Tuesday, July 28, 2009

Hibiscus Tea Lowers Blood Pressure

A cup or two of hibiscus tea is an effective remedy for hypertension.
A cup or two of hibiscus tea is an effective remedy for hypertension. (Photo by debra solomon)

Hibiscus tea (sometimes called sour tea) is a herbal drink made from the calyces of the Hibiscus sabdariffa flower. It is also commonly mixed with other ingredients such as ginger and sugar to make a chilled beverage known as agua de jamaica or rosa de jamaica.

Hibiscus tea is believed to reduce blood pressure and cholesterol. While there are no studies looking at the effect of hibiscus on cholesterol levels, I did find two studies that showed positive results in treating high blood pressure. In this post, we'll take a look at both papers.

Study methods

In the earlier study, men and women with moderate hypertension were randomly assigned to either an experimental or a control group (link). Inclusion criteria were a systolic pressure of 160-180 mmHg and/or a diastolic pressure of 100-114 mmHg. Mean age in both groups was slightly over 50 years.

The experimental group was given a box of hibiscus tea, while the control group was given ordinary tea (black tea, I assume, though the authors don't say). The participants were instructed to use two spoonfuls of tea in one glass of boiled water at least one hour before measuring blood pressure.

The newer study used sixty diabetic patients with mild hypertension (link). Participants were told to drink either hibiscus tea or black tea twice a day for one month. Blood pressure was measured on days 0, 15 and 30.


After 12 days of drinking a cup of hibiscus tea, the experimental group in the first study showed a 11.2% decrease in systolic pressure and a 10.8% decrease in diastolic pressure, as compared to the first day. The control group showed a slight decrease in systolic pressure but not in diastolic pressure.

Systolic blood pressure in hibiscus tea and black tea drinkers
The above graph shows the systolic blood pressure of the experimental and control groups. Here is the graph showing changes in diastolic blood pressure:

Diastolic blood pressure in hibiscus tea and black tea drinkers
As you can see, both systolic and diastolic blood pressure went down in those who drank hibiscus tea for 12 days and then increased from day 12 to day 15. This is because after the twelve days, the participants were told to stop drinking tea and measured their blood pressure again after three days.

After stopping tea drinking, there was almost no change in the control group, while the blood pressure of the hibiscus tea drinkers quickly catched up with the control group. Hence, blood pressure was significantly affected by hibiscus tea but only slightly by ordinary tea. Furthermore, the authors speculate that the lowered blood pressure in the control group may in fact have been a result of the health advice given at the beginning of the study.

In the study with diabetic patients, systolic blood pressure went from 134.4 to 112.7 mmHg in those who drank hibiscus tea twice daily for a month. In those who drank black tea instead, systolic blood pressure increased from 118.6 to 127.3 mmHg. No statistically significant changes were seen in diastolic blood pressure in either group.

Mean pulse pressure, which is the difference between systolic and diastolic blood pressure, decreased in the hibiscus drinkers from 52.2 to 34.5 mmHg, while it increased in the black tea drinkers from 41.9 to 47.3 mmHg.


Hibiscus tea lowers blood pressure significantly in patients with mild to moderate hypertension. In one study, both systolic and diastolic pressure were lowered as a result of drinking hibiscus tea, while in another one only systolic pressure decreased.

In diabetic patients with mild hypertension, systolic pressure increased after drinking black tea daily, while diastolic pressure remained the same. In non-diabetic patients with moderate hypertension, both systolic and diastolic blood pressure decreased slightly after drinking black tea.

For more information on tea and blood pressure, see these posts:

Intermittent Fasting with a Condensed Eating Window – Part II: Blood Pressure, Body Weight & Cholesterol
A High-Protein Diet Is Better than a High-Carbohydrate Diet for Weight Loss
Green Tea Extract Increases Insulin Sensitivity & Fat Burning during Exercise
Drinking 10 Cups of Green Tea Daily and Not Smoking Could Add 12 Years to Your Life

Read More......

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Monday, July 27, 2009

Green Tea Protects from the Psychological Effects of Stress in Rats

Feeling stressed? Enjoying a cup of green tea with your lunch may help.
Feeling stressed? Enjoying a cup of green tea with your lunch may help. (Photo by chotda)

It's no secret that a cup or two of green tea can make you relaxed, but now scientists have shown that green tea can reduce the effects of psychological stress in rats.

In a paper yet to be published, rats were put under stress and given either their usual diet or a diet enriched with green tea polyphenols (link). To see how psychological stress and green tea were related, experiments measuring cognitive performance and serum levels of stress hormones were done.

