The interest in the beneficial effects of nuts on health arises from the data obtained in epidemiological studies and can be summarised as: frequent consumption of nuts reduces the risk of suffering cardiovascular diseases and increases life expectancy without risk of suffering from this type of disease (1-9). That is, the ingestion of nuts is an easy measure to prevent the diseases which are the major cause of morbidity and mortality in the western world (10,11). These observations work to deepen the influence of nuts on the factors which can contribute to explaining the cardio-protective effects of nuts (8,9). Table 1 shows the nuts which are eaten most.
Tradition has advocated that nuts are food of great nutritional value for their facility in supplying a wide variety of beneficial substances. Nevertheless, while having a high energy value and being rich in fat nuts were avoided for years, because there was a belief that eating them would cause the eater to gain weight.
However, the latest research has produced a surprising result, since the studies which have used nuts as a supplement to the diet have not shown any increase in weight in the participants (12).
This review will comment on the scientific works related to nuts, both those that refer to their protective effects against cardiovascular risk (Table 2), and contributions that present the relation of these foods to body weight.
According to the Spanish Food Code, nuts are those fruits the edible part of which has in its composition less than 50% of water. The products of certain trees are called nuts (tree nuts): almonds, hazelnuts, macadamia nuts, walnuts, cashew nuts, pine nuts and pistachios. In this group are also included peanuts and sunflower seeds. (Table 1)
Bioactive Components of Nuts
The calorific content of nuts varies between 5.6 and 6.4 Kcal per gram of food. All nuts have a similar composition in proteins (13-26%), in sugars (15-25%) and in fats (48-63%) (13,14). Table 3 shows the energy content and macronutrients of some nuts.
In spite of their high fat content, nuts have an attractive composition from the nutritional point of view with a predominance in contributing unsaturated fatty acids, where the oleic and linoleic acids provide more than 75% of the fat contribution, although each variety has its own characteristics (13,14). Hazelnuts, almonds and pistachios are rich in oleic acid, and for that reason are a source of monounsaturated fatty acids. Walnuts are rich in linoleic acid, and in consequence contribute polyunsaturated fatty acids. In addition, walnuts contribute linolenic acid in a proportion of up to 6.8% of fat content. Nevertheless, this fatty acid is found in a smaller quantity in other nuts, being less than 1% of the fatty acids. On the other hand, in all nuts the levels of saturated fatty acids does not exceed 7% (13,14). The composition in fatty acids of some nuts can be seen in table 4 (13,14).
The quantity of fibre, mostly insoluble, is appreciable, between 5 g and 11 g per 100 g of nut, and varies according to the different varieties of fruit. An adequate intake of fibre is important to facilitate and regulate intestinal transit, thus preventing constipation (15). Nevertheless, in recent years new beneficial effects of fibre consumption have been described. On the one hand, eating insoluble type fibre, such as nuts, exerts cardiovascular protection (16). Moreover, the ingestion of soluble type fibre produces a reduction in plasmatic cholesterol, improves the control of glycaemia, and is useful in the prevention and treatment of obesity (16).
Moreover, these fruits are a good natural source of vitamin E, especially almonds and hazelnuts, which contain some 20 mg per 100 g of product (14) (Table 5). In other nuts the vitamin content is lower, of the order of 3 to 9 mg per 100 g of food. The importance of vitamin E lies in its antioxidant action, which is responsible for the neutralisation of free radicals, diminishes fat oxidation, in this way protecting the cellular membranes. There is evidence that vitamin E contributed by food is an agent which reduces cardiovascular risk. Vitamin E is also an important anticarcinogen: insufficient vitamin E intake has been associated with an increase in the risk of different types of cancer.
Another vitamin which nuts contribute, in abundance, is folic acid, with values around 60-70 g/100g, with the exception of peanuts which contain up to 240 g/100g (14). Folic acid plays a strategic role in the metabolism of homocistein, in reducing its level in the plasma and, as a consequence, diminishing atherosclerotic risk. In addition, recently, an antioxidant action of folic acid has been described. With this action the mechanisms of cardiovascular protection exerted by folic acid are widened (17).
Moreover, these fruits provide minerals such as calcium, magnesium, copper, potassium, selenium and zinc. Table 5 shows la composition in minority components of nuts.
Content of phytosterols and other phytochemical substances is also valuable (18,19,20). Phytosterols, such as sitosterol, stigmasterol and campesterol, are the sterols which come from plants and have hypocholesterolaemiant properties. Phytochemical substances are bioactive molecules of plants, present in minority quantities, which contribute significantly to the protection against cardiovascular diseases. Phytochemicals are found in a wide variety of foods. Nuts are one of their greatest sources, as well as fruits and vegetables, cereals, soya and tea. The majority of foods contain more than one type of phytochemical. In nuts, the range of phytochemicals is: ellagic acid, flavonoids (quercetin, kaempferol and rutin), phenolic compounds, luteolin, isoflavonoids and tocotrienols. The overall content of isoflavonoids in nuts is 0.26 mg per 100g of edible portion (21).
