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A Healthy Balance of Macronutrients

This article provides insights into the benefits of specific types of macronutrients relative to those that may have less beneficial or even harmful effects on health.
© University of Hohenheim / IMDEA

To identify healthy types of macronutrients, it is first of all important to ask “healthy” in comparison to what?

Healthy Macronutrients

This article provides insights into the benefits of specific types of macronutrients relative to those that may have less beneficial or even harmful effects on health.

Healthy Fats

Fats can be classified in terms of saturated, monounsaturated (MUFA), and polyunsaturated fatty acids (PUFA). Evidence suggests that saturated fat intake is too high in the standard Western diet and should be limited to < 7% energy uptake. MUFA are non-essential and can be synthesized by the liver. PUFA include essential fatty acids and are required in the diet. Not all fats should be avoided and the type or source of fat is really important since healthy fats can even prevent disease.

Increased saturated fat intake (from animal sources and some tropical oils) and especially industrial trans unsaturated fatty acids (from partially hydrogenated plant or fish oils, should be less than 1% of the daily energy intake) increase low density lipoprotein cholesterol (LDL) levels, an important biomarker of cardiovascular disease (CVD) risk.

In contrast, elevated PUFA intake (omega-3 and omega-6) can reduce total cholesterol, LDL and triglycerides thereby increasing high density lipoprotein cholesterol (HDL).

Monounsaturated fat, which seems to be also advantageous in comparison to saturated fat, also influences blood cholesterol levels and shows positive effects on the gut microbiota with the related health benefits.

Replacing saturated fats by other dietary fats (especially PUFA) or carbohydrates from whole grains and reducing dietary cholesterol has been found to have the most favourable effects on the blood lipid profile. Replacing saturated fat with refined carbohydrates does not reduce the risk of CVD.

In sum, the quality of dietary fat is important, whereas saturated fat intake should be limited and trans fats should be avoided wherever possible, there is clear evidence that MUFA and especially PUFA (with sufficient omega-3) intake is beneficial.

Healthy Carbohydrates

Foods that contain carbohydrates consists of sugars, starches, and naturally occurring dietary fibre (indigestible carbohydrates). The intake of refined carbohydrates from processed foods should not exceed 10% of the total energy intake given the disease promoting mal-nourishing profile of simple sugars. It is highly recommended to replace refined grains by whole grains and to increase the amount of dietary fibre to at least 25-29 g per day (although higher quantities have even shown additional benefits).

Dietary fibre increases satiety, modulates the metabolism of carbohydrates and lipids, is essential for a healthy microbiome by promoting microbial diversity, and helps to maintain brain health. Dietary fibres are often polymers of carbohydrates and especially many of the soluble forms can be fermented by gastrointestinal bacteria into short chain fatty acids (protective against e.g. Alzheimer’s disease). Higher intakes of fibre also predict a decreased incidence and mortality from various diseases.

Strong evidence suggests that dietary fibre intake is dose-dependently associated with a reduction in overall mortality and more specific with decreased bodyweight, systolic blood pressure, blood cholesterol levels, total CVD deaths, mortality due to respiratory diseases and diabetes, incidence of breast, colorectal, and oesophageal cancer. Implementing a predominantly whole foods plant-based diet (naturally rich in fibre) instead of a heavily animal-based diet (lacking in fibre) and reducing the consumption of free sugars (mostly found in highly processed food) is recommended. In conclusion, unrefined carbohydrates that come with sufficient fibre are strongly recommended in a balanced diet.

Healthy Proteins

Recommendations of the dietary protein intake requirements are discussed and depend on factors such as age, physical activity, and source or bioavailability of protein (e.g. plant versus animal protein).

Complete proteins (meat, eggs, dairy products) contain all proteinogenic amino acids and seem to be beneficial for babies, children, burn victims, and elderly people whereas incomplete or less complete proteins (often from plant sources) sometimes lack some proteinogenic amino acids (or contain only small amounts of certain amino acids) but may have less adverse effects in adults. However, a widely varied diet of plant-sourced foods should provide all necessary amino acids.

Low protein intake (0.7 to 0.8 g of proteins/kg of body weight/day) is usually not disadvantageous for adults below an age of 65 although a higher protein intake can bring advantages to the physically active and the older population. However, there is evidence that excessive protein intake is linked to damage of the renal function.

Diets high in animal proteins can be also linked to increased IGF-1 expression (IGF-1 (Insulin-like growth factor-1) is structurally and functionally related to insulin but has a much higher growth-promoting activity) and the production of inflammatory microbes that can be associated with damaged gut microbiota, increased intestinal permeability, inflammation, and even some types of cancer.

Excess animal proteins intake may be also connected to a heightened risk for Alzheimer’s disease, stroke, heart attack, and diabetes. In contrast, plant-based protein seems to be better tolerated by adults.

Accordingly, substitution of animal-based protein with plant-based protein can have protective effects (e.g. improved glycaemic control) despite a lower absorption relative to animal-based protein sources.

Taken together, an adequate protein intake with a high share from plant sources is appropriate to support healthy bodily functioning.

Author: Dr. Markus Burkard

© University of Hohenheim / IMDEA
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