Study method

The rats were divided into five groups: control group (CT), stress group (ST), and three stress groups given low, medium and high doses of green tea polyphenols (LG, MG and HG). The green tea polyphenol (GTP) content of the three diets were 0.1%, 0.5% and 1%, respectively.

Psychological stress was induced by keeping the rats restrained and inhibiting their movements six hours every day for three weeks. Their cognitive performance was then evaluated using an open-field test, a step-through test and a water maze. These tests measure both the activity level and memory ability of rats.

Green tea polyphenols and cognitive performance

In the open-field test, which measures how actively rats explore the arena, the stressed rats were much less active than the control rats. No significant improvement was seen in the rats fed the low dose of green tea polyphenols, while the rats given the medium or high dose were almost as active as the control rats.

The memory of the rats was also affected by stress during the step-through test and water maze test. These tests measure spatial memory and the ability to remember adverse stimuli. Again, only the medium and high doses of GTPs significantly reduced the harmful effects of stress on the rats' memory.

Green tea polyphenols and stress hormones

Stress activates the symphatetic nervous system, which results in a release of catecholamines. Catecholamines are "fight-or-flight" hormones that consist of epinephrine, norepinephrine and dopamine. They are involved in the modulation of cognition, awareness, attention, and emotional state, helping the body to cope with a stressful situation. According to the authors, when the stress level is too high for the body to cope with, cognitive impairments appear and the levels of these hormones begin to decline.

Plasma levels of norepinephrine (another stress hormone, also known as noradrenaline) and dopamine were remarkably reduced in the ST and LG rats. In the MG and HG groups norepinephrine and dopamine levels were lower than in the control group, but much higher than in the LG group. In other words, medium and higher levels of green tea polyphenols partially inhibited the stress-induced decrease in the levels of these hormones.

All four stress groups had higher levels of plasma cortisol than the control group. Cortisol is often referred to as the "stress hormone", since its levels increase in the presence of stress and anxiety. Cortisol also causes blood pressure to rise and immune responses to be reduced. Feeding the stressed rats green tea polyphenols lowered their cortisol levels, but the reduction was statistically significant only in the MG group.

The levels of reactive oxidative species (ROS) were increased in the brain tissue of stressed rats, but again, medium and high doses of GTPs partially inhibited this increase. Similarly, the total antioxidative capacity in brain tissue was reduced by stress but to a smaller extent in the MG and HG groups. The levels of superoxide dismutase showed a similar trend, but the differences were not statistically significant.

A different effect was seen in the levels of interleukin-6 and interleukin-2. While stress increased IL-6 and IL-2, feeding the rats GTPs did not inhibit this increase. In fact, green tea polyphenols increased IL-6 even further. This may be because increased levels of IL-6 can enhance the body's adaptability to stress. Similar effects have been reported in other studies on green tea.


Psychological stress negatively affected the behavior and memory of rats. This adverse effect was associated with higher levels of cortisol, reactive oxygen species, IL-2, and IL-6, and lower levels of norepinephrine, dopamine, and total antioxidative capacity.

These changes were partially inhibited by diets containing 0.5% and 1% green tea polyphenols, except for IL-6, which was further increased by GTPs. A diet containing only 0.1% GTPs did not show significant results.

For more information on green tea and cognition, see these posts:

Green Tea Protects from Bone Loss in Female Rats
Green Tea Protects from Arthritis in Rats
Does Taurine Improve Cognitive Performance and Mood?
Does Ginkgo Biloba Improve Cognitive Performance?

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Friday, July 24, 2009

Whitening Teeth & Healing Gums – Experiment Update: Colgate Sensation White

The search for the perfect teeth whitening toothpaste continues.
The search for the perfect teeth whitening toothpaste continues. (Photo by jet platypus)

It's time for another update on my teeth whitening & gum healing experiment, which has been going on for quite a while now. As you may have guessed, the idea behind the experiment is to find safe and easy ways to whiten teeth and stop gums from receding.

To recap, for the past months I've been brushing my teeth with Colgate's Sensation White. This toothpaste has something called "micro-cleaning crystals", which are supposed to get rid of stains from coffee, tea, etc. According to Colgate, regular use will have a whitening effect in general. As a sign of confidence, the toothpaste even comes with a color strip to compare your teeth against.

I thought the included color strip was a great idea, but in practice, it's surprisingly difficult to find an exact match for your teeth color. So I decided to just rely on visual inspection. Subjective as it may be, I can say with a fair amount of certainty that my teeth are no whiter than they were before using Colgate. In fact, I would go as far as to say that they may have gotten even more discolored during these months.

This is most likely due to the fact that I drink several cups of green tea per day. While it most likely has a smaller effect than black tea, it still stains teeth in the long run. Another culprit is coffee, which I love. None of the supposed nootropics I've tried so far give me that mood-lifting energy boost quite like coffee does.