Cooking or processing food eliminates, to a large extent, the viability of these substances in such a way that their benefits are reduced. For this reason, nuts are an important source of phytochemicals, since they can be eaten raw.
Nuts also form an interesting contribution of proteins of vegetable origin, especially their content of arginine, an amino acid which amongst other functions is the source from which nitric oxide is derived. This oxide acts as an endothelial vasodilator and has an antiplatelet action. A shortage of nitric oxide is associated with an endothelial dysfunction, and therefore increases the cardiovascular risk. The arginine content of nuts is from 2 g to 3 g per hundred grams of food (17)(Table 5).
In summary, various components of nuts can intervene in the mechanisms implicated in the process of arteriosclerosis, the basis of the appearance of cardiovascular diseases(Table 6).
Following are details of the epidemiological studies which have examined the relationship between the consumption of nuts and cardiovascular diseases, such as myocardial infarction or angina pectoris.
The pioneer study in this area was The Adventist Health Study, undertaken in the religious community of Seventh-day Adventists in California. (1). The results described in this religious group were embodied in three publications (1-3).
The first of these studies (1) was conducted on 31,208 people of Caucasian race practising the Adventist religion, characterised by following a particular diet which included nuts as a source of energy. After a six-year follow-up, there was evidence of a 51% reduction in the risk of non-fatal myocardial infarction and a 48% reduction in the risk of fatal cardiovascular disease in those individuals who ate nuts 5 times or more a week, when compared with subjects who ate nuts fewer than once a week. These results, described in 1992 (1), led to a change of criterion and new horizons were opened in the use of nuts, since until that time eating these foods had been discouraged in the general population.
In the second study (2), with the participation of 27,321 people, members of the Adventist community, it was observed that the risk of suffering from coronary disease was reduced by 12.4% during the course of the life of those individuals who had a high consumption of nuts, in comparison with individuals with a low consumption. In addition, the individuals with a high consumption of nuts prolonged their life expectancy by 5.6 years with no coronary events (2). To these results was added another aspect: nuts do not only offer protection from cardiovascular diseases but also favour longevity without coronary episodes.
Cardiovascular protection was also confirmed in a third study undertaken with octogenarian subjects (3). In 11,828 Adventists who were more than 84 years old the protective effects were confirmed. The risk of death owing to general causes was reduced by 18%, and especially the risk of death by coronary disease diminished by 39% in subjects who ate nuts five or more times a week in comparison with individuals who ate these products fewer than once a week (3).
Progressively, evidence was being consolidated with the contribution of the results obtained in women of different ages (4). In the large epidemiological study, Nurses' Health Study, 86,016 nurses were controlled over a period of fourteen years. A reduction of 35% in the total risk of myocardial infarction, a reduction of 39% in the risk of fatal cases, and a lowering of 32% in the risk of non-fatal infarction in those nurses who ate nuts at least five times a week in comparison with those who ate nuts fewer than once a week (4).
Likewise, the observations described in postmenopausal women were confirmed. In the Iowa Women's Study(5) 34,486 postmenopausal women who did not present cardiovascular risk factors were included and followed for a control period of seven years. The eating of nuts and seeds four times a month was associated with a reduction of 40% in the risk of coronary disease compared with those who never ate these products (5).
Later, the consumption of nuts was related to their fat profile. The Walnut Study (6) was undertaken in a nut-producing area of France, and an increase in HDL cholesterol and apolipoproteins AI was observed in 793 individuals, in association with the high consumption of nuts. These lipidic parameters confer a reduction in cardiovascular risk(6)
It must be said that nuts exercise the protective effect against cardiovascular diseases independently of the influence of other components of the diet.
In conclusion, the results of all the epidemiological studies confirm the cardiovascular protection of nuts. This protection is extended both to men and women of different races and ages, including postmenopausal. In addition, the protection, also, has been described in individuals with normal and with high blood pressure. At the same time, the consumption of nuts is associated with a low mortality rate and an increase in life expectancy without total cardiovascular disease total, which means living for a longer time free of this type of illnesses (1-9).
Effects of nuts on cholesterol and
other cardiovascular disease risk factors
The influence of nuts on cardiovascular diseases (Table 2) is explained in part by their effect on plasmatic cholesterol, one of the risk factors for this type of disease which can be changed by food (Table 7).
As is well known, the lipid factors of plasma, in particular the total cholesterol and the low density lipoproteins (LDL) cholesterol intervene in the process of arteriosclerosis, the clinical manifestations of which are cardiovascular diseases. The high levels of total cholesterol and of LDL are risk factors for cardiovascular diseases. On the other hand, high concentrations of high density lipoproteins (HDL) cholesterol protect against cardiac episodes.
