Consumer

Carbohydrate reduction and longevity, Harvard study

September 6, 2018

The University of

Harvard

considers the health risks associated with excessive deprivation or abuse of

carbohydrates

. And the benefits, at the same time, of a balanced diet where carbohydrates leave more room for

proteins and vegetable fats

.

Carbohydrates, imbalances in deficiency and excess

A

diet

extremely poor

of carbohydrates, in favor of protein and animal fat, could reduce life expectancy by up to 4 years. Likewise that which, on the other hand, exceeds in carbohydrate intake. This is the finding of a Harvard observational study, recently published in The Lancet. (1)

‘These results bring together several strands that have been controversial: too many and too few carbohydrates can be harmful, but what matters most is the type of fat, protein, and carbohydrates, as well as the total amount‘, said Walter Willett, professor of Epidemiology and Nutrition at Harvard T.H. Chan School of Public Health and co-author of the study.

The research

considered more than 15,400 consumers in the U.S. who provided information on their eating habits as part of the Atherosclerosis Risk Potential in Communities (ARIC) study between 1987 and 1989.

The subjects examined completed a questionnaire about their diet–types of foods and beverages, amount and frequency of consumption–at the beginning of the study and 6 years later. On that basis, the researchers estimated energy intakes and the shares that come from carbohydrates, fat and protein. The

follow-up

average was 25 years, a period during which 6,283 participants were missed.

As an outcome of the study

it was found that an unbalanced diet deficient in, or conversely excessive in, carbohydrates (less than 40 percent or more than 70 percent of total daily energy intake) is strongly correlated with an increased risk of premature mortality.

The results, moreover, vary Because of the source of the macronutrients. Premature mortality increased when carbohydrates were replaced with animal-derived fat or protein. And it conversely decreased when substitutions took place with plant-based proteins and fats.

Moderate consumption of carbohydrates

, equal to 50-55% of daily energy intake, was in all cases found to be associated with a lower risk of premature mortality.

Diets

low-carb

, protein and vegetable fats

The researchers estimated that, starting at age 50, people on a diet with moderate carbohydrate consumption have an additional life expectancy of 33 years. Four years more than those on extremely low-carbohydrate diets, 2.3 years more than those on low-carbohydrate diets, and 1.1 years more than the high-carbohydrate group.

The diets

low carb

have gained great popularity, in the US as well as in Europe, because they allow rapid weight loss in a short time. Randomized trials on low-carbohydrate diets actually confirm these findings, as does the

reduction of cardiovascular risk

.

The authors of the study However, they urge not to underestimate the mortality risks associated with the continuation of such diets over the long term. Risks that stand out in individuals who replace carbohydrate sources with foods high in fat and animal protein (e.g., lamb, beef, pork, and chicken).

Carbohydrate substitution With protein and vegetable fats (e.g. walnuts, dried fruit e peanuts, vegetables e whole grains), on the contrary, does not appear to have a negative impact on life expectancy. Within the general parameters of an overall varied and balanced diet.

In conclusion

, according to the researchers, a balanced diet where the carbohydrate content is reduced in favor of protein and vegetable fats appears to be able to promote an appreciable long-term quality of life.

Dario Dongo and Carlotta Suardi

Notes

(1) The Lancet. ‘

Dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis

‘. Sara B Seidelmann, Brian Claggett, Susan Cheng, Mir Henglin, Amil Shah, Lyn M Steffen, Aaron R Folsom, Eric BRimm, Walter C Willett, Scott D Solomon. Doi: 10.1016/S2468-2667(18)30135-X