A word from: Dr. Henk van den Berg

Nuts: how healthy are they?
Positive properties are ascribed to nuts: they are rich in minerals, trace elements such as potassium, magnesium and zinc, and B-vitamins (B1, B6), but they are also a good source of dietary fibre and protein. Furthermore, it is apparent from several studies that the consumption of nuts is associated with a decreased risk of cardiovascular disease. This protective effect is ‘explained’ by the favourable composition of fatty acids in nuts. Nuts contain relatively large amounts of (monounsaturated and polyunsaturated) fats, although for example Brazil nuts and cashew nuts, together with peanuts (a fatty legume that is generally looked upon as being a nut) nonetheless do have a relatively high saturated fat content (15-25%).

Despite all their positive properties, nuts are not included in the ‘Eat Healthy: Wheel of Five’, neither are they considered to be among the basic food products, but are categorized in the ‘extras’ as a snack food. This is because the Guidelines for Healthy Food Choice issued by the Netherlands Nutrition Centre are based on the Dutch eating pattern. In the Netherlands, nuts are eaten principally as a snack, and according to food consumption surveys do not make a substantial contribution in the provision of micronutrients. And in the ‘snacks’ product group they are even categorized as ‘eat by exception’ because of their (excessively) high energy content (>110 kcal/ per standard portion of 20 g), and/or an excessive saturated fat content (>13 en %). Only pistachios achieve the status of a ‘preferred option,’ as the edible proportion of this nut is smaller. Criteria such as energy and fat contents are key factors in the categorization of non-basic products in view of the importance of disease prevention (overweight).

Dr. Henk van den Berg Specialist Food and Health

Energy density and the position of nuts in the Dutch general nutritional pattern are therefore factors preventing nuts being placed in the category of a ‘healthier’ option. This would appear to be at odds with the above-mentioned experimental and observational studies. However, these studies do not yet provide sufficient evidence, and leave questions open, such as the differences in effect between types of nuts, and the energy utilization from nuts. The intestinal absorption of fatty acid from nuts was reported to be approximately 7% lower, and not compensated (BJN 2007:98:456-7). A review of the positioning of nuts in the product categorization is therefore not (yet) under consideration. Nonetheless, this by no means alters the fact that nuts certainly can – and already do – fit in within a healthy eating pattern, for example as a (complete) meat substitute, but also – in limited consumption (small portions) and unsalted – as a snack, or as a sandwich filler (nut spreads).

Nuts have a positive impact on atherosclerosis

Nuts (peanuts and tree nuts) have a beneficial effect in the reduction of the development of cardiovascular diseases by influencing several risk parameters, such as raising the antioxidant levels and realizing a more favourable blood lipid profile. However, the major underlying process in the development of cardiovascular diseases is atherosclerosis. In contrast to cardiovascular diseases, atherosclerosis cannot be detected by measuring the changes in the antioxidant levels or lipid profiles. In order to be able to reduce the mortality rates caused by cardiovascular diseases it is necessary to understand the complex process of the development of atherosclerosis. Ros studied this process and discovered that nuts also have a beneficial effect on the biomarkers of developing atherosclerosis.

Atherosclerosis; what is it exactly?
Atherosclerosis is the initial stage of the development of cardiovascular disease. During this stage, a plaque of fatty components accumulates on the wall of the arteries. Ultimately this plaque may even block the blood vessel completely. It can be caused by abnormalities in lipoprotein metabolism, oxidative stress, chronic inflammation and susceptibility to thrombosis. These determinants are related to the classical risk factors for cardiovascular disease, such as smoking, high blood pressure and increased blood cholesterol levels.

Biomarkers of atherosclerosis
In his paper, Ros discussed several epidemiological and clinical studies that investigated the impact of nuts on atherosclerosis. From these studies three different mechanisms that play a role in the development of atherosclerosis were derived: oxidation, inflammation and endothelial dysfunction. For the first two mechanisms, LDL oxidizability and C-reactive protein respectively, were used as their biomarker. The mechanism of endothelial dysfunction does not have a biochemical biomarker. The severity of the condition can be estimated by looking at the stage of deformation of the endothelial wall.

Effect of nuts on atherosclerosis
Since nuts contain in general a high level of antioxidants and monounsaturated fatty acids they do indeed have a favourable influence on LDL oxidation. However, although effects were seen in the studies examined, none of them was significant. Moreover, there is evidence that suggests that dietary polyphenols in nuts may also have anti-inflammatory effects. Several studies showed that bioactive compounds, which are also present in nuts, have a positive effect on the endothelial function of the artery wall. Nonetheless, the studies that were examined and that included nut consumption did not measure the difference in endothelial dysfunction.

Nuts may prevent the development of atherosclerosis
From this analysis the author concluded that nut consumption has a potentially favourable influence in the prevention of the development of atherosclerosis, and therefore also indirectly on the development of cardiovascular diseases.

Source:
Ros E. Nuts and novel biomarkers of cardiovascular disease. American Journal of Clinical Nutrition 2009;89(suppl):1649-1656.

Brazil nuts can help in the prevention of cancer

Brazil nuts may have a preventive effect on the development of various forms of cancer because of their nutritional composition. It is known that Brazil nuts are a good source of micronutrients and bioactive compounds. Compared to other nuts they possess relatively high levels of selenium, calcium, magnesium, vitamin E, phytosterols and the antioxidant squalene. In a recent review, Yang explained that especially the high content of selenium and antioxidants in Brazil nuts could explain the positive health effect. But how does this work exactly?

Selenium plays a critical role in the effect of antioxidants
Selenium is an essential component of antioxidant enzymes. Thus, it plays a significant role in the antioxidant process, and is therefore a major contributor to the antioxidant capacity of the Brazil nut. The effect of the antioxidants present in the nuts is enhanced when it is consumed in combination with selenium. Brazil nuts contain large amounts of selenium owing to the high selenium concentration in the Amazonian soil. One single Brazil nut provides 160% of the US Recommended Daily Allowance for selenium. Since the Brazil nuts contain large quantities of selenium and antioxidants, the antioxidant capacity is quite high.

Tumour formation greatly inhibited
The fact that antioxidants inhibit cell proliferation has already been seen in numerous in vitro studies. However, knowledge of the synergistic effects of selenium and antioxidants on the tumour formation is relatively new. Recent human studies showed beneficial effects in the prevention of several cancers, such as mammary, lung and prostate cancer. However, the evidence of nut extracts is limited, although the studies performed did show a higher tissue selenium accumulation after the consumption of Brazil nuts and high antiproliferative activity owing to the synergistic antioxidant capacity.

Regular consumption of Brazil nuts can improve health status
The author concluded that regular consumption of Brazil nuts may help in the prevention of cancer, despite the limited evidence of the underlying mechanisms of action.

Source:
Yang J. Brazil nuts and associated health benefits: a review. Food Science and Technology 2009;42:1573-1580.

Imprint

Editorial staff
Intersnack Group, Düsseldorf
Schuttelaar & Partners, The Hague

Editorial Board
Schuttelaar & Partners, The Hague

Questions / comments
Please e-mail your questions or
comments to info@aboutnuts.nl

Subscribe / unsubscribe
Subscribe or unsubscribe?
Go to the About Nuts website.

Privacy and disclaimer Our newsletters have been produced with the greatest possible care. Nevertheless, errors can occur. About Nuts cannot be held liable for the consequences of any such errors. Subscribers' data will not be used for any other purposes without their express consent.