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Showing posts with label nutrition. Show all posts
Showing posts with label nutrition. Show all posts

Wednesday, 27 July 2016

Anti-oxidants

What are anti-oxidants? 

Anti-oxidants work against oxidants, or more correctly Reactive Oxygen Species(ROS). 
As we know oxygen is vital for us. But in our body, oxygen molecules can turn into ROS and damage our cells.  ROS is a group of reactive molecules that contain oxygen, and is unstable. Thus to achieve stability it tends to react with our cells, protein, enzymes and other molecules. These reactions often cause damage to our cells, and this damage is called “oxidative stress”. 

Oxidative stress means our body has no sufficient anti-oxidant to fight off the reactive oxygen species. Thus we have damages occurring to our DNA, proteins and other cells.  

It’s widely believed that consuming a large amount of anti-oxidants will reduce the oxidative stress. 

How true is this? 

Food that are rich in Vitamin A, E and beta-carotene are often cited as anti-oxidant food.  

Vitamin A and E are fat soluble vitamin, and is found in very high levels in fruits such as oranges and pineapples. Additionally, many among us take supplements in form of tablets to ensure the take sufficient vitamins every day.  

Anti-oxidants and heart 

Image|Pixabay
Heart issues are a main concern now in developed countries. We are seeing an increasing trend of obesity and heart problems often accompany it. Selenium gained popularity as anti-oxidant with the capability to reduce atherosclerosis (hardening or blood vessels in the heart with fat). 

Selenium is a trace element found in many food. Tuna especially has 92 mcg per serving of selenium. Many other dairy products and cereal have high amount of selenium as well.  

Is selenium effective in preventing heart disease?  

A group of researchers from Cochrane collaboration pooled 12 researches that were done on this topic. After carefully looking at all the studies done on this issue, they concluded that selenium has no benefits in reducing heart diseases. But interestingly, selenium is reported to increase the risk of getting diabetes mellitus. But the risk is not strong enough for us to have any firm conclusion.  

But, we can safely conclude that as of now, Selenium has no benefits nor risk in regards to cardiovascular health. The authors of the research paper concluded that it’s not necessary for a well-nourished adult to take Selenium for heart protection.  

Vitamin E is also a fairy popular anti-oxidants taken by many. Another study done by a group of scientists from UCLA, pooled a total of 84 researches done on effect of Vitamin E on cardiovascular health. Again they concluded that Vitamin E supplementation does not protect us from heart problems.  

Anti-oxidants and Cancer 

Image by |Pixabay

Vitamin A is found in food like fish oil, milk and egg. Does it help in cancer prevention? One group of scientists looked into the claim of Vitamin A being a protective agent against bladder cancer. They concluded that eventhough the researches are showing Vitamin A to be protective against bladder cancer, no consensus can be reached in regard to how much Vitamin A is needed and what’s the best way to take it.  

Furthermore, do we all have to take Vitamin A to prevent bladder cancer? Who are the ones with high risk? Without answering these questions, taking Vitamin A daily might not be very beneficial. Not much studies have been reported for other types of cancers.  

In conclusion, taking supplements for its antioxidant activity has not been proven effective in preventing illness especially heart diseases and cancer. But daily requirement of vitamins in the form of food should be taken regularly as a general health measure.  

For further reading:  

  1. Selenium – Health Info 

  1. Vitamin A – Health Info 

  1. Vitamin A and Bladder Cancer 

  1. Vitamin E and cardiovascular health 

  1. Selenium and cardiovascular health 

Saturday, 16 July 2016

Fibre in Food- What's good about it?

What is fibre?

Fibre is an indigestible form of carbohydrate that is found in both plants and nuts. Some are soluble making it possible to be absorbed into our body system after consuming it, while others are not. It is found in many plants and nuts in varying amount.

Image\Pixabay
There are two types of fibre. Soluble, and insoluble fibre.

Soluble fibre is found in many beans and some fruits. It’s called soluble because it dissolves in water and forms a gel like material in the intestine. This gel like material binds to fatty acid and bile acid, thus reducing blood cholesterol level. Soluble fbres help in reducing rate of digestion. When the digestion process is slowed, it reduces spikes in blood glucose level. 

This helps in regulating body sugar level which is beneficial for people with diabetes and prevent high sugar level in others.

Several studies have backed this effects of soluble fibres. This positive effect of preventing the rapid rise of blood sugar has been shown by many research studies. Recently, a group of scientists from Warwick Medical School looked at 23 scientific studies done on the effects of fibres on blood cholesterol level as well as blood pressure. 


