Healthcare is an evergreen industry, meaning people will always need it, and the companies selling healthcare products and services will probably always have an opportunity. For some of the top healthcare companies, that shows in their decades of growth and shareholder returns.

For example, consider Dividend Kings. These companies are S&P 500 members that have paid and raised a dividend for at least 50 consecutive years. The two healthcare companies below are not only Dividend Kings with proven track records, but their strong fundamentals make them stocks that long-term investors can rely on moving forward.

1. Johnson & Johnson

You'll find healthcare conglomerate Johnson & Johnson (JNJ -0.21%) all over the industry; it sells consumer health products, prescription drugs, and medical devices worldwide. Collectively, Johnson & Johnson is doing more than $96 billion in annual sales, generating almost $18 billion in free cash flow.

You can see below how smooth Johnson & Johnson's growth has been. People need healthcare regardless of recessions and other major market events. The company's smooth growth and strong cash generation have fueled its 60 years of dividend growth.

Some companies struggle with dividend discipline, letting the payout ratio climb to keep the dividend streak intact. However, Johnson & Johnson has kept its dividend payout ratio manageable at 65% today. That gives the company plenty of breathing room if business slips or it wants to spend its profits elsewhere -- Johnson & Johnson is acquiring Abiomed for $16.6 billion to bolster the cardiovascular business in its MedTech segment.

Imagine, hypothetically, that Johnson & Johnson's business hits a rough patch, and it cannot afford to pay its dividend with cash flow. The company is known for its fortress-like balance sheet, which can act as a financial safety net. You never want to look at a stock as a buy-and-forget investment, but Johnson & Johnson comes about as close as you can. Long-term investors can slowly buy shares and sleep well at night as the company continues its steady growth year after year.

A bonus for investors: Johnson & Johnson is getting ready to spin off its consumer products business as its own company. Sometimes conglomerates are valued by the market at a lower valuation, so the consumer products segment might trade higher by itself. This is a potential perk for shareholders who own Johnson & Johnson before the spin-off in November of next year.

2. Becton, Dickinson & Company

Millions of people receive care daily, and Becton, Dickinson & Company (BDX 0.42%) has played a significant role in that for decades. The company sells medical supplies, devices, diagnostic tools, and lab equipment to healthcare professionals worldwide. Most injections, surgeries, or other procedures probably use a product that Becton Dickinson sells.

The company is approaching $20 billion in annual revenue. Again, you can see how growth has generally proceeded without much volatility. Healthcare can be competitive, but the demand for products is always there. A top dog like Becton, Dickinson, with a firm hold on its customers, will keep making sales. The company converts just over 8% of its revenue into free cash flow, which helps fuel its long-standing dividend growth.

Maintaining a manageable dividend payout ratio is a big part of keeping a dividend growth streak alive. Like Johnson & Johnson, Becton, Dickinson also spends approximately 65% of its cash profits on the dividend. Investors should root for a modest payout ratio so the company can do things like Becton, Dickinson's purchase of C.R. Bard for $24 billion in 2017. A company that spends all its profits on dividends must maintain organic growth, or the dividend will eventually fall under pressure.

Becton, Dickinson's balance sheet is the main knock on the stock; the company is still financially digesting that blockbuster deal from five years ago. The company has paid down a chunk of its debt, but it still stands at $16 billion. That give it a debt-to-EBITDA leverage ratio of 3.7, which is a little higher than I would like to see. However, I wouldn't let that keep you from owning shares; the low payout ratio should ensure the dividend is safe, and management should continue paying down debt over time.

Analysts believe Becton, Dickinson will grow earnings per share by 7% annually over the next three to five years, so growth doesn't look like a problem anytime soon. It won't knock your socks off, but Becton, Dickinson should be a fine defensive stock for investors looking for more stability than upside.