The effect on cholesterol is linked to a large extent to the type of fatty acids in these fruits: a low percentage of saturated fatty acids and a high unsaturated content (7-9).
Confirming the novelty of this topic, and as a proof of it, we have a considerable number of studies undertaken in the last 10 years. The results are striking and lead to similar conclusions in spite of having different designs and including diverse groups of people(7-9,22-46).
On the one hand, the evaluation of the studies which include the combination of the consumption of almonds, walnuts and hazelnuts shows a hypocholesterolaemiant effect of all these fruits. This effect, which is independent of the quantity of these products that is eaten, has been quantified as 7-15% reduction of total cholesterol and a 10-33% reduction in LDL cholesterol, while the concentrations of HDL cholesterol remain stable (22-28). In addition to this, two of the studies describe a significant reduction in triglycerides (23,26).
Another series of works analyses the effects of eating a specific type of nut with the aim of verifying its hypocholesterolaemiant capacity in plasma (29-45). There are focused studies using almonds (29,30), hazelnuts (31,32), macadamias (33,34), pecans (35,36), pistachios (37), walnuts (38-43) and peanuts (44,45) and these are explained in more detail in the following paragraphs:
With the eating of almonds a reduction of 8-12% in total cholesterol and of 9-15% in LDL cholesterol was observed. There was no evidence of any modifications in the concentrations of HDL cholesterol or of triglycerides (29,30).
In the case of hazelnuts, the studies undertaken used this nut as a supplement to the usual diet. A first study with 70 children and 104 healthy adults, men and women, demonstrated that the addition to the usual diet of the participants of 25g of hazelnuts every day over 4 months led to an increase in the HDL (31). In spite of eating an additional quantity of calories, body weight stayed constant (31).
More recently, another study with similar characteristics, with 30 participants, consisted of adding 1 g of hazelnuts for each kilo of body weight to the usual diet each day for a month. The results confirmed an increase in HDL cholesterol and a reduction in total cholesterol, LDL cholesterol and triglycerides (32).
Eating macadamias, also, has confirmed the reduction of 5-8% in total cholesterol, of 5-11% in LDL cholesterol and of 10-21% in triglycerides (33,34). One of these studies detected a reduction of 5% in the HDL cholesterol concentrations (33).
The data were obtained by comparing the effects of a diet without nuts with another that included 68 g of pecans each day. After 8 weeks, the diet rich in pecans caused a 6% reduction in LDL cholesterol (35).
Recently, another work evaluated the effects of a Step 1 type diet (30% of energy in the form of fat) and compared them with those of another diet where 20% of the energy was replaced by pecans. Both diets improved the lipid profile, but the diet rich in pecans more significantly reduced the total cholesterol (6.7%), the LDL cholesterol (10.4%) and the triglycerides (11.1%), while the HDL cholesterol increased (2.5 mg/dL) (36).
The consumption of pistachios as a substitute for other sources of fat contributes to reducing total cholesterol by 2% and increasing HDL cholesterol by 12%, while no changes in LDL cholesterol or triglycerides were detected (37).
There were four studies undertaken on walnuts which produced a reduction between 4 and 12 % in total cholesterol and 8-16% in LDL cholesterol (38-41). The effects on the HDL cholesterol are different. Although one study showed a reduction of 5% (41), another detected an increase of 14% (40) and the other two studies produced no evidence of changes (38,39). As far as triglycerides are concerned, three studies did not show any variations (39-41) and in the other a reduction of 8% in the plasmatic triglycerides was observed (38).
A recent contribution to the effects of the consumption of walnuts has been a work of crossed type undertaken with patients affected with hypercholesterolaemia (38). 49 adults participated and after a randomisation process one of the groups continued with a Mediterranean-type diet, without the presence of nuts, and the other followed the diet with walnuts. In this latter diet, between 41 and 56 g of walnuts each day replaced olive oil and other foods rich in fat integrated in the Mediterranean diet. Compared with the levels at the beginning of the study, the diet with walnuts reduced total cholesterol by 9% and LDL cholesterol by 11%, while the Mediterranean diet produced a reduction of 5% and 6%, respectively. No variations in HDL cholesterol of the plasma were observed. The triglycerides level fell by 8% after the diet with walnuts. Thus it appears evident that the hypocholesterolaemiant effect of walnuts may be comparable to that observed with other sources of unsaturated fatty acids such as olive oil (38).
Further work was done on the mechanisms of the hypocholesterolaemiant effect of walnuts and a possible explanation can be found in the increase in LDL-receptor activity (42).
Another interesting effect associated with the consumption of walnuts was that the LDL obtained after the consumption of walnuts did not increase its oxidisability compared with the LDL isolated after following a Mediterranean-type diet (38).
The beneficial effects of nuts on blood concentrations of Lp(a), a recently described independent cardiovascular risk factor of, has been established (10). Levels of Lp(a) are reduced as much by the consumption of pecans (a source of monounsaturated fatty acids) (36) as of walnuts (rich in polyunsaturated fatty acids) (38).
