It is never too late to invest in mutual funds for retirement. As such, if you plan to invest in some of the best funds, the Zacks Mutual Fund Rank can provide you with valuable guidance.

How can you tell a good mutual fund from a bad one? It's pretty basic: if the fund is diversified, has low fees, and shows strong performance, it's a keeper. Of course, there's a wide range, but using the Zacks Mutual Fund Rank, we've found three mutual funds that would be great additions to any long-term investors' portfolios.

Here are the funds that have achieved the Zacks Mutual Fund Rank #1 (Strong Buy) and have low fees.

Brandes International Equity Fund I (BIIEX): 0.85% expense ratio and 0.75% management fee. BIIEX is a Non US - Equity option, focusing their investments acoss emerging and developed markets, and can often extend across cap levels too. With annual returns of 19.63% over the last five years, this fund is a winner.

Vanguard Energy Investor (VGENX): 0.45% expense ratio and 0.43% management fee. VGENX is a Sector - Energy fund, which are comprised of various changing and hugely important industries throughout the massive global energy sector. With yearly returns of 21.98% over the last five years, VGENX is an effectively diversified fund with a long reputation of solidly positive performance.

American Funds Growth Fund of America A (AGTHX Quick QuoteAGTHX - Free Report) is an attractive large-cap allocation. AGTHX is a Large Cap Growth option; these mutual funds purchase stakes in numerous large U.S. companies that are expected to develop and grow at a faster rate than other large-cap stocks. AGTHX has an expense ratio of 0.6%, management fee of 0.25%, and annual returns of 15.94% over the past five years.

There you have it. If your financial advisor had you put your money into any of our top-ranked funds, then they've got you covered. If not, you may need to talk.