A is for AWESOME AVOCADO

This is the first of my series of blogs on functional foods. I will be looking into how some of my favourite foods are natures little nutritional powerhouses conferring health benefits on us in all seven essential areas of bodily function. When all these areas are working well and in balance we remain healthy and disease free. And unsurprisingly mother nature provides us with all the macronutrients, micro nutrients & minerals we need to keep us tickety boo in the form of REAL food, something that was recently growing and thriving outside in nature (vegetable or animal) - who knew?!! But what are the seven essential areas that make up what we call the Functional Matrix, which we need to be supporting on a daily basis?

Digestion & assimilation - how well we break down food including all organs that do this (from nose to tail - as it were!), then how well we actually absorb these nutrients out of our gut and into circulation.

Defence & repair - Essentially our immune system; inflammation - how we fight off invaders, infection or injury and then how well we heal tissues.

Energy - How we make energy not just to fuel activity but to fuel every single process in the body. We need energy to make energy and energy to sleep well.

Biotransformation & Elimination - How we recycle and reuse nutrients to make new chemicals needed for proper function at a biochemical level across the whole body, as well as how well we eliminate those things our body does not need. This happens throughout every cell in our body not just the liver and kidneys.

Transport - How well we transport and deliver everything around our body - in the blood to major organs, as well as into and out of cells at a biochemical level. Also including the health of the all the structures that are part of this transport system ie. arteries

Communication - How our organs, tissues and cells communicate to each other through hormones, neurotransmitters and chemical messengers.

Structural integrity - Focuses on how the structure from the tiniest cell to the largest organ in our body is perfectly designed for it's particular function, and how when this structure is compromised the function is negatively affected, therefore negatively impacting health.

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A is for AWESOME AVOCADO

YES, AVOCADOS ARE NOW A STAPLE OF ANY SELF-RESPECTING HIPSTER BRUNCH, BUT THEY ARE SO MUCH MORE THAN A BEARD AND AN 80'S TASH!

CONTAINING UP TO THREE TIMES THE POTASSIUM FOUND IN A BANANA AND THE HIGHEST LIPOPHYLIC TOTAL ANTI-OXIDANT CAPACITY AMONGST ALL FRUIT & VEGETABLES, THE AVOCADO IS MUCH MORE THAN JUST TRENDY, ITS A  FUNCTIONAL FOOD THAT CAN TARGET ALL AREAS OF THE FUNCTIONAL MATRIX

 

Also called the alligator pear, avocados are grown from the Persea Americana tree. The Hass and Fuerta varieties are most popular in the U.K. although there are dozens of varieties that fall into three main categories; West Indian, Guatemalan and Mexican.

Avocados are native to south and central America and have been cultivated there since 8000BC, but spread to Jamaica and the Asian tropical region in the 17th century. One average serving is half an avocado at about 65g, which is the serving size referred to throughout.


STRUCTURAL INTEGRITY

Avocados contain a whopping 185ug of lutein/zeaxanthin/serving - antioxidants in the carotenoid family

EYE HEALTH - Avocados have an important role in eye health as low dietary intake of these anti-oxidants have been associated with increased age-related eye dysfunction (3), whilst mono-unsaturated fatty acid (hereafter referred to as MUFA) rich diets seem to be protective against this (4).

JOINTS & BONES - The highly bioavailable levels of these carotenoids are also associated with decreased cartilage defects (5), and the vitamin K1 levels can support healthy bone metabolism. Making them a key ingredient for  anyone looking to support bones and joints - athletes and osteoarthritis sufferers take note! Especially as the fats in avocados also help absorption of carotenoids from other fruit and veg.

SKIN - For those looking for the anti-aging magic bullet add avocado to  your diet - The skin is often the most visible sign of aging and the bioavailable carotenoids in avocado can protect the skin from UV radiation, whilst the fat content supports skin elasticity. It's no coincidence that higher intakes of green and yellow vegetables has actually been linked with fewer wrinkles (6).

DIGESTION & ASSIMILATION

Avocado fruit carbohydrates are around 80% dietary fibre, 70% of which is insoluble and 30% soluble.