New perspectives have been defined from the administration of a supplement of walnuts in patients affected by combined hyperlipidaemia (43). In this type of patients who show an elevation of cholesterol or of plasmatic triglycerides or of both at the same time, the supplement of walnuts produced two effects: the stabilisation of body weight and modifications in the distribution of the lipids between the various lipoproteins in the plasma without changes in the concentrations of the plasmatic lipids. (43). In spite of adding 48 g of walnuts to the diet, which signifies the addition of some 288 Kcal. daily, over 6 weeks, the weight of the participants stayed stable.
The supplement of walnuts induced variations in the distribution between various lipoproteins without variations in the concentrations of the plasmatic lipids. Thus the addition of walnuts to a denominated habitual diet, which included 29% fat content (11% saturated fatty acids, 6% polyunsaturated fatty acids and 12% monounsaturated fatty acids) determined a reduction of small and dense LDL cholesterol, without observing changes in the levels of total cholesterol.
In the same way, the patients with combined hyperlipidaemia show an increase in another type of particle with a strongly atherogenic capacity, the intermediate density lipoproteins (IDL). After eating walnuts, the IDL levels were lower than those obtained with the same diet without the supplement. From what has been described, the observation of the beneficial influence of walnuts on lipoproteins with high atherogenic power (43) is suggestive.
Moreover, in this same study it was observed that adding walnuts to the usual diet reduced the concentration of HDL cholesterol, while its main apolipoprotein (apo), the apo A-I, increased (43). This observation led to an interest in delving deeper into HDL metabolism.
Nuts and body weight
Because of their high energy content and richness in fat, nuts have been avoided as a food because of the risk of increasing body weight. Ratifying this affirmation, in Spain there has been a reduction of approximately 5% in nut consumption over the last five years. Nevertheless, recent data show an increase in consumption of 1.2% in the period between 1999 and 2000 (46). Therefore it seems that this prejudice, is being abandoned in the face of the current scientific evidence demonstrating a stable body weight, even when supplements of nuts are eaten as an addition to the normal diet (12,31,32,43).
This apparent contradiction is easily explained when nuts are used as a substitute for other sources of fat. The incorporation of nuts into dishes and culinary preparations or, simply, as a substitute for the dessert or the reduction of the second course, allows them to be consumed without increasing calories.
Thus, if nuts replace other foods rich in fats, the total energy contribution remains stable and the risk of excess weight is reduced. It must be remembered that 1 g of fruit has some 6 Kcal (13,14).
The novel situation has been described when nuts are added to a diet, in the form of an appetiser or a dessert, then in spite of increasing the energy of the normal intake, the weight of the participants does not change(12,31,32,43).
To explain the stability of body weight, various hypotheses have been considered on the influence of nuts in feeling full and (12) and in control of hunger. Another possibility could be that the fibre contributed by nuts reduces the absorption of fats at the intestinal level. For each 100 g of nuts the fibre contributed varies between 5 and 11 g, according to the variety (15).
It is possible to indicate that the greater morbidity and cardiovascular mortality in the obese person, above all in obesity with a visceral or abdominal distribution, implies a great problem in the field of public health (47). This is one of the reasons why it is of especial importance to prevent or treat obesity.
For all these reasons, as well as because of their repercussions, the influence of nuts in the control of body weight is a new field of current research.
Another form of dealing with the role of nuts in body weight is by analysing the relevance of those products in dietetic measures intended for the reduction of weight.
To lose weight diets which are hypocalorific and low in fat, less than 30% of the energy total, have been suggested (47). Nevertheless, the ideal quantity of fat to maintain a long-term weight loss continues to be debated. This theme arises, largely, from the fact that diets with a low fat content do not have a very pleasant taste, and this is an aspect which makes them difficult to follow over long periods of time. In this context there has arisen an interest in defining diets to reduce body weight which allow a high degree of adherence and sufficient palatability to ensure that they are followed in the long term. To answer this question, recent data obtained from a study undertaken with overweight patients are available (48). In 101 overweight men there was a comparison between the effects of a low-fat diet (<20% of the total daily energy) with those of another diet with a moderate quantity of fat (35%) where 20% of energy was contributed by monounsaturated fatty acids, from nuts, products derived from nuts, and from olive oil. After 6 months, following the diets, the weight loss was similar in both groups.
However, the situation changed AFTER 18 MONTHS FOLLOWING THE DIETS: In the group with the diet with a moderate fat contribution an average weight loss of 4.1 Kg per person was observed, while after the low-fat diet there was an increase of 2.9 kg. Thus, after 18 months, the difference between both groups was 7 kg. Clearly, the weight loss was different in the subjects according to the type of diet (48).
