. eCollection 2014.

What should we eat?

If you want to create an animated discussion, start talking about what you should eat (or not) to protect yourself from cancer, cardiovascular disease, diabetes etc… Humans have been wondering which foods to eat since ancient times, but we still have more questions than answers!

© Skdesign | Dreamstime Stock Photos
© Skdesign | Dreamstime Stock Photos

Several large studies have shown that we should avoid excess calories, eat plenty of fruit and vegetables, reduce the amount of refined sugars and stay away from processed food, but everything else is still open for discussion. Why is this so?

Nutritional science is based on epidemiological studies, from which researchers try to determine what the effects of different foods or diets are. They can then perform interventional studies, whereby they ask half of the study participants to have more of a specific food or change their diet, and compare the effects with the other half of the participants (= the control group). In the Predimed Study for example, researchers examined the importance of olive oil and nuts in this way. Without good epidemiological studies however, researchers do not know what to look for.

I have just stumbled upon an article by Farin Kamangar and Parisa Karimi explaining how difficult it is to conduct such epidemiological studies, and here comes their list of possible errors and problems.

Measurement errors

The first problem Kamangar and Karimi mention is the way they obtain information about what you are eating. Traditionally this is done via questionnaires and interviews assessing your dietary habits over one year. It is clear that it is difficult to recall accurately what you have eaten over a year. Moreover, you might have changed your diet, and what you have eaten last year is therefore not necessarily reflecting your lifelong habits.

Some researchers ask you to write down what you have eaten for the last 24 hours. Even though you will be able to recall this accurately, it is not sure that you are having something similar each day.

Most questionnaires are really long (80 to 200 items), which can discourage even the most motivated participant.

These problems will hopefully be minimised in the future, as researchers are starting to use online self-assessment questionnaires.

Confounders

Epidemiologists try to find an association between risk factors and diseases. Confounders are factors that independently affect the risk of developing the disease, and therefore falsify the results of the study.

A classical example is the association between coffee drinking and lung cancer. Previous studies suggested this, but as coffee drinkers were more likely to be cigarette smokers, the risk of developing lung cancer had nothing to do with coffee. Another example is the association between lying in bed and dying. As most people die in bed, you would conclude that beds are the most dangerous places on earth.

As confounders are usually unknown, it is easy to see how they can falsify the results. Researchers try to avoid them by comparing populations that are very similar except for the factor they want to study. With this in mind, Beth Taylor and her colleagues compared marathon runners with their non-competitive spouses to examine the effect of strenuous exercise on your arteries.

Variability of food products

Foods are typically grown and/or prepared in different ways in different parts of the world, which might affect their nutritional value. Kamangar and Karimi cite the example of brown rice, which is a healthier choice than white rice since it contains more fibre, but in the United States it has a higher arsenic concentration than white rice. Another example is the difference between grass-fed and grain-fed beef: grass feeding typically results in leaner meat.

The correct control group

As already mentioned above, finding a good control group is a challenge: it has to resemble the study group except for the factor the researchers want to study.

In nutritional science this is very difficult, as the study participants avoiding a specific food usually replace it by something else. For example, imagine what the study results would be if participants abstaining from a specific, probably unhealthy food use to replace it by something containing plenty of simple sugars.

Interactions

Foods contain chemical substances that influence each other’s absorption and actions, and different foods can contain the same substance in different amounts and availabilities. These interactions are very complex, and researchers need large study groups to try to avoid them.

© John Valenti | Dreamstime Stock Photos
© John Valenti | Dreamstime Stock Photos

Multiple testing

Epidemiological studies about nutrition are typically large and expensive. Researchers want to use all the data and they therefore test several hypotheses at once. However, there is always a chance to come to a false conclusion by coincidence. Statistically, the probability to obtain such a false positive result is 20%, which means that if you test 20 hypotheses, you will get at least one false positive one.

And therefore…

Nutritional science is fascinating, but difficult. Keep informed, stay critical and be prepared to change your mind.