Two cups per day is my maximum at the moment. While it's not as much as many other coffee lovers I know, it probably has a significant effect on teeth color even in these amounts. And then there's dark chocolate, possibly my favourite food in the world. Goes brilliantly with coffee, mind you. I suspect consuming a copious amount of cocoa powder each day doesn't exactly make teeth sparkle, either.

It's important to note here that while staining, coffee, tea and cocoa are all good for dental health in general. It's just that the color and health of your teeth don't necessarily go together. For me, the choice between a longer life and shiny teeth is clear. Combining both would be optimal, of course.

My trust in whitening toothpastes is waning rapidly, but nonetheless, I have chosen another product for testing. This one is an ordinary store brand toothpaste with a claimed whitening effect. According to the label, the patented whitening mechanism is based on a combination triglycerides and hydrated silica. The latter is a common compound in toothpastes, as it a mild abrasive that helps in removing plaque and apparently also whitens teeth to some degree. Triglycerides in toothpaste is a new one for me, however.

I could just stop drinking tea and coffee for the duration of the experiment, but since most people looking to whiten their teeth are probably unwilling to quit enjoying their favourite beverages, I feel the experiment is much more interesting this way. If there's a product out there that can really make teeth whiter despite near-constant bombardment with tea, coffee and chocolate, then hey, we've got it made.

And if such a product indeed exists, I intend to find it.

For more information on dental health, see these posts:

Dental Health Effects of Green and Black Tea
The Role of Coenzyme Q10 in Oral Health
Tea, Coffee and Cocoa: All Good for Your Teeth
Preventing Mouth Ulcers with Tea Tree Oil Toothpaste - Results after Two Months

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Wednesday, July 22, 2009

Slowing Down Aging with Intermittent Protein Restriction

ne serving (140 g) of pasta contains 8 grams of protein.
One serving (140 g) of pasta contains 8 grams of protein. (Photo by ex.libris)

I've written a lot about the health benefits of caloric restriction and intermittent fasting on this blog. But what if those same benefits could be had by periodically restricting protein intake?

According to Ron Mignery, author of "Protein Cycling Diet" (which is free, by the way), staying away from protein every once in a while shares a lot of the health effects of caloric restriction and intermittent fasting. Obviously, protein cycling is much easier, because it's not the energy intake but the protein intake that matters. Here's a quote from the introductory chapter:

Protein cycling is intended as a way for you to live longer and healthier with minimal interference with your normal routine and diet. It is based on well-established observations that animals and people who have endured periods of famine have extended life spans compared to those who have not and on more recent observations that periodic protein restriction alone can accomplish the same thing.

The key to the benefits of protein cycling is autophagy, a process in which a cell consumes a part of itself for energy. Starvation is one way of inducing autophagy: since there is no external source of energy, the body begins to use its own cell material to keep things running smoothly. This also happens to be an effective way of getting rid of accumulated junk in the cells, something which is difficult to do otherwise.

Mignery argues that autophagy is the reason why calorie restriction (CR) and intermittent fasting (IF) work the way they do, and that by the same logic, protein cycling should extend life too. He also points out that protein cycling may be something we're evolutionarily adapted to:

Before we managed fire, our days were governed by the sun. In the tropics, the sun is down for 12 hours every day. Without fire, there is little to do in the dark but sleep. So our ancestors likely fasted at least 12 hours every night even if they ate continually throughout the day. A 12 hours fast with our ancestors' diet may have been sufficient to induce autophagy and perhaps they were already protein cycling.

So what does a protein cycling diet look like in practice? Mignery gives a lot of interesting calculations in his book, which I urge you to check out, but let's skip straight to the conclusion:

From the table we can see that 3 days a week of protein restriction would be sufficient to counteract an exponential accumulation that doubles every 2.5 years. This then is my most recommended regime: three 24 hour periods each week where very little protein is consumed.

Sound familiar? If you're a long time reader of this blog then it should, because three days of not eating protein per week is pretty much what the 24/24 hour cycle version of intermittent fasting (also known as "alternate-day calorie restriction" and "alternate-day feeding") looks like. Since you're not consuming any calories during a fast, you're obviously not consuming any protein either.

So, it seems that whatever benefits protein cycling has, intermittent fasting has too. But that is not the point, of course. The point Mignery makes is the opposite: that the benefits of intermittent fasting can be had without restricting all calories as long as you restrict proteins. Yes, you read correctly. Unlimited carbs and fat.

