Plant Power: the Wonderful World of Fruits and Vegetables
you’re now in the habit of eating sufficient quantities of complete protein sources at each meal and are probably feeling, looking and performing better as a result. As you’ve mastered this habit, it’s time to introduce the next habit on your way to wellness.
Mum was onto something when she said Eat your Vegetables!
Many people intuitively know that most fruits and vegetables are health-promoting for most people, but what does the scientific evidence suggest?
A look at traditional cultures reveals a remarkable diversity in their consumption of plant foods, with intakes often greatly exceeding our own. Recent survey results of intakes in the United Kingdom suggest that just 9% of children aged 11 to 18 years meet the ‘5 servings of fruits and vegetables a day’ recommendation, 31% of adults aged 19 to 64 years and 37% of adults aged 65 years and over. This is in stark contrast to pre-industrial intakes. While many individuals in traditional cultures passed away early due to things such as acute infections in infancy and violence, those that survived generally experienced robust good health and did not succumb to the chronic diseases that are becoming so prevalent today.
In so-called epidemiological studies that assess associations between dietary intakes and health outcomes, a higher consumption of fruits and vegetables is generally associated with a reduced risk of development of chronic diseases such as cardiovascular disease and mortality from all causes among both men and women after adjusting for confounding variables such as smoking.
There are many reasons underlying these relationships, some of which you’ve undoubtedly heard about previously. While each fruit and vegetable has a complement of nutrients unique to itself, these foods are generally rich in fibre (both insoluble and soluble), micronutrients (including minerals and vitamins, among others) and water, which is itself essential to life.
Dietary fibre is found abundantly in plant cell walls and produces an increase in stool content, thereby protecting against constipation. Fibres provide fermentable substrates for bacteria residing in the gut and can stimulate the growth of strains with demonstrated health benefits on the host. These bacteria are not inconsequential; it is estimated that we house over 10 times more bacteria than cells in our own bodies, and these exert a vast influence on all sorts of bodily processes.
An adequate intake of fibre has also been shown to be protective against diseases such as colo-rectal cancer, helps stabilise blood glucose and insulin levels in response to meals and thereby can maintain cognitive function, may have beneficial effects on blood lipids, and mitigates hunger and consequently reduces tendencies to eat in excess.
Many micronutrients in fruits and vegetables are considered to be essential; that is, many of these cannot be synthesised by our bodies at all or in sufficient quantities. The complications of deficiencies of these are readily apparent in deficiencies such as scurvy (vitamin C deficiency); therefore, we must generally obtain them from dietary sources.
Micronutrients are involved in development and growth of the body and are crucial to many biochemical functions. These include roles are precursors for enzymatic actions in metabolism and anti-oxidative effects in which these nutrients quench free radical activity that may damage cells.
It will come as no surprise that our requirements vary between people, although that is beyond the scope of this article; moreover, as many of our ancestors thrived for generations without any knowledge of these, a detailed knowledge of their intricacies needn’t be necessary to obtaining adequate intakes!
Embracing Fruits and Vegetables: from Theory to Practice
I hope it is now clear that eating a diverse array of fruits and vegetables is likely to benefit the health of most people. In no particular order, here are a few tips on maximising the benefits you gain from fruits and vegetables:
- Buy a blender. A smoothie made from an array of fruits and vegetables can be an easy way to nudge up your intake, and there are many great recipes available online
- Check out your local market. The closer to you that your fruits and vegetables are grown, the more nutrient-dense they’re likely to be; try to eat seasonally for the same reasons. It’s also nice to support your local farmers. Better yet, grow your own fruits and vegetables!