This study contributed another novel item of data in relation to the participation of the individuals and to the following of the dietetic norms. Surprisingly, 18 months after the start of this study, only 20% of the participants continued with the low-fat diet, while 54% of the members of the group with a moderate- fat diet stuck to the rules. In view of this observation, and to evaluate the adherence to the diet, it was decided to continue the study with the participants who ate a moderate-fat diet. In this group and 30 months after the beginning of the study, the average weight loss per person was 3.5 Kg. In the light of these results, it is deduced that DIETS WITH A MODERATE FAT CONTENT ARE EASIER TO FOLLOW (48).
The previous study, as well as the adequate quantity of fat threw up another unknown: the type of foods can play a role in the diets designed to lose body weight. Thus, under the conditions of the above-mentioned study, it can be suggested that the inclusion of nuts could be another factor which helps to maintain the continuity of the diet.
All these observations strongly favour the continuation in the study of the consumption of certain foods to prevent obesity or to maintain an adequate weight.
Are nuts functional foods?
In recent years a new concept of functional food has been described. What is understood by this is those natural or processed dietetic products which produce a benefit beyond aroma, flavour or nutritive value, affecting a measurable physiological parameter and useful in terms of prevention of illnesses or promotion of health which can be extended to the large majority of the population (49).
For all the healthy effects described, nuts are considered as a NATURAL FUNCTIONAL FOOD, and can be used to promote health by their easy incorporation into the usual diet of the population. Thus, eating nuts is a simple measure to prevent cardiovascular diseases, the greatest cause of morbidity and mortality in the western world.
The change of attitude in relation to consumption of nuts in recent years has been radical. Now there has been a consolidation, both in our environment and in the international scientific society (10,11), of A RECOMMENDATION TO EAT BETWEEN 1-5 PORTIONS OF NUTS A WEEK (1-9) (Table 8). One portion is equivalent to 25g of nuts, net weight and without shells. Table 9 shows the relationship between weight and number of units of each type of fruit.
Evaluation of the quantity of nuts consumed in Spain makes it possible to define the average consumption per person as some 6 g per day (50) and as has already been mentioned, there has been an increase in consumption of nuts in the last few years (46).
As an example, some 25 g of nuts contribute 16 g of fats and some 2 g of saturated fatty acids. In addition, in daily practice it is also easy to incorporate them, if the approximate weight of each unit nut is known. Thus, in the case of hazelnuts it would be about 25 units a day, since each hazelnut weighs about 1 g. As a healthy diet for the heart should have 35% of its energy in the form of fats with less than 7% in saturated fatty acids (10,11) it is easy to include up to 50 g of nuts, since these alone contribute some 4 g of saturated fatty acids.
In addition to the fatty acid content, the quantity of components present in nuts makes these products natural foods which provide benefits to health beyond those described up to this time.
Another question that often arises is whether nuts should be eaten toasted or not. Nuts contain a certain water content, from 5 to 40 %. For this reason they are stable and long-lasting foods. Toasting, cooking at high temperature maintains the content of fatty acids though it may cause losses of 5% to 10% in phosphorus or zinc. Vitamins are very sensitive to high temperatures and there may be reductions of between 5% and 20% in most of them. Also, there may be losses in the phytochemical components.
In any event, the wide variety of nuts available to the consumer facilitates dietetic advice in response to the different tastes of the public. In addition, the versatility of this type of product (raw, toasted, whole, chopped) makes it easy to include them in the diet.
From the data referred to it is possible to evaluate the great importance of all the contributions. If with the consumption of nuts the reduction in total cholesterol obtained as an average is 10%, the expected reduction in the cardiovascular risk will be 20-25%. Nevertheless, the observed reduction of the risk is greater, 35-50% (1-9). Therefore, there is greater cardiovascular protection with the consumption of nuts than can be attributed to cholesterol. One possible explanation of this fact can be found in the influence of other bioactive components present in nuts, such as vitamin E, fibre, arginine and phytochemical components, which would add to the beneficial effects obtained with the contribution of unsaturated fatty acids on the process of arteriosclerosis (8,9) (Table 5).
The HABITUAL CONSUMPTION OF NUTS IS RECOMMENDED for the prevention of cardiovascular diseases and contributes to an increase in life expectancy (1-9) (Table 2).
- The protection of nuts is explained, in part, by a favourable effect on cholesterol, LDL cholesterol, HDL cholesterol of the plasma in normolipaemic and hypercholesterolaemic individuals (22-45).
- Also, nuts have demonstrated a reduction in the levels of Lp (a) in the blood (36,38), which adds another positive effect on the lipid risk factors. (Table 7).
- More recently, the ingestion of nuts in patients affected with combined hyperlipidaemia has shown the reduction in the plasmatic concentrations of lipoproteins with a high atherogenic power: small and dense LDL and IDL (43).
It can now be stated that the beneficial effect of nuts, as well as being attributed to the type of fat, with low saturated content and a high contribution of unsaturated fatty acids, is strengthened by the group of bioactive components with antioxidant and cardiovascular protective action.