But before you order that vegetarian pizza with extra cheese to kickstart your protein fast, there's a small caveat: protein is in almost everything. And, unfortunately for our purposes here, only very little is needed to keep autophagy at bay:

A less active adult male of any weight or caloric consumption gets his minimal protein requirement when the calories he gets from protein exceed 4% of his total caloric intake.

For someone on an average 2,000 kcal diet, that would mean less than 80 kcal (or 20 grams) from protein is acceptable. Anything above that is a bad idea during a protein fast. Thus, commonly known protein-rich foods such as meat, fish, eggs, beans and lentils are obviously out of the question.

But even carbohydrate-based foods are surprisingly high in protein. For example, cooked pasta contains 6 grams of protein per 100 grams. Even rice, which has the lowest protein percentage of grains consumed in the Western diet, still has 2 g protein per 100 g. Even if you ate nothing but rice for your daily calories, you would get enough protein to prevent autophagy.

So you would have to be very careful in constructing your diet during the protein restriction periods. In practice, I think you would have to reduce total energy intake during a protein fast and choose foods that are low in protein. Fats and oils (with little to no protein) could be enjoyed liberally, while carbs (some of which come with fairly large quantities protein) would need more careful attention.

That said, if Mignery is right, protein cycling still seems easier than intermittent fasting – and much easier than caloric restriction. If you're unwilling to cut back on your total food intake or do zero-calorie fasting but would like to have some of the benefits associated with IF and CR, I encourage you to read the book. Perhaps you will find protein cycling a good place to start.

At this point, I'm not entirely convinced that either intermittent fasting or protein cycling will have the same benefits as caloric restriction, which has been studied more extensively and in a wider range of species. It's not clear to me that autophagy alone is the reason why CR works, or even why IF works.

That said, it does seem clear that autophagy has a wide range of positive health effects. Anything that reduces and reverses the accumulation of junk inside the body seems like a worthwhile effort to me. I suspect autophagy will continue to receive attention within the next few years.

For more information on caloric restriction and intermittent fasting, see these posts:

Intermittent Fasting: Switching from Alternate-Day Fasting to Condensed Eating Window
Intermittent Fasting: Understanding the Hunger Cycle
Caloric Restriction Improves Memory in the Elderly
Anti-Aging in the Media: New York Times on Caloric Restriction and Resveratrol

Read More......

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Monday, July 20, 2009

Eclipta Alba Extract Grows Hair Quicker than Minoxidil

Eclipta Alba Grows Hair Quicker than Minoxidil
Eclipta alba promotes hair growth in rodents. (Photo by ilexxx)

Eclipta alba (also known "Bhringraj" and "False Daisy") is a tropical herb that has been used to treat various illnesses. A traditional use for it in Ayurvedic medicine has been hair loss treatment and hair dyeing.

While many traditional remedies have not been scientifically studied, Eclipta alba has not one but two actual studies behind it showing hair growth promoting activity in rodents. In the first paper, petroleum ether and ethanol extracts of the herb were compared against minoxidil (link). The second paper also used minoxidil as a positive control, but this time the extract was made with methanol (link).

To get an overview of how effective Eclipta alba really is for growing hair, in this post we'll be comparing the results from both papers.

The three Eclipta alba extracts

In the first paper, 500 grams of dried coarse powder of Eclipta alba was initially extracted with petroleum ether. The resulting marc was further extracted with ethanol to make the ethanol extract. These extracts were then incorporated into an ointment base in concentrations of 2% and 5% (i.e. the resulting ointments contained 2-5% ethanol extract).

In the second paper, 1 kilogram of Eclipta alba was extracted with 95% methanol and then filtered and concentrated. The final formulations contained either 3.2 mg/kg or 1.6 mg/kg of the extract in a solution of propylene glycol and DMSO.

Study design

The petroleum ether & ethanol study used six groups of rats with their backs shaved. Group I was applied ointment base only and served as control, Group II was applied 2% ethanol extract, Group III was applied 5% ethanol extract, Group IV was applied 2% petroleum ether extract, Group V was applied 5% petroleum ether extract, and group VI was applied 2% minoxidil and acted as positive control. The ointments were applied for 30 days.

In the methanol study, mice with hair already in telogen phase were selected. Two experiments were done: the first one compared the effectiveness of 1% and 2% minoxidil to a control vehicle, and the second one looked at the effectiveness of 1.6 mg/kg and 3.2 mg/kg methanol extracts of Eclipta alba. The extracts were applied for 10 days.

Results from Eclipta alba in rats

Shaved rats treated with the petroleum ether extract of Eclipta alba began growing new hair significantly faster than rats in the control group. Whereas the control rats took 12 days to initiate hair growth, the petroleum ether extract rats took only 5 to 6 days, with the stronger ointment being slightly more effective. The time it took to completely cover the shaved area in hair was also decreased from 24 days to 20 days.