References:

F Kamangar and P Karimi. The state of nutritional epidemiology: why we are still unsure of what we should eat? Arch Iran Med. 2013; 16(8):483-486.

BA Taylor, AL Zaleski, JA Capizzi et al. Influence of chronic exercise on carotid atherosclerosis in marathon runners. BMJ Open. 2014; 4(2): e004498. doi: 10.1136/bmjopen-2013-004498.

ME Van Elswijck and SH McNeill. Impact of grass/forage feeding versus grain finishing on beef nutrients and sensory quality: the US experience. Meat Sci. 2014; 96(1):535-40.

 

A natural source of carbohydrates for long runs

What do you use as carbohydrates during long runs and marathons? I usually have gels or jelly beans but as they are highly processed foods, I would prefer a more natural source of carbohydrates.

© Daniel Gilbey | Dreamstime Stock Photos
© Daniel Gilbey | Dreamstime Stock Photos

I have experimented with portions honeycomb packed in cling film, but it was fiddly and sticky and therefore much too difficult. It is a pity, because I felt fine on it and I could obtain it locally.

Searching through the literature, I found an article describing an experiment whereby they used raisins instead of sport chews. Eleven male runners ran 80 minutes on a treadmill at 75% of their VO2max, followed by a 5 km time trial. They performed this workout tree times (on different days), once having water only, once having sports chews, and once having raisins. There was no difference in performance or gastro-intestinal comfort between the workouts with sport chews and the ones with raisins. Using water only, the runners performed less well.

The researchers also measured blood levels of glucose, insulin, free fatty acids and creatine kinase. The chews caused slightly higher insulin levels and more carbohydrate oxidation than the raisins, and creatine kinase was markedly higher in the raisin group. Elevated levels of creatine kinase are suggestive for muscle fibre disruption, and are used as a marker for delayed onset muscular soreness (doms), but the runners did not report more soreness when using raisins. The researchers could not explain this finding, which, I think, is a bit worrying.

I have not tried raisins out for myself, mainly because of the creatine kinase. Moreover, a marathon takes me so much longer than about 100 minutes of running, and therefore I am not sure that I will be fine.

Do you have any experience with this? Any advice?

 

Protein after resistance exercise

Do you need to take in extra protein after a strength exercise session and, if so, how much?
Scientists are still debating this question. It is an important one, even for endurance athletes, as we all need strength to practise our sport properly and to perform well. In the May edition of Sports Medicine, Stuart Philips from McMaster University has summarised what we know about this question.

© Milogu | Dreamstime Stock Photos
© Milogu | Dreamstime Stock Photos

Muscle proteins are in a constant turnover: some are broken down, and other are synthesised. As long as you making more muscle proteins than you are breaking down, your muscles will grow (hypertrophy) and you will get stronger, your performances will become better and, crucially for endurance sports, you will be able to maintain good form for longer and therefore reduce your risk of injury.

Resistance exercise will stimulate muscle protein synthesis for at least 24 to 48 hours. Proteins are made of amino acids, and having more amino acids in your blood will further enhance muscle protein synthesis. After a meal you tend therefore to make more proteins than you break down. The effects of eating and exercising reinforce each other, and this is why it is beneficial to have a protein rich drink or meal after your strength training session.

However, as exercise stimulates muscle synthesis for at least 24 hours, researchers such as Brad Schoenfeld and Alan Aragon believe that timing your meals is much less important than having enough protein in each of them. They think that supplements immediately after training are unnecessary as long as you are having a healthy diet containing enough protein. I have blogged about their opinions before.

There are 20 different amino acids, but our bodies can synthesise only 10 of them. The others are called the essential amino acids, as we have to get them from food. Unfortunately, we can only synthesise muscle proteins if all the essential amino acids are available, which means that we need a well balanced diet. One of them, leucine, is particularly important, as it triggers the synthesis. Foods that contain plenty of leucine, such as whey, are therefore more effective than others to build up muscles.

Working Up Sweat (ID: 74747)
© Vlad | Dreamstime Stock Photos

How much?