Unexpectedly, the consumption of nuts as a replacement for other sources of fat, or in the form of a supplement to a diet, does not alter body weight (12,31,32,43).
For these reasons nuts are considered to be a natural functional food and constitute a useful and simple tool to prevent or promote cardiovascular health (49).
The recommendation is the consumption of some 25g a day, and some five times a week, of any variety of nuts, this being the reference quantity, and the optimum to strengthen the benefits which this type of foods provides (10,11). This recommendation regarding nuts contributes towards recovering one of the characteristic components of Mediterranean food.
1. Fraser GE, Sabaté J, Beeson WL, Strahan TM. A possible protective effect of nut consumption on risk of coronary heart disease: the Adventist Health Study. Arch Intern Med 1992; 152:1416-24.
2. Fraser GE, Lindsted KD, Beeson WL. Effects of risk factor values on lifetime risk of and age at first coronary event. Am J Epidemiol 1995; 142: 746-758.
3. Fraser GE, Shavlik DJ. Risk factors for all-cause and coronary heart disease mortality in the oldest-old. Arch Intern Med 1997; 157:2249-2258.
4. Hu FB, Stampfer MJ, Manson JE, Rimm EB, Colditz GA, Rosner BA, Speizer FE, Hennekens CH, Willett WC. Frequent nut consumption and risk of coronary heart disease in women: prospective cohort study. BMJ 1998; 317:1341-5.
5. Kushi LH, folsom AR, Prineas RJ, Mink PJ, Wu Y, Bostick RM. Dietary antioxidant vitamins and death from coronary disease in postmenopausal women. N Engl J Med 1996: 334: 1156-62.
6. Lavedrine F, Zmirou D, Ravel A, Balducci F, Alary J. Blood cholesterol and walnut consumption: a cross-sectional survey in France. Prev Med 28: 33-9, 1999
7. Sabaté J. Nut consumption, vegetarian diets, ischemic heart disease risk, and all-cause mortality: evidence from epidemiologic studies. Am J Clin Nutr 1999; 70: 500S-3S
8. Fraser GE. Nut consumption, lipids and risk of a coronary event. Clin Cardiol 1999; 22 (Supp III): III-11-15.
9. Kris-Etherton PM, Zhao G, Biskoski AE, Stacie M, Coval BS, Etherton TD. Effects of nuts on coronary heart disease risk. Nutr Reviews 2001; 59: 103-111.
10. Ministerio de Sanidad y Consumo, Sociedad Espanola de cardiologia y Sociedad Española de arteriosclerosis. Control de la colesterolemia en España, 2000. Un instrumento para la prevención cardiovascular. Clin Invest Arteriosclerosis 2000; 12: 125-152
11. Krauss RM, Eckel RH, Howard B et al. AHA Dietary guidelines. Revision 2000: A statement for Healthcare professionals from the nutrition committee of the American Heart Association. Circulation 2000; 102: 2296-2311
12. Fraser GE, Jaceldo K, Sabaté J, Bennett H, Polehna P. Changes in body weight with a daily supplement of 340 calories from almonds for six months (abstr.) FASEB J 1999; 13: A539
13. Favier JC, Ripert JI, Toque C, Feinberg M. Répertoire general des aliments. Table de composition. Paris: Technique & Documentation / Inra / Ciqual-Regal, 1995.
14. USDA U.S Departament of Agriculture Research Service Nutrient Database for Standard Reference, 1998.
15. Plessi M, Bertelli D, Monzani A, et al. Dietary fiber and some elements in nuts and wheat brans. J Food Comp An. 1999; 12: 91-96.
16. Jenkins DJA, Kendall CWC, Axelsen M, Augustin LSA, Vuksan V. Viscous and nonviscous fibers, nonabsorbable and low glycaemic index carbohydrates, blood lipids and coronary heart disease. Curr Opin Lipidol 2000; 11:49-56.
17. Brown A, Hu F. Dietary modulation of endothelial function: implications for cardiovascular disease. Am J Clin Nutr 2001; 73: 673-86. 1. Jenkins DJA, Kendall CWC, Axelsen M, Augustin LSA, Vuksan V. Curr Opin Lipidol 2000; 11:49-56.
18. Craig W, Beck L. Phytochemicals: health protective effects. C J Diet P Resch 1999; 12: 729-742.
19. Mazur W. Phytoestrogen content in foods. B Clin Endo Metab 1998; 12: 729-742.
20. Van- der-Schouw YT. Phyto-oestrogens and cardiovascular disease risk. Nutr Metab Cardio Disease 2000; 10: 154-167.
21. USDA-Iowa Database on the Isoflavone content of foods, 1999.
22. Bruce B, Spiller GA, Klevay LM, Gallgher SK. A diet high in whole and unrefined foods favorably alters lipids, antioxidant defenses and colon function. J Am Coll Nutr 2000; 19: 61-67.