BACTERIA FRIENDLY - One serving can provide up to 4.6g of fibre, thus providing almost a third of our recommended daily intake. The high percentage of insoluble fibre means the avocado can be thought of as prebiotic; providing food for our friendly gut bacteria, with the soluble content helping to promote gut motility, keeping you regular! 

VITAMIN FRIENDLY - Adding 150g avocados or 24g avocado oil to a salad can enhance the absorption of lipophilic vitamins like D, E, K and carotenoids up to 15 fold! (1) ensuring all those lovely nutrients can actually be used in the body where they are needed.

STOMACH PROTECTIVE - Furthermore, avocado extracts rich in xanthophylls may even have anti Helicobacter pylori activity showing potential therapeutic benefits for gastrics ulcers - keep them in your diet to keep your gut safe! (2)


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COMMUNICATION

Fat is the most potent macronutrient in the release of hormones that tell us we are satiated and full (that's why it is so satisfying!)  But the monounsaturated fats (anti-inflammatory & healthy) found in avocados seem to do this better than any other type of fat. And not just in healthy individuals but also in type II diabetes sufferers, (7,8,22).

At 71% MUFA content, including avocados in a meal can form part of a weight loss strategy helping to decrease calories consumed via this effect on satiety hormones. So if you are looking to lose fat, don't lose it from your diet!

ENERGY

Avocado contain up to 20mg of magnesium/serving

MAKING ENERGY - The magnesium content makes them a useful dietary source of this vital mineral needed as a co-factor for more than 300 enzyme reactions; regulating a multitude of biochemical processes and being directly required for energy production, oxidative phosphorylation and glycolysis.

WEIGHT LOSS - Once again its the MUFA's that may be beneficial when it comes to fat burning. Both high MUFA diets and high MUFA meals have been shown to increase energy expenditure (9) and fatty acid oxidation, (10). Giving them a key role in a ketogenic diet and weight management - so once again eat these good fats to burn off your fat!

DEFENCE AND REPAIR

ANTI-INFLAMMATORY - The high amounts carotenoids and phytosterols alongside two families of flavonoids (catechins and procyanidins) help give the avocado it's anti-inflammatory reputation. It is no coincidence that a certain golden arched burger chain added avocado to one of their burgers to be able to call it a healthy lunch! A PILOT study using 11 healthy volunteers found vasoconstriction and inflammatory markers to be significantly decreased when a hamburger was consumed with 68g of avocado, as opposed to without, (11). Now, I am in NO WAY encouraging a fast food burger of any kind for lunch - but think about including avocado next time you eat red meat to reduce that inflammatory response! Furthermore the high MUFA content alongside the omega 3's (alpha-linoleic acids) helps to offset the high intake of omega 6's found in western diets these days, helping to balance and resolve any inflammation.

SKIN REPAIR - Avocado contains a unique lipid molecule, (polyhyrdroxylated fatty alcohol content), which has been shown to reduce UV skin damage and inflammation, enhancing DNA repair (12) - another anti-aging gold star for the avocado!

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AVOCADO COMSUMERS HAVE

- Higher HDL-cholesterol 

- Lower risk of metabolic syndrome

- Lower weight/BMI and waist circumference .

- Significantly higher levels of key shortfall nutrients; dietary fibre, vitamin K and E, potassium and magnesium (13) 

 

TRANSPORT

The high potassium content of avocados (345mg/serving) would certainly suggest a potential role in promoting normal blood pressure but avocados have a multitude of benefits in cardiovascular health.

HEART HEALTH - Free radicals oxidising LDL is an established mechanism in the pathogenies of cardiovascular disease (CVD), and dietary Xanthophyll carotenoids have been shown to reduce circulating oxidised LDL-C, also reducing fat damage through lipid peroxidation, (14). Therefore with the highest lipophilic total antioxidant capacity among fruit and vegetables (15), avocados deserve their reputation as a heart healthy fruit, full of free radical quenching anti-oxidants!