Having too much protein in your food does not help. The maximal effective amount is 0.25g protein/Kg body mass in younger people. Ageing and inactivity makes it harder to get the process of muscle synthesis started, and it is likely that we need more leucine and protein in our food as we get older. Older people may need up to 40g protein/ Kg body weight.

The rate at which the amount of amino acids rise in your blood is also important: a low level or an almost continuous delivery is much less effective than a bolus every three hours or so, as you would get from meals and snacks during a normal day.

Other components

– As yet, there is no evidence that other amino acids such glutamine or arginine, help to build up muscle.

– Carbohydrates are important to replenish your glycogen stores, but there are no reasons to believe that they influence muscle synthesis, as long as you have enough protein in your food.

In practice

Try to have at least three well balanced meals and/or snacks a day, each of which should contain sufficient protein, and schedule your workouts so that you finish before a meal. Do not eat too much protein either, as this is probably just wasteful.

As you get older, you will need more protein, especially more leucine. You will find a list of foods containing leucine by clicking here.

Never give up exercising, as inactivity and ageing are a bad combination for your muscles.

Disclaimer: this article is for general information only, and does not replace medical advice. It cannot be used to diagnose or guide treatment. If you have any concerns or questions, you should talk to a qualified health provider.

References

SM  Philips. A brief review of critical processes in exercise-induced muscular hypertrophy. Sports Med. 2014; 44 (1): 71-77.

BJ Schoenfeld,  A A Aragon and J W Krieger. The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. J Int Soc Sports Nutr. 2013; 10 (1): 53.

Extra-virgin olive oil and your health

The Mediterranean diet has been linked to a longer and healthier life, but the reason why is not completely clear yet. It is likely to be due to a multitude of factors, such as plenty of fruit and vegetables, garlic, fish, a more outdoor lifestyle…Olive oil is a key component, and the latest publication from the Predimed study shows that the extra-virgin variety is the most beneficial, suggesting that the effects are mainly due to its phytochemicals.

© Esra Paola Crugnale | Dreamstime Stock Photos
© Esra Paola Crugnale | Dreamstime Stock Photos

We assumed for many years that the benefits of olive oil are due to its high content of mono-unsaturated fatty acids. However, many foods in a typical Western diet contain plenty of mono-unsaturated fatty acids, but do not seem to be as beneficial.

Olive oil also contains many phytochemicals such as polyphenols, phytosterols and vitamin E, which are anti-oxidant and anti-inflammatory. The amount depends on the kind of olive oil: extra-virgin is the first oil obtained by mechanically pressing olives, and contains much more phytochemicals than common or virgin olive oil. If the benefits of olive oil are largely due to its phytochemicals, extra-virgin oil should be much better for you than any other variety.

The Predimed (Prevencion con Dieta Mediterranea) is a Spanish study trying to understand which components of the Mediterranean diet are the most important and why. 7216 older adults at high risk of cardiovascular disease participated, and were randomised in three groups. They all continued with their usual Mediterranean diet, but one group added more olive oil, a second group consumed extra nuts, and the third group reduced the amount of fats. In their latest publication, the researchers looked at the effects of olive oil on cardiovascular disease. (I have blogged about the results concerning nuts previously.)

Sure enough, consuming more olive oil was associated with a reduced risk of cardiovascular disease, but the association was due to the use of extra-virgin olive oil: for each 10g/day more extra-virgin olive oil the risk of having cardiovascular disease was reduced by 10%, and the risk of dying from it by 7%. Using common olive oil did not have any benefits.

The researchers could not find a reduced risk of cancer, but they did not examine specific types of cancer. Other studies however, have shown that olive oil reduces the risk of breast cancer and some digestive and respiratory cancers.

References:

M Guasch-Ferre, F B Hu, M A Martinez et al. Olive oil intake and risk of cardiovascular disease and mortality in the PREDIMED study. BMC Medicine. 2014: 12: 78. doi: 10.1186/1741-7015-12-78. Accessed on 20/05/2014.