23. Jenkins DJA, Popovich DG, Kendall CWC, Vidgen E, Tariq N, Ransom TPP, Wolever TMS, Vuksan V, Mehling CC, Boctor DL, Bolognesi C, Huang J, Patten R. Effect of diet high in vegetables, fruit and nuts on serum lipids. Metabolism 1997; 46: 530-537.
24. Bruce B, Spiller GA, Farquhar JW. Effects of a plant-based diet rich in whole grains, sun-dried raisins and nuts on serum lipoproteins. Veg Nutr: An Intl J 1997; 1(2): 58-63.
25. Abbey M, Noakes M, Belling GB, Nestel PJ. Partial replacement of saturated fatty acids with almonds or walnuts lowers total plasma cholesterol and low density lipoprotein cholesterol. Am J Clin Nutr 1994; 59: 995-999.
26. Singh RB, Rastogi SS, Verma R, Bolaki L, Singh R. An Indian experiment with nutritional modulation in acute myocardial infarction. Am J Cardiol 1992; 69:879-85.
27. Berry Em, Eisenberg S, Harats D, Friedlander Y, Norman Y, Kaufmann NA, Stein Y. Effects of diets rich in monounsaturated fatty acids on plasma lipoprotein-The Jerusalem Nutrition Study. I.High MUFA vs high PUFAs. Am J Clin Nutr 1991; 53:899-907.
28. Berry EM, Eisenberg S, Friedlander Y, Harats D, Kaufmann NA, Norman Y, Stein Y. Effects of diets rich in monounsaturated fatty acids on plasma lipoproteins-The Jerusalem Nutrition Study. II. Monounsaturated fatty acids vs carbohydrates. Am J Clin Nutr 1992; 56:394-403.
29. Spiller GA, Jenkins DAJ, Bosello O, Gates JE, Cragen LN, Bruce B. Nuts and plasma lipids: An almonds-based diet lowers LDL C while preserving HDL-C. J Am Coll Nutr 1998; 17: 285-290.
30. Spiller GA, Jenkins DJA, Cragen LN, Gates JE, Bosello O, Berra K, Rudd C, Stevenson M, Superko R. Effects of diet high in monounsaturated fat from almonds on plasma cholesterol and lipoproteins. J Am Coll Nutr 1992; 11: 126-130.
31. Masana L, Cabré P, Solà R.Importancia de los frutos secos. Revisión y aportaciones españolas a su estudio. Clin Invest Arteriosclerosis 2000; 12: 27-30
32. Durak I, koksal I, Kacmaz M, Buyukkocak S, Cimen BM, Ozturk HS. Hazelnut supplementation enhances plasma antioxidant potential and lowers plasma cholesterol levels. Clin Chim Acta 1999; 284: 113-115.
33. Curb JD, Wergowske G, Dobbs JC, Abbott RD, Huang B. Serum lipids effects of a high monounsaturated fat diet based on macadamia nuts. Arch Intern Med 2000; 160: 1154-1158.
34. Colquhoun DM, Humphries JA, Moores D, Somerset SM. Effects of a macadamia nut enriched diet on serum lipids and lipoproteins compared to a low fat diet. Food Aust: Off J Counc Aust Food Technol Assoc Aust Inst Food Sci Technol 1996; 48:216-222.
35. Morgan WA, Clayshulte BJ. Pecans lowers low-density lipoprotein cholesterol in people with normal lipid levels. J Am Diet Assoc 2000; 100: 312-318.
36. Rajaram S, Burke K, Connell B, Myint T, Sabaté J. A Monounsaturated fatty acid-rich pecan-enriched diet favorably alters the serum lipid profile of healthy men and women. J Nutr 2001; 131: 2275-2279.
37. Edwards K, Kwaw I, Matud J, Kurtz I. Effect of pistachio nuts on serum lipid levels in patients with moderate hypercholesterolemia. J Am Coll Nutr 1999; 18: 229-232.
38. Zambon D, Sabaté J, Muñoz S, Campero B, Casals E, Merlos M, Laguna JC, Ros E. Substituting walnuts for monounsaturated fat improves the serum lipid profile of hypercholesterolemic men and women. Ann Intern Med 2000; 132:538-46.
39. IwamotoM, Sato M, Kono M, Hirooka Y, Sakai K, Takeshita A, Imaizumi K. Walnuts lowers serum cholesterol in Japanese men and women. J Nutr 2000; 130: 171-176.
40. Chisholm A, Mann J, Skeaff M, Frampton C, Sutherland W, Duncan A, Tiszavari S. A diet rich in walnuts favourably influences plasma fatty acid profile in moderately hyperlipidaemic subjects. Eur J Clin Nutr 1998; 52:603-607.
41. Sabaté J, Fraser GE, Burke K, Knutsen S, Bennett H, Lindsted KD. Effects of walnuts on serum lipid levels and blood pressure in normal men. N Engl J Med 1993; 328: 603-607.