2% minoxidil reduced hair growth initiation time to 6 days and completion time to 20 days. Therefore, minoxidil was as effective as 2% petroleum ether extract but slightly less effective than 5% petroleum ether extract. Ethanolic extracts reduced the time of hair growth initiation only slightly and had no effect on completion time.

The hair growth effects were due to a marked conversion of hair follicles from telogen to anagen phase. In the control group and ethanol extract group, most of the follicles were in telogenic phase, while in the minoxidil and petroleum ether extract groups most follicles were in anagenic phase. Notably, petroleum ether extract of Eclipta alba was even more effective in inducing anagen phase than minoxidil.

Petroleum ether extract also increased the length of the hair follicles, similarly to minoxidil. In the control group only 34% of follicles were longer than 0.5 mm. In the extract and minoxidil treated groups the percentage was 44-49%, with minoxidil being most effective. Once again, ethanol extract did not have a significant effect.

Results from Eclipta alba in mice

Conversion from telogen to anagen phase was observed in 87.5% of the mice treated with the stronger methanol extract (3.2 mg/kg) and in 50% of the rats treated with the weaker extract (1.6 mg/kg). This was evidenced by the increased number of follicles in the subcutis layer and a thickening of the skin. The total number of follicles was also increased. None of the control rats showed a similar effect.

Both concentrations of minoxidil increased skin thickness, follicle count and the percentage of follicles in anagen phase. 2% minoxidil was slightly more effective than 1% minoxidil. According to the authors, the effects of minoxidil and the methanol extracts were "comparable", but looking at the data, it seems that the stronger extract of Eclipta alba was in fact significantly more effective. For example, 2% minoxidil increased mean follicle count from 43 to 73, whereas the 3.2 mg/kg methanol extract increased it from 19 to 66. The conversion from telogen to anagen was also more pronounced in the methanol extract group.


A petroleum ether extract of Eclipta alba increases hair growth in rats by converting follicles from telogen to anagen phase. The hair growth promoting effect is similar to that of minoxidil. An ethanol extract, however, showed only very modest results. No change in fur color was reported.

In mice, methanol extracts of Eclipta alba induce conversion of hair follicles from telogen to anagen phase. Eclipta alba also increases skin thickness and the number of total and subcutaneous hair follicles. These effects are even more pronounced than those seen from 1% and 2% minoxidil. Since the mice had black fur to begin with, the hair dyeing claims could not be evaluated.

Possible reasons for the lack of efficacy in ethanol extracts of Eclipta alba are the lack of wedelolactone and beta-sitosterol. While petroleum ether extracts and methanol extracts contain significant amounts of wedelolactone, ethanol extracts do not. Wedelolactone has the abilitiy to suppress caspase-11 (link) and androgen receptors expression (link).

Petroleum ether extracts are also high in beta-sitosterol, which has been shown to inhibit 5-alpha-reductase (link), a key factor in genetic hair loss. The beta-sitosterol content of methanol extracts of Eclipta alba was not reported in the study.

For more information on hair growth, see these posts:

Soy Protein Isolate Reduces DHT in Healthy Young Men
Do Flax Lignans Reduce Hair Loss from MPB?
North African Plant Extract (Erica multiflora) Increases Hair Growth
2% Nizoral Shampoo Increases Hair Growth More than 2% Minoxidil

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Friday, July 17, 2009

Who Wants to Live Forever? Results from a Global Survey

Brazilians like to enjoy life – indefinitely.
Brazilians like to enjoy life – indefinitely. (Photo by morrissey)

If you had the choice to live forever, would you?

Before answering, let me remind you that we're not talking about being doomed to spend an eternity in poor health. A million years of dementia in a nursing home is not what this question is about. Rather, we're talking about having the option to stay youthful for as long as you wish.

Reader's Digest asked this question from people around the world and got some interesting results. Seventeen countries in total participated in the questionnaire, with 150 people in each country surveyed. Here's a quote from the website:

So much for eternal youth! Most respondents to our latest global survey are just fine with their limited shelf life here on earth. Not even the younger crowd consistently chooses immortality. In fact, more than 50 percent of those 45 and under in seven countries (including the United States) report that they don't want to live forever. Brazilian youth buck the trend, with 74 percent preferring no expiration date. Two surprises: In the Philippines, everyone over 45 wants life everlasting; in China, not a single older survey-taker does.

Who would have thought that the country with the most positive attitude towards life extension would be Brazil? Apparently 72% of all Brazilians prefer living forever. Women were slightly more negative than men, with 66% and 77% answering the call to immortality, respectively.