E Waterman and B Lockwood. Active components and clinical applications of olive oil. Altern Med Rev. 2007; 12(4): 331-342.

Choose chewier food to eat less

A mounting amount of evidence shows that eating with smaller bites and keeping your food for longer in your mouth makes you take in fewer calories. However, as all these studies have been done under standardised conditions in labs, it is not clear how you could do this in daily life. How can you keep taking smaller bites and keeping food in your mouth for longer while chatting or watching television?

© Max Blain | Dreamstime Stock Photos
© Max Blain | Dreamstime Stock Photos

In her latest article on the subject, Dieuwerke Bolhuis suggests choosing harder foods, which will need more chewing, to achieve just that without having to think about it.

Bolhuis and her colleagues asked 50 volunteers to have a meal of harder foods and one of softer foods for lunch on two different days. The volunteers ate as much as needed to feel “pleasantly full” while the researchers filmed them to determine their bite size and the time it took them to chew and swallow the food. The volunteers were invited for dinner on the same day as they had lunch. They could again eat as much as needed, and the researchers calculated the amount of energy they were taking in.

Eating harder foods indeed forced the volunteers to take smaller bites and chew longer, and led to a 13% lower energy intake. They did not compensate for this at dinner, which means that had eaten substantially less over the day without noticing any difference.

Click here to see the results as a graph: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3973680/figure/pone-0093370-g002/

If you could keep having about 13% less energy a day, you would quickly lose weight indeed. Moreover, the harder or chewier foods are often the healthier ones as well, as they are likely to be less processed or to contain more fibre. Unfortunately we do not know yet whether this can go on day after day: would your body end up compensating by eating more?

Anyway, it is certainly something to try out.

Disclaimer: this article is for general information only, and does not replace medical advice. It cannot be used to diagnose or guide treatment. If you have any concerns or questions, you should talk to a qualified health provider.

References:

DP Bolhuis, CG Forde, Y Cheng et al. Slow food: sustained impact of harder foods on the reduction in energy intake over the course of the day. PloS One 2014; 9(4): e 93379. doi: 10.1371

One glass of red wine and your health

Could drinking a glass of red wine a day further decrease your risk of cardiovascular disease on top of a healthy lifestyle?

A decanter with a red wine glass

Studies in the 1970’s have shown that people who drink just one glass of red wine a day have a lower risk of cardiovascular disease, but it is not sure if that is also true for people who exercise regularly and adopt a healthy diet. In a study published in Nutrition Journal, Dirk Droste and colleagues investigated just that, and concluded that it remains true indeed.

The researchers divided 108 high-risk patients ad random in two groups. One group adopted a Mediterranean diet and started to exercise regularly, while the other group did not change their lifestyle at all. Each group was again divided in two, and one half added daily a small amount of red wine to their diet (0.2 L for men and 0.1L for women) and the other half abstained from all alcohol. The researchers obtained therefore 4 groups:

1)      patients adopting lifestyle changes and drinking one glass of red wine

2)      patients not changing their lifestyle and drinking one glass of red wine

3)      patients adopting lifestyle changes and not drinking any alcohol

4)      patient not changing their lifestyle and not drinking any alcohol

They followed all the patients by measuring blood lipids, such as low density protein (LDL or the “bad” cholesterol) and high density protein (HDL, the “good” cholesterol), since these are well known risk factors for cardiovascular disease. After 20 weeks, lifestyle changes improved the ratio LDL/HDL by an average of 8% and red wine by an average of 13% (!). Moreover, the effect of red wine was independent of the lifestyle changes; in other words: there was an additional benefit, even though the effect of red wine was more remarkable in those who did not change their lifestyle. Even patients taking statins showed improvements.

Why red wine?

Red wine is one of the richest sources of polyphenols in the human diet. Polyphenols are powerful anti-oxidants which come from the skins, seeds and stems of grapes. The strongest and best known is resveratrol, but the amount in just one glass of red wine is probably not enough to have any effect.