42. Munoz S, Merlos M, Zambón D, Rodriguez C, Sabaté J, Ros E, Laguna JC. Walnut-enriched diet increases the association of lDL from hypercholesterolemic men with human HepG2 cell. J Lipid Res 2001; 42: 2069-2076.
43. Almario RU, Vonghavaravat V, Wong R, Kasim-Karakas SE. Effects of walnuts consumption on plasma fatty acids and lipoproteins in combined hyperlipidemia. Am J Clin Nutr 2001; 74: 72-79
44. O'Byrme DJ, Knauft DA, Shireman RB. Low-fat monounsaturated diets containing high-oleic peanuts improve serum lipoprotein profiles. Lipids 1997; 32: 687-95.
45. Kris-Etherton PM, Pearson TA, Wan Y,Hargrove R, Moriarty K, Fishell, Etherton TD. High-mounsaturated fatty acid diets lower both plasma cholesterol and triacylglycerol concentrations. Am J Clin Nutr 1999; 70:1009-15.
46. Ministerio de Agricultura, Pesca y Alimentación. http:/www.mapya.es. Diciembre,1999
47. Dislipemia y obesidad. Documento de consenso. Clin Invest Arteriosclerosis 1998; 10 (Supl 1):1-42.
48. McManus K, Antinoro L, Sacks F. A randomized controlled trial of a moderate-fat, low-energy diet compared with a low fat, low-energy diet for weight loss in overweight adults. Int J Obes 2001; 25: 1503-1511.
49. Bellisle F, Diplok AT, Hornstra G, Koletzko B, Roberfroid M, Salminen S et al. Functional food science in Europe. Br J Nutr 1998; 80 (Suppl 1).
50. Salas-Salvadó J, Megias Rangil I, Arija Val V, Cabré Cabré P, Masana L, Riera I, Solà R. Frutos secos. En: Guías aliemntarias para la población española. Javier Aranceta Bartrina (ed). Madrid:IM&C, 2001.pp:87-94. ISBN:84-7867-169-2.
51. USDA. Table of nutrient retention.2000.
Table 1.- Nuts consumed most
Almond (Prunus amygdalus)
Hazelnut (Corylus hazelnut)
Brazil nuts (Bertholletia myrtaceae o excelsa)
Cashew nut (Anacardium occidentale)
Walnuts (Juglans regia)
Pecans (Carya illinoinensis)
Pine nuts (Pinus lambertiana)
Macadamias (Macadamia intergrifolia)
Pistachio (Pistacia vera)
Table 2.-Effects of nuts on cardiovascular diseases
- Reduction of cardiovascular risk: The consumption of nuts 5 times a week reduces the cardiovascular risk between 35% and 50%.
- Increase in life expectancy without risk of cardiovascular disease
Table 3.- Composition of Nuts
Per 100 g of foodstuff: Values expressed in %
USDA 1998 U.S. Department of Agriculture Research Service Nutrient Database for Standard Reference
Table 4.- Fatty acid composition in Nuts
Per 100 g of foodstuff: Values expressed in %
USDA 1998 U.S. Department of Agriculture Research Service Nutrient Database for Standard Reference
Table 5.- Composition of minority components in Nuts
Per 100 g of foodstuff: NK: Not known
USDA 1998 U.S. Department of Agriculture Research Service Nutrient Database for Standard Reference
Table 6.- Some components of nuts which can influence cardiovascular diseases
- High mono and polyunsaturated fatty acid content
- Low saturated fatty acid content
- Saturated fatty acids
- High fibre content, predominantly insoluble type
- Vitamins and minerals: Vitamin E, Folic acid, Copper, Magnesium
- Proteins: arginine
Table 7.- Effects of nuts on cardiovascular disease risk factors
- Reduction of total cholesterol and LDL cholesterol concentrations without changes in plasma HDL cholesterol.
- LDL antioxidant protection.
- Reduction in the concentration of Lp (a) in the blood.
- Reduction in the levels of plasmatic lipoproteins with high atherogenic power: small and dense LDL and IDL and in patients with combined hyperlipidaemia.
Table 8.- Food recommendation
The recommendation is to eat some 25g a day, and five times a week, of any variety of nuts, this being the reference quantity, and the optimum to harness the benefits which this type of food provides.
Table 9.- Relation between weight and number of units of each type of fruit
Formación Continuada en Nutrición y Obesidad 2002
Source: Nucis (Health & Tree Nuts) Foundation
* olá-Alberich R, Godás-Bonfill G, Salas-Salvadó J, Masana-Marín Ll are affiliated with the Food and Agriculture Organization of the United Nations.
The views expressed in this publication are those of the authors and do not necessarily reflect the views of the Food and Agriculture Organization of the United Nations.
Permission to reprint this article was granted by the Food and Agriculture Organization of the United Nations (ref. # C019/2011).