At the bottom of the longevity list are the Russians, only 36% of whom answered yes. A closer look reveals that it's really the women who are against the idea of dramatically increasing lifespans: a whopping 73% answered no, while the same figure in the male group was only 55%.

In fact, if you look at the results from each individual country, you can see that this same trend is found in many countries. For some reason, women in general appear more hostile towards life extension than men. The countries where the opposite is clearly true are China, India, Singapore, Spain and Turkey.

Some may see these results as worrying – after all, why would anyone not want to stay young and healthy? – but I'm fairly optimistic about their implications. The fact is that in over 40% of the countries, the majority of people did want to live forever. That's not a bad number at all. I'm guessing that if this same survey had been done 10 or 50 years ago, the general atmosphere would have been more negative.

It seems to me that the life extension meme is definitely spreading. All you have to do is to look at the news to see it happening. Not only are we making scientific discoveries related to aging preventation, but we're also seeing more and more positive news reports on the subject. Slowly but surely, the attitudes are changing.

And even though time is the enemy, in this case, it's also on our side. To quote the German physicist Max Planck:

A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.

So it is with life extension. Those who prefer old age, decrepitude and death to good health, youthfulness and life, will eventually disappear from the face of the earth by natural means, leaving us immortalists to pursue our search for eternal happiness. Hopefully we'll still be around.

So, time to ask the question again. If you had the choice to live forever, would you?

For more information on aging and living longer, see these posts:

How to Live Forever: My 5 Steps to Immortality
Biotechnology and the Future of Aging
Anti-Aging in the Media: Vancouver Sun on Immortality
End Aging to End Anxiety: Filmmaker Jason Silva Talks about Immortality

Read More......

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Monday, July 13, 2009

Anti-Aging in the Media: New York Times on Caloric Restriction and Resveratrol

The monkey on the left has been on a calorie restriction diet for over a decade.
The monkey on the left has been on a caloric restriction diet for over a decade.

Caloric restriction (CR) has been shown to extend the lifespan in a range of species, but the most exciting study has been the one on Rhesus monkeys. The study, led by Weindruch and Colman, has been going on for more than 20 years now.

Last week, new results regarding the monkeys were reported, and New York Times published an article discussing whether they might be translatable into humans. Dr. Weindruch, quoted in the article, seems to be very optimistic:

The researchers say that now, 20 years after the experiment began, the monkeys are showing many beneficial signs of caloric resistance, including significantly less diabetes, cancer, and heart and brain disease. “These data demonstrate that caloric restriction slows aging in a primate species,” they conclude.

I'm fairly confident we will eventually see a statistically significant increase in maximum lifespan in the monkeys, but I think it's somewhat premature to state it as a fact while the study is still running. I guess 20 years of waiting for conclusive results is a lot even for a patient scientist.

Looking at the pictures of the calorie-restriced monkeys next to the normally fed monkeys, it's evident that something good is happening – or rather, something bad is being prevented. The CR monkeys do look healthier and, well, younger. Here's a couple of more pictures (with the calorie-restricted monkey on the left):

Calorie-restricted vs. ad libitum-fed Rhesus monkeyCalorie-restricted vs. ad libitum-fed Rhesus monkey

All in all, for everyone out there doing CR this study seems to be positive news. For many others, this is just the first step, however. Learning how calorie restriction works will perhaps be even more important than seeing that it works. Drugs and treatments that target the same pathways can then be developed without the need to reduce calorie consumption dramatically. The article mentions resveratrol as a possible substance to replace calorie restriction:

Few people can keep to a diet with 30 percent fewer calories than usual. So biologists have been looking for drugs that might mimic the effects of caloric restriction, conferring the gain without the pain. One of these drugs is resveratrol, a substance found in red wine, though in quantities too small to have any effect.

Dr. Weindruch said the study data offered “very encouraging” signs that resveratrol could duplicate in people some of the effects of caloric restriction.

It's important to note that "duplicating some of the effects of caloric restriction" is not the same things as extending lifespan. Yes, it may help people with diabetes live longer, but there's no evidence out there that shows resveratrol increases maximum lifespan in healthy humans or animals.

Not to bash on resveratrol, though; I think it's one of the most interesting supplements out there. It just won't make us live to see a thousand, despite what some people would have you believe.

For more information on caloric restriction and resveratrol, see these posts:

Anti-Aging in the Media: 60 Minutes on Resveratrol
Caloric Restriction Improves Memory in the Elderly
Green Tea Increases Weight Loss during Caloric Restriction in Rats
Anti-Aging in the Media: Houston Press on Caloric Restriction

Read More......