Several studies have shown that alcohol can be good for your health if you drink it in moderation (a maximum of 1 drink or 12.5g alcohol a day for women and 2 drinks or 25 g alcohol a day for men). It increases HDL, is anti-inflammatory, and helps to prevent clot formation and to control glucose levels. More and more scientists now think that the health benefits of red wine are simply linked to a daily light consumption of alcohol and not to resveratrol. Consequently, scientists have tried to find out if beer can be just as beneficial as wine, but studies are  contradicting.

Do not drink too much!

Alcohol increases your risk of high blood pressure, stroke, liver disease and various tumours, such as breast and colorectal cancer. Even small amounts increase your risk of cancer, as there is no “safe” dose and light drinking does not protect you at all in this case. Overconsumption leads to violence and accidents. The end result is a J-shaped relationship between alcohol and overall mortality, whereby light drinking increases your chances of a long life and heavy drinking reduces it.

No Alcoholic Beverages
No Alcoholic Beverages (Photo credit: Travis S.)

What does it mean for me?

Nobody will advise you to drink alcohol to improve cholesterol levels, because the dangers linked to overconsumption are too important. It is indeed impossible to know in advance who is going to be able to remain a daily light drinker and who is not.

If you do not drink alcohol, do not start, as the risks are too large. However, if you use alcohol, try to limit your consumption to 1(women) or 2 (men) units a day.

Disclaimer: this article is for general information only, and does not replace medical advice. It cannot be used to diagnose or guide treatment. If you have any concerns or questions, you should talk to a qualified health provider

References:

D Droste, C Iliescu, M Vaillant et al. A daily glass of red wine associated with lifestyle changes independently improves blood lipids in patients with carotid arteriosclerosis: results from a randomized trial. Nutrition Journal 2013; 12: 147. doi: 10.1186/1475-2891-12-147.

J O’Keefe, K Bybee and C Lavie. Alcohol and cardiovascular health: the razor-sharp double-edged sword. JACC 2007; 50(11): 1009.

P Ronsky, S Brien, B Turner et al. Association of alcohol consumption with selected cardiovascular disease outcomes: a systematic review and meta-analysis. BMJ 2011; 22: 342. doi: 10.1136/bmj.d671.

Apple peel is good for your health

As children, we have been told that “an apple a day keeps the doctor away” and now more and more studies are showing that this is true, especially if you eat the peel as well.70.145.93.68 21:54, 9 March 2008 (UTC) Differe...

Fruit and vegetables contain phytochemicals, which are substances such as carotenoids, flavonoids and phenolic acids. Scientists have identified thousands of them, but many more are still to be discovered. They are responsible for many of the benefits of fruits and vegetables, as they are anti-oxidants, which are molecules that help to protect you against the effects of free radicals.

Reactive oxygen species

Free radicals, such as reactive oxygen or nitrogen species (for simplicity we will call all of them “ROS”), are a normal by-product of your metabolism. They can cause cell injury and death, and your body has therefore a defence system of anti-oxidants to keep them under control.

Oxidative stress occurs when there are more ROS than your defences can handle, and leads to damage of your DNA, lipids and proteins. As this accumulates over the years, it results in ageing and increases your risk of chronic illnesses such as cardiovascular disease and cancer. An effective anti-oxidant system can therefore slow down aging and help to prevent chronic disease.

As there are many different ROS, your body needs many different anti-oxidants. Your body can make some of them itself, but others have to come from your diet, and vegetables and fruits are a good source.

ROS are not totally bad though, as they are important for cell growth and inflammatory reactions. Destroying all of them is thus harmful; your body just has to be able to regulate them. The advantage of getting your anti-oxidants from your diet is that your body is able to pick and choose what it needs, and to let go what it has already in abundance.

Health effects of apples

Epidemiological studies have shown that people who eat apples on a regular basis suffer less from lung cancer, cardiovascular disease, asthma and type II diabetes. Eating apples has also been linked to weight loss.