- Consume at least one portion of fresh fruits and/or vegetables at each eating occasion. Eating them with meals containing fats such as extra-virgin olive oil may help your body take up many micronutrients
- Eat a diverse array of fruits and vegetables; there is life beyond apples, bananas, carrots, oranges, peas, and tomatoes! Challenge yourself to trying something new each week
- Eat fresh, whole fruits and vegetables that have been cooked gently using methods such as steaming; cooking can make some nutrients more bio-available to your body. Dried fruits can be very energy-dense and thus make you more likely to over-eat. Tinned fruits and vegetables may have nasty additives or be stored in containers containing toxins. Frozen fruits like berries and vegetables like spinach are generally fine and cost-effective
- Encourage yourself to eat more fruits and vegetables. Prepare your food in bulk to save time preparing it later and keep these foods handy in things like fruit bowls in the place of other foods like biscuits. There are few better snacks out there than a source of animal protein (like boiled eggs or natural yoghurt) and some peelable fruit
- Keep your intake of fruits moderate. Many of these are energy- and fructose-dense. Fructose is a mono-saccharide (type of sugar) that is readily used to replenish liver glycogen (carbohydrate) stores. Once these are full, excess fructose is rapidly converted to adipocytes (fat cells) through a process named de novo lipogenesis. Therefore, the greater your intake of added sugar, the lower your intake of fruit should be. A maximum of three servings daily for women and four servings daily for men is a good rule of thumb for most
- Those of you with the means to buy organic produce should know that certain, non-organic fruits and vegetables can have particularly high pesticide residues. Data from the Environmental Working Group have resulted in lists of these foods that you can see here: http://static.ewg.org/reports/2012/foodnews/pdf/2012-EWGPesticideGuide.pdf
- Those of you with small appetites trying to gain muscle mass may not want to eat too many fibrous fruits and vegetables as you may be less likely to meet your energy (calorie) requirements; in this instance, dried fruit such as dates may be useful
Troubleshooting Common Issues
It is wise to pay attention to how you feel in the hours following each meal such that you can identify potentially troublesome foods. Some people, especially those with impaired digestive function, may find that eating certain types of fruits and vegetables plays havoc with their digestion. These often fall into a couple of categories, namely foods high in fermentable oligo-, di-, and mono-saccharides and polyols (FODMAPs) and foods belonging to the Solanaceae or ‘nightshade’ family.
FODMAP and Solanaceae Shortcomings
FODMAPs exert osmotic effects during digestion, meaning they draw water into their vicinity, and they may be fermented by gut bacteria when eaten in excess, leaving the individual prone to digestive discomfort and diarrhoea. For this reason, those with conditions such as irritable bowel syndrome often stand to benefit from reducing their intake of these foods. A list of drinks and foods high in FODMAPs can be found at: http://livinghappywithibs.files.wordpress.com/2013/07/high-fodmap-foods-to-avoid-by-food-group-20130708.jpg
Those of you struggling to digest fruits and vegetables in general may benefit from ensuring that you are thoroughly cooking all of these foods; for example, you may wish to stew your fruits.
Solanaceae plants contain many alkaloids, some of which can be toxic to some of us. Excessive intake of glycoalkaloids, natural pesiticides concentrated in potatoes, has been linked to digestive distress, for example.
Common dietary nightshades include:
- Peppers (cayenne, chili, green, jalapeno, orange, pimento, red, and yellow)
- *Potatoes, all varieties
- Tomatoes, all varieties (including Tomatillos)
*NB sweet potatoes and yams are NOT nightshades. Beware of potato starch used in many seasonings and as a thickening agent
While not in the nightshade family, artichokes, blueberries, huckleberries and okra also contain solanine.
For those of you suspecting that you may have problems with these foods, eliminating them from your diet for several weeks may have a positive effect on your health. After this removal, you can try re-introducing them one at a time; if you notice adverse consequences, remove them once more. I would recommend not removing these foods unnecessarily as they also contain myriad other constituents shown to benefit health.
Simply nudging up your intake of fruits and vegetables may benefit your health in so many ways. Make this process easy for yourself and your loved ones and enjoy the multitude of delicious options that we’re so fortunate to have easy access to today!