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Thursday, July 9, 2009

SAs, MUFAs vs. PUFAs: Fat Storage Depends on Type of Fatty Acid in Rabbits

SAs, MUFAs vs. PUFAs: Fat Storage Depends on Type of Fatty Acid in Rabbits
The stearic acid in cocoa butter is not well stored into fat tissue. (Photo by LilyBaySoap)

When it comes to storing dietary fat into fat tissue, are all fatty acids created equal?

Recently, I've been trying to find out more information on how different types of fats are absorbed and stored as adipose tissue. In particular, I would like to see direct comparisons between saturated, monounsaturated and polyunsaturated fat and how they affect weight and fat gain in humans when energy intake is kept constant. So far, I haven't had much luck finding such studies.

What I did find is an old paper that looked into how different dietary fatty acids relate to fatty acids in adipose tissue (link). In other words, the authors studied whether the ratio of saturated and unsaturated fats in fat tissue is similar to the ratio of fats obtained from diet. To answer this question, they first starved rabbits (rabbit starvation, anyone?) for 3-4 weeks to deplete their fat stores and then put them on diets with varying fatty acids to see how it affected fatty acid distributions in adipose tissue.

Fatty acid composition of the diets

Five different diets were used, each one containing 20% by weight of either palm oil, cocoa butter, safflower oil, linseed oil (also known as flax oil) or rapeseed oil. These fats were chosen because each one is rich in a particular fatty acid: palm oil in palmitic acid, cocoa butter in stearic acid, safflower oil in linoleic acid, linseed oil in linolenic acid, and rapeseed oil in erucic acid. In addition, a low-fat control diet containing only 2.2% fat was used.

All rabbits were fed ad libitum. Though rabbits presumably consume little fat in the wild, there appear to be no special problems with feeding fat to rabbits (link, link). Rabbits eating a diet high in fat do gain more weight, however.

Fat composition of rabbit diets
The figure above shows the percentages of saturated (SA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids in each diet. As you can see, palm oil and cocoa butter are mostly saturated fat, safflower and linseed oil are mostly polyunsaturated fat, and rapeseed oil is mostly monounsaturated fat.

Saturated and unsaturated fatty acids in adipose tissue

When you feed animals various kinds of fat, you expect to see those same kinds of fat being deposited into their fat tissue, right? Saturated fat being stored as saturated fat, monounsaturated as monounsaturated and polyunsaturated as polyunsaturated. That seems logical enough but is apparently not the case.

The rabbits on diets high in saturated fat resisted the deposition of large amounts of saturated fatty acids in their fat tissue. In fact, the rabbits eating diets high in palm oil and cocoa butter had similar levels of saturated fatty acids in their adipose tissue as rabbits eating the low-fat control diet. This despite the fact that the palm oil and cocoa butter diets not only contained much more fat as a whole, but also more than twice the percentage of saturated fat relative to total fat intake than in the control diet.

Fatty acid composition of adipose tissue
The graph above shows the percentages of fatty acids in adipose tissue after each diet. As you can see, feeding the rabbits palm oil, cocoa butter or rapeseed oil resulted in a distribution that is similar to the result seen from eating the control diet. Feeding them safflower oil or linseed oil, on the other hand, resulted in a significantly different distribution, one that is high in PUFAs but low in MUFAs and SAs.

The plateau of dietary saturated fat deposition into adipose tissue does not seem to be a temporary phenomenon. To find out how long-term administration of saturated fat affected fat deposition, the authors fed two additional rabbits a diet high in cocoa butter for a year. These rabbits showed similar levels of saturated fatty acids in their fat tissue as the rabbits that consumed the same diet for only a month. In other words, saturated fat in their adipose tissue did not increase further even with prolonged intake of cocoa butter.

Individual fatty acids in adipose tissue

So the distribution of unsaturated and saturated fats in adipose tissue depends on the fat composition of the diet. As we've seen, the relationship is stronger for polyunsaturates than it is for monounsaturates and especially saturates.

What about individual fatty acids? The same discrepancy between dietary intake and adipose tissue deposition is apparent here. The palm oil diet was 164% higher in palmitic acid than the control diet, but the concentration of palmitic acid in adipose tissue was only 30% higher in the palm oil group. Similarly, the cocoa butter diet contained eight times as much stearic acid as the control diet, but stearic acid levels in the cocoa butter group were only 52% higher.

Again, things were a little different in the polyunsaturated department. The percentage of linoleic acid in the adipose tissue more than doubled on the safflower oil diet compared to the control diet, and the linolenic acid concentration in adipose tissue was 31.1% on the linseed oil diet compared to 3.9% on the control diet.

