Barry's Nutrition Report

"Eat to Live, Not Live to Eat"
John H Weisburger, 2000

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Coconut oil – good or bad nutritionally?

 

This is currently a very controversial topic, with public opinion ranging the full spectrum from it being the latest 'wonder food' to the other extreme of 'keep it out of your diet altogether'.  The following blog is just one representative example of the totally different perspectives that people can have - The Skeptical Nutritionist.    It illustrates opinions based on blind faith in the merit of traditional cuisines, to faddism, personal testimonials and anecdotes, grower self-interest, media articles with an eye on ratings, unsubstantiated marketing hype by the processing industry, lack of knowledge, and misinterpretation or incomplete consideration of the relevant scientific facts, amongst others.

The NZ National Heart Foundation became sufficiently concerned about the situation that they felt it was necessary to review the evidence and issue summary guidelines for the public (Food New Zealand (Oct-Nov 2014), p24-25, and (Dec 2014- Jan 2015), p17-19), as follows:

Indigenous populations that consume traditional diets with coconut products, along with fish and vegetables (unsaturated fats and fibre) combined with a physically active lifestyle, are unlikely to be at risk of cardiovascular disease from the consumption of coconut products. The situation for indigenous populations who eat a traditional diet is vastly different to that of people consuming a typical "Western" diet. For these populations, coconut oil is 92% saturated and nothing in the literature disputes the fact that it acts as a saturated fat and raises total cholesterol, LDL cholesterol and HDL cholesterol. Coconut oil, like all saturated fats, should be limited to 7%-10% of calorie intake according to current dietary guidelines.

Like all food, if small quantities of coconut products are enjoyed in food recipes, then this is unlikely to be a problem. They need not be eliminated from the diet but should be consumed in moderation. This can be done by including unsaturated oils of high nutritional quality such as olive, avocado or canola oil with the cooking recipe and reducing the amount of coconut oil or cream. This has the dual benefit of reducing saturated fat intake whilst increasing unsaturated fatty acid intake. Light coconut cream or milk is a sensible substitute for full fat coconut cream.

A further quote from their report  – 'The evidence that coconut oil is super-healthful is not convincing and these claims appear to be more testimonials than clinical evidence.'

For their review, the NHF found only ten human clinical trials that they considered acceptable evidence to answer this question, and they mainly based their conclusions on two of these.  There are many more epidemiological studies but these can only ever show associations and can be subject to influence by many other variables, both recognised and unrecognised.  Although they didn't include the full range of molecular biological, biochemical, physiological and other animal/human studies on the properties of coconut oil to give a more complete evaluation, they nevertheless probably got the answer right.  Coconut oil is neither of the extremes mentioned in the introduction, and consumption should be quite limited given it contains virtually no essential fatty acids and has lots of empty calories (eg see National Nutrient Database.)

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Total Antioxidants in Edible Plants

The following is a summary of a study by a Norwegian group who looked at antioxidant levels in edible plant parts, including 19 cereals, 11 roots and tubers, 31 vegetables, 24 fruits, 19 berries, 10 pulses and 4 dried fruits.   They found that fruits are by far the richest sources of these valuable phytochemicals.  Generally, berry fruit are the stars, and when added to other fruits in their average national diet they accounted for more than 70% of total antioxidants consumed.

A predominantly plant-based diet reduces the risk for development of several chronic diseases.  It is often assumed that antioxidants contribute to this protection, but results from intervention trials with single antioxidants administered as supplements quite consistently do not support any benefit.

Because dietary plants contain several hundred different antioxidants, it would be useful to know their total concentration in individual species as this might assist identification of the  most beneficial dietary plants.  We have assessed total antioxidants in a variety of dietary plants used worldwide, including various fruits, berries, vegetables, cereals, nuts and pulses.  When possible, we analysed three or more samples of dietary plants from three different geographic regions in the world.  Our results demonstrated that there is more than a 1000-fold difference among total antioxidants in various dietary plants.  Plants that contain most antioxidants include members of several families, such as Rosaceae (dog rose, sour cherry, blackberry, strawberry, raspberry), Empetraceae (crowberry), Ericaceae (blueberry), Grossulariaceae (black currant), Juglandaceae (walnut), Asteraceae (sunflower seed), Punicaceae (pomegranate) and Zingiberaceae (ginger).

In the average Norwegian diet, fruits, berries and cereals contributed 43.6%, 27.1% and 11.7%, respectively, of the total intake of plant antioxidants.  Vegetables contributed only 8.9%.  The data presented here will facilitate future research into the nutritional role of the combined effect of antioxidants in dietary plants.
  (Halvorsen et al, Journal of  Nutrition (2002) 132: 461–471)

Government and medical authorities recommend we eat more fruit and vegetables.  In addition to the above study, others have also found that fruits on average have several times the antioxidant levels of veges and similar healthy fibre content.  Some of the qualities of fruits that promote their consumption are their delightful tastes and flavours, their convenience with little or no preparation necessary for eating fresh, and their nutritional benefits for the health conscious. Although they may cost more than veges, you can offset or even eliminate such differences by growing your own,   Then you can indulge in your favourite treats knowing you're eating a nutrient dense food that's good for you, rather than the numerous culinary alternatives that have been refined over generations to be irresistible but are all too often unhealthy.