Laboratory studies have shown that the total anti-oxidant activity of 100 g apple with peel corresponds to 1500 mg vitamin C. As 100 g apple contains only 5.7 mg vitamin C, most of this anti-oxidant activity must come from a variety of phytochemicals. Researchers believe that these substances complement and stimulate each other, so that together they achieve much better results than the individual substances could ever do. This explains why it is so important to eat whole-, unprocessed foods.

Most of the anti-oxidants are in the peel. Consequently, apple juice is less good for you than the whole fruit, even though it is still a good source of anti-oxidants.

Apples lower your cholesterol levels by reducing its absorption, and research has shown that this due to the combined effects of fibres and phytochemicals.

In the lab, studies on cell cultures have demonstrated that apple can decrease the proliferation of cancer cells. Again, this was more pronounced when apples with peels were used. Different varieties of apples had different effects on cancer cells, suggesting that the unique combination of phytochemicals of each variety is important.

Phytochemicals

Researchers have noticed that different varieties of apples contain different kinds and amounts of phytochemicals. For example, Rome Beauty apples have a high phenolic content, while Jonagold contain plenty of quercetin. In general, there are more phytochemicals in sun ripened fruit than in fruit that has grown in the shade. Storage on the other hand, does not have much effect.

English: Apples on an apple-tree. Ukraine. Рус...

Do not waste the peels

As mentioned earlier, most of the phytochemicals are situated in the peel. By processing apples to make juice or puddings, we lose much of the health benefits of apples, unless, of course, we could keep the peels. Research has shown that blanching them for 10 seconds and then air- or freeze-drying them conserves most of the phytochemicals. The treated peels could then be used in food, or turned into a powder to promote health.

How could we use apple peels in food? If you have any ideas, please let us know.

References

Boyer J and Lu RH. Apple phytochemicals and their health benefits. Nutr J. 2004; 12: 3-5.

Lu RH. Potential synergy of phytochemicals in cancer prevention: mechanism of action. J Nutr. 2004; 134 (12 Suppl): 3479S-3485S.

Wolfe KL and Lu RH. Apple peels as a value-added food ingredient. J Agric Food Chem. 2003; 51(6):1676-1683.

Fats, carbohydrates and how to keep your heart healthy

A breakfast very high in saturated fat

Saturated fat from your diet increases your LDL and total cholesterol, but stating that this puts you at an increased risk of cardiovascular disease, as we have done for many years, is too simplistic.

Most fats in your food and in your body are triglycerides, which consist of 3 fatty acids. Whether these fatty acids are saturated or unsaturated varies with your diet, as triglycerides can be made up of fats that you have eaten or fats made by your liver from other energy sources such as carbohydrates.

Cholesterol is another kind of fat that you can get from food or produced by your liver.

As fat cannot dissolve in blood, most of it is moved around your body in small particles, called lipoproteins. The most important ones are the low density lipoproteins (LDL) and the high density lipoproteins (HDL). LDL carries cholesterol and fat from the liver to the rest of your body, where they are needed by your cells for energy production and to make essential substances such as hormones. HDL picks up the surplus of LDL from your blood and brings it back to your liver.

Atherosclerosis

How exactly atherosclerosis plaques develop is still not well understood, but as far as we know LDL particles get trapped in the vessel wall, where they become oxidized by free radicals. This creates an inflammatory reaction which leads eventually to the formation of a plaque.

Too much saturated fat in your blood can also cause an inflammatory reaction, and can therefore start and/or aggravate the situation.

Studies have shown that too much low density lipoprotein or LDL puts you at a higher risk of cardiovascular disease, and that high density lipoprotein or HDL protects you. LDL is therefore often called “bad” cholesterol and HDL “good” cholesterol, and clinicians use the LDL/HDL ratio or the total cholesterol/HDL ratio to estimate your risk. The amount of triglycerides in your blood is also important.

To keep your vessels healthy, you want a diet that is anti-oxidant and anti-inflammatory, improves the LDL/HDL ratio and lowers the amount of triglycerides.

