Nutrition - Phytochemicals update

Friday 04 May 2018

 There has been such a lot of information around the subject of phytochemicals and health and cancer that I thought that it was time for a fresh look at the subject.

What are phytochemicals?

Firstly, let us remind ourselves what phytochemicals are. Phyto of course means Plant in Greek. They are natural compounds found in plants that are responsible for the colour, taste and aroma of foods. There are thousands of them and they are being discovered all of the time.

Some examples of names of some phytochemicals that you may be familiar with are Lycopene found in tomatoes, carotene found in red fruits and vegetables, Allicin found in garlic and Ellagic acid found mostly in berry fruits. Phytochemicals can be broken down into sub groups like polyphenols, phenolic acids. terpenoids etc. but knowing this will only complicate matters. What we are really interested in is why they are important and where they can be found.

why are phytochemicals  important?

The precise biochemical mechanisms through which phytochemicals exert their anti-cancer effects are still being explored as their actions are wide ranging and complex but significant advances have been made in understanding their actions. The World Cancer Research Fund and other academic bodies, report that individuals eating phytochemical rich foods have a lower risk of cancer or relapse after treatments.

Findings from laboratory studies have shown the phyto-chemicals have the potential to;
• Stimulate the immune system
• Block substances we eat, drink and breath from becoming carcinogenic.
• Reduce the inflammation that makes cancer growth more likely.
• Prevent DNA damage and help with DNA repair.
• Reduce the kind of oxidative damage to cells that can spark cancer.
• Slow the growth rate of cancer cells.
• Trigger damaged cells to self-destruct before they can reproduce.
• Help to regulate hormones.

This is quite an impressive list of potential protective properties which I took from a paper by the American Institute for Cancer Research. They have also produced a table of each of the phytochemical groups where they come from and the potential benefit.

How can I easily include phytochemicals in my diet?

The benefits are listed above and rather than knowing each phyto-chemical and where it is found (which is a lot to get your head around), I think it is far more useful to make sure that you eat a wide variety of fruits and vegetables and make sure that on your meal plate you have as much colour as possible. This is because the different coloured pigments of the plants have different phytochemicals in them.

When I think of this I also recommend that you look at your colourful intake over a period of a week rather than daily because for many reasons it is difficult to hit targets every day but over a week it would give a more realistic picture.

Are phytochemicals affected by cooking?

Many people ask me if the phytochemical content is reduced by cooking in a similar way to reduced levels of vitamins and minerals that can occur with cooking.

This is an interesting question and there is not a cut and dried answer because in some cases the phytochemical content is enhanced through cooking. The best example of this is the Lycopene found in tomatoes. This is much higher in cooked tomatoes than raw.

Also the phytochemical in garlic is destroyed by cooking but if the garlic is cut and exposed to the air for 10 minutes when the original phytochemical is converted into another substance that appears responsible for its cancer protection and heat does not destroy this. However boiling as a method of cooking seems to deplete the phytochemical content in a similar way that it depletes the vitamin and mineral content but steaming seems to retain most of them.

Variety is key but make it manageable for you.

So as with everything rather than getting too bogged down with too much detail of which does what, the rule of thumb is to include a variety of cooking methods. This not only adds interest to the diet but ensures a good variety of phytochemicals.

Include preparation methods like juicing, having a colourful salad or make a stir fry or a tray of oven roasted vegetables, make a soup or even a steamed medley. You will have also picked up I am sure that the more vegetables that you can include in a day the better.

Ideally 50% of your total food intake in a day should come from vegetables. Of course this is not always possible and some people may have restricted diets for a while that limits the fibre in the diet but when all is back to normal 50% should be the aim.

If you do decide to increase the amount of fruits and vegetables in your diet then do this slowly over a period of time. To do it all at once may have anti -social repercussions because the body has not adjusted slowly to the changes. Living well programmes, slowly being introduced in the UK are beginning to highlight the importance of phytochemical rich diets along with other lifestyle factors.

So reading the above and looking at the evidence we cannot really afford to ignore the messages but as with everything it is important to do the best that you can and not to get stressed or overly concerned if for whatever reason the ideal cannot be reached.

American Institute for Cancer Research: Phytochemicals in your food

You may also be interested in Caroline's previous blogs on Phytochemicals  parts 1 and 2 (2012)

Blog originally written by Caroline Aug 2016

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