It seems that out of the six individual fatty acids studied, oleic acid (primarily found in cocoa butter and palm oil) and linoleic acid (primarily found in safflower oil) were deposited most effectively. Oleic acid (a monounsaturated fat) in adipose tissue constantly exceeded the amount of oleic acid present in the diets. Erucic acid (mainly in rapeseed oil) and stearic acid (mainly in cocoa butter) showed the least deposition.

Conclusion and discussion

Adipose tissue takes up many different fatty acids from the diet. The degree to which these fatty acids are absorbed varies, however. Specifically, a diet high in saturated fat raises saturated fat in rabbit adipose tissue only modestly, whereas a diet high in polyunsaturates increases PUFA levels in adipose tissue dramatically.

Several reasons may explain these differences in dietary and adipose tissue fat composition. First, the authors note that since the control rabbits did have saturated fat in their adipose tissue despite consuming a diet very low in fat, they presumably synthesized saturated fat from carbohydrates in the diet. Therefore, when the intake of certain fatty acids is low, the body adapts by producing them through other means, using carbohydrates or other fatty acids.

Second, when the intake of certain fatty acids exceeds certain limits, the body is able to convert dietary fats from one form into another. According to the authors, retroconversion (chain-shortening) and desaturation of dietary fats may be a necessary function of the body to ensure optimum cell membrane fluidity. That is, when saturated fat intake is very high, the body converts some of the saturated fat into unsaturated fat to keep things working properly.

This mechanism does not appear to be in place in rabbits for polyunsaturated fats, however. The fatty acid ratios in adipose tissue appear to reflect those in the diet very strongly when the diet is high in PUFAs. This makes me wonder whether a similar effect happens in other mammals, especially humans.

The authors do not report whether calorie intake varied between groups or how much actual adipose tissue the groups had. They only mention that during the 4-week experiment, all rabbits in the five experimental groups were healthy and gained weight.

For more information on fats and health, see these posts:

Blood Test Analysis: The Cholesterol and Saturated Fat Issue Revisited
Green Tea Extract Increases Insulin Sensitivity & Fat Burning during Exercise
Low-Carb vs. Low-Fat: Effects on Weight Loss and Cholesterol in Overweight Men
A Typical Paleolithic High-Fat, Low-Carb Meal of an Intermittent Faster

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Monday, July 6, 2009

Blood Test Analysis: My Experience with Vitamin D3 Supplements

Blood Test Analysis: My Experience with Vitamin D3 Supplements
For those who stay out of the sun, vitamin D3 supplements are a must. (Photo by respres)

In my last post, I analyzed my cholesterol levels and revisited the debate surrounding saturated fat. The main reason I went to have a blood test, however, was to see how my vitamin D levels were.

I have learned about the importance of vitamin D only quite recently. After some reading, I decided to start taking vitamin D3 supplements. For the first couple of months, I took 2,000 IU (equal to 40 mcg) daily, which is fairly conservative and often the minimum dose recommended by people who've done their homework. Conventional wisdom on the other hand still sees 400 IU of vitamin D2 as sufficient, even though it produces serum levels that are way too low for optimal health.

About one month before the blood test I increased my intake to 5,000 IU per day. Since I still had plenty of 2,000 IU capsules left, I took 2 capsules every other day and 3 every other day, thus averaging 5,000 IU. Since the serum half-life of vitamin D is quite long, this shouldn't make any difference.

After supplementing with 2,000 IU vitamin D3 for a few months and then increasing to 5,000 IU for a month, my serum 25-hydroxyvitamin D levels were 113 nmol/L, or about 45 ng/mL. This is considered to be within the optimal range, which is 32-100 ng/mL (link).

Considering that
  1. Most people have suboptimal serum levels of 25-hydroxyvitamin D
  2. Most foods provide only small amounts of vitamin D
  3. I live in the north and avoid the sun,
I think it's safe to say that the fact my serum levels are within the optimal range is mainly due to supplementation. I'm also fairly certain that prior to starting taking supplements, my levels have been even lower than average – that is, I've been deficient in vitamin D for most of my life.

Whether or not you enjoy the sun, I encourage you to get your vitamin D levels checked. And if you have already done that, feel free to post your results in the comments. I'm currently collecting data from other people to do a post on how people's serum levels have varied with and without vitamin D3 supplements.

For more information on vitamins, sun and health, see these posts:

Topical Vitamin C for Skin: Re-examining the Case
How to Get Natural Sun Protection by Eating the Right Foods
Sesame Seeds Increase Absorption of Vitamin E Tocotrienols by Up to 500%
Lutein for Skin Elasticity, Hydration and Photo-Protection – Experiment Begins

Read More......

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