Trans-fats

Everybody agrees that industrial trans-fats are bad for your health. They are made by hydrogenating vegetable oils and, as they are more stable than other fats, are ideal for frying and making processed food. However, they increase LDL and lower HDL, and you should therefore avoid them. Some whole foods such as milk contain small amounts of trans-fats, but there is evidence that these are different from the industrial ones and do not harm you.

Salers Cow. Milk and meat from cows and other ...
Salers Cow. Milk and meat from cows and other ruminants contains naturally occurring trans fats in small quantities (Photo credit: Wikipedia)

Saturated fats

Saturated fats are typically found in red and processed meat, butter and other forms of animal fats. Previously, scientists thought that eating too much saturated fats increases your risk of cardiovascular disease, as they raise your LDL. However, studies do not confirm this.

Their effects on your health vary depending on which food they come from. Red meat contains cholesterol and heme iron that probably increase the risk, and processed meats contain preservatives that are bad for your health. Milk and milk products on the other hand, are a good source of nutrients such as calcium, potassium, phosphorus and vitamin D. As a result, they lower your risk of cardiovascular disease.

Different foods contain different proportions of specific saturated fats, combined or not with other fats, and affect therefore your risk factors in different ways. Unfortunately, we do not understand this fully yet and we need more research.

Most scientists agree that you should try to limit your intake to about 10% of your energy, but it is very controversial that limiting it even further is helpful. Moreover, an important question is by what you replace it.

Mono-and poly unsaturated fats

Replacing saturated fats by mono-unsaturated fats improves the LDL/HDL ratio slightly. A Mediterranean diet is good for your heart and blood vessels, but modern studies could not proof that this was due to its high mono-unsaturated fat content.

Many studies have shown that replacing saturated fats by polyunsaturated fats is beneficial. Unfortunately, they did not differentiate between trans-fats and saturated fats and some scientists think that the beneficial effects were due to the fact that the trans-fats were taken out of the diet, and had nothing to do with reducing the saturated fats.

This is a controversial and rapidly evolving subject, and it is therefore a good idea to keep informed about the latest findings. As yet, it is prudent to reduce the amount of saturated fats in your diet to about 10%, and to favour polyunsaturated fats.

Sources of mono-unsaturated fat include nuts, olives, vegetable oils and avocados, but also beef and milk. You will find polyunsaturated fats in food such as seeds, nuts and fish.

Carbohydrates

In practice, fats are often replaced by carbohydrates. Unfortunately, this increases the risk of cardiovascular disease, because your liver transforms the surplus of carbohydrates into saturated fats. These interact then with your immune system, which leads to a chronic, low-level inflammation and stimulates the formation of atherosclerotic plaques.

The situation is especially bad when you are eating high glycemic index foods.

The glycemic index ranks carbohydrate-containing foods according to how quickly they increase the glucose levels in your blood. Foods such as white bread, pretzels or sugary drinks are high glycemic, as they have a score of more than 70, while carrots, lentils or apples are low glycemic (their score is less than 55). You can find lists in books or online, for example here.

We should therefore reduce the amount of carbohydrates with a high glycemic index, eliminate industrial trans-fats from our diet and consume more vegetables, fruit and fish.

Saturated fats are not the only cause of chronic inflammation: sleep deprivation, smoking, inactivity and stress are also important factors. It is not enough to have a healthy diet; you need to have a healthy lifestyle.

English: vegetablesDisclaimer: this article is for general information only, and does not replace medical advice. It cannot be used to diagnose or guide treatment. If you have any concerns or questions, you should talk to a qualified health provider.

References:

M de Oliveira Otto, D Mozaffarian, D Kromhout et all. Dietary intake of saturated fat by food source and incident cardiovascular disease: the multi-ethnic study of atherosclerosis. Am J Clin Nutr. 2012; 96(2): 397-404.

R Kuipers, D de Graaf, M Luxwolda et al. Saturated fat, carbohydrates and cardiovascular disease. Neth J Med. 2011; 69(9): 372-378.

K Kingsbury and G Bondy. Understanding the essentials of blood lipid metabolism. www. medscape. com; accessed 13/10/2013.