Potato is the backbone of agriculture and diets in high-altitude food systems of Peru, where farmers grow diverse varietal portfolios. Here we report on the role of diverse landraces and modern potato varieties in the Andean diet. The dry matter, energy, protein, iron and zinc content of 12 floury and 9 bitter landraces was determined. The contribution of varietal diversity to the dietary intake of energy, protein, iron and zinc was established during two contrasting periods of overall food availability. Results show that the potato and intraspecific diversity make an important contribution to nutrition. Most floury landraces contain higher concentrations of protein and iron compared to the reference value reported in the 2009 Peruvian food composition table for a boiled and peeled floury landrace. Traditional freeze-drying of bitter landraces doesn’t affect energy or iron concentrations, but reduces protein and zinc content considerably. Protein and iron contents in boiled chuño derived from the bitter landraces are lower compared to the mean value reported in the food composition table. The contribution of varietal diversity ideally needs to be taken into account when conducting nutrition studies in diversity hotspots like the Andes where potato is a main staple. The potato adds positively to the nutritional balance and the recommended requirements for energy, protein, iron and zinc of women and children. Floury landraces and modern varieties complement each other in light of seasonality, providing valuable nutrients during contrasting periods of the year. The potato thus contributes positively to food security. However, the overall diversity of the diet was found to be poor, resulting in micronutrient deficiencies. Options to strengthen food based approaches to attend undernutrition are discussed.