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Phytochemical health benefits of fruit and vegetables

Liu, American Journal of Clinical Nutrition (2003) 78, S175-S205

Cardiovascular disease and cancer are ranked as the first and second leading causes of death in the US and in most industrialized countries. Regular consumption of fruit and vegetables is associated with reduced risks of cancer, cardiovascular disease, stroke, Alzheimer disease, cataracts, and some of the functional declines associated with aging. Prevention is a more effective strategy than is treatment of chronic diseases. Functional foods that contain significant amounts of bioactive components may provide desirable health benefits beyond basic nutrition and play important roles in the prevention of chronic diseases. The key question is whether a purified phytochemical (eg vitamin C) has the same health benefit as does the whole food or mixture of foods in which the phytochemical is present. We found, for example, that the vitamin C in non-skinned apples accounts for only 0.4% of the total antioxidant activity, suggesting that most of the antioxidants come from phenolics and flavonoids. We propose that the additive effects of the numerous phytochemicals in fruit and vegetables are responsible for their potent antioxidant and anticancer activities, and that the benefit of a diet rich in them is attributed to the complex mixture of phytochemicals present in whole foods.

This study illustrates why the common emphasis on food content of just the small number of commonly known vitamins usually misses the bigger picture. Consider vitamin C where oranges are often regarded as the reference standard for other fruits, with about 50mg/100g flesh. Apples (non-skinned) have less than a tenth this level, but when all antioxidant components in each are included they're approximately three times higher. The report also suggests why taking supplements is nowhere near as good nutritionally as consuming whole foods. About 5000 non-nutritive (ie not carbohydrates, proteins etc) phytochemicals have so far been characterised in plant products, but many thousands still remain unidentified. Activity differences between the common vitamins and whole foods are further accentuated as some of these less familiar phytochemicals can interact synergistically - ie their combined effects are greater than expected by simple addition.

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Fruit consumption and BMI

Like all developed countries of the world, the US has a massive obesity problem having profound negative health effects. Questions posed in this USDA study were – do the overweight/obese eat differently from thinner people ie choose different foods or consume larger quantities or both? Or is it a result of metabolism and activity level or all of these things? Government agencies and medical societies have been urging Americans for years now to eat more fruits and vegetables, both in quantity and variety, as healthy substitutes to improve their usual diet mix of high calorie foods. So the USDA looked at the relationship between consumption of fruits and veges and obesity in 4709 men and 4408 women over the age of 19, and tracked them over a 3 year period to assess their regular eating habits. BMI (body mass index) was used as the measure of obesity.

They found that the more fruit regularly consumed (measured as no of servings, including whether eaten as single foods or incorporated into food products eg blueberry muffins) the less likely they were to be overweight or obese. But they didn't find any significant change in BMI with increasing consumption of veges. A surprising result given that on average veges are even lower in calories than fruit. And worse still, when potatoes were examined separately from all other veges, the more of these they ate the fatter they were.

They concluded the explanation was in the way veges are normally eaten. Fruit are most often eaten raw or as juices without the necessity of processing as they're sufficiently edible and sweet by themselves. Although veges are also eaten fresh in salads and juices, they are more often processed/cooked in different ways before eating. They suggested that Americans may too often deep-fry their veges (think French fries), top them with high-fat dressings or sour creams, or include them in other high fat culinary delights. Another contributor they mentioned was that some people who are in the habit of having morning and afternoon snacks could be eating fruit rather than biscuits, chocolate bars, cakes or other high cal foods. Fresh veges don't have the same attraction as fruit for such a substitution. (Food Review, 2002, 25, 28-32)

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Nibbling Nuts

We're all aware that nuts are part of the healthy Mediterranean diet, and the following scientific review by Ros (Nutrients 2010, 2, 652-682) sketches out the story.

Nuts (tree nuts and peanuts) are nutrient dense foods with complex matrices rich in unsaturated fatty and other bioactive compounds: high-quality vegetable protein, fiber, minerals, tocopherols, phytosterols, and phenolic compounds. By virtue of their unique composition, nuts are likely to beneficially impact health outcomes. Epidemiologic studies have associated nut consumption with a reduced incidence of coronary heart disease and gallstones in both genders and diabetes in women. Limited evidence also suggests beneficial effects on hypertension, cancer, and inflammation. Interventional studies consistently show that nut intake has a cholesterol-lowering effect, even in the context of healthy diets, and there is emerging evidence of beneficial effects on oxidative stress, inflammation, and vascular reactivity. Blood pressure, visceral adiposity and the metabolic syndrome also appear to be positively influenced by nut consumption.

Thus it is clear that nuts have a beneficial impact on many cardiovascular risk factors. Contrary to expectations, epidemiologic studies and clinical trials suggest that regular nut consumption is unlikely to contribute to obesity and may even help in weight loss. Safety concerns are limited to the infrequent occurrence of nut allergy in children. In conclusion, nuts are nutrient rich foods with wide-ranging cardiovascular and metabolic benefits, which can be readily incorporated into healthy diets.

Good enough reasons to find room for a macadamia in the yard somewhere?

Barry Madsen

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