Furthermore fruit phenolics like those found in avocados (30mg/serving) seem to beneficial in further reducing CVD risk not only by combatting oxidative and inflammatory stress, but enhancing blood flow and arterial health, also inhibiting platelet aggregation. (16)

As if this wasn't enough, this little heart health warrior can also lower cholesterol through its high amounts of oleic acid and linoleic acid, and their phytosterol content. At 57mg/serving avocados are the richest known fruit source of phytosterols (17). And how clever is nature - the natural packaging of the avocado (in the form of its emulsified fat matrix) is likely to promote a stronger intestinal blocking of cholesterol (18) abosrbing less and excreting more! (19).

In terms of heart health its a WIN WIN WIN situation!

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DID YOU KNOW?

 

 

As the fruit ripens the saturated fat content decreases and the mono- unsaturated oleic acid increases (20)

 

Xanthophyll levels of up to 1100ug/half fruit have been found in avocados at time of harvest (19). 

BIOTRANSFORMATION & ELIMINATION

Avocados are one of the few foods containing significant levels of both antioxidants vitamins C and E at 6mg/serving and 1.34g/ serving respectively.

Vitamin C plays an vital role in the recycling of vitamin E in order to maintain circulatory antioxidant protection (23). Vitamin C is also essential for detoxification in the liver, especially helping to remove heavy metals toxins which are unfortunately all around us these days, and actually in our food!

Additionally, the avocados levels of folate and b vitamins give them a role in efficient methylation, which is essential to healthy DNA replication, avoiding mutations that can lead to cancer. These nutrients are also central to maintaining healthy homocysteine levels which have been implicated in both CVD and Alzheimers progression.

A WORD OF CAUTION...

  • Unfortunately persons with latex sensitivities should avoid touching or eating avocados as they contain enzymes called chitinases that can cause allergic reactions. The ethylene gas used to induce ripening can increases the presence of these allergenic enzymes; therefore choose organic as always!
  • There is concern around avocado consumption and anti-coagulant medication due to the vitamin K content, however the avocado level of vitamin K1 per ounce is 150 times lower than the level expected to interfere with medication (1000ug of K1!), (21). 
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IN SUMMARY

 

Avocados are so versatile - add them to salads; have them sliced or smashed on a pancake with your eggs in the morning; keep it simple and have half an avocado by itself with a good glug of French dressing for a satisfying anti-inflammatory snack; even add them to a smoothie to make it nice and smooth, giving you important healthy fats whilst increasing  absorption of other nutrients in the drink.

They make a good salsa into a great salsa - why not try this anti-inflammatory mango & coconut salsa or simply smash one up with some of your favourite herbs and spices to add flavour, texture, nutrients and "fullness" to any meal. This is my favourite combo;

1 avocado, diced

1 tsp smoked paprika

juice of 1/2 lime

finely diced spring onion & red chill

1 tsp coriander seeds - roughly ground in a mortar & pestle

good grind of sea salt and pepper

Grab a fork and roughly smash all the ingredients together - YUM!

 

Avocados are a delicious and powerful little fruit that can be used as a functional food to support many areas of health. However, due to the recent popularity of this fruit, illegal rainforest clearance has been taking place in order to grow more to meet demand- therefore I would encourage buying both organic and fairtrade to look after our planet as well as our health.

References

1.     Unlu, N. Z. et al., 2005. Carotenoid absorption from salad and salsa by humans is enhanced by the addition of avocado or avocado oil. Journal of Nutrition, 135(3), pp. 431-6.

2.     Castillo-Juárez, I. et al., 2009. Anti-Helicobacter pylori activity of plants used in Mexican traditional medicine for gastrointestinal disorders. J Ethnopharmacol.22, pp. 402–405.

3.     Ma, L. and Lin, X.-M. 2010. Effects of lutein and zeaxanthin on aspects of eye health. J. Sci. Food Agric., 90, pp. 2–12.

4.     Chong E. W. T. et al., 2009. Fat consumption and its association with age-related macular degeneration. Arch. Ophthalmol. 127(5), pp. 674–680.

