Eating "nuts" on a daily basis could prove beneficial for your health -
© M. Grabkowska / Unsplash
A cluster of clues suggests that nuts could help us “age well” by protecting us from various chronic pathologies, according to our partner The Conversation.
Despite their high calorie and fat content, their daily consumption seems to reduce the level of "bad cholesterol" and protect against cardiovascular disease ... without having any effect on weight!
The analysis of this phenomenon was carried out by Boris Hansel (doctor, university professor and hospital practitioner), Diana Kadouch (hospital practitioner in diabetology-nutrition) and Jérémy Puyraimond-Zemmour (assistant specialist in diabetology-nutrition).
They are called oleaginous fruits: notwithstanding their high fat content, because of their many health benefits, almonds, hazelnuts and other nuts are now among the foods whose consumption is encouraged, in Canada as in the United States. , in Europe, or in France - at the rate of a small handful each day.
From a nutritional point of view, these nuts are characterized in particular by high levels (50 to 75%) of unsaturated fatty acids (which have the reputation of being "good fats"), not insignificant contents of. proteins (10 to 25%), or the presence of minerals (copper, magnesium, potassium), vitamins (B3, B9, B6, E), dietary fibers, antioxidants and plant sterols.
A bundle of clues suggests that they could help us age well, by protecting us from various chronic pathologies.
A reduced level of "bad" cholesterol
If there is one area in which oilseeds have proven themselves, it is cholesterol control.
Reducing animal fat intake or consuming soluble fiber have certainly proven their benefit in reducing LDL-cholesterol (LDL-C) levels, that is to say “bad cholesterol”. .
But many studies have also highlighted the favorable impact of a daily handful of almonds.
This appears to be true for all oleaginous fruits.
Thus, in 2010, the study of data collected during 25 clinical trials, carried out on men and women suffering from hypercholesterolemia, showed that by consuming 67 grams of fruit every day for three to eight weeks. hull, we could reduce his LDL-C level by 7.4% - with effects all the more important as this level is high at the start.
Another systematic review of the scientific data confirmed these results, albeit in smaller proportions.
Conducted in 2018, it analyzed the results of 26 clinical trials: this time its authors note a 3.7% reduction in LDL-C levels following a diet enriched with oleaginous fruits (from 15 to 108 g / day) carried out for one to twelve months.
However, we know that a drop in the LDL-C level is associated with a lower risk of total and cardiovascular mortality, especially if said level is initially high.
While no clinical study has yet shown that the consumption of nuts can reduce the risk of cardiovascular accidents, there is no lack of arguments to support such a hypothesis.
Lower risk of cardiovascular disease
We can first cite the results of a meta-analysis published in 2019. Based on the Cochrane inclusion criteria, its authors selected 19 studies and found that an intake of 28 g / day d Oilseeds are associated with a 13% reduction in cardiovascular risk and a 29% decrease in cardiovascular disease mortality.
We can also mention a large multicenter, randomized and controlled study on the interest of a Mediterranean diet enriched in oilseeds in the prevention of cardiovascular risk.
Its participants, aged 55 to 80 years and presenting a significant cardiovascular risk, were followed, on average for almost 5 years, by being assigned to three types of diets: a low-fat diet, a Mediterranean diet enriched in oil. olive, and another supplemented with nuts.
Ultimately, cardiovascular events were found to be less frequent in the two groups who followed a Mediterranean diet.
The Mediterranean diet would protect against cardiovascular diseases © LC-click / Pixabay
Fat that doesn't make you gain weight
On the energy side, 30 g of almonds, peanuts, pistachios or cashews provide 180 kcal, and we need 220 to 230 kcal with walnuts, pecans, Brazil nuts.
This is roughly the equivalent of 30 to 40g of milk chocolate.
However, calories being essentially the result of fats, one may be led to believe that one should be wary of oilseeds if one wants to monitor one's weight.
Wrongly…
Indeed, a recent study sifted through six prospective cohort studies and 62 randomized feeding trials.
However, according to its conclusions, the regular consumption of nuts for a shorter or longer period of time (between 3 and 336 weeks) is on average accompanied by a very slight loss of weight (200 g on average), and a waist size which tends to decrease (approximately - 0.5 cm).
If the reasons for these counter-intuitive observations are not fully explained, several hypotheses are proposed.
On the one hand, the matrix which includes the fats of the nuts partially limits their absorption in the intestine: in short, part of the fat is eliminated in the stool rather than being assimilated.
On the other hand, thanks to their effect on satiety, almonds and other nuts reduce food intake during meals, so that the total calorie intake is not increased, and may even decrease.
Do nuts have anticancer properties?
Other benefits are attributed to oilseeds.
Particularly with regard to cancer prevention, although the level of evidence is low - the studies concerned are based on observations and have different interpretative biases.
Thus, according to the analysis of some 33 studies published before June 2019, a high consumption of nuts is significantly associated with a decrease in the risk of cancer by 10%.
And this protective effect would be more marked for digestive cancers, with a decrease in risk of 17%.
The high levels of antioxidants in tree nuts could be involved.
But before digging into this hypothesis, it would still be necessary to confirm these observational data by real controlled and randomized clinical trials: for the moment, there is nothing to confirm that eating nuts protects us from cancer.
Fewer neurodegenerative diseases?
Fat is essential for the brain.
After adipose tissue, it is in fact the organ of the body the richest in lipids - which are found in the membranes of neurons and their supporting cells, but also in the myelin through which the nerve impulse is propagated. quickly.
Also, several scientific teams have sought to evaluate the benefits of nuts for the central nervous system.
What do they teach us?
We discover in particular that after 8 weeks of a diet more or less enriched in nuts, the psychomotor performances of 19-month-old rats are modified: a diet of 2% nuts improves walking on rod, to 6% walking on board, and at these two rates the working memory is better.
These results were confirmed over a shorter period (28 days), with a significant improvement in rodent learning and memory.
As for humans, the PREDIMED dietary intervention trial showed that a Mediterranean diet enriched with nuts improves working memory.
It has also been shown, biologically, a reduced risk of low plasma levels of BDNF - a protein that encourages the growth and differentiation of new neurons.
Nuts therefore appear to be able to prove beneficial in preventing age-related cognitive decline.
But there is a lack of direct evidence to say that eating regularly reduces the risk of neurodegenerative diseases.
Our "Regime" file
At first glance, nuts present all the attributes that allow us to consider them as allies of our health.
If they are high in calories and fat, 30 g per day indeed seem to reduce the level of "bad cholesterol" and protect us from cardiovascular disease, without having any effect on weight.
There is no lack of arguments that suggest a positive impact both on other pathologies and on age-related cognitive decline.
Good reasons to recommend that everyone include in their diet a daily handful of almonds, hazelnuts or other nuts every day - obviously without added sugar or salt!
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This analysis was written by Boris Hansel - doctor, university professor, hospital practitioner (Inserm U1148, Faculty of Health, University of Paris) -, Diana Kadouch - hospital practitioner (Bichat Hospital, Diabetology-Nutrition Department, AP-HP) , lecturer in the DU of nutrition (University of Paris) - and Jérémy Puyraimond-Zemmour - specialist assistant (Department of Diabetology-Nutrition, Bichat Hospital, AP-HP), lecturer in the DU of nutrition (University from Paris).
The original article was published on The Conversation website.
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