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Vision Loss – We Compensate

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Good news. It seems that adults are able compensate for loss of vision much more readily than was previously thought. This suggests that the brain is adaptable at least for vision compensation. This is very good news for the majority of us whose vision is deteriorating as we age.

It has long been known that babies and kids are very adaptable. They can rapidly and easily compensate for many changes. For many things, adults are not thought to be able to compensate so easily.

A study in PLoS One (Public Library of Science) suggests that we can compensate for loss of vision. The authors suggest that we have responses such as tactile (touch) that are masked when we can see, but on loss or reduction of vision they are activated.

In the study adults, where blindfolded for up to 5 days and changes in their brains monitored before, while and after blindfolding. Significant changes could be detected by fMRI scans. Both blindfolded and non-blindfolded participants were trained in tactile responses including Braille. The blindfolded group rapidly became much more proficient than the non-blindfolded group.

This research suggests that we may in part compensate for the loss of vision that occurs for most people as they age. We may unconsciously use touch, and other cues to make up for the loss of clear vision of things close to us, as we have more difficulty seeing things that are close up.

photo credit: kainita

Technorati Tags: vision loss, compensate, tactile

Popularity: 38% [?]

Why Eyelids Sag With Age

You know you are getting older when your eyelid start to sag. You look in the mirror and your eyes look baggier and puffy, and give you a tired look. So what is the reason that eyelids sag with age?

I would have guessed that it was because they were losing some underlying fat that kept them firm and taut. My reason for this is, as explained in a previous post is the fact that one of the major reasons for the aging of our faces is loss of deep fat pockets in our cheeks. However, it seems my guess is wrong.

Apparently it is the reverse.

Previously the bulging and sagging of the lower eyelid has been attributed to the covering for the fat in our eye socks becomes weaker and does not hold the fat in place. This then results in the fat bulging out making the eyes look baggy and puffy.

However, new research suggests that there is actually an increase in fat that puts pressure on the fat covering and so makes a bulge. So unlike your cheeks, where there is the loss of fat, there is an increase in the amount of fat round the eye.

Currently procedures to get rid of the sagginess (blepharoplasty) will reposition fat and/or tighten muscles or ligaments round the eye. This new research suggests that there should also be fat removal.

Perhaps the fat migrates from our cheeks to our eye sockets as we age.

photo credit: Martin Kingsley

Technorati Tags: eyelid, sagging, bulging, aging, fat

Popularity: 41% [?]

Aging, Carbohydrates, Appetite and Weight Gain

A new study has interesting evidence that a diet high in simple carbohydrates may over time damage the cells in the brain that control appetite. If this is correct it may mean that with aging, control of appetite may be blunted and this may account for the weight gain that occurs with aging.

This is just a theory, and may be rubbish. Instead it might just be that as our metabolism slows down with aging, we are less active and along with the natural loss of muscle that occurs with aging (sarcopenia), that we use fewer calories, so more of our energy intake (food) is converted to fat.

Ghrelin is a hormone that increases when we are hungry and decreases after we have eaten. This is the reverse of the appetite control hormone called leptin, which is low when we are hungry and high after a meal. A previous post talked about how leptin might be the key to weight loss and maintenance.

Ghrelin is made by certain cells in the stomach, the pancreas and the brain. In some bariatric procedures where part of the stomach is removed, as well as the decreased stomach capacity, there will be reduced appetite since some of the cells that produce ghrelin will have been removed.

In the brain ghrelin acts in several areas and causes an increase in activities of a number of enzymes associated with mitochondria (the “powerhouses” of cells). Some of these enzymes are involved in neutralization of ROS (reactive oxygen species) and are cellular antioxidants.

The new theory is that meals high in simple carbohydrates cause a large increase in ROS, and this ghrelin-caused increase in ROS overwhelms the antioxidant increase. The ROS then start to cause damage to the appetite controlling cells in the brain.

Certainly could be right, but the current evidence is rather flimsy. An article about the findings gives more details.

If age-related weight gain is due the loss of appetite control cells, then we should be increasingly eating more as we age. I’m not sure that this is the case. My guess is that we just use less calories.

photo credit: viZZZual.com

Technorati Tags: ghrelin, appetite, aging, weight gain, ROS, antioxidant

Popularity: 60% [?]

Irradiation Of Food; What, Why, Pros, Cons

So what do you think of irradiation of food? The FDA has just extended the allowed use of irradiation to produce such as lettuce and spinach.

Do you actually know what irradiation of food is?

Everything is naturally exposed to radiation, it comes from space and from the earth. Think of a radioactive substance as something (a source) that sends out (emits) high energy. Different sources send out different amounts of energy. Importantly, this energy can be felt (detected) without touching the radioactive source.