"aiming for 30g of soluble fibre per day has been proven to reduce blood cholesterol level and help in blood sugar control"



Image|Pixabay

They concluded that increasing dietary fibres improves blood cholesterol as well as surprisingly reducing diastolic blood pressure.  Diastolic blood pressure is the denominator of the blood pressure reading, and it’s best kept below 90mmHg to prevent the heart from pumping too hard.




What is the role of Insoluble Fibre?


while this form of fibre does not dissolve to be taken into the blood stream it has benefits on stool formation. One consumed it works in the large bowel by absorbing water and contributing to ‘bulking the stools’. This relieves constipation.

Where do we get fibres from?


Best method of getting the fibre is by eating the food rich in fibre. Recommended fibre intake by the US Department of Health is 14g per 1000 calorie. This roughly translates to about 28 to 35g of fibre intake per day, depending on your calorie intake.

Image |Pixabay
So which food has the highest amount of fibre? Navy beans contain the highest amount of fibre. According to US Department of Health, cooked navy beans have 9.6g of soluble and insoluble fibre in half cup. 

Apart from fibre, navy beans are also filled with Vitamin C, Vitamin E and Iron. Chickpeas are also rich in fibres. It contains 8.1g of fibre in ½ cup.
Locally available fruits such as papaya and durian are rich in fibre too. Banana contains 3.1g of fibre in each. Papaya has 2.1g of fibre, and durian has approximately 1g of fibre in each of its seeds.

As we know , soluble fibre is more effective in controlling blood cholesterol level along with reducing blood sugar. Among fruits, passion fruit has the highest amount of soluble fibre with 6.5g of fibre per 125ml juice. Avocado contains 2.1 g of fibre in half fruit.

In conclusion, aiming for 30g of soluble fibre per day has been proven to reduce blood cholesterol level and help in blood sugar control. Let’s choose fibre rich food to be added in our diet and live a healthy life!

For Further Reading

US Dietary Guidelines 2015 –http://health.gov/dietaryguidelines/2015/

Food Sources rich in soluble fibre, by Dietitians of Canada - 
http://www.dietitians.ca/Downloads/Factsheets/Food-Sources-of-Soluble-Fibre.aspx

Systemic review on dietary fibre’s effect on cardiovascular health http://www.ncbi.nlm.nih.gov/pubmed/26758499

Saturday, 25 June 2016

How safe is microwave cooking?

Image|Youtube

Microwave oven uses electromagnetic waves to heat up food. When the oven is switched on, electromagnetic waves will spread across the oven and be reflected by the inside of the oven. Water molecules in the food will vibrate when these microwaves pass through it and thus the food is heated up.

The question that often arises among us is "Will the microwaves affect us?"

The electromagnetic waves in theory should not leave the oven. Microwave ovens are designed in such manner that the waves are contained inside the oven and will only be active when the oven is switched on. Microwaves are not absorbed through the oven wall. But there is a possibility of microwave leakage if the oven is faulty.

So what happens if our body come in contact with the waves? The molecules in our body will vibrate and heat it up. But only certain organs in our body are sensitive to heat, such as eye balls and genitalia.

For the small amount of microwaves to cause heat induced damage, two conditions need to be met

i) There must be leakage from your microwave

ii) There must be significant time of exposure, which is rare as cooking in microwave oven is commonly just for a short time.

"Many nutrients break down when they're heated, regardless of the source"


So we can confidently decide that microwave oven will not harm us, except if the unit is faulty in which there is a small possibility of wave leakage.

What about the food heated or cooked using microwave oven? Does microwave heating change any molecule that might make food carcinogenic ( ability to cause cancer )? Does it remove the nutrients of the food?

Key issue to understand is that microwave oven cook by production of heat. And many nutrients break down when they're heated, regardless of the source. 

Image|Wikimedia
A research done by Monreal J et al specifically compared effect of different cooking methods on anti-oxidant level of vegetables showed that microwave cooking has the lowest effect on the anti-oxidant level of vegetables such as celery and ginger. Boiling them has the highest effect,causing the vegetables to lose their anti-oxidant properties.

Essentially all cooking method will make some nutrients to break down. The key is to reduce the amount of time the food is exposed to heat. Microwave oven heats up quickly, thus reducing the amount of time the food is exposed, and effectively reducing the amount of nutrient loss compared to other cooking methods.