A little bit of AI correction here:
Your argument is largely correct from an economic perspective: a surprisingly cheap diet can provide most of the calories and macronutrients necessary for human survival and basic functioning.
However, there are a few nutritional distinctions worth making.
1. Your five basic foods
Food Main nutritional contribution
Milk Protein, fat, calcium, B12, riboflavin
Peanuts Protein, fat, vitamin E, magnesium, niacin
Eggs Protein, fat, vitamins A, D, B12, choline
Sugar Cheap carbohydrates and calories
Vegetable oil Extremely cheap calories, essential fatty acids (depending on oil)
Together, these provide:
- Carbohydrates
- Protein
- Dietary fats
- Essential fatty acids
- Several important vitamins and minerals
- A substantial amount of daily energy at relatively low cost.
2. What is missing?
There are some nutritional gaps beyond vitamin C and K.
Nutrient Potential problem Cheap solution
Vitamin C Very little Lemon, cabbage, peppers
Vitamin K LowSpinach, cabbage, wild greens
Fiber Very little Beans, cabbage, wild plants
Potassium Potentially insufficient Potatoes, beans, vegetables
Iodine Depends on milk and other foodsIodized salt
Omega-3 Potentially insufficient Flaxseed, walnuts, certain oils
One important distinction: vegetable oils aren't interchangeable. For example, sunflower oil provides vitamin E but relatively little omega-3.
3. Foraging could reduce costs further
Common Nettle - The Foraging Foodie
Dandelion. Freshly picked dandelion leaves in plate.
Foraging in March: spring's edible plants - Woodland Trust
4
Depending on the area, some inexpensive or freely available nutritional sources include:
- Nettle: vitamin C, vitamin K, minerals.
- Dandelion leaves: vitamins A, C and K.
- Chickweed: vitamin C and other micronutrients.
- Wild garlic: vitamins and minerals.
Naturally, correct identification is essential. Some poisonous plants resemble edible ones.
4. The bigger economic argument
Your idea illustrates an important distinction:
The cost of obtaining sufficient calories and essential nutrients is not necessarily the same as the cost of eating a varied, convenient and enjoyable diet.
A person doesn't necessarily need expensive meat, processed foods, supplements or elaborate meals to meet basic nutritional requirements.
There are two things I would change in your proposed diet:
- Include some cheap vegetables or legumes regularly rather than relying on occasional vitamin supplementation through foraging.
- Don't let sugar and oil dominate calorie intake. They are cheap energy sources, but provide very little nutritional value per calorie.
Overall, your five-food foundation is economically interesting, but adding a few inexpensive foods such as cabbage, beans and potatoes would make it considerably more nutritionally complete.