When food is is irradiated it does NOT come in contact with the radioactive source. It placed close too, but not against a source. It gets a dose of short really high energy that may be bad or good (see below) but it does NOT make the food radioactive.

The food being radioactive is used as a scare tactic, the real pros and cons are elsewhere. As always the answer is not totally black and white.

The blast of high levels of ionizing radiation from a radioactive source can slow the ripening of fruits and damage the DNA of microbes so that are unable to divide and grow in foods. UV light also affects DNA and can be used to sterilize things. Radiation is more effective since it can penetrate into things.

Probably the most widespread use of irradiation is for sterilization of health items, particularly for use in hospitals.

Low doses of radiation are used to delay ripening of some fruits and slow the sprouting of some tubers such as potato and bulbs. Higher doses are used to decrease the level of viable microbes so that shelf life is extended. Even higher doses are used to effectively sterilize products so that they can be stored at room temperature for extended periods of time.

Exposing anything to high doses of ionizing energy sources will cause changes in cells including damaging DNA. The main aim for irradiation when being used to stop the growth of microbes, is to cause sufficient damage to the DNA of the microbes that they can no longer grow and divide. (Of course there will some effect on the DNA of the cells of fruit or Vegetable. However, the fruit or vegetable has been harvested, is now dying and so few if any cells will be dividing.) This damage to the DNA of the microbes either slows the rate of, or stops, food spoiling.

It has been legal to irradiate many products for years. Irradiation of spices and herbs controls both any insects and bacteria present. Irradiation of fruit will both control any pests on the fruit and slow the ripening. For instance strawberries will be easier to transport, can be transported further and will not rot in your fridge so quickly. Hamburger patties can be irradiated to reduce the risk of food poisoning from virulent E. coli. The recent addition of spinach and lettuce, makes sense, they are hard to wash effectively and can be accidentally contaminated, while being grown, with run off containing animal waste.

However though there are a wide range of foods that can be irradiated, due to consumer concerns, only a small proportion of the eligible food is irradiated.

So the pros are fruit that will ripen slower, an extended shelf life for foods and a reduction in the likelihood of getting food poisoning.

The cons are a bit less well defined.

What exactly is the effect of the blast of ionizing radiation on food? The radiation and any heat generated will affect the proteins, fats, DNA etc of the cells. Are any of these effects negative? Is the nutritional quality of the food affected? Some people suggest that there may be toxic byproducts. Though there does not seem to any firm idea of what these toxic byproducts might be. Of course it is possible that in some cases the nutritional quality could be improved (like exposing tomatoes to heat makes more lycopene available).

The effect on food is complicated by the fact that there is a wide range of strength of irradiation of food. So there is going to be a range of effects. In a photo credit: Mike Licht, NotionsCapital.com

Technorati Tags: irradiation food, DNA, ripening, vitamin K

Popularity: 44% [?]

Aging, Sleep, Light and Bad Vision

Something that I had not thought about before is that some of those with certain types of bad vision may have problems with sleeping. This is likely to become more of a problem as the population ages. A lack of perception of light may have a negative effect on setting their biological clock and sleep/wake cycles.

It has long been known that we use light to set our biological clocks and keep us on a regular daily cycle. For instance experiments have been conducted with people who were in rooms with no windows and so we not aware of the whether it was light or dark outside and did not know the time. They only had artificial light that they controlled. Under these circumstances, people do not have a 24 hour day, some have longer days, some shorter. Their clocks were not reset to a 24 hour cycle by the input of daylight.

A regular cycle of light and dark also controls our sleeping patterns. Those who do shift work have confused body clocks and often have trouble sleeping. We seem to be programmed to sleep when it is dark and awake when it is light. Having to sleep when it is light and be alert when it is dark is hard for many people.

It had not occurred to me before, that those whose who have bad vision, may not get sufficient light input to keep their biological clock on a 24 hour cycle. One consequence is that many with bad vision have sleep problems, particularly if previously they had good vision.

With the population aging and more and more people living longer, there are going to be increasing number of people who have a significant age-related decline in vision. For some this decline results in much less light entering the eye, which will affect both resetting the biological clock and controlling sleep patterns.

There are many researchers trying to find the signaling pathways in the eye and brain that connect light to control of the daily cycle and to control of sleep. Recent research has found that “knocking out” a pigment and a recycling protein in the eye in mice causes them to switch from being awake at night, to awake during the day.

This and similar research may provide information about how to mimic the effect of light on the eye. Perhaps in the future there may be eye drops of something similar that will reset the biological clock and help with nromal sleep patterns.