5.     Wang, Y. et al., 2007. Effect of antioxidants on knee cartilage and bone in healthy, middle-aged subjects: a cross-sectional study. Arthritis Research and Therapy, 9, 9 pages

6.     Nagataka, L. et al., 2010. Association of dietary fat, vegetables and antioxidant micronutrients with skin ageing in Japanese women. British Journal of Nutrition, 103(10), pp.1493-8.

7.     Maljaars, J. et al., 2009. Effect of fat saturation on satiety, hormone release, and food intake. The American Journal of Clinical Nutrition, 89(4), pp. 1019-24.

8.     Thomsen, C. et al., 2003. Differential effects of saturated and monounsaturated fats on postprandial lipemia and glucagon-like peptide 1 responses in patients with type 2 diabetes. American Journal of Clinical Nutrition, 77(3), pp. 605-11

9.     Jones, P. J., Jew, S. and Abumweis, S. 2008. The effect of dietary oleic, linoleic, and linolenic acids on fat oxidation and energy expenditure in healthy men. Metabolism, 57, pp. 1198–1203.

10.  Clevenger, H. C. et al., 2014. Acute effect of dietary fatty acid composition on postprandial metabolism in women. Exp Physiol, 99(9), pp. 1182-90.

11.  Li, Z. et al., 2013. Hass avocado modulates postprandial vascular reactivity and postprandial inflammatory responses to a hamburger meal in healthy volunteers. Food function Journal, 4(3), pp. 384-91.

12.  Rosenblat, G. et al., 2011. Polyhyrdroxylated fatty alcohols derived from avocado suppress inflammatory response and provide non-sunscreen protection against UV-induced damage in skin cells. Archives of dermatological research, 303(4), pp. 239-46.

13.  Fulgoni, V. L., Dreher, M. L.  And Davenport, A. J. 2013. Avocado consumption is associated with better diet quality and nutrient intake, and lower metabolic syndrome risk in US adults: results from the National Health and Nutrition Examination Survey (NHANES) 2001–2008. Nutrition Journal, 12(1), 6 pages.

14.  Hozawa A. et al., 2007. Relationships of circulating carotenoid concentrations with several markers of inflammation, oxidative stress, and endothelial dysfunction: The coronary artery risk development in young adults (CAR-DIA)/young adult longitudinal trends in antioxidants (YALTA) study. Clin. Chem. 53(3), pp. 447–455.

15.  Wu, X. et al., 2004. Development of a database for total antioxidant capacity in foods: a preliminary study. Journal of Food composition and Analysis, 17, pp. 407-22.

16.  Chong M. F. F., Macdonald R., and Lovegrove J. A. 2010. Fruit polyphenols and CVD risk: A review of human intervention studies. Br. J. Nutr. 104, S28–S39.

17.  Duester K. C. 2001. Avocado fruit is a rich source of beta-sitosterol. J. Am. Diet. Assoc., 101(4), pp. 404–405.

18.  Lin X., et al., 2009. Phytosterol glycosides reduce cholesterol absorption in humans. Am. J. Physiol. Gastrointestinal Liver Physiol., 296, G931–G935.

19.  Lu, Q. Y. et al., 2010. California Hass Avocado: Profiling of Carotenoids, tocopherol, fatty acid, and fat content during maturation and from different growing areas. J Agric Food Chem, 57(21), pp. 10408-13.

20.  Dreher, M. L. and Davenport, A. J., 2013. Hass Avocado Composition and Potential Health Effects. Crit Rev Food Sci Nutr. 53(7), pp. 738–750.

21.  Dismore K. L., 2003. Vitamin K content of nuts and fruits in the US diet. J. Am. Diet. Assoc., 103(12), pp. 1650–1652.

22.  Wein, M. et al., 2013. A randomized 3x3 crossover study to evaluate the effect of Hass avocado intake on post-ingestive satiety, glucose and insulin levels, and subsequent energy intake in overweight adults. Nutrition Journal, 12(155), 9 pages.

23.  Salonen R. M., 2003. Six-year effect of combined vitamin C and E supplementation on atherosclerotic progression. Circulation, 107, pp. 947–953.