Pineapple

Pineapple (Ananas comosus)

The pineapple (in Hebrew “אננס”) is one of the few fruits that contain an active protein-digesting enzyme — bromelain — and quite a few health claims have been built around it. Some are well founded, most are exaggerated. That said, pineapple is good even without the story: 100 grams provides more than half the daily value of vitamin C and about 40% of manganese, for just 50 calories.

This page also has a practical fact that saves money: pineapple does not ripen after picking. It is not a climacteric fruit, meaning it does not convert starch to sugar after it has been picked. A pineapple picked green will stay sour forever — it will only get softer.

Nutrition facts per 100 grams (fresh)

For comparison: the same 100 grams of pineapple provides almost the same amount of vitamin C as an orange (53 mg), and twice as much manganese. Manganese is needed for antioxidant enzymes (mitochondrial SOD), for carbohydrate metabolism and for building connective tissue and bone.

Bromelain — what it really does

Bromelain is not a single enzyme but a mixture of protein-digesting enzymes (proteases). It is concentrated mainly in the stem and core of the fruit, less in the flesh we eat. Commercial bromelain supplements are almost always extracted from the stem.

What is well founded:

• It really does break down protein. That’s why it is used to tenderize meat, and why jelly (gelatin) won’t set with fresh pineapple — the bromelain breaks down the gelatin.
• It is deactivated by heat. Canned pineapple is pasteurized, so its bromelain is no longer active. That’s why canned pineapple does work in jelly.
• The burning on the tongue is caused by bromelain starting to break down proteins in the lining of the mouth. It goes away on its own, and the lining regenerates.
• At supplement doses (hundreds of mg a day, concentrated from the stem) there is reasonable evidence of benefit for swelling after surgery and for sinusitis.

What is not well founded:

• The bromelain in a slice of pineapple won’t “digest your meal for you.” The amount in the flesh is small, and a considerable part of it is neutralized by stomach acid. Eating pineapple is not equivalent to taking a bromelain supplement.
• “Pineapple burns fat” — there is no basis for this. Bromelain breaks down protein, not fat.

Benefits

• Vitamin C for 50 calories: 53% of the daily value per 100 grams — supporting collagen production, immune function and absorption of plant iron.
• Manganese: 40% of the daily value — one of the best sources of it in the fruit world.
• High water content and low calorie load: 86% water, a fruit that is filling relative to its calories.
• Polyphenols and phenolic acids that contribute to its antioxidant capacity.
• Medium glycemic index with low load: despite its sweetness, a normal serving of pineapple (100-150 grams) does not create a high glycemic load.
• Bromelain at supplement doses — reasonable evidence for swelling and for upper respiratory inflammation, in the context of a supplement and not of the fruit.

Downsides and considerations

• Relatively high sugar, relatively low fiber. 9.9 grams of sugar versus only 1.4 grams of fiber — a less favorable ratio than that of a pear or an apple. Anyone monitoring sugar should measure their portion.
• Burning and sores in the mouth. Bromelain irritates the lining of the mouth, especially in unripe fruit or when eating a large amount. It goes away on its own.
• Skin irritation when handling fresh fruit. Peeling large quantities can irritate the skin by the same mechanism.
• Canned pineapple in syrup. “Heavy syrup” versions add 10-15 grams of sugar per 100 grams. In light syrup or “natural juice” it’s better, but still not like fresh, and without active bromelain.
• Interaction with anticoagulants. Bromelain has a mild effect on platelet aggregation. At food amounts this is not practical, but people taking Coumadin or aspirin who also take a bromelain supplement should consult a doctor.
• Acidity. pH around 3.3 — may worsen heartburn in sensitive people and erode enamel with very frequent consumption.
• The core is hard but edible. It is richer in fiber and bromelain than the flesh; anyone willing to chew it benefits.

Practical use

• Buy a ripe pineapple, don’t expect it to ripen. Because pineapple is not climacteric, it won’t get sweeter at home. Signs of a good fruit: a sweet smell at the base, a yellow-golden rather than entirely green skin, and a heavy weight for its size. A central leaf that pulls out easily is not a reliable sign.
• Short marinades only. Fresh pineapple tenderizes meat — but soaking it too long will turn it to mush. 20-30 minutes is enough.
• Jelly: use canned (pasteurized) pineapple or boil the fresh fruit for a minute — otherwise the dessert won’t set.
• Eat it with a plant source of iron — lentils, tofu or spinach — the vitamin C significantly improves iron absorption.
• A reasonable serving: 100-150 grams. One thick slice, not a quarter of the fruit.
• Keep it cut in the refrigerator for up to 3 days in an airtight container. Commercial pineapple juice is another story — sugar without fiber, and without active bromelain.

Summary

Pineapple is an excellent source of vitamin C and manganese at 50 calories per 100 grams, and that alone justifies it. Bromelain is an interesting story but overhyped: it really does break down protein — enough to tenderize meat, ruin jelly and burn your tongue — but eating a slice of pineapple is not the same as taking a supplement. And the most practical thing to remember: pineapple doesn’t ripen at home. What you buy is what you get.