The majority of elderly have problems sleeping or some form of sleep disturbance. Perhaps in the near future, many of them will be helped by artificially resetting the clock. Of course the advice to try to go outside and get some bright light will be helpful to many until then.

photo credit: Matt Biddulph

Technorati Tags: aging, light, sleep, bad vision, biological clock

Popularity: 52% [?]

Mushrooms – The Next Wonder Food?

Mushrooms are being suggested to be a food that you should be eating frequently. They contain a number of important minerals, vitamins, including vitamin D, and an antioxidant, and high in fiber, and they are low in calories.

An interesting study looked at substituting mushrooms for meat in a several dishes. The mushroom substituted dishes had less calories (less energy dense). The research showed that the study participants only ate slightly more food to compensate for there being less calories. After 4 days the participants when on the mushroom diet had consumed on average almost 1500 less calories, than when they were on the meat diet. This suggests that mushrooms as part of prepared dishes could help reduce the number of calories that are consumed.

The dishes prepared were lasagna (meat 1026 kcal, mushroom 451 kcal), savory napoleon, a dish with layers of puff pastry (meat 679 kcal, mushroom 359 kcal), sloppy joe (meat 822 kcal, mushroom 248 kcal) and chili (meat 604 kcal, mushroom 300 kcal).

Recently, a lot of research has shown that many people do not get enough vitamin D. There is a trend that number of people vitamin D deficient increases with age. See the recent post Low vitamin D increases the risk of death.

Commercial mushrooms are for the most part grown in the dark. The standard white button mushroom grown this way has about 15 IU of vitamin D. However, if mushrooms are given a brief exposure to UV light after harvesting, the level of vitamin D increases significantly and can even be close to 400 IU, which is the recommended intake for those 50 to 71 years. The exposure does darken the mushrooms, but this change in appearance is a small price for the improvement in the level of vitamin D. Some commercial growers are now working on ways to expose mushrooms to light before packing and shipping.

Mushrooms contain the antioxidant ergothioneine, the minerals copper, potassium and selenium and the B vitamins riboflavin (B2), niacin (B3) and pantothenic acid (B5), and are high in fiber. All in a great food to include frequently in your diet. If only there were a little cheaper.

photo credit: e1ther

Technorati Tags: mushrooms, calories, vitamin D

Popularity: 45% [?]

How Related Are Weight And Health? – Comments

Yesterdays post was about analysis of NHANES data that showed that body weight and health are not always related. The analysis looked at “metabolic markers of obesity” which were high triglycerides, low levels of HDL (the good) cholesterol, high level of fasting glucose and high blood pressure. The data demonstrated that there are some people who are “overweight” that do not have metabolic markers of obesity, and some people who are “normal” weight who have the metabolic markers.

For some diseases there is a straightforward genetic relationship. You have a particular form of a gene you get the disease. For many other diseases it is not so straightforward. There are a number of factors and genes that have can interact and affect whether you get the disease, and also how severely you get it.

With this in mind the data in that being normal weight or overweight does not completely correlate with whether a person has the metabolic markers makes more sense.

Some people will have a combination of genes that makes them very susceptible to having, as an example, high triglycerides. For these people they are going have high triglycerides whatever. The triglyceride levels will probably be even higher if they are overweight vs normal, but even if really skinny they will probably have high triglycerides.

Other lucky people will have a combination of genes that makes it unlikely that they will ever get high triglycerides, high fasting glucose etc., whatever their weight and lifestyle.

Most of us fall in the middle ground. The combinations of our genes make us susceptible to getting the metabolic markers of obesity. For us, an increase in weight is a strong negative interacting factor. Introduction of this strong factor (weight gain) into the mix will make it more likely that we will get one or more markers, or if we already have any, that they will get worse. For many in this category, putting on weight, particularly round the middle is going to be unhealthy.

If you read the previous post and looked at the percentages, you would have noticed that as people aged the likelihood increased, whatever their body weight, that they would have markers of obesity. This suggests that age is an independent interacting factor for getting the metabolic markers. Previously, the increase in the metabolic markers with age has often been suggested to be due to the fact that we tend to put on weight as we age. While this is true, this data suggests, that since the increase in metabolic markers occurred in normal weight participants too, that age itself plays a role.

So for the majority of people, with regards to the metabolic markers, though we can try to keep our weight down, unfortunately, we cannot stop aging.

Technorati Tags: weight, metabolic, age, genes, triglycerides, HDL cholesterol, NHANES

Popularity: 42% [?]

How Related Are Weight And Health?

The conventional wisdom is that if you are normal sized you are healthy and if you are overweight you are unhealthy. However, a recent analysis has suggested that it is not that simple and that weight and health may not be related in a straightforward way.

More data from NHANES (National Health and Nutrition Examination Survey) suggests that some “normal weight” people are unhealthy and that some people considered overweight do not have signs of cardiac disease or other diseases that have been conventionally associated with obesity.

Of course being thin has never necessarily meant healthy. For instance, my mother who suffers form Crohn’s disease is thin due to her disease. However, in this analysis of the NHANES surveys, of those with normal weight there were a significant proportion who had what the authors called “metabolic markers of obesity”.

What were considered to be metabolic markers of obesity? They included high blood pressure, elevated triglycerides, high fasting blood glucose, high levels of C reactive protein (hsCRP) and low levels of HDL (the good) cholesterol.

The proportion of normal weight people with these markers increased with age, from 10.3% for ages 20 to 24 years , 16.9% between 35 and 49 years, 41.7% between 50 and 64 years, 54.7% between 65 and 79 years, and 56.2% 80 years and older.

Conversely, for those considered overweight and would be expected to have the metabolic markers, there were many who were in the optimal range. Healthy levels of the markers decreased with age, but represented a substantial proportion of the survey participants. The ranges were 47.7% between 20 and 34 years, 31.1% between 35 and 49 years, 20.4% between 50 and 64 years, 14.3% between 65 and 79 years, and 22.1% 80 years and older.

This sort of goes against what we are told. It will be interesting to see how the discussion of the data develops. The data does suggest that you need to go and get tested for cholesterol, glucose, triglycerides etc, whatever your size. Find out what your numbers are, then go from there.

photo credit: Fujoshi

Technorati Tags: weight, metabolic, obesity, NHANES

Popularity: 68% [?]

Low Vitamin D Increases Risk Of Death

Seems like there are studies every couple of weeks that show that low levels of vitamin D pose a risk for some disease. So it is not surprise that low vitamin D decreases the overall risk of death.

The most recent study looked at NHANES (National Health and Nutrition Examination Survey) data. The researchers analyzed data from 13,331 participants who were at least 20 years of age and were first enrolled between October 1988 and October 1994 and were followed until the end of 2000. Levels of 25-hydroxyvitamin D were correlated to all cause mortality.

The results show that the highest rates of death were in the participants whose vitamin D levels were in the lowest quarter less than 17.8 ng/ml). There was a 26% increase in mortality.

This study indicated that the rate cancer and cardiovascular disease may increase in those individuals with the lowest vitamin D levels. This is in agreement with a number of other studies that have indicated that cardiovascular disease including peripheral artery disease (blocked arteries in the legs which causes numbness and pain, and may make walking difficult) and several cancers.

Vitamin D is found in many fish, fortified dairy products and is made by the skin in response to sunlight. In the skin if too much vitamin is made it is broken down. There is some evidence that over supplementation with vitamin D is not good. So if you chose to take supplements stick within the recommended range with currently are; ages 19-50 200 IU, ages 51-70 400 IU and aged 71 and over 600 IU.

photo credit: m00by

Technorati Tags: vitamin D, death, mortality, NHANES

Popularity: 29% [?]

Frailty Affects Risk of Alzheimer’s and Physical Activity Improves Cognition

Both the amount of physical activity and the level of frailty affect the risk of developing Alzheimer’s. Increased physical activity improves cognition, and increased frailty increases the risk of Alzheimer’s. This provides another reason for keeping active as you age.

A study shows that those elderly with a high level of frailty were at increased risk for getting Alzheimer’s. The findings demonstrated that those with Alzheimer’s disease were twice as likely to be frail as those who did not have the pathology of this disease.

Due to the association of frailty and Alzheimer’s, the researchers suggest that when a person becomes frail, it might be a good time to test them for Alzheimer’s and perhaps diagnose it early, if it is developing.

The findings do not indicate whether being frail increases the risk of Alzheimer’s or whether becoming frail is associated with the development of the disease.

In another study, the level of physical activity was linked to cognition. Those who had higher physical activity levels were found to have higher cognition levels. Interestingly, this held true when the researchers measured activity, but not for self reported activity. Different people have different ideas of how much physical activity that they do.

Again it may be a chicken and egg situation. Does less activity lead to lower cognition, or are those who have lower cognition levels liable to do less exercise. I think I am not going to wait for them to find out, but will try to keep my moderate exercise (mainly walking) program. Better safe than sorry. I just want to poop out one day, and not have a long increasingly restricted decline. Time will tell.

photo credit: daniel arnold!

Technorati Tags: frailty, Alzheimer’s, physical activity, cognition

Popularity: 34% [?]

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